Simple model of cable-stayed bridge deck subjected to static wind loading

Science.gov (United States)

Kang, Yi-Lung; Wang, Yang Cheng

1997-05-01

Cable-stayed bridges have been known since 18th century with aesthetics design. The structural system and the structural behavior are significantly different from those of continuous bridges. Compared to continuous bridge, cable- stayed bridges have more flexure bridge deck than those of continuous bridges.On the other hand, cable-stayed bridges have less stiffness to resist wind loading especially for lateral loads. The first considering of bridge engineering is safety. In 1940's, Tacoma Narrows Suspension Bridge destroyed by wind loading is a good example even though it is not a cable-stayed bridge. After the bridge was destroyed, a lot of research articles have been published regarding cable supported bridge subjected to wind loading. In recent days, high strength materials have been served. The bridge engineers use the advantages to expand the span length of cable-stayed bridges. Due to the span length increased and the use of high strength materials, cable- stayed bridges have more significant nonlinear behavior subjected to wind loading. In this paper, a slice bridge deck of cable-stayed bridge connected to internal support cables is considered. The deck has been considered to be subjected to lateral static wind loading. Since cables can not take compressive force, the deck has strongly nonlinear behavior even though the materials are linear elastic. Several primary load combinations have ben considered in this paper such as the bridge deck supposed to be moved horizontally without rotation or the bridge deck supposed to be moved horizontally with rotational deformation. The mathematical formulas and the numerical solutions are found and represented in graphical forms. The results can be provided to bridge designers and researchers for further study of this type of structure subjected to wind loading.

PARAMETRIC STUDY OF SKEW ANGLE ON BOX GIRDER BRIDGE DECK

OpenAIRE

Shrikant D. Bobade *, Dr. Valsson Varghese

2016-01-01

Box girder bridge deck, is the most common type of bridges in world and India, it consists of several Slab or girders. The span in the direction of the roadway and connected across their tops and bottoms by a thin continuous structural stab, the longitudinal box girders can be made of steel or concrete. The Simple supported single span concrete bridge deck is presented in present study. Skewed bridges are suitable in highway design when the geometry of straight bridges is not possible. The sk...

Field performance of timber bridges. 7, Connell Lake stress-laminated deck bridge

Science.gov (United States)

L. E. Hislop; M. A. Ritter

The Connell Lake bridge was constructed in early 1991 on the Tongass National Forest, Alaska, as a demonstration bridge under the Timber Bridge Initiative. The bridge is a stress-laminated deck structure with an approximate 36-ft length and 18-ft width and is the first known stress-laminated timber bridge constructed in Alaska. Performance of the bridge was monitored...

Analysis, prediction, and case studies of early-age cracking in bridge decks

Science.gov (United States)

ElSafty, Adel; Graeff, Matthew K.; El-Gharib, Georges; Abdel-Mohti, Ahmed; Mike Jackson, N.

2016-06-01

Early-age cracking can adversely affect strength, serviceability, and durability of concrete bridge decks. Early age is defined as the period after final setting, during which concrete properties change rapidly. Many factors can cause early-age bridge deck cracking including temperature change, hydration, plastic shrinkage, autogenous shrinkage, and drying shrinkage. The cracking may also increase the effect of freeze and thaw cycles and may lead to corrosion of reinforcement. This research paper presents an analysis of causes and factors affecting early-age cracking. It also provides a tool developed to predict the likelihood and initiation of early-age cracking of concrete bridge decks. Understanding the concrete properties is essential so that the developed tool can accurately model the mechanisms contributing to the cracking of concrete bridge decks. The user interface of the implemented computer Excel program enables the user to input the properties of the concrete being monitored. The research study and the developed spreadsheet were used to comprehensively investigate the issue of concrete deck cracking. The spreadsheet is designed to be a user-friendly calculation tool for concrete mixture proportioning, temperature prediction, thermal analysis, and tensile cracking prediction. The study also provides review and makes recommendations on the deck cracking based mainly on the Florida Department of Transportation specifications and Structures Design Guidelines, and Bridge Design Manuals of other states. The results were also compared with that of other commercially available software programs that predict early-age cracking in concrete slabs, concrete pavement, and reinforced concrete bridge decks. The outcome of this study can identify a set of recommendations to limit the deck cracking problem and maintain a longer service life of bridges.

Analysis of Biaxially Stressed Bridge Deck Plates

DEFF Research Database (Denmark)

Jönsson, Jeppe; Bondum, Tommi Højer

2012-01-01

The ultimate state analysis of bridge deck plates at the intersection zone between main girders and transverse beams is complicated by biaxial membrane stresses, which may be in compression or tension in either direction depending on the bridge configuration and the specific location. This paper...

Field performance of timber bridges. 6, Hoffman Run stress-laminated deck bridge

Science.gov (United States)

M. A. Ritter; P. D. Hilbrich Lee; G. J. Porter

The Hoffman Run bridge, located just outside Dahoga, Pennsylvania, was constructed in October 1990. The bridge is a simple-span, single-lane, stress-laminated deck superstructure that is approximately 26 ft long and 16 ft wide. It is the second stress-laminated timber bridge to be constructed of hardwood lumber in Pennsylvania. The performance of the bridge was...

Field performance of timber bridges. 17, Ciphers stress-laminated deck bridge

Science.gov (United States)

James P. Wacker; James A. Kainz; Michael A. Ritter

In September 1989, the Ciphers bridge was constructed within the Beltrami Island State Forest in Roseau County, Minnesota. The bridge superstructure is a two-span continuous stress-laminated deck that is approximately 12.19 m long, 5.49 m wide, and 305 mm deep (40 ft long, 18 ft wide, and 12 in. deep). The bridge is one of the first to utilize red pine sawn lumber for...

Field performance of timber bridges. 10, Sanborn Brook stress-laminated deck bridge

Science.gov (United States)

P. D. Hilbrich Lee; J. P. Wacker; M. A. Ritter

The Sanborn Brook bridge was constructed in August 1991, 10 miles northeast of Concord, New Hampshire, as part of the demonstration timber bridge program of the USDA Forest Service. The bridge is a simple-span, double-lane, stress-laminated deck superstructure constructed from Southern Pine lumber and is approximately 25 ft long and 28 ft wide with a skew of 14 degrees...

Issues in bridge deck damage evaluation using aerial photos

Science.gov (United States)

Natarajan, M.; Chen, S. E.; Boyle, C.; Martin, E.; Hauser, E.

2012-04-01

Small format aerial photography (SFAP) with low flying technique is proposed for damage evaluation of bridge decks. High resolution images obtained using under-belly photography can be used to quantify the various bridge deck problems. The conventional truck-mount or vehicle-mount deck imaging technologies require a large number of image samples. Hence the physical scanning is time consuming and it is also challenging consider the size and location of a bridge. Aerial imaging overcomes these issues, but they face different kinds of challenges that are posed by obstacles such as shadow from trees, power lines and vehicles, signs and luminaries structures. The image resolution uncertainty, which is a function of the pilot skills and flying conditions, may also add additional challenges to aerial imaging technique. Hence different image processing tools have to be integrated into a single package to achieve the desired task. This paper summarizes the challenges faced and the preliminary results are presented and discussed.

Field performance of timber bridges. 5, Little Salmon Creek stress-laminated deck bridge

Science.gov (United States)

M. A. Ritter; J. A. Kainz; G. J. Porter

The Little Salmon Creek bridge was constructed in November 1988 on the Allegheny National Forest in Pennsylvania. The bridge is a simple span, single-lane, stress-laminated deck superstructure that is approximately 26-ft long and 16-ft wide. The bridge is unique in that it is the first known stress-laminated timber bridge to be constructed of hardwood lumber. The...

Field performance of timber bridges. 9, Big Erick`s stress-laminated deck bridge

Science.gov (United States)

J. A. Kainz; J. P. Wacker; M. Nelson

The Big Erickas bridge was constructed during September 1992 in Baraga County, Michigan. The bridge is 72 ft long, 16 ft wide, and consists of three simple spans: two stress-laminated deck approach spans and a stress-laminated box center span. The bridge is unique in that it is one of the first known stress-laminated timber bridge applications to use Eastern Hemlock...

Vertical impedance measurements on concrete bridge decks for assessing susceptibility of reinforcing steel to corrosion

Science.gov (United States)

Bartholomew, Paul D.; Guthrie, W. Spencer; Mazzeo, Brian A.

2012-08-01

Corrosion is a pressing problem for aging concrete infrastructure, especially bridge decks. Because of its sensitivity to factors that affect corrosion of reinforcing steel in concrete, resistivity is an important structural health indicator for reinforced concrete structures. In this research, an instrument was developed to measure vertical impedance on concrete bridge decks. Measurements of vertical impedance on slabs prepared in the laboratory, on slabs removed from decommissioned bridge decks, and on an in-service bridge deck in the field demonstrate the utility of the new apparatus.

Quantifying reinforced concrete bridge deck deterioration using ground penetrating radar

Science.gov (United States)

Martino, Nicole Marie

Bridge decks are deteriorating at an alarming rate due to corrosion of the reinforcing steel, requiring billions of dollars to repair and replace them. Furthermore, the techniques used to assess the decks don't provide enough quantitative information. In recent years, ground penetrating radar (GPR) has been used to quantify deterioration by comparing the rebar reflection amplitudes to technologies serving as ground truth, because there is not an available amplitude threshold to distinguish healthy from corroded areas using only GPR. The goal of this research is to understand the relationship between GPR and deck deterioration, and develop a model to determine deterioration quantities with GPR alone. The beginning of this research determines that not only is the relationship between GPR and rebar corrosion stronger than the relationship between GPR and delaminations, but that the two are exceptionally correlated (90.2% and 86.6%). Next, multiple bridge decks were assessed with GPR and half-cell potential (HCP). Statistical parameters like the mean and skewness were computed for the GPR amplitudes of each deck, and coupled with actual corrosion quantities based on the HCP measurements to form a future bridge deck model that can be used to assess any deck with GPR alone. Finally, in order to understand exactly which component of rebar corrosion (rust, cracking or chloride) attenuates the GPR data, computational modeling was carried out to isolate each variable. The results indicate that chloride is the major contributor to the rebar reflection attenuation, and that computational modeling can be used to accurately simulate GPR attenuation due to chloride.

Field performance of timber bridges. 15, Pueblo County, Colorado, stress-laminated deck bridge

Science.gov (United States)

L. E. Hislop

The Pueblo County 204B bridge was constructed in March 1990 in Pueblo, Colorado, as a demonstration bridge under the USDA Forest Service Timber Bridge Initiative. The stress-laminated deck superstructure is approximately 10 m long, 9 m wide, and 406 mm deep, with a skew of 10 degrees. Performance monitoring was conducted for 3 years, beginning at...

Flow field analysis of a pentagonal-shaped bridge deck by unsteady RANS

Directory of Open Access Journals (Sweden)

Md. Naimul Haque

2016-01-01

Full Text Available Long-span cable-stayed bridges are susceptible to dynamic wind effects due to their inherent flexibility. The fluid flow around the bridge deck should be well understood for the efficient design of an aerodynamically stable long-span bridge system. In this work, the aerodynamic features of a pentagonal-shaped bridge deck are explored numerically. The analytical results are compared with past experimental work to assess the capability of two-dimensional unsteady RANS simulation for predicting the aerodynamic features of this type of deck. The influence of the bottom plate slope on aerodynamic response and flow features was investigated. By varying the Reynolds number (2 × 104 to 20 × 104 the aerodynamic behavior at high wind speeds is clarified.

Precision monitoring of bridge deck curvature change during replacement.

Science.gov (United States)

2016-05-01

This project was focused on development and deployment of a system for monitoring vertical : displacement in bridge decks and bridge spans. The system uses high precision wireless inclinometer : sensors to monitor inclinations at various points of a ...

Fatigue Assessment of Full-Scale Retrofitted Orthotropic Bridge Decks

NARCIS (Netherlands)

Teixeira De Freitas, S.; Kolstein, M.H.; Bijlaard, F.S.K.

2017-01-01

Full-scale fatigue tests were performed on two retrofitted orthotropic bridge decks (OBDs). The retrofitting systems consist of adding a second steel plate on the top of the existing deck. The aim is to reduce the stresses at the fatigue-sensitive details and therefore extend the fatigue life of

A Highly Accurate and Efficient Analytical Approach to Bridge Deck Free Vibration Analysis

Directory of Open Access Journals (Sweden)

D.J. Gorman

2000-01-01

Full Text Available The superposition method is employed to obtain an accurate analytical type solution for the free vibration frequencies and mode shapes of multi-span bridge decks. Free edge conditions are imposed on the long edges running in the direction of the deck. Inter-span support is of the simple (knife-edge type. The analysis is valid regardless of the number of spans or their individual lengths. Exact agreement is found when computed results are compared with known eigenvalues for bridge decks with all spans of equal length. Mode shapes and eigenvalues are presented for typical bridge decks of three and four span lengths. In each case torsional and non-torsional modes are studied.

Structural Performance Evaluation of Tsing MA Bridge Deck Using Long-Term Monitoring Data

Science.gov (United States)

Ni, Y. Q.; Xia, H. W.; Ko, J. M.

The Tsing Ma Bridge in Hong Kong is suspension bridge with a main span of 1377 m carrying both highway and railway traffic. After completing its construction in 1997, the bridge was instrumented by the Hong Kong SAR Government Highways Department with a long-term structural health monitoring system comprising about 300 sensors permanently installed on the bridge. As part of this monitoring system, a total of 110 strain gauges have been installed to measure strain at the deck cross-sections and bearings. In this study, a method for real-time structural performance evaluation of the stiffening deck system making use of long-term strain measurement data is proposed and verified using the strain monitoring data from a typical deck cross-section of the Tsing Ma Bridge.

Multidisciplinary health monitoring of a steel bridge deck structure

NARCIS (Netherlands)

Pahlavan, P.L.; Pijpers, R.J.M.; Paulissen, J.H.; Hakkesteegt, H.C.; Jansen, T.H.

2013-01-01

Fatigue cracks in orthotropic bridge decks are an important cause for the necessary renovation of existing bridges. Parallel utilization of various technologies based on different physical sensing principles can potentially maximize the efficiency of structural health monitoring (SHM) systems for

Recommendations for Longitudinal Post-Tensioning in Full-Depth Precast Concrete Bridge Deck Panels

OpenAIRE

Bowers, Susan Elizabeth

2007-01-01

Full-depth precast concrete panels offer an efficient alternative to traditional cast-in-place concrete for replacement or new construction of bridge decks. Research has shown that longitudinal post-tensioning helps keep the precast bridge deck in compression and avoid problems such as leaking, cracking, spalling, and subsequent rusting on the beams at the transverse panel joints. Current design recommendations suggest levels of initial compression for precast concrete decks in a very limit...

Hybrid FRP-concrete bridge deck system final report I : development and system performance validation.

Science.gov (United States)

2009-10-01

In this study, the concept of the hybrid FRP-concrete structural systems was applied to both bridge : superstructure and deck systems. Results from the both experimental and computational analysis for : both the hybrid bridge superstructure and deck ...

Rapid multichannel impact-echo scanning of concrete bridge decks from a continuously moving platform

Science.gov (United States)

Mazzeo, Brian A.; Larsen, Jacob; McElderry, Joseph; Guthrie, W. Spencer

2017-02-01

Impact-echo testing is a non-destructive evaluation technique for determining the presence of defects in reinforced concrete bridge decks based on the acoustic response of the bridge deck when struck by an impactor. In this work, we build on our prior research with a single-channel impactor to demonstrate a seven-channel impact-echo scanning system with independent control of the impactors. This system is towed by a vehicle and integrated with distance measurement for registering the locations of the impacts along a bridge deck. The entire impact and recording system is computer-controlled. Because of a winch system and hinged frame construction of the apparatus, setup, measurement, and take-down of the apparatus can be achieved in a matter of minutes. Signal processing of the impact responses is performed on site and can produce a map of delaminations immediately after data acquisition. This map can then be used to guide other testing and/or can be referenced with the results of other testing techniques to facilitate comprehensive condition assessments of concrete bridge decks. This work demonstrates how impact-echo testing can be performed in a manner that makes complete bridge deck scanning for delaminations rapid and practical.

Abrasion-resistant concrete mix designs for precast bridge deck panels.

Science.gov (United States)

2010-08-01

The report documents laboratory investigations undertaken to develop high performance concrete (HPC) for precast and pre-stressed bridge deck components that would reduce the life-cycle cost of bridges by improving the studded tire wear (abrasion) re...

Shrinkage and durability study of bridge deck concrete.

Science.gov (United States)

2010-12-01

The Mississippi Department of Transportation is incorporating changes to material : specifications and construction procedures for bridge decks in an effort to reduce shrinkage : cracking. These changes are currently being implemented into a limited ...

Fatigue analysis and life prediction of composite highway bridge decks under traffic loading

Directory of Open Access Journals (Sweden)

Fernando N. Leitão

Full Text Available Steel and composite (steel-concrete highway bridges are currently subjected to dynamic actions of variable magnitude due to convoy of vehicles crossing on the deck pavement. These dynamic actions can generate the nucleation of fractures or even their propagation on the bridge deck structure. Proper consideration of all of the aspects mentioned pointed our team to develop an analysis methodology with emphasis to evaluate the stresses through a dynamic analysis of highway bridge decks including the action of vehicles. The design codes recommend the application of the curves S-N associated to the Miner's damage rule to evaluate the fatigue and service life of steel and composite (steel-concrete bridges. In this work, the developed computational model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the ANSYS program. The investigated highway bridge is constituted by four longitudinal composite girders and a concrete deck, spanning 40.0m by 13.5m. The analysis methodology and procedures presented in the design codes were applied to evaluate the fatigue of the bridge determining the service life of the structure. The main conclusions of this investigation focused on alerting structural engineers to the possible distortions, associated to the steel and composite bridge's service life when subjected to vehicle's dynamic actions.

Algorithms for highway-speed acoustic impact-echo evaluation of concrete bridge decks

Science.gov (United States)

Mazzeo, Brian A.; Guthrie, W. Spencer

2018-04-01

A new acoustic impact-echo testing device has been developed for detecting and mapping delaminations in concrete bridge decks at highway speeds. The apparatus produces nearly continuous acoustic excitation of concrete bridge decks through rolling mats of chains that are placed around six wheels mounted to a hinged trailer. The wheels approximately span the width of a traffic lane, and the ability to remotely lower and raise the apparatus using a winch system allows continuous data collection without stationary traffic control or exposure of personnel to traffic. Microphones near the wheels are used to record the acoustic response of the bridge deck during testing. In conjunction with the development of this new apparatus, advances in the algorithms required for data analysis were needed. This paper describes the general framework of the algorithms developed for converting differential global positioning system data and multi-channel audio data into maps that can be used in support of engineering decisions about bridge deck maintenance, rehabilitation, and replacement (MR&R). Acquisition of position and audio data is coordinated on a laptop computer through a custom graphical user interface. All of the streams of data are synchronized with the universal computer time so that audio data can be associated with interpolated position information through data post-processing. The audio segments are individually processed according to particular detection algorithms that can adapt to variations in microphone sensitivity or particular chain excitations. Features that are greater than a predetermined threshold, which is held constant throughout the analysis, are then subjected to further analysis and included in a map that shows the results of the testing. Maps of data collected on a bridge deck using the new acoustic impact-echo testing device at different speeds ranging from approximately 10 km/h to 55 km/h indicate that the collected data are reasonably repeatable. Use

Evaluation of bridge deck with shrinkage-compensating concrete.

Science.gov (United States)

2016-04-01

Concrete bridge decks are susceptible to premature cracking and to corrosion of reinforcing steel. Low-permeability : concrete does not always ensure durability if the concrete has excessive cracks that facilitate the intrusion of aggressive solution...

Experimental studies on multicellular GFRP bridge deck panels ...

Indian Academy of Sciences (India)

M P MUTHURAJ

2017-11-20

Nov 20, 2017 ... design of a new bridge deck panel made of GFRP. .... cient manufacturing processes with minimal wastage. But re-use of the remaining FRP elements during manufacture ... Energy consumption for production of different.

Fatigue Properties of Orthotropic Decks on Railway Bridges

Czech Academy of Sciences Publication Activity Database

Frýba, Ladislav; Gajdoš, Lubomír

1999-01-01

Roč. 21, č. 7 (1999), s. 639-652 ISSN 0141-0296 Grant - others:XX(CZ) ERRI D 191 Keywords : railway bridges * orthotropic decks * fatigue Subject RIV: JM - Building Engineering Impact factor: 0.364, year: 1999

Rapid replacement of Tangier Island bridges including lightweight and durable fiber-reinforced polymer deck systems.

Science.gov (United States)

2009-01-01

Fiber-reinforced polymer (FRP) composite cellular deck systems were used as new bridge decks on two replacement bridges on Tangier Island, Virginia. The most important characteristics of this application were reduced self-weight and increased durabil...

Bridge deck concrete volume change : final contract report.

Science.gov (United States)

2010-02-01

Concrete structures such as bridge decks, with large surface area relative to volume, shrink and crack, thus reducing service life performance and increasing operation costs. The project evaluated the early, first 24 hours, and long-term, 180 days, s...

Using artificial neural networks in the design of orthotropic bridge decks

Directory of Open Access Journals (Sweden)

Ahmed Shamel Fahmy

2016-12-01

Full Text Available For orthotropic bridge decks a lot of progress has been made in the development of codes to aid in the design process, in addition to software tools for numerical analysis and design. However, professional software tools will not aid the designer in choosing a preliminary economic layout at the conceptual design stage. Designers would go through iterative, lengthy and expensive procedures to reach the best configuration. The present research provides a methodology to investigate the contingency of using artificial neural networks for conceptual design of orthotropic steel-deck bridge. A neural network model was trained with different combinations of dimensions, and eight types of safety checks were performed on all of them. The resulting network can predict whether the deck is safe or not. It is found that this approach for the selection of orthotropic deck dimensions is a better and cost-effective option compared with international codes or expert opinion.

Research on construction technology for orthotropic steel deck pavement of Haihe River Chunyi Bridge

Science.gov (United States)

Xue, Y. C.; Qian, Z. D.; Zhang, M.

2017-01-01

In order to ensure the good service quality of orthotropic steel deck pavement of Haihe River Chunyi Bridge in Tianjin, and to reduce the occurrence of pavement diseases like lateral and longitudinal cracks, the key working procedures such as steel deck cleaning, anticorrosive coating, bonding layer spraying, seam cutting, epoxy asphalt concrete’s mixing, transportation, paving and compaction were studied. The study was based on the main features of epoxy asphalt concrete which is the pavement materials of Haihe River Chunyi Bridge, and combined with the basic characteristics and construction conditions of Haihe River Chunyi Bridge. Furthermore, some processing measures like controlling time and temperature, continuous paving with two pavers, lateral feeding, and improving the compaction method were proposed. The project example shows that the processing measures can effectively solve the technical difficulties in the construction of orthotropic steel deck pavement of Haihe River Chunyi Bridge, can greatly improve the construction speed and quality, and can provide reference for the same kinds of orthotropic steel deck pavement construction.

Measurement of bridge deck layout prior to concrete placement : final report.

Science.gov (United States)

2017-01-01

The main objective of this research was to develop a method of measuring and : producing as built bridge drawings. This was the first step in the feasibility : assessment for automated bridge deck paving. The research goes to show the : standard meth...

To the question of reliability and durability ballastless deck of bridge

Directory of Open Access Journals (Sweden)

V.V. Prystynskaya

2012-12-01

Full Text Available The principal causes of operational defects in bridge ballastless deck plates are considered in the article. The drawbacks of these plates construction that prevent from achieving a higher level of bridge framework reliability and durability have been analysed.

Deck and Cable Dynamic Testing of a Single-span Bridge Using Radar Interferometry and Videometry Measurements

Science.gov (United States)

Piniotis, George; Gikas, Vassilis; Mpimis, Thanassis; Perakis, Harris

2016-03-01

This paper presents the dynamic testing of a roadway, single-span, cable-stayed bridge for a sequence of static load and ambient vibration monitoring scenarios. Deck movements were captured along both sideways of the bridge using a Digital Image Correlation (DIC) and a Ground-based Microwave Interfererometer (GBMI) system. Cable vibrations were measured at a single point location on each of the six cables using the GBMI technique. Dynamic testing involves three types of analyses; firstly, vibration analysis and modal parameter estimation (i. e., natural frequencies and modal shapes) of the deck using the combined DIC and GBMI measurements. Secondly, dynamic testing of the cables is performed through vibration analysis and experimental computation of their tension forces. Thirdly, the mechanism of cable-deck dynamic interaction is studied through their Power Spectra Density (PSD) and the Short Time Fourier Transform (STFT) analyses. Thereby, the global (deck and cable) and local (either deck or cable) bridge modes are identified, serving a concrete benchmark of the current state of the bridge for studying the evolution of its structural performance in the future. The level of synergy and complementarity between the GBMI and DIC techniques for bridge monitoring is also examined and assessed.

Plans for crash-tested wood bridge railings for concrete decks

Science.gov (United States)

Michael A. Ritter; Ronald K. Faller; Barry T. Rosson; Paula D. Hilbrich Lee; Sheila Rimal. Duwadi

1998-01-01

As part of a continuing cooperative research between the Midwest Roadside Safety Facility (MwRSF); the USDA Forest Service, Forest Products Laboratory (FPL); and the Federal Highway Administration (FHWA), several crashworthy wood bridge railings and approach railing transitions have been adapted for use on concrete bridge decks. These railings meet testing and...

Comparison between major repair and replacement options for a bridge deck life cycle assessment: A case study

Directory of Open Access Journals (Sweden)

Abu Dabous Saleh

2017-01-01

Full Text Available Material production, manufacturing, transportation, usage, and end of lifeprocessing are usually the main contributors defining the life cycle assessment (LCA. Bridge infrastructure is important to the economy and the society. Over their life cycle, highway bridges experience several stressors that can significantly affect their structural performance and therefore require rehabilitation. This paper discusses the life cycle analysis of bridge rehabilitation decisions and demonstrates the analysis with a case study of a bridge located in Ontario, Canada. The LCA of the bridge deck is analyzed for two rehabilitation strategies: major repair and replacement. The study focuses on evaluating the different life cycle phases of the bridge deck by assessing their carbon dioxide emission, energy consumption and cost. Also, the paper presents the impact of the different elements within each phase to identify the most contributing elements. The LCA of the bridge deck is analyzed and estimated with the aid of CES EduPack 2016 software that includes a database of more than 4000 different materials and more than 200 manufacturing processes. Analysis of the case study shows that material phase causes significant life cycle impact. The study concluded that the deck replacement yields higher environmental impact and life cycle cost compared to repairing and strengthening the deck.

Characterization of stormwater runoff from bridge decks in eastern Massachusetts, 2014–16

Science.gov (United States)

Smith, Kirk P.; Sorenson, Jason R.; Granato, Gregory E.

2018-05-02

The quality of stormwater runoff from bridge decks (hereafter referred to as “bridge-deck runoff”) was characterized in a field study from August 2014 through August 2016 in which concentrations of suspended sediment (SS) and total nutrients were monitored. These new data were collected to supplement existing highway-runoff data collected in Massachusetts which were deficient in bridge-deck runoff concentration data. Monitoring stations were installed at three bridges maintained by the Massachusetts Department of Transportation in eastern Massachusetts (State Route 2A in the city of Boston, Interstate 90 in the town of Weston, and State Route 20 near Quinsigamond Village in the city of Worcester). The bridges had annual average daily traffic volumes from 21,200 to 124,000 vehicles per day; the land use surrounding the monitoring stations was 25 to 67 percent impervious.Automatic-monitoring techniques were used to collect more than 160 flow-proportional composite samples of bridge-deck runoff. Samples were analyzed for concentrations of SS, loss on ignition of suspended solids (LOI), particulate carbon (PC), total phosphorus (TP), total dissolved nitrogen (DN), and particulate nitrogen (PN). The distribution of particle size of SS also was determined for composite samples. Samples of bridge-deck runoff were collected year round during rain, mixed precipitation, and snowmelt runoff and with different dry antecedent periods throughout the 2-year sampling period.At the three bridge-deck-monitoring stations, median concentrations of SS in composite samples of bridge-deck runoff ranged from 1,490 to 2,020 milligrams per liter (mg/L); however, the range of SS in individual composites was vast at 44 to 142,000 mg/L. Median concentrations of SS were similar in composite samples collected from the State Route 2A and Interstate 90 bridge (2,010 and 2,020 mg/L, respectively), and lowest at the State Route 20 bridge (1,490 mg/L). Concentrations of coarse sediment (greater

Performance evaluation of concrete bridge decks reinforced with MMFX and SSC rebars.

Science.gov (United States)

2006-01-01

This report investigates the performance of bridge decks reinforced with stainless steel clad (SSC) and micro-composite multistructural formable steel (MMFX) rebars. The two-span Galloway Road Bridge on route CR5218 over North Elkhorn Creek in Scott ...

Development and validation of deterioration models for concrete bridge decks - phase 1 : artificial intelligence models and bridge management system.

Science.gov (United States)

2013-06-01

This research documents the development and evaluation of artificial neural network (ANN) models to predict the condition ratings of concrete highway bridge decks in Michigan. Historical condition assessments chronicled in the national bridge invento...

Effects of Adhesive Connection on Composite Action between FRP Bridge Deck and Steel Girder

Directory of Open Access Journals (Sweden)

Xu Jiang

2017-01-01

Full Text Available The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper, depending on the experimental investigations of FRP to steel girder system, the Finite Element (FE models on experiments were developed and analyzed. Comparison between experiments and FE results indicated that the FE models were much stiffer for in-plane shear stiffness of the FRP deck panel. To modify the FE models, rotational spring elements were added between webs and flanges of FRP decks, to simulate the semirigid connections. Numerical analyses were also conducted on four-point bending experiments of FRP-steel composite girders. Good agreement between experimental results and FE analysis was achieved by comparing the load-deflection curves at midspan and contribution of composite action from FRP decks. With the validated FE models, the parametric studies were conducted on adhesively bonded connection between FRP decks and steel girders, which indicated that the loading transfer capacity of adhesive connection was not simply dependent on the shear modulus or thickness of adhesive layer but dominated by the in-plane shear stiffness K.

Aerodynamic and aeroelastic characteristics of typical bridge decks equipped with wind barriers at the windward bridge-deck edge

Czech Academy of Sciences Publication Activity Database

Buljac, Andrija; Kozmar, H.; Pospíšil, Stanislav; Macháček, Michael

2017-01-01

Roč. 137, April (2017), s. 310-322 ISSN 0141-0296 R&D Projects: GA ČR(CZ) GA15-01035S; GA MŠk(CZ) LO1219 Keywords : bridge decks * roadway wind barrier * aerodynamic forces and moments * galloping * flutter * wind-tunnel experiments Subject RIV: JM - Building Engineering OBOR OECD: Construction engineering , Municipal and structural engineering Impact factor: 2.258, year: 2016 http://www.sciencedirect.com/science/ article /pii/S014102961730278X

Service Life and Maintenance Modelling of Reinforced Concrete Bridge Decks

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

Recent research in the area of assessment and maintenance of reinforced concrete bridge decks is presented in this paper. Three definitions of service lifetime are introduced and the difficult problem of assessing the service life is discussed. A stochastic modelling of corrosion and corrosion...... cracking is introduced and the site dependency of corrosion is stressed. Finally, a recently developed optimal repair strategy for bridges is briefly explained....

Unmanned Ground Vehicle for Autonomous Non-Destructive Testing of FRP Bridge Decks

Science.gov (United States)

Klinkhachorn, P.; Mercer, A. Scott; Halabe, Udaya B.; GangaRao, Hota V. S.

2007-03-01

Current non-destructive techniques for defect analysis of FRP bridge decks have a narrow scope. These techniques are very good at detecting certain types of defects but are not robust enough to detect all defects by themselves. For example, infrared thermography (IRT) can detect air filled defects and Ground Penetrating Radar (GPR) is good at detecting water filled ones. These technologies can be combined to create a more robust defect detection scheme. To accomplish this, an Unmanned Ground Vehicle (UGV) has been designed that incorporates both IR and GPR analysis to create a comprehensive defect map of a bridge deck. The UGV autonomously surveys the deck surface and acquires data. The UGV has two 1.5 GHz ground coupled GPR antennas that are mounted on the front of the UGV to collect GPR data. It also incorporates an active heating source and a radiometric IR camera to capture IR images of the deck, even in less than ideal weather scenarios such as cold cloudy days. The UGV is designed so that it can collect data in an assembly line fashion. It moves in 1 foot increments. When moving, it collects GPR data from the two antennas. When it stops it heats a section of the deck. The next time it stops to heat a section, the IR camera is analyzing the preheated deck section while preparing for the next section. Because the data is being continually collected using this method, the UGV can survey the entire deck in an efficient and timely manner.

Performance of Rail Fastening Systems on an Open-Deck Bridge

Science.gov (United States)

2018-02-01

Transportation Technology Center, Inc. (TTCI) monitored the performance of rail fasteners on an open-deck bridge and its approaches, located at Norfolk Southern Corporations (NS's) eastern mega site. The project was co-sponsored by the Federal Rai...

Nondestructive Evaluation of Concrete Bridge Decks with Automated Acoustic Scanning System and Ground Penetrating Radar.

Science.gov (United States)

Sun, Hongbin; Pashoutani, Sepehr; Zhu, Jinying

2018-06-16

Delamanintions and reinforcement corrosion are two common problems in concrete bridge decks. No single nondestructive testing method (NDT) is able to provide comprehensive characterization of these defects. In this work, two NDT methods, acoustic scanning and Ground Penetrating Radar (GPR), were used to image a straight concrete bridge deck and a curved intersection ramp bridge. An acoustic scanning system has been developed for rapid delamination mapping. The system consists of metal-ball excitation sources, air-coupled sensors, and a GPS positioning system. The acoustic scanning results are presented as a two-dimensional image that is based on the energy map in the frequency range of 0.5⁻5 kHz. The GPR scanning results are expressed as the GPR signal attenuation map to characterize concrete deterioration and reinforcement corrosion. Signal processing algorithms for both methods are discussed. Delamination maps from the acoustic scanning are compared with deterioration maps from the GPR scanning on both bridges. The results demonstrate that combining the acoustic and GPR scanning results will provide a complementary and comprehensive evaluation of concrete bridge decks.

A feasibility study of bridge deck deicing using geothermal energy.

Science.gov (United States)

2015-04-01

In this study, we investigated the feasibility of a ground-coupled system that utilizes heat energy harvested from the ground for : deicing of bridge decks. Heat exchange is performed using circulation loops integrated into the deep foundations suppo...

Demonstration and Validation of a Composite Grid Reinforcement System for Bridge Decks

Science.gov (United States)

2016-09-01

presence of chlorides from road salts that can pene- trate into the concrete deck and cause corrosion of standard steel reinforcement. Installation of the... Corrosion of Metal and Alloys – Corrosivity of Atmospheres – Classification, Determination and Estimation.” Geneva, Switzerland: International Standards...one year), an atmospheric corrosion test rack, (equipped with sensors to monitor corrosion and chlorides were in- serted in the bridge deck), and

Effects of Adhesive Connection on Composite Action between FRP Bridge Deck and Steel Girder

NARCIS (Netherlands)

Jiang, X.; Luo, Chengwei; Qiang, X.; Kolstein, M.H.; Bijlaard, F.S.K.

2017-01-01

The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper,

Evaluation of bridge decks using non-destructive evaluation (NDE) at near highway speeds for effective asset management.

Science.gov (United States)

2015-06-01

Remote sensing technologies allow for the condition evaluation of bridge decks at near highway speed. : Data collection at near highway speed for assessment of the top of the concrete deck and proof of : concept testing for the underside of the deck ...

Ground penetrating radar utilization in exploring inadequate concrete covers in a new bridge deck

Directory of Open Access Journals (Sweden)

Md. Istiaque Hasan

2014-01-01

Full Text Available The reinforced concrete cast in place four span deck of a concrete bridge near Roanoke, Texas, was recently completed. Due to possible construction errors, it was suspected that the concrete covers in the deck did not conform to drawings and specifications. A full scale non-destructive evaluation of the concrete covers was carried out using ground penetrating radar (GPR equipment. Cover values were determined from the radargram generated from the scan. The estimated covers were plotted on contour maps. Migration data can substitute the drilling based ground truth data without compromising the concrete cover estimations, except for areas with very high cover values. Areas with high water content may result in inaccurate concrete dielectric constants. Based on the results, significant retrofitting of the bridge deck, such as additional overlay, was recommended.

Structural condition assessment and service load performance of deteriorated prestressed concrete deck beam bridges

Science.gov (United States)

Fuentes, Juan Bolivar

Precast pretensioned deck beam bridges are a generic bridge type widely used by IDOT for new construction through the end of the 1970's and still widely used on county roads throughout Illinois. While these bridges were economical to build, IDOT discontinued their use because reflective cracks developed along the length of the longitudinal joints between beams. Three 30 years old deteriorated beams were removed from an existing bridge over Spoon River in Fulton County, IL and delivered to Newmark Civil Engineering Laboratory. The program consisted of a series of comprehensive, destructive and non-destructive, tests and evaluations of the three beams with emphasis on three major areas; (1) The Condition Assessment of the as-delivered beams. (2) The service load performance of the bridge sub-assemblage constructed from those beams. After a comprehensive inspection of the beams was completed, the beams were integrated together into a bridge subassembly that simulated a bridge lane. (3) Following the service load tests, the three beams were separated and tested individually to failure. The critical signs to be observed in existing structures that will lead the inspectors to conclude that a deck beam is being overloaded were are also studied. Several conclusions were found. Cracking of the longitudinal joint has little effect on the stiffness of the bridge if the transverse rod is snug. The presence of a snug transverse tie rod increases the strength of the longitudinal joint. After a longitudinal joint has fractured, reincorporating a snug transverse rod can significantly reestablish the stiffness of the longitudinal joint and reduce overloading of a deteriorated beam. Participation factors must be based on relative bending moments of one beam with respect to the total amount of bending moment produced by the applied load and not to the amount of total vertical displacement. The participation factors will vary along the span of the bridge deck and will depend on the

Latex-modified fiber-reinforced concrete bridge deck overlay : construction/interim report.

Science.gov (United States)

1993-06-01

Latex-modified concrete (LMC) is Portland cement concrete (PCC) with an admixture of latex. LMC is considered to be nearly impermeable to chlorides and is extensively used to construct bridge deck overlays. Unfortunately, some of these overlays have ...

a finite element model for the analysis of bridge decks

African Journals Online (AJOL)

Dr Obe

A FINITE ELEMENT MODEL FOR THE ANALYSIS OF BRIDGE DECKS. NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 27 NO.1, MARCH 2008. 59. (a) Beam-plate system. (b) T-beam structural model. Fig. 1 Beam-plate structure idealisations. The matrix displacement method of analysis is used. The continuum structure is.

Bridge deck cracking : effects on in-service performance, prevention, and remediation.

Science.gov (United States)

2015-08-01

The main objectives of this project were: (a) to identify the causes of early-age cracking in concrete bridge decks, (b) to provide : recommendations for effective mitigation of early-age cracking, (c) to assess the effect of cracks on the long-term ...

Numerical simulations and experimental measurements of steel and ice impacts on concrete for acoustic interrogation of delaminations in bridge decks

Energy Technology Data Exchange (ETDEWEB)

Mazzeo, Brian A.; Patil, Anjali N.; Klis, Jeffrey M. [Brigham Young University, Department of Electrical and Computer Engineering, Provo, Utah, 84602 (United States); Hurd, Randy C.; Truscott, Tadd T. [Brigham Young University, Department of Mechanical Engineering, Provo, Utah, 84602 (United States); Guthrie, W. Spencer [Brigham Young University, Department of Civil and Environmental Engineering, Provo, Utah, 84602 (United States)

2014-02-18

Delaminations in bridge decks typically result from corrosion of the top mat of reinforcing steel, which leads to a localized separation of the concrete cover from the underlying concrete. Because delaminations cannot be detected using visual inspection, rapid, large-area interrogation methods are desired to characterize bridge decks without disruption to traffic, without the subjectivity inherent in existing methods, and with increased inspector safety. To this end, disposable impactors such as water droplets or ice chips can be dropped using automatic dispensers onto concrete surfaces to excite mechanical vibrations while acoustic responses can be recorded using air-coupled microphones. In this work, numerical simulations are used to characterize the flexural response of a model concrete bridge deck subject to both steel and ice impactors, and the results are compared with similar experiments performed in the laboratory on a partially delaminated concrete bridge deck slab. The simulations offer greater understanding of the kinetics of impacts and the responses of materials.

Implementing statistical analysis in multi-channel acoustic impact-echo testing of concrete bridge decks: Determining thresholds for delamination detection

Science.gov (United States)

Hendricks, Lorin; Spencer Guthrie, W.; Mazzeo, Brian

2018-04-01

An automated acoustic impact-echo testing device with seven channels has been developed for faster surveying of bridge decks. Due to potential variations in bridge deck overlay thickness, varying conditions between testing passes, and occasional imprecise equipment calibrations, a method that can account for variations in deck properties and testing conditions was necessary to correctly interpret the acoustic data. A new methodology involving statistical analyses was therefore developed. After acoustic impact-echo data are collected and analyzed, the results are normalized by the median for each channel, a Gaussian distribution is fit to the histogram of the data, and the Kullback-Leibler divergence test or Otsu's method is then used to determine the optimum threshold for differentiating between intact and delaminated concrete. The new methodology was successfully applied to individual channels of previously unusable acoustic impact-echo data obtained from a three-lane interstate bridge deck surfaced with a polymer overlay, and the resulting delamination map compared very favorably with the results of a manual deck sounding survey.

Impact of overweight vehicles (with heavy axle loads) on bridge deck deterioration.

Science.gov (United States)

2012-03-01

Bridge deck slabs develop compressive stresses from global flexural deformation and locally from high-level : wheel loads when it is subjected to overweight trucks. This study quantified the impact of overweight vehicles : with heavy axle loads on br...

Composite Action in Prestressed NU I-Girder Bridge Deck Systems Constructed with Bond Breakers to Facilitate Deck Removal : Technical Summary

Science.gov (United States)

2017-11-01

Results are reported from tests of small-scale push-off and large-scale composite NU I-girder specimens conducted to establish an interface connection detail that (1) Facilitates in-situ removal of the bridge deck without damaging prestressed girders...

Effectiveness of polymer bridge deck overlays in highway noise reduction : technical paper.

Science.gov (United States)

2016-04-01

The Kansas Department of Transportation (KDOT) began placing multi-layer polymer bridge deck overlays in 1999 and at the present time have over 200 in service. A few years after placing the overlays, individuals indicated that they noticed how quiet ...

3D laser scanning for quality control and assurance in bridge deck construction.

Science.gov (United States)

2014-08-01

The inspection of installations of rebar and other embedded components in bridge deck construction is a tedious : task for eld inspectors, requiring considerable eld time for measurement and verication against code requirement. The verica...

Moving dynamic loads caused by bridge deck joint unevenness - a case study

CSIR Research Space (South Africa)

Steyn, WJV

2004-11-01

Full Text Available This paper focus on the general guidelines regarding maximum unevenness from bridge deck joints for typical South African heavy vehicles, in order to minimize the generation of moving variable loads. In a recent investigation it was found that areas...

Structural design guidelines for concrete bridge decks reinforced with corrosion-resistant reinforcing bars.

Science.gov (United States)

2014-10-01

This research program develops and validates structural design guidelines and details for concrete bridge decks with : corrosion-resistant reinforcing (CRR) bars. A two-phase experimental program was conducted where a control test set consistent : wi...

An Advanced Coupled Genetic Algorithm for Identifying Unknown Moving Loads on Bridge Decks

Directory of Open Access Journals (Sweden)

Sang-Youl Lee

2014-01-01

Full Text Available This study deals with an inverse method to identify moving loads on bridge decks using the finite element method (FEM and a coupled genetic algorithm (c-GA. We developed the inverse technique using a coupled genetic algorithm that can make global solution searches possible as opposed to classical gradient-based optimization techniques. The technique described in this paper allows us to not only detect the weight of moving vehicles but also find their moving velocities. To demonstrate the feasibility of the method, the algorithm is applied to a bridge deck model with beam elements. In addition, 1D and 3D finite element models are simulated to study the influence of measurement errors and model uncertainty between numerical and real structures. The results demonstrate the excellence of the method from the standpoints of computation efficiency and avoidance of premature convergence.

Two-course bonded concrete bridge deck construction : condition and performance after six years.

Science.gov (United States)

1981-01-01

This report presents the findings from a six-year study of two-course bonded concrete bridge decks constructed in Virginia. Each of three special portland cement concretes was applied as an overlay, or wearing course, on two experimental spans. The o...

Evaluation of performance and maximum length of continuous decks in bridges : part 1.

Science.gov (United States)

2011-06-01

The purpose of this research was to evaluate the performance history of continuous bridge decks in the State of Georgia, to determine why the current design detail works, to recommend a new design detail, and to recommend the maximum and/or optimum l...

A review on the suitability of rubberized concrete for concrete bridge decks

Science.gov (United States)

Syamir Senin, Mohamad; Shahidan, Shahiron; Radziah Abdullah, Siti; Anting Guntor, Nickholas; Syazani Leman, Alif

2017-11-01

Road authorities manage a large population of ageing bridges, a substantial number of which fail to meet the current requirements either due to deterioration and other structural deficiencies or as a result of the escalating demands imposed by increased traffic. This problem is related to the dynamic load from vehicles. This problem can be solved by producing a type of concrete that can reduce the amplitude of oscillation or vibration such as rubberized concrete. Green construction has been a very important aspect in concrete production field in the last decade. One of the most problematic waste materials is scrap tires. The use of scrap tires in civil engineering is increasing by producing rubberized concrete. Rubberized concrete is a type of concrete that is mixed with rubber. The purpose of this review is to justify the suitability of rubberized concrete for concrete bridge decks. Several parameters named physical, chemical and mechanical properties were measured to ensure the suitability of rubberized concrete for concrete bridge decks. Rubberized concrete has similar workability to normal concrete. The rubber reduced the density and compressive strength of the concrete while increased the flexural strength, water absorption and damping ratio. The used of rubber in concrete beyond 20% is not recommended due to decreasing in compressive strength. Rubberized concrete recommended to be used in circumstances where vibration damping was required such as in bridge construction as shock-wave absorber.

Experimental Analysis of Stiffness of the Riveted Steel Railway Bridge Deck Members’ Joints

Directory of Open Access Journals (Sweden)

Gocál Jozef

2014-12-01

Full Text Available The paper deals with the real behaviour of the riveted steel railway bridge deck members’ connections with respect to their bending stiffness. Attention is paid to the stringer-to-cross beam connection as well as the cross beam-to-main girder connection. The stiffness of the two connections is investigated on the basis of evaluation of the experimentally determined stress response of the observed structural members to the actual traffic load on an existing railway bridge.

Analysis on Adhesively-Bonded Joints of FRP-steel Composite Bridge under Combined Loading : Arcan Test Study and Numerical Modeling

NARCIS (Netherlands)

Jiang, X.; Qiang, X.; Kolstein, M.H.; Bijlaard, F.S.K.

2016-01-01

The research presented in this paper is an experimental study and numerical analysis on mechanical behavior of the adhesively-bonded joint between FRP sandwich bridge deck and steel girder. Generally, there are three typical stress states in the adhesively-bonded joint: shear stress, tensile stress,

CRASH TEST AND EVALUATION OF RESTRAINED SAFETY-SHAPE CONCRETE BARRIERS ON CONCRETE BRIDGE DECK

Science.gov (United States)

2018-01-01

This research designed and tested a new portable concrete barrier that meets the performance of MASH TL-4 and can be used in temporary and permanent applications on bridge decks. Additionally, this new barrier system will minimize deflection, allowin...

Influence of fly ash, slag cement and specimen curing on shrinkage of bridge deck concrete.

Science.gov (United States)

2014-12-01

Cracks occur in bridge decks due to restrained shrinkage of concrete materials. Concrete materials shrink as : cementitious materials hydrate and as water that is not chemically bonded to cementitious materials : migrates from the high humid environm...

Arch-Axis Coefficient Optimization of Long-Span Deck-Type Concrete-Filled Steel Tubular Arch Bridge

Science.gov (United States)

Liu, Q. J.; Wan, S.; Liu, H. C.

2017-11-01

This paper is based on Nanpuxi super major bridge which is under construction and starts from Wencheng Zhejiang province to Taishun highway. A finite element model of the whole bridge is constructed using Midas Civil finite element software. The most adverse load combination in the specification is taken into consideration to determine the method of calculating the arch-axis coefficient of long-span deck-type concrete-filled steel tubular arch bridge. By doing this, this paper aims at providing references for similar engineering projects.

Modelling and fatigue life assessment of orthotropic bridge deck details using FEM

Czech Academy of Sciences Publication Activity Database

Aygül, M.; AL-Emrani, M.; Urushadze, Shota

2012-01-01

Roč. 40, July (2012), s. 129-142 ISSN 0142-1123 R&D Projects: GA MŠk(CZ) 7E08098 Grant - others:evropská komise(XE) RFSR-CT-2008-00033 (BRIFAG) Institutional support: RVO:68378297 Keywords : orthotropic bridge deck * open ribs * structural hot spot stress * effective notch stress Subject RIV: JM - Building Engineering Impact factor: 1.976, year: 2012

Estimation of Structure-Borne Noise Reduction Effect of Steel Railway Bridge Equipped with Floating Ladder Track and Floating Reinforced-Concrete Deck

Science.gov (United States)

Watanabe, Tsutomu; Sogabe, Masamichi; Asanuma, Kiyoshi; Wakui, Hajime

A number of steel railway bridges have been constructed in Japan. Thin steel members used for the bridges easily tend to vibrate and generate structure-borne noise. Accordingly, the number of constructions of steel railway bridges tends to decrease in the urban areas from a viewpoint of environmental preservation. Then, as a countermeasure against structure-borne noise generated from steel railway bridges, we have developed a new type of the steel railway bridge equipped with a floating-ladder track and a floating reinforced-concrete (RC) deck. As a result of train-running experiment, it became apparent that the new steel railway bridge installed by double floating system has reduced a vibration velocity level by 10.5 dB(A) at main girder web as compared with a steel railway bridge installed by directly fastened track. This reduction effect was achieved by the ladder track and RC deck supported by resilient materials.

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

Science.gov (United States)

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

Long-term behaviour of a steel-concrete composite railway bridge deck

OpenAIRE

STAQUET, S; TAILHAN, JL; ESPION, B

2005-01-01

A prefabricated, composite and prestressed railway bridge deck has been instrumented in June 2000 with strain gages and vibrating wire extensometers. The purpose of this paper is to report on the comparison between strains recorded in situ up to four years with values computed within the framework of an original time-dependent analysis base on the evolution of the degree of hydration and the internal relative humidity in concrete. These fundamental parameters used in the proposed model to com...

Development and validation of deterioration models for concrete bridge decks - phase 2 : mechanics-based degradation models.

Science.gov (United States)

2013-06-01

This report summarizes a research project aimed at developing degradation models for bridge decks in the state of Michigan based on durability mechanics. A probabilistic framework to implement local-level mechanistic-based models for predicting the c...

Experimental Investigation of Membrane Materials used in Multilayer Surfacing Systems for Orthotropic Steel Deck Bridges

NARCIS (Netherlands)

Tzimiris, G.

2017-01-01

In the Netherlands asphaltic surfacings on orthotropic steel deck bridges (OSDB) mostly consist of two structural layers. The upper layer consists of what is known as very open porous asphalt (ZOAB) for noise reduction. For the lower layer Guss Asphalt (GA) is used. Earlier investigations have shown

Optimizing rib width to height and rib spacing to deck plate thickness ratios in orthotropic decks

Directory of Open Access Journals (Sweden)

Abdullah Fettahoglu

2016-12-01

Full Text Available Orthotropic decks are composed of deck plate, ribs, and cross-beams and are frequently used in industry to span long distances, due to their light structures and load carrying capacities. Trapezoidal ribs are broadly preferred as longitudinal stiffeners in design of orthotropic decks. They supply the required stiffness to the orthotropic deck in traffic direction. Trapezoidal ribs are chosen in industrial applications because of their high torsional and buckling rigidity, less material and welding needs. Rib width, height, spacing, thickness of deck plate are important parameters for designing of orthotropic decks. In the scope of this study, rib width to height and rib spacing to deck plate thickness ratios are assessed by means of the stresses developed under different ratios of these parameters. For this purpose a FE-model of orthotropic bridge is generated, which encompasses the entire bridge geometry and conforms to recommendations given in Eurocode 3 Part 2. Afterwards necessary FE-analyses are performed to reveal the stresses developed under different rib width to height and rib spacing to deck plate thickness ratios. Based on the results obtained in this study, recommendations regarding these ratios are provided for orthotropic steel decks occupying trapezoidal ribs.

Super-long bridges with floating towers: the role of multi-box decks and Hardware-In-the-Loop technology for wind tunnel tests

Science.gov (United States)

Zasso, A.; Argentini, T.; Bayati, I.; Belloli, M.; Rocchi, D.

2017-12-01

The super long fjord crossings in E39 Norwegian project pose new challenges to long span bridge design and construction technology. Proposed solutions should consider the adoption of bridge deck with super long spans or floating solutions for at least one of the towers, due to the relevant fjord depth. At the same time, the exposed fjord environment, possibly facing the open ocean, calls for higher aerodynamic stability performances. In relation to this scenario, the present paper addresses two topics: 1) the aerodynamic advantages of multi-box deck sections in terms of aeroelastic stability, and 2) an experimental setup in a wind tunnel able to simulate the aeroelastic bridge response including the wave forcing on the floating.

Structural improvement of strengthened deck panels with externally bonded plates

International Nuclear Information System (INIS)

Sim, Jongsung; Oh, Hongseob

2005-01-01

Concrete bridge decks require eventual replacement and rehabilitation due to decreasing load-carrying capacity. This paper compares different strengthening design procedures that improve the usability and structural performance of bridge decks. The failure characteristics of bridge decks strengthened with various materials such as carbon fiber sheet, glass fiber sheet, steel plate, and grid CFRP and GFRP are analyzed, and the theoretical load-carrying capacities are evaluated using traditional beam and yield line theory, and punching shear analysis. The strengthening materials increase the punching shear strength of the deck and change the failure mode of the strengthened panel

Design of X-joints in Sandwich Structures for Naval Vessels

DEFF Research Database (Denmark)

Hayman, Brian; Berggreen, Christian; Lundsgaard-Larsen, Christian

2007-01-01

In many naval ships of fibre composite sandwich construction, an X-joint exists where the end bulkhead of the superstructure is attached to the deck, with an internal bulkhead placed in the same vertical plane below the deck. This joint is subjected to alternating tensile and compressive loading...

Analysis of an Orthotropic Deck Stiffened with a Cement-Based Overlay

DEFF Research Database (Denmark)

Walter, Rasmus; Olesen, John Forbes; Stang, Henrik

2007-01-01

decks. A solution might be to enhance the stiffness of the traditional orthotropic bridge deck by using a cement-based overlay. In this paper, an orthotropic steel bridge deck stiffened with a cement-based overlay is analyzed. The analysis is based on nonlinear fracture mechanics, and utilizes......Over the past years, with increasing traffic volumes and higher wheel loads, fatigue damage in steel parts of typical orthotropic steel bridge decks has been experienced on heavily trafficked routes. A demand exists to find a durable system to increase the fatigue safety of orthotropic steel bridge...... the finite-element method. The stiffness of the steel deck reinforced with an overlay depends highly on the composite action. The composite action is closely related to cracking of the overlay and interfacial cracking between the overlay and underlying steel plate (debonding). As an example, a real size...

Evaluation of bridge decks using non-destructive evaluation (NDE) at near highway speeds for effective asset management - pilot project.

Science.gov (United States)

2016-09-29

This project piloted the findings from an initial research and development project pertaining to the detection, : quantification, and visualization of bridge deck distresses through the use of remote sensing techniques, specifically : combining optic...

Numerical Simulation of Early Age Cracking of Reinforced Concrete Bridge Decks with a Full-3D Multiscale and Multi-Chemo-Physical Integrated Analysis

Directory of Open Access Journals (Sweden)

Tetsuya Ishida

2018-03-01

Full Text Available In November 2011, the Japanese government resolved to build “Revival Roads” in the Tohoku region to accelerate the recovery from the Great East Japan Earthquake of March 2011. Because the Tohoku region experiences such cold and snowy weather in winter, complex degradation from a combination of frost damage, chloride attack from de-icing agents, alkali–silica reaction, cracking and fatigue is anticipated. Thus, to enhance the durability performance of road structures, particularly reinforced concrete (RC bridge decks, multiple countermeasures are proposed: a low water-to-cement ratio in the mix, mineral admixtures such as ground granulated blast furnace slag and/or fly ash to mitigate the risks of chloride attack and alkali–silica reaction, anticorrosion rebar and 6% entrained air for frost damage. It should be noted here that such high durability specifications may conversely increase the risk of early age cracking caused by temperature and shrinkage due to the large amounts of cement and the use of mineral admixtures. Against this background, this paper presents a numerical simulation of early age deformation and cracking of RC bridge decks with full 3D multiscale and multi-chemo-physical integrated analysis. First, a multiscale constitutive model of solidifying cementitious materials is briefly introduced based on systematic knowledge coupling microscopic thermodynamic phenomena and microscopic structural mechanics. With the aim to assess the early age thermal and shrinkage-induced cracks on real bridge deck, the study began with extensive model validations by applying the multiscale and multi-physical integrated analysis system to small specimens and mock-up RC bridge deck specimens. Then, through the application of the current computational system, factors that affect the generation and propagation of early age thermal and shrinkage-induced cracks are identified via experimental validation and full-scale numerical simulation on real

Laboratory Testing of Precast Bridge Beck Panel Transverse Connections for Use in Accelerated Bridge Construction

OpenAIRE

Porter, Scott D.

2009-01-01

Precast concrete bridge deck panels have been used for decades to accelerate bridge construction. Cracking of the transverse connection between panels is a common problem that can damage deck overlays and cause connection leaking leading to corrosion of lower bridge elements. To better understand the behavior of bridge deck transverse female-to-female connections, shear and moment lab testing were performed at Utah State University for the Utah Department of Transportation. Two existing UDOT ...

Finite-Element Investigation of the Structural Behavior of Basalt Fiber Reinforced Polymer (BFRP- Reinforced Self-Compacting Concrete (SCC Decks Slabs in Thompson Bridge

Directory of Open Access Journals (Sweden)

Lingzhu Zhou

2018-06-01

Full Text Available The need for a sustainable development and improved whole life performance of concrete infrastructure has led to the requirement of more durable and sustainable concrete bridges alongside accurate predictive analysis tools. Using the combination of Self-Compacting Concrete (SCC with industrial by-products and fiber-reinforced polymer (FRP, reinforcement is anticipated to address the concerns of high carbon footprint and corrosion in traditional steel-reinforced concrete structures. This paper presents a numerical investigation of the structural behavior of basalt fiber-reinforced polymer (BFRP-reinforced SCC deck slabs in a real bridge, named Thompson Bridge, constructed in Northern Ireland, U.K. A non-linear finite element (FE model is proposed by using ABAQUS 6.10 in this study, which is aimed at extending the previous investigation of the field test in Thompson Bridge. The results of this field test were used to validate the accuracy of the proposed finite element model. The results showed good agreement between the test results and the numerical results; more importantly, the compressive membrane action (CMA inside the slabs could be well demonstrated by this FE model. Subsequently, a series of parametric studies was conducted to investigate the influence of different parameters on the structural performance of the deck slabs in Thompson Bridge. The results of the analyses are discussed, and conclusions on the behavior of the SCC deck slabs reinforced by BFRP bars are presented.

Experimental and Numerical Study of Interface Crack Propagation in Foam Cored Sandwich Beams

DEFF Research Database (Denmark)

Berggreen, Carl Christian; Simonsen, Bo Cerup; Borum, Kaj Kvisgård

2007-01-01

application example is to tear off one of the face laminates from the sandwich. This configuration can be found in many applications but is considered here to be occurring in a ship structure, particularly at the hard spot where the superstructure meets the deck. Face tearing experiments are carried out...... experiments and theory. For cores with higher density, the crack tends to propagate in the laminate itself with extensive fiber bridging leading to rather conservative numerical predictions. However, for structural configurations where LEFM can be applied, the presented procedure is sufficiently robust...... and accurate to be used in a number of important engineering applications, for example risk-based inspection and repair schemes....

Improving Performance of Polymer Fiber Reinforced Sandwich X-Joints in Naval Vessels

DEFF Research Database (Denmark)

Berggreen, Christian; Lundsgaard-Larsen, Christian; Karlsen, Kasper

2007-01-01

In many naval ships of fiber composite sandwich construction an X-joint exists where the end bulkhead of the superstructure is attached to the deck, with a bulkhead placed in the same vertical plane below the deck. As the hull girder flexes this joint is subjected to alternating tensile and compr...

Design of Experimental Suspended Footbridge with Deck Made of UHPC

Directory of Open Access Journals (Sweden)

Blank Marek

2016-01-01

Full Text Available This paper deals with the static and dynamic design of experimental footbridge for pedestrians and cyclists in the municipality Lužec nad Vltavou in Czech Republic, Europe. This work aims to familiarize the reader with calculations carried out and the results obtained, describing the static and dynamic properties of proposed footbridge. The construction of footbridge is designed as a suspended structure with prestressed bridge deck consisting of prefabricated UHPC panels and reversed “V” shaped steel pylon with height of approximately 40 meters. The deck is anchored using 24 steel hangers in one row in a steel pylon - 17 ropes in the main span and 7 cables on the other side. Range of the main span is 99.18 meters and the secondary span is 31.9 m. Deck width is 4.5 meters with 3.0 meters passing space. The bridge is designed for the possibility of passage of vehicles weighting up to 3.5 tons. Deck panels are made of UHPC with reinforcement. At the edge of the bridge on the side of the shorter span the bridge deck is firmly connected with abutment and on the other deck it is stored using a pair of sliding bearings. The utilization of the excellent properties of UHPC allows to design a very thin and lightweight construction of the deck, which could not be achieved with the use of normal concrete.

Fiber reinforced polymer bridge decks.

Science.gov (United States)

2011-01-01

The overarching goal of this study was to perform a comprehensive evaluation of various issues related to the strength and serviceability : of the FRP deck panels that are available in the industry. Specific objectives were to establish critical limi...

Modal analysis of cable-stayed UHPC bridge

Directory of Open Access Journals (Sweden)

Tej Petr

2017-01-01

Full Text Available This paper deals with the dynamic analysis of cable-stayed UHPC bridge over the Vltava river near town Melnik in Czech Republic, Europe. Bridge serves for pedestrians and cyclists. This work aims to familiarize the reader with dynamic calculations carried out and the results obtained, describing the dynamic properties of proposed bridge. The construction of bridge is designed as a cable-stayed structure with prestressed bridge deck consisting of prefabricated UHPC panels and reversed “V” shaped steel pylon with height of approximately 40 meters. The deck is anchored using 24 steel hangers in one row in a steel pylon - 17 ropes in the main span and 7 cables on the other side. Range of the main span is 99.18 meters and the secondary span is 31.9 m. Deck width is 4.5 meters with 3.0 meters passing space. The bridge is designed for the possibility of passage of vehicles weighting up to 3.5 tonnes. Deck panels are made of UHPC with reinforcement. At the edge of the bridge on the side of the shorter span the bridge deck is firmly connected with abutment and on the other deck it is stored using a pair of sliding bearings.

The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

Directory of Open Access Journals (Sweden)

Wei Wang

2014-01-01

Full Text Available Based on forced vibration tests for high-performance concrete (HPC, the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

Experimental evaluation of the buckling phenomena in the new joint design for upper deck structure of a bridge

Directory of Open Access Journals (Sweden)

Solazzi L.

2010-06-01

Full Text Available This paper is concerned with the experimental mechanical analysis of a new design of a joint for a main components of a upper deck of a road bridge. These components are subject to the compression state stress induced by the weight and the load acting on the road. Each upper deck of a bridge (positioned on each side of the bridge is composed by four tubular structures that must be joint each together. The joint must to take in to account many aspects, for example that the length of each component is not the same (because, obviously, there is a mechanical tolerance. This phenomena induce different compression stress on each component and so is very important non only the critical buckling load but also the post buckling behaviour of the structure. It is very important that if a single tubular structure reaches the critical load of instability, it still has load capacity . This is to avoid that, in the case where a column reaches the instability, the entire load acting on a column increase the load on the remaining three. For this purpose many different geometrical solutions have been designed (elaborated by fem analyses and successively tested experimentally. This work reports the main experimental results on the best joint solution and how this increase the load capacity and the displacement respect to the solution without this flange.

ANDERS: future of concrete bridge deck evaluation and rehabilitation

Science.gov (United States)

Gucunski, Nenad; Moon, Franklin

2011-04-01

The Automated Nondestructive Evaluation and Rehabilitation System (ANDERS) aims to provide a uniquely comprehensive tool that will transform the manner in which bridge decks are assessed and rehabilitated. It is going to be achieved through: 1) much higher evaluation detail and comprehensiveness of detection at an early stage deterioration, 2) comprehensive condition and structural assessment at all stages of deterioration, and 3) integrated assessment and rehabilitation that will be minimally invasive, rapid and cost effective. ANDERS is composed of four systems. that merge novel imaging and NDE techniques, together with novel intervention approaches to arrest the deterioration processes. These technologies are incorporated within a series of human-operated and robotic vehicles. To perform assessments, ANDERS will be equipped with two complimentary nondestructive approaches. The first, Multi-Modal Nondestructive Evaluation (MM-NDE) System aims to identify and characterize localized deterioration with a high degree of resolution. The second, Global Structural Assessment (GSA) System aims to capture global structural characteristics and identify any appreciable effects of deterioration on a bridge structure. Output from these two approaches will be merged through a novel Automated Structural Identification (Auto St-Id) approach that will construct, calibrate, and utilize simulation models to assess overall structural vulnerability and capacity. These three systems comprise the assessment suite of ANDERS and will directly inform the Nondestructive Rehabilitation (NDR) System. The NDR System leverages robotics for the precision and rapid delivery of novel materials capable of halting the early-stage deterioration identified.

Ground penetrating radar and microwave tomography 3D applications for the deck evaluation of the Musmeci bridge in Potenza, Italy

International Nuclear Information System (INIS)

Bavusi, Massimo; Loperte, Antonio; Lapenna, Vincenzo; Soldovieri, Francesco; Di Napoli, Rosario; Di Cesare, Antonio; Carlo Ponzo, Felice

2011-01-01

An extensive experimental and numerical investigation has been carried out to assess the status of the 'Ponte sul Basento' (1967–1976), in the town of Potenza (Basilicata region, southern Italy), better known as the Musmeci bridge. Architecturally, the bridge is a considerable reinforced 20th century concrete structure that was designed and built by the Italian architect Sergio Musmeci (1926–1981). Moreover, the bridge represents an important element of the infrastructural network, linking the city centre to the Potenza-Sicignano highway, crossing the Basento river and the railway close to the main train station of the city. Recently, due to ageing and continuous and significant traffic, the bridge started to be affected by several problems such as water infiltration. Within the presented study, a widespread ground penetrating radar (GPR) survey has been designed to investigate the geometrical characteristics of the bridge deck (Gerber saddles, internal stiffening walls, pillar supports) and detect the presence of defects or damage due to water infiltration and traffic fatigue. Concerning this, a 900 MHz 3D GPR survey has been performed along a zone of one of the lanes on the road surface. Moreover, a second 1500 MHz 3D survey has been carried out at the bottom of the bridge deck in order to gain detailed information about an important structural element of the bridge, the Gerber saddle. Both results have been processed following two approaches: the first a classical time-domain processing session based on commercial software and the use of migration; the second in microwave tomography, an advanced frequency domain automatic PC-based inversion algorithm. In this paper, we present a comparative interpretation of both kinds of processed results, and provide considerations about the investigated structures

Christian Menn's recent bridge designs - Reducing structural elements to the simplest solution

OpenAIRE

Brühwiler, E.; Mahmoud, Khaled M.

2009-01-01

The conceptual designs by Christian Menn of four landmark bridges are presented: 1) a 350-m span cable-stayed bridge with jointless deck girder, 2) a cable-stayed bridge with a single “spindle-shaped” pylon, 3) a bridge with an arch reaching high above the deck (both carrying a horizontally curved deck girder), and 4) a cable stayed bridge with three pylons monolithically connected to the deck girder. All of the original bridge designs are driven by the aim to optimize the flow of force...

Semiempirical Methodology for Estimating the Service Life of Concrete Deck Panels Strengthened with Fiber-Reinforced Polymer

Directory of Open Access Journals (Sweden)

Eon-Kyoung Kim

2014-01-01

Full Text Available Deterioration of concrete bridge decks affects their durability, safety, and function. It is therefore necessary to conduct structural rehabilitation of damaged concrete decks by strengthening them with fiber-reinforced polymer. Of the recent studies on the strengthened structures, most have focused on static behavior; only a few studies have investigated fatigue behavior. Accurate analysis of fatigue in concrete deck performance requires a more realistic simulated moving load. This study developed a theoretical live-load model to reflect the effect of moving vehicle loads, based on a statistical approach to the measurement of real traffic loads over various time periods in Korea. It assessed the fatigue life and strengthening effect of bridge decks strengthened with either carbon fiber sheets or grid carbon fiber polymer plastic using probabilistic and reliability analyses. It used extrapolations and simulations to derive maximum load effects for time periods ranging from 1 day to 75 years. Limited fatigue tests were conducted and probabilistic and reliability analyses were carried out on the strengthened concrete bridge deck specimens to predict the extended fatigue life. Analysis results indicated that strengthened concrete decks provide sufficient resistance against increasing truck loads during the service life of a bridge.

T-section glulam timber bridge modules : modeling and performance

Science.gov (United States)

Paul A. Morgan; Steven E. Taylor; Michael A. Ritter; John M. Franklin

1999-01-01

This paper describes the design, modeling, and testing of two portable timber bridges, each consisting of two noninterconnected longitudinal glued-laminated timber (glulam) deck panels 1.8 m (6 ft) wide. One bridge is 12.2 m (40 ft) long while the other bridge is 10.7 m (35 ft) long. The deck panels are fabricated in a unique double-tee cross section. The bridges...

Embodied Energy Optimization of Prestressed Concrete Slab Bridge Decks

Directory of Open Access Journals (Sweden)

Julián Alcalá

2018-04-01

Full Text Available This paper presents one approach to the analysis and design of post-tensioned cast-in-place concrete slab bridge decks. A Simulated Annealing algorithm is applied to two objective functions: (i the economic cost; and (ii the embodied energy at different stages of production materials, transport, and construction. The problem involved 33 discrete design variables: five geometrical ones dealing with the thickness of the slab, the inner and exterior web width, and two flange thicknesses; concrete type; prestressing cables, and 26 variables for the reinforcement set-up. The comparison of the results obtained shows two different optimum families, which indicates that the traditional criteria of economic optimization leads to inefficient designs considering the embodied energy. The results indicate that the objectives are not competing functions, and that optimum energy designs are close to the optimum cost designs. The analysis also showed that the savings of each kW h of energy consumed carries an extra cost of 0.49€. The best cost solution presents 5.3% more embodied energy. The best energy solution is 9.7% more expensive than that of minor cost. In addition, the results have showed that the best cost solutions are not the best energy solutions.

Integral Abutment and Jointless Bridges

Directory of Open Access Journals (Sweden)

Cristian-Claudiu Comisu

2005-01-01

Full Text Available Integral bridges, or integral abutment and jointless bridges, as they are more commonly known in the USA, are constructed without any movement joints between spans or between spans and abutments. Typically these bridges have stub-type abutments supported on piles and continuous bridge deck from one embankment to the other. Foundations are usually designed to be small and flexible to facilitate horizontal movement or rocking of the support. Integrally bridges are simple or multiple span ones that have their superstructure cast integrally with their substructure. The jointless bridges cost less to construct and require less maintenance then equivalent bridges with expansion joints. Integral bridges present a challenge for load distribution calculations because the bridge deck, piers, abutments, embankments and soil must all be considered as single compliant system. This paper presents some of the important features of integral abutment and jointless bridge design and some guidelines to achieve improved design. The goal of this paper is to enhance the awareness among the engineering community to use integral abutment and jointless bridges in Romania.

Experimental Investigation of a Self-Sensing Hybrid GFRP-Concrete Bridge Superstructure with Embedded FBG Sensors

OpenAIRE

Wang, Yanlei; Li, Yunyu; Ran, Jianghua; Cao, Mingmin

2012-01-01

A self-sensing hybrid GFRP-concrete bridge superstructure, which consists of two bridge decks and each bridge deck is comprised of four GFRP box sections combined with a thin layer of concrete in the compression zone, was developed by using eight embedded FBG sensors in the top and bottom flanges of the four GFRP box sections at midspan section of one bridge deck along longitudinal direction, respectively. The proposed self-sensing hybrid bridge superstructure was tested in 4-point loading to...

Super-Light Prefabricated Deck Element Integrated in Traditional Concrete Prefabricated Element Construction

DEFF Research Database (Denmark)

Christensen, Jacob Ellehauge; Hertz, Kristian Dahl

Super-light structures in form of deck elements have been used for the first time in a building to construct indoor pedestrian bridges. Examples of connections to external structures and other super-light deck elements are given along with other details. Other examples on the great versatility...

reliability assessment of stringers spacings in bridges as function

African Journals Online (AJOL)

user

A timber bridge deck is modelled on timber stringers in accordance with current .... simple linear formulation for supporting stringers ... new generation design codes, evaluation of existing ... transverse plank deck the span of the deck is.

Influence of Pavement on Fatigue Performance of Urban Steel Box Girder Deck

Directory of Open Access Journals (Sweden)

Zheng Zhongyue

2016-01-01

Full Text Available Based on spatial finite element analysis method, the Influence of pavement on fatigue performance of orthotropic steel deck was analyzed in terms of pavement system, asphalt pavement stiffness. The result shows that compared with asphalt pavement system, RPC pavement system can not only obviously improve the stress condition of steel bridge deck, but also significantly extend the fatigue life of steel bridge panel; Increasing the stiffness of pavement layer can obviously reduce the stress amplitude of fatigue details, especially for direct contact with the pavement.

Bridge management systems: An asset management tool for road structures

CSIR Research Space (South Africa)

Nordengen, Paul A

2012-10-01

Full Text Available Culverts Ret Walls Buildings Traffic Storm water Etc ? Combined Priorities and Budget Optimised Programme Bridge Project Funding ? Road projects and bridge projects compete for the same ?pot? of funds ? Road failures are more common and more... & retaining walls 18. Longitudinal members 8. Surfacing/ballast (decks & arches) 9. Deck drainage 19. Transverse members 10. Kerbs/sidewalks 20. Deck slabs & arches 11. Parapets & handrails 21. Miscellaneous Condition Survey ? Survey is required...

RECONSTRUCTION AND REINFORCEMENT OF BRIDGE ACROSS THE RIVER. SYLVA IN KUNGUR, RUSSIA

Directory of Open Access Journals (Sweden)

R. Ye. Heizn

2010-04-01

Full Text Available Sylva Bridge at Kungur city is one of the oldest road bridges in Perm region, the West Urals, Russia. Its erection was begun in 1912 and was interrupted with the First World War and the further events in Russia. The bridge was opened only in 1931. For 75 years of bridge operation the most part of bridge constructions has been acquired plural damages, both mechanical and corrosion. After the bridge inspection in 2003 and according to the calculations of its capacity, the decision on reconstruction of the bridge was accepted. The purpose of rehabilitation was to replace the timber deck by steel orthotropic deck with asphalt pavement. A new deck was to be engaged in combined action with the existing metal structures with the help of socles with high-strength bolts. Due to this, the bridge carrying capacity was increased as required by the present standards. In 2006, after tests, the bridge was opened for traffic.

Skateboard deck materials selection

Science.gov (United States)

Liu, Haoyu; Coote, Tasha; Aiolos; Charlie

2018-03-01

The goal of this project was to identify the ideal material for a skateboard deck under 200 in price, minimizing the weight. The material must have a fracture toughness of 5 MPa/m2, have a minimum lifetime of 10, 000 cycles and must not experience brittle fracture. Both single material and hybrid solutions were explored. When further selecting to minimize weight, woods were found to be the best material. Titanium alloy-wood composites were explored to determine the optimal percentage composition of each material.A sandwich panel hybrid of 50% titanium alloy and 50% wood (Ti-Wood) was found to be the optimum material, performing better than the currently used plywood.

Investigation on the performance of bridge approach slab

Directory of Open Access Journals (Sweden)

Abdelrahman Amr

2018-01-01

Full Text Available In Egypt, where highway bridges are to be constructed on soft cohesive soils, the bridge abutments are usually founded on rigid piles, whereas the earth embankments for the bridge approaches are directly founded on the natural soft ground. Consequently, excessive differential settlement frequently occurs between the bridge deck and the bridge approaches resulting in a “bump” at both ends of the bridge deck. Such a bump not only creates a rough and uncomfortable ride but also represents a hazardous condition to traffic. One effective technique to cope with the bump problem is to use a reinforced concrete approach slab to provide a smooth grade transition between the bridge deck and the approach pavement. Investigating the geotechnical and structural performance of approach slabs and revealing the fundamental affecting factors have become mandatory. In this paper, a 2-D finite element model is employed to investigate the performance of approach slabs. Moreover, an extensive parametric study is carried out to appraise the relatively optimum geometries of approach slab, i.e. slab length, thickness, embedded depth and slope, that can yield permissible bumps. Different geo-mechanical conditions of the cohesive foundation soil and the fill material of the bridge embankment are examined.

Structural evaluation of the John A. Roebling Suspension Bridge : element level analysis.

Science.gov (United States)

2008-07-01

The primary objective of the structural evaluation of the John A. Roebling Bridge is to determine the maximum allowable gross vehicle weight (GVW) that can be carried by the bridge deck structural elements such as the open steel grid deck, channels, ...

Seismic performance evaluation of an historical concrete deck arch bridge using survey and drawing of the damages, in situ tests, dynamic identification and pushover analysis

Science.gov (United States)

Bergamo, Otello; Russo, Eleonora; Lodolo, Fabio

2017-07-01

The paper describes the performance evaluation of a retrofit historical multi-span (RC) deck arch bridge analyzed with in situ tests, dynamic identification and FEM analysis. The peculiarity of this case study lies in the structural typology of "San Felice" bridge, an historical concrete arch bridge built in the early 20th century, a quite uncommon feature in Italy. The preservation and retrofit of historic cultural heritage and infrastructures has been carefully analyzed in the international codes governing seismic response. A complete survey of the bridge was carried out prior to sketching a drawing of the existing bridge. Subsequently, the study consists in four steps: material investigation and dynamic vibration tests, FEM analysis and calibration, retrofit assessment, pushover analysis. The aim is to define an innovative approach to calibrate the FEM analysis through modern experimental investigations capable of taking structural deterioration into account, and to offer an appropriate and cost-effective retrofitting strategy.

Numerical investigation of the bearing capacity of transversely prestressed concrete deck slabs

NARCIS (Netherlands)

Amir, S.; Van der Veen, C.; Walraven, J.C.; De Boer, A.

2014-01-01

The research subject of this paper is the bearing capacity of transversely prestressed concrete bridge decks between concrete girders under concentrated loads. Experiments on a 1:2 scale model of this bridge were carried out in the laboratory and a 3D nonlinear finite element model was developed in

The approximation function of bridge deck vibration derived from the measured eigenmodes

Directory of Open Access Journals (Sweden)

Sokol Milan

2017-12-01

Full Text Available This article deals with a method of how to acquire approximate displacement vibration functions. Input values are discrete, experimentally obtained mode shapes. A new improved approximation method based on the modal vibrations of the deck is derived using the least-squares method. An alternative approach to be employed in this paper is to approximate the displacement vibration function by a sum of sine functions whose periodicity is determined by spectral analysis adapted for non-uniformly sampled data and where the parameters of scale and phase are estimated as usual by the least-squares method. Moreover, this periodic component is supplemented by a cubic regression spline (fitted on its residuals that captures individual displacements between piers. The statistical evaluation of the stiffness parameter is performed using more vertical modes obtained from experimental results. The previous method (Sokol and Flesch, 2005, which was derived for near the pier areas, has been enhanced to the whole length of the bridge. The experimental data describing the mode shapes are not appropriate for direct use. Especially the higher derivatives calculated from these data are very sensitive to data precision.

Environmental life cycle assessment of railway bridge materials using UHPFRC

Science.gov (United States)

Bizjak, Karmen Fifer; Šajna, Aljoša; Slanc, Katja; Knez, Friderik

2016-10-01

The railway infrastructure is a very important component of the world's total transportation network. Investment in its construction and maintenance is significant on a global scale. Previously published life cycle assessment (LCA) studies performed on road and rail systems very seldom included infrastructures in detail, mainly choosing to focus on vehicle manufacturing and fuel consumption. This article presents results from an environmental study for railway steel bridge materials for the demonstration case of the Buna Bridge in Croatia. The goal of these analyses was to compare two different types of remediation works for railway bridges with different materials and construction types. In the first part, the environmental impact of the classical concrete bridge construction was calculated, whereas in the second one, an alternative new solution, namely, the strengthening of the old steel bridge with ultra-high-performance fibre-reinforced concrete (UHPFRC) deck, was studied. The results of the LCA show that the new solution with UHPFRC deck gives much better environmental performance. Up to now, results of LCA of railway open lines, railway bridges and tunnels have been published, but detailed analyses of the new solution with UHPFRC deck above the old bridge have not previously been performed.

Guardrails for Use on Historic Bridges: Volume 2—Bridge Deck Overhang Design

OpenAIRE

Frosch, Robert J.; Morel, Adam J.

2016-01-01

Bridges that are designated historic present a special challenge to bridge engineers whenever rehabilitation work or improvements are made to the bridges. Federal and state laws protect historically significant bridges, and railings on these bridges can be subject to protection because of the role they play in aesthetics. Unfortunately, original railings on historic bridges do not typically meet current crash-test requirements and typically do not meet current standards for railing height and...

Development and layout of a protocol for the field performance of concrete deck and crack sealers.

Science.gov (United States)

2009-09-01

The main objective of this project was to develop and layout a protocol for the long-term monitoring and assessment of the performance of concrete deck and crack sealants in the field. To accomplish this goal, a total of six bridge decks were chosen ...

Precast Pearl-Chain concrete arch bridges

DEFF Research Database (Denmark)

Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

2015-01-01

A Pearl-Chain Bridge is a closed-spandrel arch bridge consisting of a number of straight pre-fabricated so called Super-Light Deck elements put together in an arch shape by post-tensioning cables. Several Pearl-Chain arches can be positioned adjacent to each other by a crane to achieve a bridge...... of a desired width. On top of the arch is a filling material to level out the surface of the above road. The filling only transfers vertical loads to the arch. The geometry and material properties of Super-Light Decks are presented, and we refer to several fullscale tests of Pearl-Chain arches where...... the technology was used. We also study other important components and details in the Pearl-Chain Bridge concept and review the effects of different types of loads. A theoretical case study of a circular 30 m span Pearl-Chain Bridge is presented showing the influence of a number of parameters: The number of post...

Bridges analysis, design, structural health monitoring, and rehabilitation

CERN Document Server

Bakht, Baidar

2015-01-01

This book offers a valuable guide for practicing bridge engineers and graduate students in structural engineering; its main purpose is to present the latest concepts in bridge engineering in fairly easy-to-follow terms. The book provides details of easy-to-use computer programs for: ·      Analysing slab-on-girder bridges for live load distribution. ·      Analysing slab and other solid bridge components for live load distribution. ·      Analysing and designing concrete deck slab overhangs of girder bridges under vehicular loads. ·      Determining the failure loads of concrete deck slabs of girder bridges under concentrated wheel loads. In addition, the book includes extensive chapters dealing with the design of wood bridges and soil-steel bridges. Further, a unique chapter on structural health monitoring (SHM) will help bridge engineers determine the actual load carrying capacities of bridges, as opposed to their perceived analytical capacities. The chapter addressing structures...

Field performance of timber bridges. 13, Mohawk Canal stress-laminated bridge

Science.gov (United States)

P. D. Hilbrich Lee; X. Lauderdale

The Mohawk Canal bridge was constructed in August 1994, just outside Roll, Arizona. It is a simple-span, double-lane, stress-laminated deck superstructure, approximately 6.4 m (21 ft) long and 10.4 m (34 ft) wide and constructed with Combination 16F-V3 Douglas Fir glued-laminated timber beam laminations. The performance of the bridge was monitored continuously for 2...

Light-weight aluminium bridges and bridge decks. An overview of recent applications

NARCIS (Netherlands)

Maljaars, J.; Soetens, F.; Kluyver, D. de

2008-01-01

The last decades have shown a large increase in the application of aluminium alloys for light-weight bridges. For bridge construction, aluminium alloys have some specific advantages, but also some points of attention. This paper deals with some recent projects of aluminium bridges, and for these

Investigation of Influence Factors of Wind-Induced Buffeting Response of a Six-Tower Cable-Stayed Bridge

Directory of Open Access Journals (Sweden)

Zhi-Qiang Zhang

2016-01-01

Full Text Available This paper presents an investigation of the wind-induced buffeting responses of the Jiashao Bridge, the longest multispan cable-stayed bridge in the world. A three-dimensional finite element model for the Jiashao Bridge is established using the commercial software package ANSYS and a 3D fluctuating wind field is simulated for both bridge deck and towers. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS with the aeroelastic effect included. The characteristics of buffeting responses of the six-tower cable-stayed bridge are studied in some detail, focusing on the effects including the difference in the longitudinal stiffness between the side towers and central towers, partially longitudinal constraints between the bridge deck and part of bridge towers, self-excited aerodynamic forces, and the rigid hinge installed in the middle of the bridge deck. The analytical results can provide valuable references for wind-resistant design of multispan cable-stayed bridges in the future.

Analysis on Adhesively-Bonded Joints of FRP-steel Composite Bridge under Combined Loading: Arcan Test Study and Numerical Modeling

Directory of Open Access Journals (Sweden)

Xu Jiang

2016-01-01

Full Text Available The research presented in this paper is an experimental study and numerical analysis on mechanical behavior of the adhesively-bonded joint between FRP sandwich bridge deck and steel girder. Generally, there are three typical stress states in the adhesively-bonded joint: shear stress, tensile stress, and combination of both. To realize these stress states in the adhesively-bonded joint during tests, a specific loading device is developed with the capacity of providing six different loading angles, which are 0°(pure tension, 18°, 36°, 54°, 72° and 90°(pure shear. Failure modes of adhesively-bonded joints are investigated. It indicates that, for the pure shear loading, the failure mode is the cohesive failure (near the interface between the adhesive layer and the steel support in the adhesive layer. For the pure tensile and combined loading conditions, the failure mode is the combination of fiber breaking, FRP delamination and interfacial adhesion failure between the FRP sandwich deck and the adhesive layer. The load-bearing capacities of adhesive joints under combined loading are much lower than those of the pure tensile and pure shear loading conditions. According to the test results of six angle loading conditions, a tensile/shear failure criterion of the adhesively-bonded joint is obtained. By using Finite Element (FE modeling method, linear elastic simulations are performed to characterize the stress distribution throughout the adhesively-bonded joint.

Timber in Bridge Structures

OpenAIRE

Detkin, Viktoria

2016-01-01

The purpose of this final year project was to study the properties of timber as a structural material and the suitability of wood in load bearing members for bridge structures. For a case study, an existing timber bridge was selected. Due to its condition the bridge should be replaced. The design of a new bridge with steel beams holding a glulam deck was made. During the case study the replacement of steel beams by glulam timber ones was discussed. Some calculations were made in order to ...

Compressive Membrane Action in Prestressed Concrete Deck Slabs

NARCIS (Netherlands)

Amir, S.

2014-01-01

One of the most important questions that structural engineers all over the world are dealing with is the safety of the existing structures. In the Netherlands, there are a large number of transversely prestressed bridge decks that have been built in the last century and now need to be investigated

Environmental life cycle assessment of railway bridge materials using UHPFRC

Directory of Open Access Journals (Sweden)

Bizjak Karmen Fifer

2016-10-01

Full Text Available The railway infrastructure is a very important component of the world’s total transportation network. Investment in its construction and maintenance is significant on a global scale. Previously published life cycle assessment (LCA studies performed on road and rail systems very seldom included infrastructures in detail, mainly choosing to focus on vehicle manufacturing and fuel consumption. This article presents results from an environmental study for railway steel bridge materials for the demonstration case of the Buna Bridge in Croatia. The goal of these analyses was to compare two different types of remediation works for railway bridges with different materials and construction types. In the first part, the environmental impact of the classical concrete bridge construction was calculated, whereas in the second one, an alternative new solution, namely, the strengthening of the old steel bridge with ultra-high-performance fibre-reinforced concrete (UHPFRC deck, was studied. The results of the LCA show that the new solution with UHPFRC deck gives much better environmental performance. Up to now, results of LCA of railway open lines, railway bridges and tunnels have been published, but detailed analyses of the new solution with UHPFRC deck above the old bridge have not previously been performed.

Estimating bridge stiffness using a forced-vibration technique for timber bridge health monitoring

Science.gov (United States)

James P. Wacker; Xiping Wang; Brian Brashaw; Robert J. Ross

2006-01-01

This paper describes an effort to refine a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the frequency response of several simple-span, sawn timber beam (with plank deck) bridges located in St. Louis County, Minnesota. Static load deflections were also measured to...

Bridge deck surface temperature monitoring by infrared thermography and inner structure identification using PPT and PCT analysis methods

Science.gov (United States)

Dumoulin, Jean

2013-04-01

One of the objectives of ISTIMES project was to evaluate the potentialities offered by the integration of different electromagnetic techniques able to perform non-invasive diagnostics for surveillance and monitoring of transport infrastructures. Among the EM methods investigated, we focused our research and development efforts on uncooled infrared camera techniques due to their promising potential level of dissemination linked to their relative low cost on the market. On the other hand, works were also carried out to identify well adapted implementation protocols and key limits of Pulse Phase Thermography (PPT) and Principal Component Thermography (PCT) processing methods to analyse thermal image sequence and retrieve information about the inner structure. So the first part of this research works addresses infrared thermography measurement when it is used in quantitative mode (not in laboratory conditions) and not in qualitative mode (vision applied to survey). In such context, it requires to process in real time thermal radiative corrections on raw data acquired to take into account influences of natural environment evolution with time, thanks to additional measurements. But, camera sensor has to be enough smart to apply in real time calibration law and radiometric corrections in a varying atmosphere. So, a complete measurement system was studied and developed [1] with low cost infrared cameras available on the market. In the system developed, infrared camera is coupled with other sensors to feed simplified radiative models running, in real time, on GPU available on small PC. The whole measurement system was implemented on the "Musmeci" bridge located in Potenza (Italy). No traffic interruption was required during the mounting of our measurement system. The infrared camera was fixed on top of a mast at 6 m elevation from the surface of the bridge deck. A small weather station was added on the same mast at 1 m under the camera. A GPS antenna was also fixed at the

Reduction of a cerium(III) siloxide complex to afford a quadruple-decker arene-bridged cerium(II) sandwich

Energy Technology Data Exchange (ETDEWEB)

Kelly, Rory P.; Scopelliti, Rosario; Mazzanti, Marinella [Institut des Sciences et Ingenierie Chimiques, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Maron, Laurent [Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquees, Toulouse (France)

2017-12-04

Organometallic multi-decker sandwich complexes containing f-elements remain rare, despite their attractive magnetic and electronic properties. The reduction of the Ce{sup III} siloxide complex, [KCeL{sub 4}] (1; L=OSi(OtBu){sub 3}), with excess potassium in a THF/toluene mixture afforded a quadruple-decker arene-bridged complex, [K(2.2.2-crypt)]{sub 2}[{(KL_3Ce)(μ-η"6:η"6-C_7H_8)}{sub 2}Ce] (3). The structure of 3 features a [Ce(C{sub 7}H{sub 8}){sub 2}] sandwich capped by [KL{sub 3}Ce] moieties with a linear arrangement of the Ce ions. Structural parameters, UV/Vis/NIR data, and DFT studies indicate the presence of Ce{sup II} ions involved in δ bonding between the Ce cations and toluene dianions. Complex 3 is a rare lanthanide multi-decker complex and the first containing non-classical divalent lanthanide ions. Moreover, oxidation of 1 by AgOTf (OTf=O{sub 3}SCF{sub 3}) yielded the Ce{sup IV} complex, [CeL{sub 4}] (2), showing that siloxide ligands can stabilize Ce in three oxidation states. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Wind tunnel test of musi VI bridge

Science.gov (United States)

Permata, Robby; Andika, Matza Gusto; Syariefatunnisa, Risdhiawan, Eri; Hermawan, Budi; Noordiana, Indra

2017-11-01

Musi VI Bridge is planned to cross the Musi River in Palembang City, South Sumatera Province, Indonesia. The main span is a steel arch type with 200 m length and side span length is 75 m. Finite element analysis results showed that the bridge has frequency ratio for torsional and heaving mode (torsional frequency/heaving frequency)=1.14. This close to unity value rises concern about aerodynamic behaviour and stability of the bridge deck under wind loading. Sectional static and free vibration wind tunnel test were performed to clarify this phenomena in B2TA3 facility in Serpong, Indonesia. The test followed the draft of Guide of Wind Tunnel Test for Bridges developed by Indonesian Ministry of Public Works. Results from wind tunnel testing show that the bridge is safe from flutter instability and no coupled motion vibration observed. Therefore, low value of frequency ratio has no effect to aerodynamic behaviour of the bridge deck. Vortex-induced vibration in heaving mode occurred in relatively low wind velocity with permissible maximum amplitude value.

Soil-structure interaction studies for understanding the behavior of integral abutment bridges.

Science.gov (United States)

2012-03-01

Integral Abutment Bridges (IAB) are bridges without any joints within the bridge deck or between the : superstructure and the abutments. An IAB provides many advantages during construction and maintenance of : a bridge. Soil-structure interactions at...

History of cable-stayed bridges

DEFF Research Database (Denmark)

Gimsing, Niels Jørgen

1999-01-01

The principle of supporting a bridge deck by inclined tension members leading to towers on either side of the span has been known for centuries. However, the real development of cable-stayed bridges did not begin before the 1950s. Since then the free span has been increased from 183 m in the Strö...

Effects of ambient temperature changes on integral bridges.

Science.gov (United States)

2008-09-01

Integral bridges (IBs) are jointless bridges whereby the deck is continuous and monolithic with abutment walls. IBs are outperforming their non-integral counterparts in economy and safety. Their principal advantages are derived from the absence of ex...

Railway bridge monitoring during construction and sliding

Science.gov (United States)

Inaudi, Daniele; Casanova, Nicoletta; Kronenberg, Pascal; Vurpillot, Samuel

1997-05-01

The Moesa railway bridge is a composite steel concrete bridge on three spans of 30 m each. The 50 cm thick concrete deck is supported on the lower flanges of two continuous, 2.7 m high I-beams. The bridge has been constructed alongside an old metallic bridge. After demolishing this one, the new bridge has been slid for 5 m by 4 hydraulic jacks and positioned on the refurbished piles of the old bridge. About 30 fiber optic, low-coherence sensors were imbedded in the concrete deck to monitor its deformations during concrete setting and shrinkage, as well as during the bridge sliding phase. In the days following concrete pour it was possible to follow its thermal expansion due to the exothermic setting reaction and the following thermal and during shrinkage. The deformations induced by the additional load produced by the successive concreting phases were also observed. During the bridge push, which extended over six hours, the embedded and surface mounted sensors allowed the monitoring of the curvature variations in the horizontal plane due to the slightly uneven progression of the jacks. Excessive curvature and the resulting cracking of concrete could be ruled out by these measurements. It was also possible to observe the bridge elongation under the heating action of the sun.

Punching shear strength of transversely prestressed concrete decks

NARCIS (Netherlands)

Amir, S.; Van der Veen, C.; Walraven, J.C.

2012-01-01

In the Netherlands, there is a need to determine the capacity of bridge decks as a large number of them were built back in the 60’s and 70’s. Since then, not only a lot of additional safety requirements have been incorporated into the modern codes but the traffic flow has also increased drastically.

Improvement of fatigue properties of orthotropic decks

Czech Academy of Sciences Publication Activity Database

Frýba, Ladislav; Urushadze, Shota

2011-01-01

Roč. 33, č. 4 (2011), s. 1166-1169 ISSN 0141-0296 R&D Projects: GA ČR GA103/08/1340; GA MŠk(CZ) 7E08098 Grant - others:BRIFAG -Bridge Fatigue Guidance(XE) RFSR_CT-2008-00033 Institutional research plan: CEZ:AV0Z20710524 Keywords : orthotropic deck * fatigue * prolonged life Subject RIV: JM - Building Engineering Impact factor: 1.351, year: 2011

Investigation of early timber–concrete composite bridges in the United States

Science.gov (United States)

James P. Wacker; Alfredo Dias; Travis K. Hosteng

2017-01-01

The use of timber–concrete composite (TCC) bridges in the United States dates back to circa 1925. Two different TCC systems were constructed during this early period. The first system included a longitudinal nail-laminated deck composite with a concrete deck top layer. The second system included sawn timber stringers supporting a concrete deck top layer. Records...

Assessment of concrete bridge decks with alkali silica reactions

DEFF Research Database (Denmark)

Eriksen, Kirsten; Jansson, Jacob; Geiker, Mette Rica

2008-01-01

Based on investigations of concrete from an approximately 40 years old bridge a procedure to support the management of maintenance and repair of alkali silica damaged bridges is proposed. Combined petrography and accelerated expansion testing were undertaken on cores from the Bridge at Skovdiget......, Bagsværd, Denmark to provide information on the damage condition as well as the residual reactivity of the concrete. The Danish Road Directory’s guidelines for inspection and assessment of alkali silica damaged bridges will be briefly presented, and proposed modifications will be describe...

Cost and Ecological Feasibility of using UHPC in Highway Bridges

Science.gov (United States)

2017-11-15

There is a growing interest in expanding the use of Ultra-high performance concrete (UHPC) from bridge deck joints for accelerated bridge construction to complex architectural and advanced structural applications. The high costs currently associated ...

Structure-borne noise of railway composite bridge: Numerical simulation and experimental validation

Science.gov (United States)

Li, Xiaozhen; Liu, Quanmin; Pei, Shiling; Song, Lizhong; Zhang, Xun

2015-09-01

In order to investigate the characteristics of the noise from steel-concrete composite bridges under high-speed train loading, a model used to predict the bridge-borne noise is established and validated through a field experiment. The numerical model for noise prediction is developed based on the combination of spatial train-track-bridge coupled vibration theory and Statistical Energy Analysis (SEA). Firstly, train-track-bridge coupled vibration is adopted to obtain the velocity time history of the bridge deck vibration. Then, the velocity time history is transferred into frequency domain through FFT to serve as the vibratory energy of SEA deck subsystems. Finally, the transmission of the vibratory energy is obtained by solving the energy balance equations of SEA, and the sound radiation is computed using the vibro-acoustic theory. The numerically computed noise level is verified by a field measurement. It is determined that the dominant frequency of steel-concrete composite bridge-borne noise is 20-1000 Hz. The noise from the bottom flange of steel longitudinal girder is less than other components in the whole frequency bands, while the noise from web of steel longitudinal girder is dominant in high frequency range above 315 Hz. The noise from concrete deck dominates in low-frequency domain ranges from 80 Hz to 160 Hz.

Load Distribution Factors for Composite Multicell Box Girder Bridges

Science.gov (United States)

Tiwari, Sanjay; Bhargava, Pradeep

2017-12-01

Cellular steel section composite with a concrete deck is one of the most suitable superstructures in resisting torsional and warping effects induced by highway loading. This type of structure has inherently created new design problems for engineers in estimating its load distribution when subjected to moving vehicles. Indian Codes of Practice does not provide any specific guidelines for the design of straight composite concrete deck-steel multi-cell bridges. To meet the practical requirements arising during the design process, a simple design method is needed for straight composite multi-cell bridges in the form of load distribution factors for moment and shear. This work presents load distribution characteristics of straight composite multi-cell box girder bridges under IRC trains of loads.

Tailoring Sandwich Face/Core Interfaces for Improved Damage Tolerance

DEFF Research Database (Denmark)

Lundsgaard-Larsen, Christian; Berggreen, Christian; Carlsson, Leif A.

2010-01-01

Various modifications of the face/core interface in foam core sandwich specimens are examined in a series of two papers. This paper constitutes part I and describes the finite element analysis of a sandwich test specimen, i.e. a DCB specimen loaded by uneven bending moments (DCB-UBM). Using...... this test almost any mode-mixity between pure mode I and mode II can be obtained. A cohesive zone model of the mixed mode fracture process involving large-scale bridging is developed. Results from the analysis are used in Part II, which describes methods and results of a series of experiments....

Development of a precast bridge deck overhang system for the rock creek bridge.

Science.gov (United States)

2008-12-01

Precast, prestressed panels are commonly used at interior beams for bridges in Texas. The use of these : panels provides ease of construction, sufficient capacity, and good economy for the construction of : bridges in Texas. Current practice for the ...

Passive Control System for Mitigation of Longitudinal Buffeting Responses of a Six-Tower Cable-Stayed Bridge

Directory of Open Access Journals (Sweden)

Fangfang Geng

2016-01-01

Full Text Available This paper presents an investigation of mitigation of longitudinal buffeting responses of the Jiashao Bridge, the longest multispan cable-stayed bridge in the world. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS with the aeroelastic effect included. The characteristics of longitudinal buffeting responses of the six-tower cable-stayed bridge are studied in some detail, focusing on the effects of insufficient longitudinal stiffness of central towers and partially longitudinal constraints between the bridge deck and part of bridge towers. The effectiveness of viscous fluid dampers on the mitigation of longitudinal buffeting responses of the bridge is further investigated and a multiobjective optimization design method that uses a nondominating sort genetic algorithm II (NSGA-II is used to optimize parameters of the viscous fluid dampers. The results of the parametric investigations show that, by appropriate use of viscous fluid dampers, the top displacements of central towers and base forces of bridge towers longitudinally restricted with the bridge deck can be reduced significantly, with hampering the significant gain achieved in the base forces of bridge towers longitudinally unrestricted with the bridge deck. And the optimized parameters for the viscous fluid dampers can be determined from Pareto-optimal fronts using the NSGA-II that can satisfy the desired performance requirements.

On the typography of flight-deck documentation

Science.gov (United States)

Degani, Asaf

1992-01-01

Many types of paper documentation are employed on the flight-deck. They range from a simple checklist card to a bulky Aircraft Flight Manual (AFM). Some of these documentations have typographical and graphical deficiencies; yet, many cockpit tasks such as conducting checklists, way-point entry, limitations and performance calculations, and many more, require the use of these documents. Moreover, during emergency and abnormal situations, the flight crews' effectiveness in combating the situation is highly dependent on such documentation; accessing and reading procedures has a significant impact on flight safety. Although flight-deck documentation are an important (and sometimes critical) form of display in the modern cockpit, there is a dearth of information on how to effectively design these displays. The object of this report is to provide a summary of the available literature regarding the design and typographical aspects of printed matter. The report attempts 'to bridge' the gap between basic research about typography, and the kind of information needed by designers of flight-deck documentation. The report focuses on typographical factors such as type-faces, character height, use of lower- and upper-case characters, line length, and spacing. Some graphical aspects such as layout, color coding, fonts, and character contrast are also discussed. In addition, several aspects of cockpit reading conditions such as glare, angular alignment, and paper quality are addressed. Finally, a list of recommendations for the graphical design of flight-deck documentation is provided.

On the use of a woven mat to control the crack path in composite sandwich structures

DEFF Research Database (Denmark)

Lundsgaard-Larsen, Christian; Berggreen, Christian; Carlsson, Leif A.

2008-01-01

tractionsbetween the separated crack surfaces [4, 5]. The outline of a crack propagating under large scale bridging in a sandwich structure can be seen in Figure 1. The fiber bridging mechanism possesses an increased potential damage tolerance capacity for the sandwich structure if it can be predicatively....... The sign of the moment ratio can be reversed by changing the mounting direction of the wire. If moments with opposite signs are applied e.g. M1/M2 = -1, crack opening in the normal direction is dominating (mode I). If moments with the same sign are applied the crack opening in the tangential direction...

Utilization of bagasse and coconut fibers waste as fillers of sandwich composite for bridge railway sleepers

Science.gov (United States)

Soehardjo, K. A.; Basuki, A.

2017-07-01

The bridge railway sleepers is an essential component in the construction of railways, as the foundation of the rail support in order to withstand the load a train that runs above it. Sleepers used in bridge construction are expected to have a longer service life, lighter weight and durable so that can be used more efficient. This research was carried out to create a model of bridges railway sleepers made of sandwich structured composite from fiber glass, epoxy resin with fillers waste of bagasse (sugar cane pulp mill) or coconut fiberboard (copra industry) that using polyurethane as an adhesive. The process of making was conditioned for small and medium industrial applications. Railway sleepers’ specifications adapted to meet the requirements of end user. The process steps in this research include; lay-up fiberglass combined with bagasse/coconut fiberboard (as fillers), gluing with epoxy resin, molded it with pressure to be solid, curing after solidification process. The specimens of composite, bagasse and coconut fiber board were tested for tensile and compressive strength. The prototype were tested of mechanical test: flexural moment test to the stand rail, flexural moment test to the middle of the sleepers and tensile strength test on one side of the sleepers, in accordance to SNI 11-3388-1994 Method testing of single block concrete sleepers and bearing single rail fastening systems. The results of mechanical testing all variations meet the technical specifications of end user such as test results for flexural moment on all prototypes, after load test, there is no visible crack. While in the tensile strength test, it seem the prototype with coconut fiberboard filler, shows better performance than bagasse fiberboard filler, the decisions is just depended on techno economic and lifetime.

Bridge Deck Runoff: Water Quality Analysis and BMP Effectiveness

Science.gov (United States)

2010-12-01

The Alaska Department of Transportation (ADOT) is responsible for more than 700 bridges - most span water bodies. Are these water bodies affected by stormwater runoff from ADOT bridges? What are the regulatory and economic constraints on the ADOT reg...

Precast concrete elements for accelerated bridge construction : laboratory testing of precast substructure components, Boone County bridge.

Science.gov (United States)

2009-01-01

Vol. 1-1: In July 2006, construction began on an accelerated bridge project in Boone County, Iowa that was composed of precast substructure : elements and an innovative, precast deck panel system. The superstructure system consisted of full-depth dec...

Golden Gate Bridge response: a study with low-amplitude data from three earthquakes

Science.gov (United States)

Çelebi, Mehmet

2012-01-01

The dynamic response of the Golden Gate Bridge, located north of San Francisco, CA, has been studied previously using ambient vibration data and finite element models. Since permanent seismic instrumentation was installed in 1993, only small earthquakes that originated at distances varying between ~11 to 122 km have been recorded. Nonetheless, these records prompted this study of the response of the bridge to low amplitude shaking caused by three earthquakes. Compared to previous ambient vibration studies, the earthquake response data reveal a slightly higher fundamental frequency (shorter-period) for vertical vibration of the bridge deck center span (~7.7–8.3 s versus 8.2–10.6 s), and a much higher fundamental frequency (shorter period) for the transverse direction of the deck (~11.24–16.3 s versus ~18.2 s). In this study, it is also shown that these two periods are dominant apparent periods representing interaction between tower, cable, and deck.

The future of rapid bridge deck replacement.

Science.gov (United States)

2015-06-01

Replacing aging, deteriorated infrastructure often requires road closures and traffic detours which impose : inconvenience and delay on commerce and members of the motoring public. Accelerated bridge construction : techniques often use precast member...

Pennsylvania hardwood timber bridges : field performance after 10 years

Science.gov (United States)

James P. Wacker; Carlito Calil

2004-01-01

Several hardwood demonstration timber bridges were built by the Pennsylvania Department of Transportation in the early nineteen nineties. These bridge superstructures are of the recently developed stress-laminated deck design-type using Red Oak lumber laminations that were pressure-treated with creosote preservatives. This paper will describe the data acquisition...

Track-Bridge Longitudinal Interaction of Continuous Welded Rails on Arch Bridge

Directory of Open Access Journals (Sweden)

Rong Chen

2013-01-01

Full Text Available Taking arch bridges, including deck, half-through, and through arch bridges (short for DAB, HTAB, and TAB as examples, mechanics analysis models of longitudinal interaction between continuously welded rails (short for CWRs and arch bridges are established. Based on the finite element method (FEM, the longitudinal interaction calculation software of CWR on arch bridges has been developed. Focusing on an HTAB, the tension, compression, and deflection conditions are calculated and analyzed. The results show that the mechanics analysis models of three types of arch bridges can truly reflect the real state of the structure; the calculation software can be used for systematic research of the CWR on arch bridge; as for HTAB, temperature difference of arch rib has a small effect on rail tension/compression, and arch bridge can be simplified as a continuous beam for rail tension/compression additional force calculation; in calculation of deflection conditions of HTAB, it is suggested that train loads are arranged on half span and full span and take the direction of load entering bridge into account. Additionally, the deflection additional force variation of CFST basket handle arch bridge is different from that of ordinary bridge.

Evaluation of concrete bridge mix designs for control of cracking, phase I.

Science.gov (United States)

2014-11-01

Cracking of concrete is a common problem with concrete structures such as bridge decks, pavements and bridge : rail. The Agency of Transportation (VTrans) has recently invested in higher performing concrete mixes that are : more impervious and has hi...

Standard plans for timber bridge superstructures

Science.gov (United States)

James P. Wacker; Matthew S. Smith

2001-01-01

These standardized bridge plans are for superstructures consisting of treated timber. Seven superstructure types are includes: five longitudinal and two transverse deck systems. Both HS520 and HS25 loadings are included, along with L/360 and L/500 deflection criteria.

Probabilistic and sensitivity analysis of Botlek Bridge structures

Directory of Open Access Journals (Sweden)

Králik Juraj

2017-01-01

Full Text Available This paper deals with the probabilistic and sensitivity analysis of the largest movable lift bridge of the world. The bridge system consists of six reinforced concrete pylons and two steel decks 4000 tons weight each connected through ropes with counterweights. The paper focuses the probabilistic and sensitivity analysis as the base of dynamic study in design process of the bridge. The results had a high importance for practical application and design of the bridge. The model and resistance uncertainties were taken into account in LHS simulation method.

Special Fluid Viscous Dampers For The Messina Strait Bridge

International Nuclear Information System (INIS)

Colato, Gian Paolo; Infanti, Samuele; Castellano, Maria Gabriella

2008-01-01

The Messina Strait Bridge would be the world's longest suspension bridge, with a design earthquake characterised by a PGA value of 0.58 g and a distance between the ipocenter and the bridge of 15 km. Said critical structure of course would need a suitable restraint system for traffic braking loads, wind and seismic actions. Each type of load requires a specific behaviour of the restraint system, making its design a big challenge.The restraint system comprises special types of fluid viscous dampers, installed both in longitudinal and transverse direction, both at the towers and at the anchorages. In seismic conditions they behave as viscous dampers, to reduce the forces on the structural elements and the movements of the bridge deck. But in service dynamic conditions, e.g. under traffic or wind load, the devices shall behave like shock transmission units, thus preventing the longitudinal and transverse movements of the deck.FIP Industriale cooperated with the selected General Contractor, a consortium lead by Impregilo, in the design of said viscous dampers. This paper describes the main features of said devices

Performance of stress-laminated timber highway bridges in cold climates

Science.gov (United States)

James P. Wacker

2009-01-01

This paper summarizes recent laboratory and field data studies on thermal performance of stress-laminated timber highway bridges. Concerns about the reliability of stress-laminated deck bridges when exposed to sub-freezing temperatures triggered several investigations. Two laboratory studies were conducted to study the effects of wood species, preservative, moisture...

Is deck B a disadvantageous deck in the Iowa Gambling Task?

Directory of Open Access Journals (Sweden)

Chiu Yao-Chu

2007-03-01

Full Text Available Abstract Background The Iowa gambling task is a popular test for examining monetary decision behavior under uncertainty. According to Dunn et al. review article, the difficult-to-explain phenomenon of "prominent deck B" was revealed, namely that normal decision makers prefer bad final-outcome deck B to good final-outcome decks C or D. This phenomenon was demonstrated especially clearly by Wilder et al. and Toplak et al. The "prominent deck B" phenomenon is inconsistent with the basic assumption in the IGT; however, most IGT-related studies utilized the "summation" of bad decks A and B when presenting their data, thereby avoiding the problems associated with deck B. Methods To verify the "prominent deck B" phenomenon, this study launched a two-stage simple version IGT, namely, an AACC and BBDD version, which possesses a balanced gain-loss structure between advantageous and disadvantageous decks and facilitates monitoring of participant preferences after the first 100 trials. Results The experimental results suggested that the "prominent deck B" phenomenon exists in the IGT. Moreover, participants cannot suppress their preference for deck B under the uncertain condition, even during the second stage of the game. Although this result is incongruent with the basic assumption in IGT, an increasing number of studies are finding similar results. The results of the AACC and BBDD versions can be congruent with the decision literatures in terms of gain-loss frequency. Conclusion Based on the experimental findings, participants can apply the "gain-stay, loss-shift" strategy to overcome situations involving uncertainty. This investigation found that the largest loss in the IGT did not inspire decision makers to avoid choosing bad deck B.

Parametrically excited oscillation of stay cable and its control in cable-stayed bridges.

Science.gov (United States)

Sun, Bing-nan; Wang, Zhi-gang; Ko, J M; Ni, Y Q

2003-01-01

This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.

Coupling vibration research on Vehicle-bridge system

Science.gov (United States)

Zhou, Jiguo; Wang, Guihua

2018-01-01

The vehicle-bridge coupling system forms when vehicle running on a bridge. It will generate a relatively large influence on the driving comfort and driving safe when the vibration of the vehicle is bigger. A three-dimensional vehicle-bridge system with biaxial seven degrees of freedom has been establish in this paper based on finite numerical simulation. Adopting the finite element transient numerical simulation to realize the numerical simulation of vehicle-bridge system coupling vibration. Then, analyze the dynamic response of vehicle and bridge while different numbers of vehicles running on the bridge. Got the variation rule of vertical vibration of car body and bridge, and that of the contact force between the wheel and bridge deck. The research results have a reference value for the analysis about the vehicle running on a large-span cabled bridge.

Polyurethane foam infill for fiber-reinforced polymer (FRP) bridge deck panels.

Science.gov (United States)

2014-05-01

Although still in their infancy, fiber-reinforced polymer (FRP) bridges have shown great promise in eliminating corrosion : concerns and meeting (or exceeding) FHWAs goal of 100-year life spans for bridges. While FRP bridges are cost-effective in ...

A new multiconstraint method for determining the optimal cable stresses in cable-stayed bridges.

Science.gov (United States)

Asgari, B; Osman, S A; Adnan, A

2014-01-01

Cable-stayed bridges are one of the most popular types of long-span bridges. The structural behaviour of cable-stayed bridges is sensitive to the load distribution between the girder, pylons, and cables. The determination of pretensioning cable stresses is critical in the cable-stayed bridge design procedure. By finding the optimum stresses in cables, the load and moment distribution of the bridge can be improved. In recent years, different research works have studied iterative and modern methods to find optimum stresses of cables. However, most of the proposed methods have limitations in optimising the structural performance of cable-stayed bridges. This paper presents a multiconstraint optimisation method to specify the optimum cable forces in cable-stayed bridges. The proposed optimisation method produces less bending moments and stresses in the bridge members and requires shorter simulation time than other proposed methods. The results of comparative study show that the proposed method is more successful in restricting the deck and pylon displacements and providing uniform deck moment distribution than unit load method (ULM). The final design of cable-stayed bridges can be optimised considerably through proposed multiconstraint optimisation method.

A New Multiconstraint Method for Determining the Optimal Cable Stresses in Cable-Stayed Bridges

Directory of Open Access Journals (Sweden)

B. Asgari

2014-01-01

Full Text Available Cable-stayed bridges are one of the most popular types of long-span bridges. The structural behaviour of cable-stayed bridges is sensitive to the load distribution between the girder, pylons, and cables. The determination of pretensioning cable stresses is critical in the cable-stayed bridge design procedure. By finding the optimum stresses in cables, the load and moment distribution of the bridge can be improved. In recent years, different research works have studied iterative and modern methods to find optimum stresses of cables. However, most of the proposed methods have limitations in optimising the structural performance of cable-stayed bridges. This paper presents a multiconstraint optimisation method to specify the optimum cable forces in cable-stayed bridges. The proposed optimisation method produces less bending moments and stresses in the bridge members and requires shorter simulation time than other proposed methods. The results of comparative study show that the proposed method is more successful in restricting the deck and pylon displacements and providing uniform deck moment distribution than unit load method (ULM. The final design of cable-stayed bridges can be optimised considerably through proposed multiconstraint optimisation method.

Design and Analysis of Collapsible Scissor Bridge

Directory of Open Access Journals (Sweden)

Biro Mohamad Nabil Aklif

2018-01-01

Full Text Available Collapsible scissor bridge is a portable bridge that can be deployed during emergency state to access remote areas that are affected by disaster such as flood. The objective of this research is to design a collapsible scissor bridge which is able to be transported by a 4x4 vehicle and to be deployed to connect remote areas. The design is done by using Solidworks and numerical analysis for structural strength is conducted via ANSYS. The research starts with parameters setting and modelling. Finite element analysis is conducted to analyze the strength by determining the safety factor of the bridge. Kutzbach equation is also analyzed to ensure that the mechanism is able to meet the targeted degree of motion. There are five major components of the scissor structure; pin, deck, cross shaft and deck shaft. The structure is controlled by hydraulic pump driven by a motor for the motions. Material used in simulation is A36 structural steel due to limited library in ANSYS. However, the proposed material is Fiber Reinforced Polymer (FRP composites as they have a high strength to weight ratio. FRP also tends to be corrosion resistance and this characteristic is useful in flooded area.

Experimental Validation of a Numerical Model for Three-Dimensional High-Speed Railway Bridge Analysis by Comparison with a Small-Scale Model

DEFF Research Database (Denmark)

Sneideris, J.; Bucinskas, Paulius; Agapii, L.

2015-01-01

The aim of this paper is to perform dynamic analysis of a multi-span railway bridge interacting with the underlying soil. A small-scale model of a bridge structure is constructed for experimental testing and the results are compared with a computational model. The computational model in this paper...... dimensional 10-degrees-of-freedom system. The subsoil model utilizes Green’s function for a horizontally layered half-space. The small-scale experimental model consists of bridge deck, columns and footings which are made from Plexiglas. An electric vehicle travels along the bridge deck on a track to simulate...

Statistical variations in chloride diffusion in concrete bridges

Czech Academy of Sciences Publication Activity Database

Tikalsky, P.; Pustka, D.; Marek, Pavel

2005-01-01

Roč. 102, č. 3 (2005), s. 481-486 ISSN 0889-3241 Institutional research plan: CEZ:AV0Z20710524 Keywords : bridge deck * corrosion * durability Subject RIV: JM - Building Engineering Impact factor: 0.544, year: 2005

MASH test 3-11 of the TxDOT single slope bridge rail (type SSTR) on pan-formed bridge deck

Science.gov (United States)

2011-03-01

The objective of this crash test was to determine whether the TxDOT Single Slope Traffic Rail (Type : SSTR) would perform acceptably on a pan-formed deck when tested according to the guidelines set forth in : Manual for Assessing Safety Hardware (MAS...

Seismic Responses of a Cable-Stayed Bridge with Consideration of Uniform Temperature Load

Directory of Open Access Journals (Sweden)

Junjun Guo

2016-12-01

Full Text Available The effects of temperature load on the dynamic responses of cable-stayed bridges have attracted the attention of researchers in recent years. However, these investigations mainly focus on the influence of temperature on the dynamic characteristics of structures, such as vibration mode and frequency. This paper discusses the effects of uniform temperature changes on the seismic responses of a cable-stayed bridge. A three dimensional finite element model of a cable-stayed bridge using OpenSees is established for nonlinear time history analysis, and uniform temperature load is applied to the prototype bridge before the conducting of seismic excitation. Three ground motion records are selected from the PEER strong motion database based on the design spectrum. Case studies are then performed considering the varying temperature and the connections between the deck and pylons of the bridge. The result shows that the seismic responses of the bridge are significantly increased with the consideration of temperature load. Meanwhile, the types between the deck and pylon also have notable impacts on the seismic responses of the bridge with and without temperature changes. This research could provide a reference for designers during the design phase of cable-stayed brides.

FEATURES OF DESIGN OF TIED-ARCH BRIDGES WITH FLEXIBLE INCLINED SUSPENSION HANGERS

Directory of Open Access Journals (Sweden)

V. O. Samosvat

2017-10-01

Full Text Available Purpose. Investigation and analysis of the hanger arrangement and the structural stability of a Network arch bridge – a tied-arch bridge with inclined hangers that cross each other at least twice. It is also necessary to make a comparative analysis with other types of hanger arrangements. Methodology. The authors in their research investigated a large number of parameters to determine their influence in the force distribution in the arch. Eventually they determined optimal values for all parameters. These optimal values allowed developing a design guide that leads to optimal arch design. When solving this problem, the authors used three-dimensional finite element models and the objective was to determine the most suitable solution for a road bridge, with a span of 100 meters, consisting of two inclined steel arches, located on a road with two traffic lanes, subjected to medium traffic. The virtual prototype of the model is performed by finite element simulator Midas Civil. Findings. In this study, for the bridge deck, a concrete tie appears to be the best solution considering the structural behavior of network arches, but economic advantages caused by easier erection may lead to steel or a composite bridge deck as better alternatives. Design requirements and local conditions of each particular bridge project will decide the most economic deck design.Originality. To ensure passenger comfort and the stability and continuity of the track, deformations of bridges are constricted. A network arch is a stiff structure with small deflections and therefore suitable to comply with such demands even for high speed railway traffic.
A network arch bridge with a concrete tie usually saves more than half the steel required for tied arches with vertical hangers and concrete ties. Practical value. Following the study design advice given in this article leads to savings of about 60 % of structural steel compared with conventional tied arch bridges with

Multiobjective Optimal Control of Longitudinal Seismic Response of a Multitower Cable-Stayed Bridge

Directory of Open Access Journals (Sweden)

Geng Fangfang

2016-01-01

Full Text Available The dynamic behavior of a multitower cable-stayed bridge with the application of partially longitudinal constraint system using viscous fluid dampers under real earthquake ground motions is presented. The study is based on the dynamic finite element model of the Jiashao Bridge, a six-tower cable-stayed bridge in China. The prime aim of the study is to investigate the effectiveness of viscous fluid dampers on the longitudinal seismic responses of the bridge and put forth a multiobjective optimization design method to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multitower cable-stayed bridge with the partially longitudinal constraint system is to yield maximum reductions in the base forces of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base forces of bridge towers longitudinally unrestricted with the bridge deck. To this end, a multiobjective optimization design method that uses a nondominating sort genetic algorithm II (NSGA-II is used to optimize parameters of the viscous fluid dampers. The effectiveness of the proposed optimization design method is demonstrated for the multitower cable-stayed bridge with the partially longitudinal constraint system, which reveals that a design engineer can choose a set of proper parameters of the viscous fluid dampers from Pareto optimal fronts that can satisfy the desired performance requirements.

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders.

Science.gov (United States)

2012-03-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

Directory of Open Access Journals (Sweden)

E. Tubaldi

2015-01-01

Full Text Available Partially isolated bridges are a particular class of bridges in which isolation bearings are placed only between the piers top and the deck whereas seismic stoppers restrain the transverse motion of the deck at the abutments. This paper proposes an analytical formulation for the seismic analysis of these bridges, modelled as beams with intermediate viscoelastic restraints whose properties describe the pier-isolator behaviour. Different techniques are developed for solving the seismic problem. The first technique employs the complex mode superposition method and provides an exact benchmark solution to the problem at hand. The two other simplified techniques are based on an approximation of the displacement field and are useful for preliminary assessment and design purposes. A realistic bridge is considered as case study and its seismic response under a set of ground motion records is analyzed. First, the complex mode superposition method is applied to study the characteristic features of the dynamic and seismic response of the system. A parametric analysis is carried out to evaluate the influence of support stiffness and damping on the seismic performance. Then, a comparison is made between the exact solution and the approximate solutions in order to evaluate the accuracy and suitability of the simplified analysis techniques for evaluating the seismic response of partially isolated bridges.

Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

Science.gov (United States)

Hawileh, Rami A.; Rasheed, Hayder A.

2017-12-01

This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders : appendices.

Science.gov (United States)

2012-01-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders : final report.

Science.gov (United States)

2012-03-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Economic impact of multi-span, prestressed concrete girder bridges designed as simple span versus continuous span : final report.

Science.gov (United States)

2016-10-01

The objective of this study was to determine the economic impact of designing pre-tensioned prestressed concrete beam (PPCB) : bridges utilizing the continuity developed in the bridge deck as opposed to the current Iowa Department of Transportation (...

Strength and durability of near-surface mounted CFRP bars for shear strengthening reinforced concrete bridge girders : final report appendices.

Science.gov (United States)

2012-03-01

During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candida...

Dynamic response of the train-track-bridge system subjected to derailment impacts

Science.gov (United States)

Ling, Liang; Dhanasekar, Manicka; Thambiratnam, David P.

2018-04-01

Derailments on bridges, although not frequent, when occurs due to a complex dynamic interaction of the train-track-bridge structural system, are very severe. Furthermore, the forced vibration induced by the post-derailment impacts can toss out the derailed wagons from the bridge deck with severe consequences to the traffic underneath and the safety of the occupants of the wagons. This paper presents a study of the train-track-bridge interaction during a heavy freight train crossing a concrete box girder bridge from a normal operation to a derailed state. A numerical model that considers the bridge vibration, train-track interaction and the train post-derailment behaviour is formulated based on a coupled finite-element - multi-body dynamics (FE-MBD) theory. The model is applied to predict the post-derailment behaviour of a freight train composed of one locomotive and several wagons, as well as the dynamic response of a straight single-span simply supported bridge containing ballast track subjected to derailment impacts. For this purpose, a typical derailment scenario of a heavy freight train passing over a severe track geometry defect is introduced. The dynamic derailment behaviour of the heavy freight train and the dynamic responses of the rail bridge are illustrated through numerical examples. The results exhibit the potential for tossing out of the derailed trains from the unstable increase in the yaw angle signature and a lower rate of increase of the bridge deck bending moment compared to the increase in the static axle load of the derailed wheelset.

Economic impact of multi-span, prestressed concrete girder bridges designed as simple span versus continuous span : tech transfer summary.

Science.gov (United States)

2016-10-01

The objective of this study was to determine the economic impact of : designing pre-tensioned prestressed concrete beam (PPCB) bridges : utilizing the continuity developed in the bridge deck as opposed to the : current Iowa Department of Transportati...

Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

Science.gov (United States)

Flaga, Kazimierz; Furtak, Kazimierz

2015-03-01

Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life). The most commonly found in practice are composite girder bridges, particularly in highway bridges of small and medium spans, but the spans may reach over 200 m. In larger spans steel truss girders are applied. Bridge composite structures are also employed in cable-stayed bridge decks of the main girder spans of the order of 600, 800 m. The aim of the article is to present the cionstruction process and strength analysis problems concerning of this type of structures. Much attention is paid to the design and calculation of the shear connectors characteristic for the discussed objects. The authors focused mainly on the issues of single composite structures. The effect of assembly states on the stresses and strains in composite members are highlighted. A separate part of problems is devoted to the influence of rheological factors, i.e. concrete shrinkage and creep, as well as thermal factors on the stresses and strains and redistribution of internal forces.

A sensor network system for the health monitoring of the Parkview bridge deck.

Science.gov (United States)

2010-01-31

Bridges are a critical component of the transportation infrastructure. There are approximately 600,000 bridges in : the United State according to the Federal Highway Administration. Four billion vehicles traverse these bridges daily. : Regular inspec...

Development of precast bridge deck overhang system : technical report.

Science.gov (United States)

2011-07-01

The implementation of full-depth, precast overhang panel systems has the potential to improve constructability, : productivity, and make bridges more economical. Initial testing and analyses reported in the 0-6100-2 report resulted in : a design that...

Stress Regression Analysis of Asphalt Concrete Deck Pavement Based on Orthogonal Experimental Design and Interlayer Contact

Science.gov (United States)

Wang, Xuntao; Feng, Jianhu; Wang, Hu; Hong, Shidi; Zheng, Supei

2018-03-01

A three-dimensional finite element box girder bridge and its asphalt concrete deck pavement were established by ANSYS software, and the interlayer bonding condition of asphalt concrete deck pavement was assumed to be contact bonding condition. Orthogonal experimental design is used to arrange the testing plans of material parameters, and an evaluation of the effect of different material parameters in the mechanical response of asphalt concrete surface layer was conducted by multiple linear regression model and using the results from the finite element analysis. Results indicated that stress regression equations can well predict the stress of the asphalt concrete surface layer, and elastic modulus of waterproof layer has a significant influence on stress values of asphalt concrete surface layer.

Reduction of seismic response long-span PC cable-stayed bridge by passive dampers; Damper ni yoru saidai PC shachokyo no jishinji oto no teigen

Energy Technology Data Exchange (ETDEWEB)

Takeda, T.; Yamanobe, S.; Niihara, Y. [Kajima Corp., Tokyo (Japan)

1994-10-31

It is important in designing a PC cable-stayed bridge to properly estimate the seismic response of the bridge for reduction of the response. In this paper, an improvement of the seismic resistance of PC cable-stayed bridges when dampers are installed between the deck and piers and lateral vibration of the deck is restricted is investigated using a time history response model. PC cable-stayed bridges with a span length of 400 m, particularly two types of bridges of harp and semi-harp are investigated and the following is found by analyzing the case where there are installed hysteresis type dampers (with 1 cm yield displacement and secondary rigidity assumed to be 1/10 times that of initial rigidity, the initial rigidity being parametrically changed.) or viscous type dampers (a damping factor is changed.) The result shows that the dampers can reduce the seismic response of a PC cable-stayed bridge and that a semi-harp configuration of stay cables where stay cable members are substantially vertically arranged is more effective than a harp configuration for the seismic performance of PC cable-stayed bridges. The damper partly bear inertial force of the bridge upon earthquake whereby tension of the stay cable members is reduced and bending moment of the deck is reduced. There is existing an optimum characteristic value of the damper concerning the bending moment of the piers. 5 refs., 7 figs., 2 tabs.

Active aerodynamic stabilisation of long suspension bridges

DEFF Research Database (Denmark)

Nissen, Henrik Ditlev; Sørensen, Paul Haase; Jannerup, Ole Erik

2004-01-01

The paper describes the addition of actively controlled appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suppension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to make...... use of control analysis and design techniques, a linear model of the structural and aerodynamic motion around equilibriun is developed. The model is validated through comparison with finite element calculations and wind tunnel experimental data on the Great Belt East Bridge in Denmark. The developed...... active control scheme is local in that the flap control signal at a given longitudinal position along the bridge only depends on local motion measurements. The analysis makes use of the Nyquist stability criteria and an anlysis of the sensitivity function for stability analysis. The analysis shows...

Critical traffic loading for the design of prestressed concrete bridge

International Nuclear Information System (INIS)

Hassan, M.I.U.

2009-01-01

A study has been carried out to determine critical traffic loadings for the design of bridge superstructures. The prestressed concrete girder bridge already constructed in Lahore is selected for the analysis as an example. Standard traffic loadings according to AASHTO (American Association of State Highway and Transportation Officials) and Pakistan Highway Standards are used for this purpose. These include (1) HL-93 Truck, (2) Lane and (3) Tandem Loadings in addition to (4) Military tank loading, (5) Class-A, (6) Class-B and (7) Class-AA loading, (8) NLC (National Logistic Cell) and (9) Volvo truck loadings. Bridge superstructure including transom beam is analyzed Using ASD and LRFD (Load and Resistance Factor Design) provisions of AASHTO specifications. For the analysis, two longer and shorter spans are selected. This includes the analysis of bridge deck; interior and exterior girder; a typical transom beam and a pier. Dead and live loading determination is carried out using both computer aided and manual calculations. Evaluation of traffic loadings is done for all the bridge components to find out the critical loading. HL-93 loading comes out to be the most critical loading and where this loading is not critical in case of bridge decks; a factor of 1.15 is introduced to make it equivalent with HL-93 -Ioading. SAP-2000 (Structural Engineering Services of Pakistan) and MS-Excel is employed for analysis of bridge superstructure subjected to this loading. Internal forces are obtained for the structural elements of the bridge for all traffic loadings mentioned. It is concluded that HL-93 loading can be used for the design of prestressed concrete girder bridge. Bridge design authorities like NHA (National Highway Authority) and different cities development authorities are using different standard traffic loadings. A number of suggestions are made from the results of the research work related to traffic loadings and method of design. These recommendations may be

Constitutive and numerical modeling of soil and soil-pile interaction for 3D applications and Kealakaha stream bridge case study.

Science.gov (United States)

2011-12-01

This study is concerned with developing new modeling tools for predicting the response of the new Kealakaha : Stream Bridge to static and dynamic loads, including seismic shaking. The bridge will span 220 meters, with the : deck structure being curve...

Durability of Materials in Pearl-Chain Bridges

DEFF Research Database (Denmark)

Lund, Mia Schou Møller

. The construction of the Pearl-Chain arch is simple. The arch is assembled on its side, next to the road that the bridge will span, by placing a number of plane prefabricated Super-Light Decks that consist of lightweight aggregate concrete and conventional concrete, in the desired arch shape. Mortar joints are cast...... is stabilized by casting a fill material between the spandrel walls of the arch. Finally, the road surface is cast on top of the fill material. New bridges are designed for a service lifetime of at least 100 years. Hence, the specifications of the materials used in Pearl-Chain Bridges are high. This PhD study...... and pervious concrete were also investigated. The most suitable fill material for Pearl-Chain Bridges depends on the particular bridge design; the results obtained and presented in the present PhD study provide guidance on how to decide which fill material is most suitable regarding strength, permeability...

Progressive collapse susceptibility of a long span suspension bridge

DEFF Research Database (Denmark)

Olmati, Pierluigi; Giuliani, Luisa

2013-01-01

Long span bridges are complex structural systems, often having strategic roles in the network infrastructures; consequently their susceptibility to a disproportionate response in case of local failures needs to be assessed. In particular, current regulations prescribe that the structural robustness...... should be maintained in case of an accidental hanger detachment. Local damages in bridges, which are characterized by an horizontal load transfer system, may progress along the deck or along the suspension system, as the dynamic overloading of the structural elements immediately adjacent to the failed...

Determination of in-situ strength on selected bridge element concrete girder and slab of Nagtahan bridge using rebound hammer test

International Nuclear Information System (INIS)

Uy, Bernadette Betsy B.; Banaga, Renato T.

2013-01-01

This study examined the extent of the damage due to fire on the affected areas of the bridge structure. The need to assess the damage of the Nagtahan Bridge is very useful to provide appropriate measures in the repair or in the reinforcement of the bridge, hence will ensure its strength and integrity. The study included two (2) spans of the bridge deck/slab with specific locations of the bridge that were subjected for testing. The Rebound Hammer was used as a preliminary test in evaluating the bridge condition. Its capability is to assess the in-place uniformity of concrete, to delineate regions in a structure of poor quality or deteriorated concrete, and to estimate the in-place strength; and ultimately, for relative comparison between the different structures of the bridge. With the use of the NDT Rebound Hammer Test, the researchers were able to determine whether or not the in-situ strength of the bridge's concrete has been weakened due to fire. The DPW-Standard Specification is the government acceptable manual, containing the acceptance criteria, used as the basis for standard construction procedures in the department.(author)

Strategic Planning for the National Bridge Stock of Iran

Directory of Open Access Journals (Sweden)

Ali Sahrapeyma

2013-06-01

Full Text Available The National Bridge Stock of Iran consists of about 330,000 bridges, of which around 50% are older than 30 years. Since 2010, Iran Road Maintenance & Transportation Organization has started implementing a comprehensive Bridge Management System in order to manage this aged stock efficiently. To predict future conditions of bridge stock, a heuristic numerical method is presented. This methodology is based on Markovian process to model deterioration of bridge decks and a multi-objective optimization problem to find the best solutions. The optimization problem involves three decision variables regarding management strategies, and has three objectives regarding cost minimization. Constraints of the problem are the percentage of deficient bridges, the percentage of bridges under MR&Rs (Maintenance, Repair and Rehabilitation and the average value of condition scores. The results show that to avoid future challenges, the annual budget for bridge maintenance should be increased, the current maintenance strategy should be improved as soon as possible, and national manuals and instructions for inspection, condition rating and maintenance should be developed.

SIGNS The sandwich sign

African Journals Online (AJOL)

The sandwich sign is demonstrated on cross-sectional imaging, commonly on CT or ultrasound. It refers to homogeneous soft- tissue masses representing mesenteric lymphadenopathy as the two halves of a sandwich bun, encasing the mesenteric fat and tubular mesenteric vessels that constitute the 'sandwich filling' (Figs ...

Live load distribution on longitudinal glued-laminated timber deck bridges : final report : conclusions and recommendations

Science.gov (United States)

Fouad Fanous; Jeremy May; Terry Wipf; Michael Ritter

2010-01-01

Over the past few years the United States Department of Agriculture (USDA), Forest Products Laboratory (FPL), and the Federal Highway Administration (FHWA) have supported several research programs. This paper is a result of a study sponsored by FPL, with the objective of determining how truckloads are distributed to the deck panels of a longitudinal glued-laminated...

Seismic Retrofitting of an Existing Steel Railway Bridge by Fluid Viscous Dampers

Science.gov (United States)

Gangopadhyay, Avijit; Ghosh, Aparna Dey

2016-09-01

There are over a lakh of bridges in the Indian Railways, many of which have become seismically deficient, either through aging or due to inadequate seismic design considerations. The extensive damage of bridges all over the world in recent earthquakes has propelled significant advancement in earthquake protection and retrofitting of bridges. Amongst various passive control systems that are reliable as well as cost-effective, Fluid Viscous Dampers (FVDs) are proving to be successful in bridge vibration control. Orificed FVDs, commercially available as Taylor Devices, have already been successfully installed in several bridges worldwide. However, there has been no such application or study related to Indian railway bridges. In this paper, an existing thirty years' old railway bridge in Jharkhand, India, has been analyzed in SAP2000v14 considering reduced stiffness and found deficient when subjected to spectrum-compatible accelerograms. Subsequent retrofitting of the bridge superstructure with FVDs has been carried out and the results indicate substantial reductions in the responses of the bridge deck.

Identification of aeroelastic forces and static drag coefficients of a twin cable bridge stay from full-scale ambient vibration measurements

DEFF Research Database (Denmark)

Acampora, Antonio; Georgakis, Christos T.; Macdonald, J.H.G.

2014-01-01

Despite much research in recent years, large amplitude vibrations of inclined cables continue to be of concern for cable-stayed bridges. Various excitation mechanisms have been suggested, including rain-wind excitation, dry inclined cable galloping, high reduced velocity vortex shedding...... and excitation from the deck and/or towers. Although there have been many observations of large cable vibrations on bridges, there are relatively few cases of direct full-scale cable vibration and wind measurements, and most research has been based on wind tunnel tests and theoretical modelling.This paper...... presents results from full-scale measurements on the special arrangement of twin cables adopted for the Øresund Bridge. The monitoring system records wind and weather conditions, as well as accelerations of certain cables and a few locations on the deck and tower. Using the Eigenvalue Realization Algorithm...

Determination of brace forces caused by construction loads and wind loads during bridge construction : [summary].

Science.gov (United States)

2014-04-01

Bridges are constructed in stages as pilings, : columns, girders, decks, and other components : are added. At each stage, the structure must be : stable. Girders, which add significant weight to : the developing structure, rest on elastomeric : beari...

A serials of sandwich-like trinuclear and one-dimensional chain cyanide-bridged iron(III)-copper(II) complexes: Syntheses, crystal structures and magnetic properties

Science.gov (United States)

Shi, Jingwen; Lan, Wenlong; Ren, Yanjie; Liu, Qingyun; Liu, Hui; Dong, Yunhui; Zhang, Daopeng

2018-04-01

Four pyridinecarboxamide trans-dicyanideiron(III) building blocks and one macrocyclic copper(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in a serials of cyanide-bridged FeIII-CuII complexes with different structure types. The series of complexes can be formulated as: {[Cu(Cyclam)][Fe(bpb)(CN)2]2}·4H2O (1), {{[Cu(Cyclam)][Fe(bpb)(CN)2]}ClO4}n·nH2O (2), and {[Cu(Cyclam)][Fe(bpmb)(CN)2]2}·4H2O (3), {[Cu(Cyclam)][Fe(bpClb)(CN)2]2}·4H2O (4) and {{[Cu(Cyclam)][Fe(bpdmb)(CN)2]}ClO4}n·2nCH3OH (5) (bpb2- = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2- = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpClb2- = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate, bpdmb2- = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, Cyclam = 1,4,8,11-tetraazacyclotetradecane). All the complexes have been characterized by elemental analysis, IR spectra and structural determination. Single X-ray diffraction analysis shows the similar neutral sandwich-like structures for complexes 1, 3 and 4, in which the two cyano precursors acting as monodentate ligand through one of their two cyanide groups were coordinated face to face to central Cu(II) ion. The complexes 2 and 5 can be structurally characterized as one-dimensional cationic single chain consisting of alternating units of [Cu(Cyclam)]2+ and [Fe(bpb/bpdmb)(CN)2]- with free ClO4- as balanced anion. Investigation over magnetic properties of the whole serials of complexes reveals the antiferromagnetic magnetic coupling between the neighboring cyanide-bridged Fe(III) and Cu(II) ions in complexes 3 and 4 and the ferromagnetic interaction in complexes 1, 2 and 5, respectively.

Aerodynamic problems of cable-stayed bridges spanning over one thousand meters

Institute of Scientific and Technical Information of China (English)

Chen Airong; Ma Rujin; Wang Dalei

2009-01-01

Tbe elongating of cable-stayed bridge brings a series of aerodynamic problems. First of all, geometric nonlin-ear effect of extreme long cable is much more significant for cable-stayed bridge spanning over one thousand meters. Lat-eral static wind load will generate additional displacement of long cables, which causes the decrease of supporting rigidi-ty of the whole bridge and the change of dynamic properties. Wind load, being the controlling load in the design of ca-hie-stayed bridge, is a critical problem and needs to be solved. Meanwhile, research on suitable system between pylon and deck indicates fixed-fixed connection system is an effective way for improvement performance of cable-stayed bridges under longitudinal wind load. In order to obtain aerodynamic parameters of cable-stayed bridge spanning over one thou-sand meters, identification method for flutter derivatives of full bridge aero-elastic model is developed in this paper. Furthermore, vortex induced vibration and Reynolds number effect are detailed discussed.

46 CFR 108.486 - Helicopter decks.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Helicopter decks. 108.486 Section 108.486 Shipping COAST... Fire Extinguishing Systems Fire Protection for Helicopter Facilities § 108.486 Helicopter decks. At least two of the accesses to the helicopter landing deck must each have a fire hydrant on the unit's...

Identification of aeroelastic forces on bridge cables from full-scale measurements

DEFF Research Database (Denmark)

Acampora, Antonio; Macdonald, J.H.G.; Georgakis, Christos

2011-01-01

Despite much research in recent years, large amplitude vibrations of inclined cables continue to be of concern for cable-stayed bridges. Various mechanisms have been suggested for their excitation, including rain-wind excitation, dry inclined cable galloping, high reduced velocity vortex shedding...... Bridge. The system records wind conditions and weather conditions, as well as accelerations of certain cables and a few locations on the deck and tower. Using state-of-the-art methods of output-only system identification, the vibration modes of the cables have been identified. From these modes...

Bridge Management Strategy Based on Extreme User Costs for Bridge Network Condition

Directory of Open Access Journals (Sweden)

Ladislaus Lwambuka

2014-01-01

Full Text Available This paper presents a practical approach for prioritization of bridge maintenance within a given bridge network. The maintenance prioritization is formulated as a multiobjective optimization problem where the simultaneous satisfaction of several conflicting objectives includes minimization of maintenance costs, maximization of bridge deck condition, and minimization of traffic disruption and associated user costs. The prevalence of user cost during maintenance period is twofold; the first case refers to the period of dry season where normally the traffic flow is diverted to alternative routes usually resurfaced to regain traffic access. The second prevalence refers to the absence of alternative routes which is often the case in the least developed countries; in this case the user cost referred to results from the waiting time while the traffic flow is put on hold awaiting accomplishment of the maintenance activity. This paper deals with the second scenario of traffic closure in the absence of alternative diversion routes which in essence results in extreme user cost. The paper shows that the multiobjective optimization approach remains valid for extreme cases of user costs in the absence of detour roads as often is the scenario in countries with extreme poor road infrastructure.

Benefits of measuring half-cell potentials and rebar corrosion rates in condition surveys of concrete bridge decks.

Science.gov (United States)

1992-01-01

The practice of conducting a half-cell potential survey during the assessment of the condition of a concrete deck was reexamined with the objective of eliminating some of the doubts concerning its benefits. It was found that the survey grid size of 4...

75 FR 4584 - Wire Decking From China

Science.gov (United States)

2010-01-28

... Decking From China AGENCY: United States International Trade Commission. ACTION: Scheduling of the final... subsidized and less-than-fair-value imports from China of wire decking, provided for in subheadings 9403.90... China of wire decking, and that such [[Page 4585

Study on load test of 100m cross-reinforced deck type concrete box arch bridge

Science.gov (United States)

Shi, Jing Xian; Cheng, Ying Jie

2018-06-01

Found in the routine quality inspection of highway bridge that many vertical fractures on the main beam (10mT beam) of the steel reinforced concrete arch bridge near the hydropower station. In order to grasp the bearing capacity of this bridge under working conditions with cracks, the static load and dynamic load test of box arch bridge are carried out. The Midas civil theory is calculated by using the special plate trailer - 300 as the calculation load, and the deflection and stress of the critical section are tested by the equivalent cloth load in the test vehicle. The pulsation test, obstacles and no obstacle driving test were carried out. Experimental results show that the bridge under the condition of the test loads is in safe condition, main bearing component of the strength and stiffness meet the design requirements, the crack width does not increase, in the process of loading bridge overall work performance is good.

Discussion on runoff purification technology of highway bridge deck based on water quality safety

Science.gov (United States)

Tan, Sheng-guang; Liu, Xue-xin; Zou, Guo-ping; Xiong, Xin-zhu; Tao, Shuang-cheng

2018-06-01

Aiming at the actual problems existing, including a poor purification effect of highway bridge runoff collection and treatment system across sensitive water and necessary manual emergency operation, three kinds of technology, three pools system of bridge runoff purification, the integral pool of bridge runoff purification and ecological planting tank, are put forward by optimizing the structure of purification unit and system setting. At the same time, we come up with an emergency strategy for hazardous material leakage basing on automatic identification and remote control of traffic accidents. On the basis of combining these with the optimized pool structure, sensitive water safety can be guaranteed and water pollution, from directly discharging of bridge runoff, can be decreased. For making up for the shortages of green highway construction technology, the technique has important reference value.

46 CFR 132.320 - Helicopter-landing decks.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Helicopter-landing decks. 132.320 Section 132.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS FIRE-PROTECTION EQUIPMENT Miscellaneous § 132.320 Helicopter-landing decks. Each vessel with a helicopter-landing deck must...

Life-cycle assessment of redwood decking in the United States with a comparison to three other decking materials

Science.gov (United States)

R. Bergman; H. Sup-Han; E. Oneil; I. Eastin

2013-01-01

The goal of the study was to conduct a life-cycle inventory (LCI) of California redwood (Sequoia sempervirens) decking that would quantify the critical environmental impacts of decking from cradle to grave. Using that LCI data, a life-cycle assessment (LCA) was produced for redwood decking. The results were used to compare the environmental footprint...

Strain features and condition assessment of orthotropic steel deck cable-supported bridges subjected to vehicle loads by using dense FBG strain sensors

Science.gov (United States)

Wei, Shiyin; Zhang, Zhaohui; Li, Shunlong; Li, Hui

2017-10-01

Strain is a direct indicator of structural safety. Therefore, strain sensors have been used in most structural health monitoring systems for bridges. However, until now, the investigation of strain response has been insufficient. This paper conducts a comprehensive study of the strain features of the U ribs and transverse diaphragm on an orthotropic steel deck and proposes a statistical paradigm for crack detection based on the features of vehicle-induced strain response by using the densely distributed optic fibre Bragg grating (FBG) strain sensors. The local feature of strain under vehicle load is highlighted, which enables the use of measurement data to determine the vehicle loading event and to make a decision regarding the health status of a girder near the strain sensors via technical elimination of the load information. Time-frequency analysis shows that the strain contains three features: the long-term trend item, the short-term trend item, and the instantaneous vehicle-induced item (IVII). The IVII is the wheel-induced strain with a remarkable local feature, and the measured wheel-induced strain is only influenced by the vehicle near the FBG sensor, while other vehicles slightly farther away have no effect on the wheel-induced strain. This causes the local strain series, among the FBG strain sensors in the same transverse locations of different cross-sections, to present similarities in shape to some extent and presents a time delay in successive order along the driving direction. Therefore, the strain series induced by an identical vehicle can be easily tracked and compared by extracting the amplitude and calculating the mutual ratio to eliminate vehicle loading information, leaving the girder information alone. The statistical paradigm for crack detection is finally proposed, and the detection accuracy is then validated by using dense FBG strain sensors on a long-span suspension bridge in China.

Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System

Directory of Open Access Journals (Sweden)

Xiao-Wei Ye

2018-02-01

Full Text Available In this paper, a fiber Bragg grating (FBG-based stress monitoring system instrumented on an orthotropic steel deck arch bridge is demonstrated. The FBG sensors are installed at two types of critical fatigue-prone welded joints to measure the strain and temperature signals. A total of 64 FBG sensors are deployed around the rib-to-deck and rib-to-diagram areas at the mid-span and quarter-span of the investigated orthotropic steel bridge. The local stress behaviors caused by the highway loading and temperature effect during the construction and operation periods are presented with the aid of a wavelet multi-resolution analysis approach. In addition, the multi-modal characteristic of the rainflow counted stress spectrum is modeled by the method of finite mixture distribution together with a genetic algorithm (GA-based parameter estimation approach. The optimal probability distribution of the stress spectrum is determined by use of Bayesian information criterion (BIC. Furthermore, the hot spot stress of the welded joint is calculated by an extrapolation method recommended in the specification of International Institute of Welding (IIW. The stochastic characteristic of stress concentration factor (SCF of the concerned welded joint is addressed. The proposed FBG-based stress monitoring system and probabilistic stress evaluation methods can provide an effective tool for structural monitoring and condition assessment of orthotropic steel bridges.

Design and Construction of Operation Bridge for Research Reactor

International Nuclear Information System (INIS)

Jung, Kwangsub; Choi, Jinbok; Lee, Jongmin; Oh, Jinho

2015-01-01

The operation bridge contains a lower working deck mounted on a saddle that travels on rails. Upright members are mounted on the saddle to support the upper structure and two hoist monorails. The saddle contains an anti-derail system that is composed of seismic lugs and guide rollers. The operation bridge travels along the rails to transport the fuel assembly, irradiated object, and reactor components in the pools by using tools. Hoists are installed at the top girder. The hoist is suspended from the monorail by means of a motor driven trolley that runs along the monorail. Movements of hoist and trolley are controlled by using the control pendant switch. Processes of design and construction of the operation bridge for the research reactor are introduced. The operation bridge is designed under consideration of functions of handling equipment in the pool and operational limits for safety. Structural analysis is carried out to evaluate the structural integrity in the seismic events. Tests and inspections are also performed during fabrication and installation to confirm the function and safety of the operation bridge

Upstand Finite Element Analysis of Slab Bridges

OpenAIRE

O'Brien, Eugene J.; Keogh, D.L.

1998-01-01

For slab bridge decks with wide transverse edge cantilevers, the plane grillage analogy is shown to be an inaccurate method of linear elastic analysis due to variations in the vertical position of the neutral axis. The upstand grillage analogy is also shown to give inaccurate results, this time due to inappropriate modelling of in-plane distortions. An alternative method, known as upstand finite element analysis, is proposed which is sufficiently simple to be used on an everyday basis in the ...

46 CFR 28.565 - Water on deck.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Water on deck. 28.565 Section 28.565 Shipping COAST... VESSELS Stability § 28.565 Water on deck. (a) Each vessel with bulwarks must comply with the requirements... energy, “b” in Figure 28.565, must not be less than the water on deck heeling energy, “a” in Figure 28...

Duality and the Deck effect

CERN Document Server

Törnqvist, N A

1972-01-01

As shown by Deck, the double-peripheral model for three-particle final states gives a substantial low-mass enhancement over phase space in two-body subchannels. With the advent of duality it was conjectured that the Deck effect and a true resonance are just different manifestations of the same phenomena. Thus the presence of a Deck enhancement could be interpreted as evidence for the existence of the A/sub 1/ resonance. The conjecture has been subject to criticism of two different kinds. These two points are clarified by constructing a counter example to the conjecture of Chew and Pignotti, using the five-point amplitude (B/sub 5/) of the generalized Veneziano model. (8 refs).

Computational and experimental investigation of free vibration and flutter of bridge decks

Science.gov (United States)

Helgedagsrud, Tore A.; Bazilevs, Yuri; Mathisen, Kjell M.; Øiseth, Ole A.

2018-06-01

A modified rigid-object formulation is developed, and employed as part of the fluid-object interaction modeling framework from Akkerman et al. (J Appl Mech 79(1):010905, 2012. https://doi.org/10.1115/1.4005072) to simulate free vibration and flutter of long-span bridges subjected to strong winds. To validate the numerical methodology, companion wind tunnel experiments have been conducted. The results show that the computational framework captures very precisely the aeroelastic behavior in terms of aerodynamic stiffness, damping and flutter characteristics. Considering its relative simplicity and accuracy, we conclude from our study that the proposed free-vibration simulation technique is a valuable tool in engineering design of long-span bridges.

Strengthening of Existing Bridge Structures for Shear and Bending with Carbon Textile-Reinforced Mortar

Directory of Open Access Journals (Sweden)

Martin Herbrand

2017-09-01

Full Text Available Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly. The CTRM layer is a combination of a corrosion resistant carbon fiber reinforced polymer (CFRP fabric and an efficient mortar. In this paper, the strengthening method and the experimental results obtained at RWTH Aachen University are presented.

Strengthening of Existing Bridge Structures for Shear and Bending with Carbon Textile-Reinforced Mortar.

Science.gov (United States)

Herbrand, Martin; Adam, Viviane; Classen, Martin; Kueres, Dominik; Hegger, Josef

2017-09-19

Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM) to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly. The CTRM layer is a combination of a corrosion resistant carbon fiber reinforced polymer (CFRP) fabric and an efficient mortar. In this paper, the strengthening method and the experimental results obtained at RWTH Aachen University are presented.

An ultrasensitive sandwich-type electrochemical immunosensor based on the signal amplification system of double-deck gold film and thionine unite with platinum nanowire inlaid globular SBA-15 microsphere.

Science.gov (United States)

Wang, Ping; Li, Mingdang; Pei, Fubin; Li, Yueyun; Liu, Qing; Dong, Yunhui; Chu, Qingyan; Zhu, Hongjun

2017-05-15

A novel thionine unites with platinum nanowire inlaid globular SBA-15 (Pt NWs@g-SBA-15/Thi) not only utilizes as an efficient electrical signal probe but also constitutes an amplifying system with double-deck gold film (D-Au film) have been applied to the fabrication of sandwich-type immunosensor for detecting hepatitis B surface antigen (HBs Ag). The D-Au film can accelerate the electron transfer on the electrode interface due to the tunneling effect between the two Au films and can improve the load capacity of primary antibodies (Ab 1 ) because of the good biocompatibility. The Pt NWs@g-SBA-15/Thi with uniform globular morphology not only can effectively reduce the spatial limitation for loading the secondary antibodies (Ab 2 ) but also can provide outstanding pore accessibility of guest species from outside and offer catalytically active sites in a large scale. Besides, the presence of Thi can well enhance the electrical conductivity of Pt NWs@g-SBA-15/Thi. With the good cooperation between D-Au film and Pt NWs@g-SBA-15/Thi, a linear relationship between current signals and the concentrations of HBs Ag was obtained in the wide range from 10 fg/mL to 100ng/mL and the detection limit of HBs Ag was 3.3 fg/mL (signal-to-noise ratio of 3). Furthermore, the designed immunosensor with excellent selectivity, reproducibility and stability shows excellent performance in detection of human serum samples and provides a promising capacity for detecting a wide range of other tumor markers in clinical application. Copyright © 2017 Elsevier B.V. All rights reserved.

46 CFR 108.487 - Helicopter deck fueling operations.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Helicopter deck fueling operations. 108.487 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Fire Protection for Helicopter Facilities § 108.487 Helicopter deck fueling operations. (a) Each helicopter landing deck on which fueling operations are...

Fatigue evaluation for Tsing Ma Bridge using structural health monitoring data

Science.gov (United States)

Chan, Hung-tin Tommy; Ko, Jan Ming; Li, Zhao-Xia

2001-08-01

Fatigue assessment for the Tsing Ma Bridge (TMB) are presented based on the British standard BS5400 and the real-time structural health monitoring data under railway loading. TMB, as an essential portion of transport network for the Hong Kong airport, is the longest suspension bridge in the world carrying both highway and railway traffic. The bridge design has been mainly based on BS5400. A structural health monitoring system - Wind and Structural Health Monitoring System (WASHMS) for TMB has been operated since the bridge commissioning in May 1997. In order to assess the fatigue behavior of TMB under railway loading, strain gauges were installed on the bridge deck to measure the strain-time histories as soon as the bridge is loaded by a standard railway loading due to the service of an actual train. The strain-time history data at the critical members are then used to determine the stress spectrum, of which the rainflow method recommended for railway bridges by BS5400 is applied to count cycles of stress range. Miner's law is employed to evaluate fatigue damage and remaining service life of the bridge. The evaluated results of fatigue damage and remaining service life would help us to well understand about the fatigue design of the bridge and status in fatigue accumulation.

Simple Program to Investigate Hysteresis Damping Effect of Cross-Ties on Cables Vibration of Cable-Stayed Bridges

Directory of Open Access Journals (Sweden)

Panagis G. Papadopoulos

2012-01-01

Full Text Available A short computer program, fully documented, is presented, for the step-by-step dynamic analysis of isolated cables or couples of parallel cables of a cable-stayed bridge, connected to each other and possibly with the deck of the bridge, by very thin pretensioned wires (cross-ties and subjected to variation of their axial forces due to traffic or to successive pulses of a wind drag force. A simplified SDOF model, approximating the fundamental vibration mode, is adopted for every individual cable. The geometric nonlinearity of the cables is taken into account by their geometric stiffness, whereas the material nonlinearities of the cross-ties include compressive loosening, tensile yielding, and hysteresis stress-strain loops. Seven numerical experiments are performed. Based on them, it is observed that if two interconnected parallel cables have different dynamic characteristics, for example different lengths, thus different masses, weights, and geometric stiffnesses, too, or if one of them has a small additional mass, then a single pretensioned very thin wire, connecting them to each other and possibly with the deck of the bridge, proves effective in suppressing, by its hysteresis damping, the vibrations of the cables.

46 CFR 174.215 - Drainage of weather deck.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

46 CFR 173.062 - Drainage of weather deck.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Drainage of weather deck. 173.062 Section 173.062 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO VESSEL USE School Ships § 173.062 Drainage of weather deck. The weather deck of each sailing...

Noise from Aft Deck Exhaust Nozzles: Differences in Experimental Embodiments

Science.gov (United States)

Bridges, James E.

2014-01-01

Two embodiments of a rectangular nozzle on an aft deck are compared. In one embodiment the lower lip of the nozzle was extended with the sidewalls becoming triangles. In a second embodiment a rectangular nozzle was fitted with a surface that fit flush to the lower lip and extended outward from the sides of the nozzle, approximating a semi-infinite plane. For the purpose of scale-model testing, making the aft deck an integral part of the nozzle is possible for relatively short deck lengths, but a separate plate model is more flexible, accounts for the expanse of deck to the sides of the nozzle, and allows the nozzle to stand off from the deck. Both embodiments were tested and acoustic far-field results were compared. In both embodiments the extended deck introduces a new noise source, but the amplitude of the new source was dependent upon the span (cross-stream dimension) of the aft deck. The noise increased with deck length (streamwise dimension), and in the case of the beveled nozzle it increased with increasing aspect ratio. In previous studies of slot jets in wings it was noted that the increased noise from the extended aft deck appears as a dipole at the aft deck trailing edge, an acoustic source type with different dependence on velocity than jet mixing noise. The extraneous noise produced by the aft deck in the present studies also shows this behavior both in directivity and in velocity scaling.

Cone calorimeter tests of wood-based decking materials

Science.gov (United States)

Robert H. White; Mark A. Dietenberger; Nicole M. Stark

2007-01-01

New technologies in building materials have resulted in the use of a wide variety of materials in decks. As part of our effort to address fire concerns in the wildland-urban interface, the Forest Products Laboratory has been examining the fire performance of decking products. In addition to preservative-treated wood, decking products include wood-plastic composites and...

46 CFR 12.15-13 - Deck engine mechanic.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer. The...

Energy Dissipation in Sandwich Structures During Axial Compression

DEFF Research Database (Denmark)

Urban, Jesper

2002-01-01

The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full-scale structu......The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full...

Effects of CFRP Strengthening on Dynamic and Fatigue Responses of Composite Bridge

Directory of Open Access Journals (Sweden)

Kittisak Kuntiyawichai

2014-01-01

Full Text Available This paper investigates the effect of CFRP strengthening on dynamic and fatigue responses of composite bridge using finite element program ABAQUS. Dynamic and fatigue responses of composite bridge due to truck load based on AASHTO standard are investigated. Two types of CFRP strengthening techniques, CFRP sheets and CFRP deck, are applied to both the damaged and undamaged bridges. For the case of damaged bridge, two through-thickness crack sizes, 3 mm and 6 mm in depth, are assumed at midspan of the steel girders. Furthermore, effects of the number of steel girders on the dynamic and fatigue responses are also considered. The results show that the maximum responses of composite bridges occur for dual lane cases. By using CFRP as a strengthening material, the maximum stress and deflection of the steel girders reduce and consequently increase the fatigue life of the girders. After introducing initial crack into the steel girders of the composite bridges, the fatigue life of the bridges is dramatically reduced. However, the overall performance of the damaged composite bridge can be improved by using CFRP, albeit with less effectiveness. Therefore, if cracks are found, steel welding must be performed before strengthening the composite bridge by CFRP.

Modal Parameter Identification and Numerical Simulation for Self-anchored Suspension Bridges Based on Ambient Vibration

Science.gov (United States)

Liu, Bing; Sun, Li Guo

2018-06-01

This paper chooses the Nanjing-Hangzhou high speed overbridge, a self-anchored suspension bridge, as the research target, trying to identify the dynamic characteristic parameters of the bridge by using the peak-picking method to analyze the velocity response data under ambient excitation collected by 7 vibration pickup sensors set on the bridge deck. The ABAQUS is used to set up a three-dimensional finite element model for the full bridge and amends the finite element model of the suspension bridge based on the identified modal parameter, and suspender force picked by the PDV100 laser vibrometer. The study shows that the modal parameter can well be identified by analyzing the bridge vibration velocity collected by 7 survey points. The identified modal parameter and measured suspender force can be used as the basis of the amendment of the finite element model of the suspension bridge. The amended model can truthfully reflect the structural physical features and it can also be the benchmark model for the long-term health monitoring and condition assessment of the bridge.

Application of an automated wireless structural monitoring system for long-span suspension bridges

International Nuclear Information System (INIS)

Kurata, M.; Lynch, J. P.; Linden, G. W. van der; Hipley, P.; Sheng, L.-H.

2011-01-01

This paper describes an automated wireless structural monitoring system installed at the New Carquinez Bridge (NCB). The designed system utilizes a dense network of wireless sensors installed in the bridge but remotely controlled by a hierarchically designed cyber-environment. The early efforts have included performance verification of a dense network of wireless sensors installed on the bridge and the establishment of a cellular gateway to the system for remote access from the internet. Acceleration of the main bridge span was the primary focus of the initial field deployment of the wireless monitoring system. An additional focus of the study is on ensuring wireless sensors can survive for long periods without human intervention. Toward this end, the life-expectancy of the wireless sensors has been enhanced by embedding efficient power management schemes in the sensors while integrating solar panels for power harvesting. The dynamic characteristics of the NCB under daily traffic and wind loads were extracted from the vibration response of the bridge deck and towers. These results have been compared to a high-fidelity finite element model of the bridge.

Application of AN Automated Wireless Structural Monitoring System for Long-Span Suspension Bridges

Science.gov (United States)

Kurata, M.; Lynch, J. P.; van der Linden, G. W.; Hipley, P.; Sheng, L.-H.

2011-06-01

This paper describes an automated wireless structural monitoring system installed at the New Carquinez Bridge (NCB). The designed system utilizes a dense network of wireless sensors installed in the bridge but remotely controlled by a hierarchically designed cyber-environment. The early efforts have included performance verification of a dense network of wireless sensors installed on the bridge and the establishment of a cellular gateway to the system for remote access from the internet. Acceleration of the main bridge span was the primary focus of the initial field deployment of the wireless monitoring system. An additional focus of the study is on ensuring wireless sensors can survive for long periods without human intervention. Toward this end, the life-expectancy of the wireless sensors has been enhanced by embedding efficient power management schemes in the sensors while integrating solar panels for power harvesting. The dynamic characteristics of the NCB under daily traffic and wind loads were extracted from the vibration response of the bridge deck and towers. These results have been compared to a high-fidelity finite element model of the bridge.

Full-Scale Evaluation of DuraDeck (registered trademark) and MegaDeck (trademark) Matting Systems

Science.gov (United States)

2013-07-01

plates studded with threaded bolts were placed ERDC/GSL TR-13-27 10 underneath two pre-drilled corners of the panel. The plates were positioned so...metal plates studded with threaded ERDC/GSL TR-13-27 4 Figure 1. DuraDeck® mat panel, top surface. Figure 2. DuraDeck® mat panel, bottom surface...ERDC/GSL TR-13-27 5 bolts , as shown in Figure 3, underneath the mat corners and then installing special connector nuts from the top surface

New "sandwich" structures conformed from three dimensional

Directory of Open Access Journals (Sweden)

Alba, Juan J.

1996-03-01

Full Text Available Poor interlaminar properties as well as poor-skin-to-core adhesion properties are very often the common existing problems we find when designing with "sandwich" structures. A new type of 3D-fabric "sandwich" structure is being developed in order to avoid these problems. Although the manufacturing process is very simple, a very complex "sandwich" structure is obtained as a result of the complexity of the 3D-fabric used. This 3D-fabric is a 3D woven glass fabric produced on velvet weaving machines with glass yarns. It is an integrally woven "sandwich" laminate for all kinds of composite products. The strength of the vertical fibers makes, that also after impregnation with a resin matrix, the "sandwich" structure is maintained. The result is a laminate with high strength and stiffness and low weight. On each side of this "sandwich" laminate additional reinforcement materials can be laminated and a synthetic foam can be injected in the hollow structure. This will allow to establish the mechanical properties of a finished product.

Las pobres propiedades, tanto interlaminares como de adhesión entre piel y núcleo, constituyen uno de los grandes problemas cuando se diseñan estructuras utilizando paneles tipo "sandwich". Un nuevo tipo de panel "sandwich", configurado a partir de tejidos tridimensionales, está siendo desarrollado en la actualidad con el objetivo de eliminar esos problemas. Aunque el proceso de fabricación es muy simple, el panel "sandwich" obtenido es de estructura compleja, como resultado de la complejidad del tejido tridimensional utilizado. Este tejido tridimensional (3D es un tejido de fibra de vidrio producido en máquinas de tejer especializadas. La resistencia de las fibras verticales hace que, después de la impregnación con una resina, se mantenga la configuración tipo "sandwich". El resultado es un laminado de alta resistencia, gran rigidez y bajo peso. Sobre cada uno de los lados del panel "sandwich" se pueden

Sound transmission loss of composite sandwich panels

Science.gov (United States)

Zhou, Ran

Light composite sandwich panels are increasingly used in automobiles, ships and aircraft, because of the advantages they offer of high strength-to-weight ratios. However, the acoustical properties of these light and stiff structures can be less desirable than those of equivalent metal panels. These undesirable properties can lead to high interior noise levels. A number of researchers have studied the acoustical properties of honeycomb and foam sandwich panels. Not much work, however, has been carried out on foam-filled honeycomb sandwich panels. In this dissertation, governing equations for the forced vibration of asymmetric sandwich panels are developed. An analytical expression for modal densities of symmetric sandwich panels is derived from a sixth-order governing equation. A boundary element analysis model for the sound transmission loss of symmetric sandwich panels is proposed. Measurements of the modal density, total loss factor, radiation loss factor, and sound transmission loss of foam-filled honeycomb sandwich panels with different configurations and thicknesses are presented. Comparisons between the predicted sound transmission loss values obtained from wave impedance analysis, statistical energy analysis, boundary element analysis, and experimental values are presented. The wave impedance analysis model provides accurate predictions of sound transmission loss for the thin foam-filled honeycomb sandwich panels at frequencies above their first resonance frequencies. The predictions from the statistical energy analysis model are in better agreement with the experimental transmission loss values of the sandwich panels when the measured radiation loss factor values near coincidence are used instead of the theoretical values for single-layer panels. The proposed boundary element analysis model provides more accurate predictions of sound transmission loss for the thick foam-filled honeycomb sandwich panels than either the wave impedance analysis model or the

Seismic response of cable stayed bridges under multi support excitation

Directory of Open Access Journals (Sweden)

Mahmoud Reza ُُShiravand

2017-07-01

Full Text Available In this Study, the seismic response of cable stayed bridges have been evaluated under multi-support excitations. There are three sources that cause the earthquake wave characteristics change during its propagation path. Local site effect, loss of coherency and wave passage effect are three sources of spatial variation of seismic ground motions. In long span structures, such as cable supported bridges, this phenomenon is more evident and traditional analyzing (uniform excitation may not be valid and be conservative. Thus, it is necessary to investigate the response of cable stayed bridges under non-uniform excitations. For this purpose, the non-uniform time histories were artificially generated using Kriging method based on a set of known time history in the west support of bridge. Nonlinear time history analysis was performed and cables axial force, deck moment, pylons moment and finally drift ratio of bridge have been examined in order to investigate how non-uniform excitation change the seismic response of bridge compared with uniform excitations. Results show non-uniform excitation in some bridge components increase responses and decreases in the others. In non-uniform excitation, although total time history energy is lesser than uniform excitation, it can significantly change the distribution of the forces and makes differential displacement between cables supports and increase the possibility of failure.

Fatigue in Steel Highway Bridges under Random Loading

DEFF Research Database (Denmark)

Agerskov, Henning; Nielsen, J.A.; Vejrum, Tina

1997-01-01

on welded plate test specimens have been carried through. The materials that have been used are either conventional structural steel with a yield stress of ~ 400-410 MPa or high-strength steel with a yield stress of ~ 810-840 MPa.The fatigue tests have been carried out using load histories, which correspond......In the present investigation, fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis.In the experimental part of the investigation, fatigue test series...... to one week's traffic loading, determined by means of strain gage measurements on the orthotropic steel deck structure of the Farø Bridges in Denmark.The test series which have been carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...

Fatigue in Steel Highway Bridges under Random Loading

DEFF Research Database (Denmark)

Agerskov, Henning; Nielsen, Jette Andkjær

1999-01-01

have been carried through. The materials that have been used are either conventional structural steel with a yield stress of f(y) similar to 400-410 MPa or high-strength steel with a yield stress of f(y) similar to 810-840 MPa. The fatigue tests have been carried out using load histories, which......Fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series on welded plate test specimens...... correspond to one week's traffic loading, determined by means of strain gauge measurements on the orthotropic steel deck structure of the Faro Bridges in Denmark. The test series carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...

WORM: A general-purpose input deck specification language

International Nuclear Information System (INIS)

Jones, T.

1999-01-01

Using computer codes to perform criticality safety calculations has become common practice in the industry. The vast majority of these codes use simple text-based input decks to represent the geometry, materials, and other parameters that describe the problem. However, the data specified in input files are usually processed results themselves. For example, input decks tend to require the geometry specification in linear dimensions and materials in atom or weight fractions, while the parameter of interest might be mass or concentration. The calculations needed to convert from the item of interest to the required parameter in the input deck are usually performed separately and then incorporated into the input deck. This process of calculating, editing, and renaming files to perform a simple parameter study is tedious at best. In addition, most computer codes require dimensions to be specified in centimeters, while drawings or other materials used to create the input decks might be in other units. This also requires additional calculation or conversion prior to composition of the input deck. These additional calculations, while extremely simple, introduce a source for error in both the calculations and transcriptions. To overcome these difficulties, WORM (Write One, Run Many) was created. It is an easy-to-use programming language to describe input decks and can be used with any computer code that uses standard text files for input. WORM is available, via the Internet, at worm.lanl.gov. A user's guide, tutorials, example models, and other WORM-related materials are also available at this Web site. Questions regarding WORM should be directed to wormatlanl.gov

Rapid replacement of bridge deck expansion joints study - phase I : [tech transfer summary].

Science.gov (United States)

2014-12-01

This initial research phase focused on documenting the current : means and methods of bridge expansion joint deterioration, : maintenance, and replacement and on identifying improvements : through all of the input gathered.

Experimental study on AR fiberglass connectors for bridges made of composite materials

Directory of Open Access Journals (Sweden)

Tolosana, N.

2006-06-01

Full Text Available One highly relevant aspect in composite material bridgedesing is the study of the shear connectors to be used.Composite material bridges most commonly comprise acomposite deck resting on steel or reinforced concrete girders.This article analyzes the connectors most frequentlyused in such bridges.It also reviews the connectors used in the King StormwaterChannel Bridge, whose fibreglass deck is supported bygirders made of concrete-filled carbon fibre girders.The paper advances proposals for several types of connectorsand discusses the results of push-out test run ona number of prototypes with different geometries.The results are analyzed to identify the optimum model forthe “Autovia del Cantabrico” Overpass, with its 46-m span,carbon fibre girders and AR glass shear connectors.Un aspecto relevante dentro del proyecto de un puenterealizado en materiales compuestos es el estudio de losconectores. El caso mas frecuente de puente en materialescompuestos es aquel que presenta un tablero de materialescompuestos soportado por vigas metalicas o de hormigonarmado. En este trabajo se analizaran los tipos deconectores mas utilizados en este tipo de puentesSe analizaran tambien los conectores utilizados en elKing Stormwater Channel Bridge, donde ademas deltablero en fibra de vidrio, se fabricaron las vigas en fibrasde carbono rellenas de hormigon.En este articulo se propondran varios tipos de conectoresy se presentaran los resultados experimentales correspondientesal ensayo de “push-out” de varios prototipos condiferentes geometrias.Tras evaluar los resultados, se determinara el mas idoneopara su implantacion en el Paso Superior de la Autovia delCantabrico, de 46 metros de luz y que presenta las vigasen fibra de carbono y los conectores de vidrio AR.

Super-bridges suspended over carbon nanotube cables

Science.gov (United States)

Carpinteri, Alberto; Pugno, Nicola M.

2008-11-01

In this paper the new concept of 'super-bridges', i.e. kilometre-long bridges suspended over carbon nanotube cables, is introduced. The analysis shows that the use of realistic (thus defective) carbon nanotube bundles as suspension cables can enlarge the current limit main span by a factor of ~3. Too large compliance and dynamic self-excited resonances could be avoided by additional strands, rendering the super-bridge anchored as a spider's cobweb. As an example, we have computed the limit main spans of the current existing 19 suspended-deck bridges longer than 1 km assuming them to have substituted their cables with carbon nanotube bundles (thus maintaining the same geometry, with the exception of the length) finding spans of up to ~6.3 km. We thus suggest that the design of the Messina bridge in Italy, which would require a main span of ~3.3 km, could benefit from the use of carbon nanotube bundles. We believe that their use represents a feasible and economically convenient solution. The plausibility of these affirmations is confirmed by a statistical analysis of the existing 100 longest suspended bridges, which follow a Zipf's law with an exponent of 1.1615: we have found a Moore-like (i.e. exponential) law, in which the doubling of the capacity (here the main span) per year is substituted by the factor 1.0138. Such a law predicts that the realization of the Messina bridge using conventional materials will only occur around the middle of the present century, whereas it could be expected in the near future if carbon nanotube bundles were used. A simple cost analysis concludes the paper.

Super-bridges suspended over carbon nanotube cables

International Nuclear Information System (INIS)

Carpinteri, Alberto; Pugno, Nicola M

2008-01-01

In this paper the new concept of 'super-bridges', i.e. kilometre-long bridges suspended over carbon nanotube cables, is introduced. The analysis shows that the use of realistic (thus defective) carbon nanotube bundles as suspension cables can enlarge the current limit main span by a factor of ∼3. Too large compliance and dynamic self-excited resonances could be avoided by additional strands, rendering the super-bridge anchored as a spider's cobweb. As an example, we have computed the limit main spans of the current existing 19 suspended-deck bridges longer than 1 km assuming them to have substituted their cables with carbon nanotube bundles (thus maintaining the same geometry, with the exception of the length) finding spans of up to ∼6.3 km. We thus suggest that the design of the Messina bridge in Italy, which would require a main span of ∼3.3 km, could benefit from the use of carbon nanotube bundles. We believe that their use represents a feasible and economically convenient solution. The plausibility of these affirmations is confirmed by a statistical analysis of the existing 100 longest suspended bridges, which follow a Zipf's law with an exponent of 1.1615: we have found a Moore-like (i.e. exponential) law, in which the doubling of the capacity (here the main span) per year is substituted by the factor 1.0138. Such a law predicts that the realization of the Messina bridge using conventional materials will only occur around the middle of the present century, whereas it could be expected in the near future if carbon nanotube bundles were used. A simple cost analysis concludes the paper.

Disassembly of an arch bridge deformed due to landslide activity and the replacement of a new bridge in the same site. Jisuberi ni yori henkei shita arch bashi no kaitai to shinbashi no kakekae

Energy Technology Data Exchange (ETDEWEB)

Sano, S; Morimoto, C; Tomoda, T; Mizukawa, Y; Onushi, M; Ito, T [Kawasaki Heavy Industries, Ltd., Tokyo (Japan)

1991-10-20

This report describes the replacement process of an arch bridge deformed due to landslide activity, selection and contents of the disassembly method, and configuration of the new bridge and its design method. The Ryugu Bridge had been damaged by landslides over an extended period. It was a deck arch bridge having originally a span of 74 meters, but it had shortened by 424 mm due to landslide activity during 14 years since its completion. Then it was decided to be replaced by a new bridge having an adjustable structure to support the movement of its abutments. As disassembly of the deformed arch bridge could be dangerous, the best methodology was studied, and the disassembly was carried out by the cable method. The new bridge had box-girder parts in both side of the main truss, so as to be adjustable to the change of the span length, and the bridge was designed for a working life of 50 years if the bearing supports and expansion joints were reset every 10 years. Concerning the connecting parts between the box-girder and the main truss, appropriateness of the sectional configuration was verified by FEM analysis. 9 refs., 18 figs., 2 tab.

Monitoring of Bridges by a Laser Pointer: Dynamic Measurement of Support Rotations and Elastic Line Displacements: Methodology and First Test.

Science.gov (United States)

Artese, Serena; Achilli, Vladimiro; Zinno, Raffaele

2018-01-25

Deck inclination and vertical displacements are among the most important technical parameters to evaluate the health status of a bridge and to verify its bearing capacity. Several methods, both conventional and innovative, are used for structural rotations and displacement monitoring; however, none of these allow, at the same time, precision, automation, static and dynamic monitoring without using high cost instrumentation. The proposed system uses a common laser pointer and image processing. The elastic line inclination is measured by analyzing the single frames of an HD video of the laser beam imprint projected on a flat target. For the image processing, a code was developed in Matlab ® that provides instantaneous rotation and displacement of a bridge, charged by a mobile load. An important feature is the synchronization of the load positioning, obtained by a GNSS receiver or by a video. After the calibration procedures, a test was carried out during the movements of a heavy truck maneuvering on a bridge. Data acquisition synchronization allowed us to relate the position of the truck on the deck to inclination and displacements. The inclination of the elastic line at the support was obtained with a precision of 0.01 mrad. The results demonstrate the suitability of the method for dynamic load tests, and the control and monitoring of bridges.

Monitoring of Bridges by a Laser Pointer: Dynamic Measurement of Support Rotations and Elastic Line Displacements: Methodology and First Test

Directory of Open Access Journals (Sweden)

Serena Artese

2018-01-01

Full Text Available Deck inclination and vertical displacements are among the most important technical parameters to evaluate the health status of a bridge and to verify its bearing capacity. Several methods, both conventional and innovative, are used for structural rotations and displacement monitoring; however, none of these allow, at the same time, precision, automation, static and dynamic monitoring without using high cost instrumentation. The proposed system uses a common laser pointer and image processing. The elastic line inclination is measured by analyzing the single frames of an HD video of the laser beam imprint projected on a flat target. For the image processing, a code was developed in Matlab® that provides instantaneous rotation and displacement of a bridge, charged by a mobile load. An important feature is the synchronization of the load positioning, obtained by a GNSS receiver or by a video. After the calibration procedures, a test was carried out during the movements of a heavy truck maneuvering on a bridge. Data acquisition synchronization allowed us to relate the position of the truck on the deck to inclination and displacements. The inclination of the elastic line at the support was obtained with a precision of 0.01 mrad. The results demonstrate the suitability of the method for dynamic load tests, and the control and monitoring of bridges.

Wave impact on a deck or baffle

Science.gov (United States)

Md Noar, Nor Aida Zuraimi; Greenhow, Martin

2015-02-01

Some coastal or ocean structures have deck-like baffles or horizontal platforms that can be exposed to wave action in heavy seas. A similar situation may occur in partially-filled tanks with horizontal baffles that become engulfed by sloshing waves. This can result in dangerous wave impact loads (slamming) causing a rapid rise of pressures which may lead to local damaging by crack initiation and/or propagation. We consider the wave impact against the whole of underside of horizontal deck (or baffle) projecting from a seawall (or vertical tank wall), previously studied by Wood and Peregrine (1996) using a different method based on conformal mappings. The approach used is to simplify the highly time-dependent and very nonlinear problem by considering the time integral of the pressure over the duration of the impact pressure-impulse, P (x, y). Our method expresses this in terms of eigenfunctions that satisfy the boundary conditions apart from that on the impact region and the matching of the two regions (under the platform and under the free surface); this results in a matrix equation to be solved numerically. As in Wood and Peregrine, we found that the pressure impulse on the deck increases when the length of deck increases, there is a strong pressure gradient beneath the deck near the seaward edge and the maximum pressure impulse occurs at the landward end of the impact zone.

Sound-proof Sandwich Panel Design via Metamaterial Concept

Science.gov (United States)

Sui, Ni

Sandwich panels consisting of hollow core cells and two face-sheets bonded on both sides have been widely used as lightweight and strong structures in practical engineering applications, but with poor acoustic performance especially at low frequency regime. Basic sound-proof methods for the sandwich panel design are spontaneously categorized as sound insulation and sound absorption. Motivated by metamaterial concept, this dissertation presents two sandwich panel designs without sacrificing weight or size penalty: A lightweight yet sound-proof honeycomb acoustic metamateiral can be used as core material for honeycomb sandwich panels to block sound and break the mass law to realize minimum sound transmission; the other sandwich panel design is based on coupled Helmholtz resonators and can achieve perfect sound absorption without sound reflection. Based on the honeycomb sandwich panel, the mechanical properties of the honeycomb core structure were studied first. By incorporating a thin membrane on top of each honeycomb core, the traditional honeycomb core turns into honeycomb acoustic metamaterial. The basic theory for such kind of membrane-type acoustic metamaterial is demonstrated by a lumped model with infinite periodic oscillator system, and the negative dynamic effective mass density for clamped membrane is analyzed under the membrane resonance condition. Evanescent wave mode caused by negative dynamic effective mass density and impedance methods are utilized to interpret the physical phenomenon of honeycomb acoustic metamaterials at resonance. The honeycomb metamaterials can extraordinarily improve low-frequency sound transmission loss below the first resonant frequency of the membrane. The property of the membrane, the tension of the membrane and the numbers of attached membranes can impact the sound transmission loss, which are observed by numerical simulations and validated by experiments. The sandwich panel which incorporates the honeycomb metamateiral as

Truck-based mobile wireless sensor networks for the experimental observation of vehicle–bridge interaction

International Nuclear Information System (INIS)

Kim, Junhee; Lynch, Jerome P; Lee, Jong-Jae; Lee, Chang-Geun

2011-01-01

Heavy vehicles driving over a bridge create a complex dynamic phenomenon known as vehicle–bridge interaction. In recent years, interest in vehicle–bridge interaction has grown because a deeper understanding of the phenomena can lead to improvements in bridge design methods while enhancing the accuracy of structural health monitoring techniques. The mobility of wireless sensors can be leveraged to directly monitor the dynamic coupling between the moving vehicle and the bridge. In this study, a mobile wireless sensor network is proposed for installation on a heavy truck to capture the vertical acceleration, horizontal acceleration and gyroscopic pitching of the truck as it crosses a bridge. The vehicle-based wireless monitoring system is designed to interact with a static, permanent wireless monitoring system installed on the bridge. Specifically, the mobile wireless sensors time-synchronize with the bridge's wireless sensors before transferring the vehicle response data. Vertical acceleration and gyroscopic pitching measurements of the vehicle are combined with bridge accelerations to create a time-synchronized vehicle–bridge response dataset. In addition to observing the vehicle vibrations, Kalman filtering is adopted to accurately track the vehicle position using the measured horizontal acceleration of the vehicle and positioning information derived from piezoelectric strip sensors installed on the bridge deck as part of the bridge monitoring system. Using the Geumdang Bridge (Korea), extensive field testing of the proposed vehicle–bridge wireless monitoring system is conducted. Experimental results verify the reliability of the wireless system and the accuracy of the vehicle positioning algorithm

High temperature structural sandwich panels

Science.gov (United States)

Papakonstantinou, Christos G.

High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

46 CFR 109.575 - Accumulation of liquids on helicopter decks.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks. ...

Experiments and theory on deck and girder crushing

DEFF Research Database (Denmark)

Simonsen, Bo Cerup; Ocakli, Hasan

1999-01-01

-deflection curves and modes of deformation for decks, stringer decks and deep thin-walled beams subjected to central or excentric point loads between transverse frames. Based on theory and experiments, various modelling aspects of the local/global failure of the beams are discussed. The agreement between......This paper is concerned with theoretical and experimental analysis of deep plastic collapse of a deck or deep girder subjected to an in-plane, concentrated load. A theory is derived which is valid until initition of fracture in the structure. The presented experimental results show load...

Evaluation of Different Software Packages in Flow Modeling under Bridge Structures

Directory of Open Access Journals (Sweden)

Mohammad Taghi Dastorani

2007-01-01

Full Text Available This study is an independent and a comparative research concerning the accuracy, capability and suitability of three well-known packages ofISIS, MIKE11 and HEC-RAS as hydraulic river modeling software packages for modeling the flow through bridges. The research project was designed to assess the ability of each software package to model the flow through bridge structures. It was carried out using the data taken from experiments completed by a 22-meter laboratory flume at theUniversityofBirmingham. The flume has a compound cross section containing a main channel and two flood plains on either side. For this study a smooth main channel and a smooth floodplain have been assumed. Two types of bridges are modeled in this research; a multiple opening semi-circular arch bridge and a single opening straight deck bridge. For each bridge, two different simulations were carried out using two different upstream boundaries as low flow and high flow simulations. According to the results, all three packages were able to model arch and US BPR bridges but in some cases they presented different results. The highest water elevation upstream the bridge (maximum afflux was the main parameter to be compared to the measured values.ISISand HEC-RAS (especially HEC-RAS seem to be more efficient to model arch bridge. However, in some cases, MIKE 11 produced considerably higher results than those of the other two packages. To model USBPR bridge, all three packages produced reasonable results. However, the results by HEC-RAS are the best when the outputs are compared to the experimental data.

The effect of span length and girder type on bridge costs

Directory of Open Access Journals (Sweden)

Batikha Mustafa

2017-01-01

Full Text Available Bridges have an important role in impacting the civilization, growth and economy of cities from ancient time until these days due to their function in reducing transportation cost and time. Therefore, development of bridges has been a knowledge domain in civil engineering studies in terms of their types and construction materials to confirm a reliable, safe, economic design and construction. Girder-bridge of concrete deck and I-beam girder has been used widely for short and medium span bridges because of ease and low-cost of fabrication. However, many theoretical and practical investigations are still undertaken regarding the type of beam girder; i.e steel composite or prestressed concrete. This paper evaluates the effect of bridge span and the type of girder on the capital cost and life cycle costs of bridges. Three types of girders were investigated in this research: steel composite, pre-tensioned pre-stressed concrete and post-tensioned pre-stressed concrete. The structural design was analyzed for 5 span lengths: 20, 25, 30, 35 and 40m. Then, the capital construction cost was accounted for 15 bridges according to each span and construction materials. Moreover, the maintenance required for 50 years of bridge life was evaluated and built up as whole life costs for each bridge. As a result of this study, the influence of both span length and type of girder on initial construction cost and maintenance whole life costs were assessed to support the decision makers and designers in the selection process for the optimum solution of girder bridges.

Development of test method for assessing the bonding characteristics of membrane layers in wearing course laid on orthotropic steel bridge decks

NARCIS (Netherlands)

Liu, X.; Scarpas, A.; Li, J.; Tzimiris, G.; Hofman, R.; Voskuilen, J.

2013-01-01

In order to adequately characterize the adhesive bonding strength of the various membranes with surrounding materials on orthotropic steel decks and collect the necessary parameters for FE modeling, details of the Membrane Adhesion Test (MAT) are introduced. Analytical constitutive relations of the

Creep of sandwich beams with metallic foam cores

International Nuclear Information System (INIS)

Kesler, O.; Crews, L.K.; Gibson, L.J.

2003-01-01

The steady state creep deflection rates of sandwich beams with metallic foam cores were measured and compared with analytical and numerical predictions of the creep behavior. The deflection rate depends on the geometry of the sandwich beam, the creep behavior of the foam core and the loading conditions (stress state, temperature). Although there was a considerable scatter in the creep data (both of the foams and of the sandwich beams made using them), the data for the sandwich beams were fairly well described by the analysis

Creep of sandwich beams with metallic foam cores

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Crews, L.K.; Gibson, L.J

2003-01-20

The steady state creep deflection rates of sandwich beams with metallic foam cores were measured and compared with analytical and numerical predictions of the creep behavior. The deflection rate depends on the geometry of the sandwich beam, the creep behavior of the foam core and the loading conditions (stress state, temperature). Although there was a considerable scatter in the creep data (both of the foams and of the sandwich beams made using them), the data for the sandwich beams were fairly well described by the analysis.

Formulation of Equations of Motion for a Simply Supported Bridge under a Moving Railway Freight Vehicle

Directory of Open Access Journals (Sweden)

Ping Lou

2007-01-01

Full Text Available Based on energy approach, the equations of motion in matrix form for the railway freight vehicle-bridge interaction system are derived, in which the dynamic contact forces between vehicle and bridge are considered as internal forces. The freight vehicle is modelled as a multi-rigid-body system, which comprises one car body, two bogie frames and four wheelsets. The bogie frame is linked with the car body through spring-dashpot suspension systems, and the bogie frame is rigidly linked with wheelsets. The bridge deck, together with railway track resting on bridge, is modelled as a simply supported Bernoulli-Euler beam and its deflection is described by superimposing modes. The direct time integration method is applied to obtain the dynamic response of the vehicle-bridge interaction system at each time step. A computer program has been developed for analyzing this system. The correctness of the proposed procedure is confirmed by one numerical example. The effect of different beam mode numbers and various surface irregularities of beam on the dynamic responses of the vehicle-bridge interaction system are investigated.

Vibration analysis of concrete bridges during a train pass-by using various models

International Nuclear Information System (INIS)

Li, Qi; Wang, Ke; Cheng, Shili; Li, Wuqian; Song, Xiaodong

2016-01-01

The vibration of a bridge must be determined in order to predict the bridge noise during a train pass-by. It can be generally solved with different models either in the time domain or the frequency domain. The computation cost and accuracy of these models vary a lot in a wide frequency band. This study aims to compare the results obtained from various models for recommending the most suitable model in further noise prediction. First, train-track-bridge models in the time domain are developed by using the finite element method and mode superposition method. The rails are modeled by Timoshenko beam elements and the bridge is respectively modeled by shell elements and volume elements. Second, power flow models for the coupled system are established in the frequency domain. The rails are modelled by infinite Timoshenko beams and the bridge is respectively represented by three finite element models, an infinite Kirchhoff plate, and an infinite Mindlin plate model. The vibration at given locations of the bridge and the power input to the bridges through the rail fasteners are calculated using these models. The results show that the shear deformation of the bridge deck has significant influences on the bridge vibration at medium-to-high frequencies. The Mindlin plate model can be used to represent the U-shaped girder to obtain the power input to the bridge with high accuracy and efficiency. (paper)

The Influence of the Track Axis Curvature at Railway Filler-Beam Deck Bridges

Directory of Open Access Journals (Sweden)

Răzvan Marian Stănescu

2016-06-01

Full Text Available The article presents a comparative study between the simplified method calculation proposed by the prescriptions of design codes and the analysis with the FEM program LUSAS [1], regarding the influence of the curvature of the track axis at railway bridges with steel beams embedded in concrete.

Damage Localization of Cable-Supported Bridges Using Modal Frequency Data and Probabilistic Neural Network

Directory of Open Access Journals (Sweden)

X. T. Zhou

2014-01-01

Full Text Available This paper presents an investigation on using the probabilistic neural network (PNN for damage localization in the suspension Tsing Ma Bridge (TMB and the cable-stayed Ting Kau Bridge (TKB from simulated noisy modal data. Because the PNN approach describes measurement data in a Bayesian probabilistic framework, it is promising for structural damage detection in noisy conditions. For locating damage on the TMB deck, the main span of the TMB is divided into a number of segments, and damage to the deck members in a segment is classified as one pattern class. The characteristic ensembles (training samples for each pattern class are obtained by computing the modal frequency change ratios from a 3D finite element model (FEM when incurring damage at different members of the same segment and then corrupting the analytical results with random noise. The testing samples for damage localization are obtained in a similar way except that damage is generated at locations different from the training samples. For damage region/type identification of the TKB, a series of pattern classes are defined to depict different scenarios with damage occurring at different portions/components. Research efforts have been focused on evaluating the influence of measurement noise level on the identification accuracy.

Advanced Mechanical Testing of Sandwich Materials

DEFF Research Database (Denmark)

Hayman, Brian; Berggreen, Christian; Jenstrup, Claus

2008-01-01

An advanced digital optical system has been used to measure surface strains on sandwich face and core specimens tested in a project concerned with improved criteria for designing sandwich X-joints. The face sheet specimens were of glass reinforced polyester and were tested in tension. The core sp...

Fatigue Performance Assessment of Composite Arch Bridge Suspenders Based on Actual Vehicle Loads

Directory of Open Access Journals (Sweden)

Bin Chen

2015-01-01

Full Text Available In the through arch bridges, the suspenders are the key components connecting the arch rib and the bridge deck in the middle, and their safety is an increasing focus in the field of bridge engineering. In this study, various vehicle traffic flow parameters are investigated based on the actual vehicle data acquired from the long-term structural health monitoring system of a composite arch bridge. The representative vehicle types and the probability density functions of several parameters are determined, including the gross vehicle weight, axle weight, time headway, and speed. A finite element model of the bridge structure is constructed to determine the influence line of the cable force for various suspenders. A simulated vehicle flow, generated using the Monte Carlo method, is applied on the influence lines of the target suspender to determine the stress process, and then the stress amplitude spectrum is obtained based on the statistical analysis of the stress process using the rainflow counting method. The fatigue performance levels of various suspenders are analyzed according to the Palmgren-Miner linear cumulative damage theory, which helps to manage the safety of the suspenders.

Low Velocity Impact Properties of Aluminum Foam Sandwich Structural Composite

Directory of Open Access Journals (Sweden)

ZHAO Jin-hua

2018-01-01

Full Text Available Sandwich structural composites were prepared by aluminum foam as core materials with basalt fiber(BF and ultra-high molecular weight polyethylene(UHMWPE fiber composite as faceplate. The effect of factors of different fiber type faceplates, fabric layer design and the thickness of the corematerials on the impact properties and damage mode of aluminum foam sandwich structure was studied. The impact properties were also analyzed to compare with aluminum honeycomb sandwich structure. The results show that BF/aluminum foam sandwich structural composites has bigger impact damage load than UHMWPE/aluminum foam sandwich structure, but less impact displacement and energy absorption. The inter-layer hybrid fabric design of BF and UHMWPE has higher impact load and energy absorption than the overlay hybrid fabric design faceplate sandwich structure. With the increase of the thickness of aluminum foam,the impact load of the sandwich structure decreases, but the energy absorption increases. Aluminum foam sandwich structure has higher impact load than the aluminum honeycomb sandwich structure, but smaller damage energy absorption; the damage mode of aluminum foam core material is mainly the fracture at the impact area, while aluminum honeycomb core has obvious overall compression failure.

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges

Science.gov (United States)

Qu, Wei-Lian; Qin, Shun-Quan; Tu, Jian-Weia; Liu, Jia; Zhou, Qiang; Cheng, Haibin; Pi, Yong-Lin

2009-12-01

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the developed theory, a full-scale 500 kN smart magnetorheologic (MR) damper has been designed, fabricated and used to carry out experiments on the intelligent control of braking-induced longitudinal vibration. The procedure for using the developed intelligent method in conjunction with the full-scale 500 kN MR dampers has been proposed and used to control the longitudinal vibration responses of the deck of floating-type railway bridges induced by train braking and axle-loads of moving trains. This procedure has been applied to the longitudinal vibration control of the Tian Xingzhou highway and railway cable-stayed bridge over the Yangtze River in China. The simulated results have shown that the intelligent control system using the smart MR dampers can effectively control the longitudinal response of the floating-type railway bridge under excitations of braking and axle-loads of moving trains.

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges

International Nuclear Information System (INIS)

Qu, Wei-Lian; Tu, Jian-Weia; Liu, Jia; Zhou, Qiang; Qin, Shun-Quan; Cheng, Haibin; Pi, Yong-Lin

2009-01-01

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the developed theory, a full-scale 500 kN smart magnetorheologic (MR) damper has been designed, fabricated and used to carry out experiments on the intelligent control of braking-induced longitudinal vibration. The procedure for using the developed intelligent method in conjunction with the full-scale 500 kN MR dampers has been proposed and used to control the longitudinal vibration responses of the deck of floating-type railway bridges induced by train braking and axle-loads of moving trains. This procedure has been applied to the longitudinal vibration control of the Tian Xingzhou highway and railway cable-stayed bridge over the Yangtze River in China. The simulated results have shown that the intelligent control system using the smart MR dampers can effectively control the longitudinal response of the floating-type railway bridge under excitations of braking and axle-loads of moving trains

Cyclic and dynamic response of a bridge pier model located at the Volvi European test site in Greece

International Nuclear Information System (INIS)

Manos, G.C.; Kourtides, V.; Soulis, V.J.

2005-01-01

the presence or not of diagonal cables between the foundation and the deck as well the presence or not of extra mass at the deck apart from the concrete slab. The deck acceleration response was recorded and was studied in the frequency domain in order to extract the most significant eigen-modes and eigen-frequencies for the various configurations of the pier bridge model, which are presented here in a summary form. Moreover, an extensive numerical simulation of the response was also performed, which includes the flexibility of the foundation. Good agreement can be seen when the measured values are compared with the corresponding numerical predictions. (authors)

Structural and failure mechanics of sandwich composites

CERN Document Server

Carlsson, LA; Carlsson, Leif A

2011-01-01

Focusing on important deformation and failure modes of sandwich structures, this volume describes the mechanics behind fracture processes. The text also reviews test methods developed for the cr, structural integrity, and failure mechanisms of sandwich structures.

Thermal conductivity of newspaper sandwiched aerated lightweight concrete panel

Energy Technology Data Exchange (ETDEWEB)

Ng, Soon-Ching; Low, Kaw-Sai [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, Setapak, 53300 Kuala Lumpur, Wilayah Persekutuan (Malaysia)

2010-12-15

Investigation on the thermal conductivity of newspaper sandwiched aerated lightweight concrete (ALC) panels is the main purpose of this study. Various densities of ALC panels ranging from 1700, 1400 and 1100 kg/m{sup 3} with three different aerial intensities of newspaper sandwiched were produced. Investigation was limited to the effect of aerial intensity of newspaper sandwiched and the effect of density of ALC on thermal conductivity. It is found that the thermal conductivity of newspaper sandwiched ALC panels reduced remarkably compared to control ALC panels. The reduction was recorded at 18.0%, 21.8% and 20.7% correspond to densities of 1700, 1400 and 1100 kg/m{sup 3} with just a mere 0.05 g/cm{sup 2} aerial intensity of newspaper sandwiched. Newspaper sandwiched has a significant impact on the performance of thermal conductivity of ALC panels based on regression analysis. (author)

Predicting safe sandwich production

DEFF Research Database (Denmark)

Birk, Tina; Duan, Zhi; Møller, Cleide Oliveira de Almeida

2014-01-01

Time and temperature control is crucial to avoid growth of pathogens during production and serving of cold ready-to-eat meals. The Danish guidelines state that chilled foods, such as sandwiches, should not be outside the cold chain for more than 3 hours including the time for preparation...... and serving. However, Danish sandwich producing companies find it challenging to comply with this and have expressed a need for more flexibility. The Danish guidelines do allow for a prolongation of the acceptable time outside the cold chain, if the safety of the specific production can be documented...

Development of MIDAS/SMR Input Deck for SMART

International Nuclear Information System (INIS)

Cho, S. W.; Oh, H. K.; Lee, J. M.; Lee, J. H.; Yoo, K. J.; Kwun, S. K.; Hur, H.

2010-01-01

The objective of this study is to develop MIDAS/SMR code basic input deck for the severe accidents by simulating the steady state for the SMART plant. SMART plant is an integrated reactor developed by KAERI. For the assessment of reactor safety and severe accident management strategy, it is necessary to simulate severe accidents using the MIDAS/SMR code which is being developed by KAERI. The input deck of the MIDAS/SMR code for the SMART plant is prepared to simulate severe accident sequences for the users who are not familiar with the code. A steady state is obtained and the results are compared with design values. The input deck will be improved through the simulation of the DBAs and severe accidents. The base input deck of the MIDAS/SMR code can be used to simulate severe accident scenarios after improvement. Source terms and hydrogen generation can be analyzed through the simulation of the severe accident. The information gained from analyses of severe accidents is expected to be helpful to develop the severe accident management strategy

Identification of causes and solution strategies for deck cracking in jointless bridges : research report.

Science.gov (United States)

2012-07-01

Bridges have traditionally relied on a system of expansion joints and flexible bearings to accommodate movements due to temperature, creep, and shrinkage loading. Joints and elements in their vicinity experience a high amount of degradation; thus mod...

Numerical Modelling of the Dynamic Response of High-Speed Railway Bridges Considering Vehicle-Structure and Structure-Soil-Structure Interaction

DEFF Research Database (Denmark)

Bucinskas, Paulius; Agapii, L.; Sneideris, J.

2015-01-01

is idealized as a multi-degree-of-freedom system, modelled with two layers of spring-dashpot suspension systems. Coupling the vehicle system and railway track is realized through interaction forces between the wheels and the rail, where the irregularities of the track are implemented as a random stationary......The aim of this paper is the dynamic analysis of a multi-support bridge structure exposed to high-speed railway traffic. The proposed computational model has a unified approach for simultaneously accounting for the bridge structure response, soil response and forces induced by the vehicle....... The bridge structure is modelled in three dimensions based on the finite element method using two-noded three-dimensional beam elements. The track structure is composed of three layers: rail, sleepers and deck which are connected through spring-dashpot systems. The vehicle travelling along a bridge...

Development of Aircraft Sandwich Parts

Directory of Open Access Journals (Sweden)

J. Křena

2000-01-01

Full Text Available The presented paper shows the design and development process of sandwich parts. A spoiler plate and a main landing gear door are developed. Sandwich parts are made of C/E composite facings and a foam core. FE models have been used for optimization of structures. Emphasis has been placed on deformations of parts under a few load cases. Experimental tests have been used for a verification of structure parts loaded by concentrated forces.

Cation-mediated conversion of the state of charge in uranium arene inverted-sandwich complexes

Energy Technology Data Exchange (ETDEWEB)

Camp, Clement; Mougel, Victor; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Maron, Laurent [LCPNO, CNRS and INSA, UPS, Universite de Toulouse (France)

2013-12-16

Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (3) and [K{sub 2}{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (2) with stoichiometric amounts of KC{sub 8} yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U{sup V}-(arene{sup 4-})-U{sup V}, KU{sup IV}-(arene{sup 4-})-U{sup V}, and K{sub 2}U{sup IV}-(arene{sup 4-})-U{sup IV} for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U{sup IV} mononuclear complex [U(OSi(OtBu){sub 3}){sub 3}(OTf)(thf){sub 2}] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

ITO-TiN-ITO Sandwiches for Near-Infrared Plasmonic Materials.

Science.gov (United States)

Chen, Chaonan; Wang, Zhewei; Wu, Ke; Chong, Haining; Xu, Zemin; Ye, Hui

2018-05-02

Indium tin oxide (ITO)-based sandwich structures with the insertion of ultrathin (ITO layers show TiN-thickness-dependent properties, which lead to moderate and tunable effective permittivities for the sandwiches. The surface plasmon polaritons (SPP) of the ITO-TiN-ITO sandwich at the telecommunication window (1480-1570 nm) are activated by prism coupling using Kretschmann configuration. Compared with pure ITO films or sandwiches with metal insertion, the reflectivity dip for sandwiches with TiN is relatively deeper and wider, indicating the enhanced coupling ability in plasmonic materials for telecommunications. The SPP spatial profile, penetration depth, and degree of confinement, as well as the quality factors, demonstrate the applicability of such sandwiches for NIR plasmonic materials in various devices.

Monitoring of wind load and response for cable-supported bridges in Hong Kong

Science.gov (United States)

Wong, Kai-yuen; Chan, Wai-Yee K.; Man, King-Leung

2001-08-01

Structural health monitoring for the three cable-supported bridges located in the West of Hong Kong or the Tsing Ma Control Area has been carried out since the opening of these bridges to public traffic. The three cable-supported bridges are referred to as the Tsing Ma (suspension) Bridge, the Kap Shui Mun (cable-stayed) Bridge and the Ting Kau (cable-stayed) Bridge. The structural health monitoring works involved are classified as six monitoring categories, namely, wind load and response, temperature load and response, traffic load and response, geometrical configuration monitoring, strains and stresses/forces monitoring and global dynamic characteristics monitoring. As wind loads and responses had been a major concern in the design and construction stages, this paper therefore outlines the work of wind load and response monitoring on Tsing Ma, Kap Shui Mun and Ting Kau Bridges. The paper starts with a brief description of the sensory systems. The description includes the layout and performance requirements of sensory systems for wind load and responses monitoring. Typical results of wind load and response monitoring in graphical forms are then presented. These graphical forms include the plots of wind rose diagrams, wind incidences vs wind speeds, wind turbulence intensities, wind power spectra, gust wind factors, coefficient of terrain roughness, extreme wind analyses, deck deflections/rotations vs wind speeds, acceleration spectra, acceleration/displacement contours, and stress demand ratios. Finally conclusions on wind load and response monitoring on the three cable-supported bridges are drawn.

Experimental formability analysis of bondal sandwich sheet

Science.gov (United States)

Kami, Abdolvahed; Banabic, Dorel

2018-05-01

Metal/polymer/metal sandwich sheets have recently attracted the interests of industries like automotive industry. These sandwich sheets have superior properties over single-layer metallic sheets including good sound and vibration damping and light weight. However, the formability of these sandwich sheets should be enhanced which requires more research. In this paper, the formability of Bondal sheet (DC06/viscoelastic polymer/DC06 sandwich sheet) was studied through different types of experiments. The mechanical properties of Bondal were determined by uniaxial tensile tests. Hemispherical punch stretching and hydraulic bulge tests were carried out to determine the forming limit diagram (FLD) of Bondal. Furthermore, cylindrical and square cup drawing tests were performed in dry and oil lubricated conditions. These tests were conducted at different blank holding forces (BHFs). An interesting observation about Bondal sheet deep drawing was obtaining of higher drawing depths at dry condition in comparison with oil-lubricated condition.

Effects of concrete moisture on polymer overlay bond over new concrete : [technical summary].

Science.gov (United States)

2015-06-01

Epoxy polymer overlays have been used for decades on existing bridge decks to protect : the deck and extend its service life. The polymer overlays ability to seal a bridge deck : is now being specified for new construction. Questions exist about t...

Vibro-acoustics of lightweight sandwich structures

CERN Document Server

Lu, Tianjian

2014-01-01

Vibro-Acoustics of Lightweight Sandwich Structures introduces the study of the coupled vibration and acoustic behavior of lightweight sandwich structures in response to harmonic force and sound pressure. This book focuses on the theoretical modeling and experimental investigation of lightweight sandwich structures in order to provide a predictive framework for vibro-acoustic characteristics of typical engineering structures. Furthermore, by developing solution tools, it concentrates on the influence of key systematic parameters leading to effective guidance for optimal structure design toward lightweight, high-stiffness and superior sound insulation capability. This book is intended for researchers, scientists, engineers and graduate students in mechanical engineering especially in structural mechanics, mechanics and acoustics. Fengxian Xin and Tianjian Lu both work at the School of Aerospace, Xi’an Jiaotong University.

"The Battery" designed with Super-Light (concrete) Decks

DEFF Research Database (Denmark)

Castberg, Niels Andreas; Hertz, Kristian Dahl

This paper describes how Super-Light structures can be used as a structural principle for the buildings in the project ‘The Battery’ designed by Bjarke Ingels Group. The overall structural concept is described and the advantages of using super-light slabs for the project are explored. Especially...... the cantilevered internal corridors are investigated. Super-Light Structures is a newly patented structural concrete concept. Slabs based on the concept are the first structural element developed under the patent. The slabs called SL-decks have multiple advantages compared to traditional hollow core slabs....... The paper aims to describe the concept of how the deck can be used in these innovative buildings and how the special advantages of the SL-decks are applied....

Non-linear Behavior of Curved Sandwich Panels

DEFF Research Database (Denmark)

Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.

2003-01-01

In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure loa...

46 CFR 45.143 - Hull openings above freeboard deck.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Hull openings above freeboard deck. 45.143 Section 45.143 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.143 Hull openings above freeboard deck. Closures for openings above...

Aluminium bridges, aluminium bridge decks

NARCIS (Netherlands)

Soetens, F.; Straalen, IJ.J. van

2003-01-01

Applications of aluminium have grown considerably in building and civil engineering the last decade. In building and civil engineering the increase of aluminium applications is due to various aspects like light weight, durability and maintenance, use of extrusions, and esthetics. The paper starts

Nonglobal proof of the thin--sandwich conjecture

International Nuclear Information System (INIS)

Pereira, C.M.

1981-01-01

A gravitational thin--sandwich conjecture was first proposed by Wheeler and coworkers during the period 1962--4. The present paper contains a proof of the nonglobal form of this gravitational thin--sandwich conjecture. The proof (a) applies for arbitrary choices of the spatial metric and its time derivative; and (b) demonstrates the existence on a spacelike three-surface of solutions which satisfy conditions of continuity known to be sufficient to obtain existence and uniqueness of solutions to Einstein's equations off the three-surface and existence and uniqueness of geodesics. Riquier's existence theorem plays an important role in the proof. The relationship of the present results to previous work is discussed. Some global questions associated with the thin--sandwich conjecture are clarified. Some aspects of the relationship of the thin--sandwich conjecture to the problem of the quantization of the gravitational field are noted. Both the vacuum case and the case of a nonviscous fluid are included. The discussion allows for an arbitrary equation of state p = p

Influence of ceiling systems on room temperature and energy efficiency in steel sheet deckings; Einfluss von Deckensystemen auf Raumtemperatur und Energieeffizienz im Stahlgeschossbau

Energy Technology Data Exchange (ETDEWEB)

Doering, Bernd

2008-07-01

Over the past years the use of flooring systems to affect the indoor climate of buildings is of increasing interest, including both thermo-active and also passive systems. The amendment of the German Energy saving ordinance (Energieeinsparverordnung 2007) requires, that in future projects, the energy demand for cooling and ventilation has to be considered for the calculation of the energy demand of non-residential buildings. Due to this circumstance, solutions for energy efficient cooling will come more into the focus. Up to now, the use of flooring systems in steel structures have not been investigated regarding this aspect. In this thesis, six different flooring systems were investigated: two passive acting solutions, using the effects of enlarging the surface and integrating phase change materials (PCM), one system comprising ducts that pass cold air through the floor during the night and three thermo-active deck systems (i.e. profiled steel sheet decking, a hollow-core slab, and a laser-welded steel sandwich panel). Generally, the thermal behaviour of such elements is described only using one-dimensional multilayer structure (for standardized calculations or for thermal building simulation), this concept is not adequate for profiled and homogeneous components. Therefore three-dimensional Finite Elemente investigations were performed to consider the specific properties. Based on these results a simplified method using equivalent parameters was developed, which allows the implementation of the considered flooring systems in standardized calculations (ISO 13786). For selected systems, validation by in-service measurements was performed. By using Thermal Building Simulation tools, a parametric study was carried out to specify the range and limits of application in respect of climate and internal heat gains. The results can be summarized as follows: - Profiled steel sheet decking show a higher effective thermal capacity than conventional flat slabs. - PCM increases

Characterization of sandwich panels for indentation and impact

International Nuclear Information System (INIS)

Shazly, M; Salem, S; Bahei-El-Din, Y

2013-01-01

The integrity of sandwich structures which are susceptible to impact may deteriorate significantly due to collapse of the core material and delamination of the face sheets. The integration of a thin polyurethane interlayer between the composite face sheet and foam core is known to protect the core material and substantially improve the resistance to impact. The objective of the present work is to characterize the response of sandwich panels, as well as that of the constituents to impact. In particular, the response of polyurethane and foam samples under a range of quasi-static and dynamic loading rates is determined experimentally. Furthermore, the response of sandwich panels to quasi-static indentation and low velocity impact is examined to quantify the extent of damage and how it is affected by the integration of polyurethane interlayers in their construction. This information is useful in the modelling of high velocity impact of sandwich panels; an effort which is currently underway. The results illustrate the benefit of using polyurethane interlayers within the construction of sandwich panels in enhancing their performance under quasi-static indentation and impact loads

Determining Time Variation of Cable Tension Forces in Suspended Bridges Using Time-Frequency Analysis

Directory of Open Access Journals (Sweden)

Gannon Stromquist-LeVoir

2018-01-01

Full Text Available A feasibility study was conducted to develop a novel method to determine the temporal changes of tensile forces in bridge suspender cables using time-frequency analysis of ambient vibration measurements. An analytical model of the suspender cables was developed to evaluate the power spectral density (PSD function of a cable with consideration of cable flexural stiffness. Discrete-time, short-time Fourier transform (STFT was utilized to analyze the recorded acceleration histories in both time and frequency domains. A mathematical convolution of the analytical PSD function and time-frequency data was completed to evaluate changes in cable tension force over time. The method was implemented using acceleration measurements collected from an in-service steel arch bridge with a suspended deck to calculate the temporal variation in cable forces from the vibration measurements. The observations served as proof of concept that the proposed method may be used for cable fatigue life calculations and bridge weigh-in-motion studies.

Flexible concrete link slabs used as expansion joints in bridge decks

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor

2011-01-01

of water through the expansion joint and subsequent corrosion of girders and girder bearings. Investigations on joint-less superstructures using conventional steel reinforcement in so-called concrete link slabs indicate improved performance and economic feasibility. However, this concept requires...... relatively large amounts of steel reinforcement for crack control purposes and consequently provides a relatively large flexural stiffness and negative moment capacity at the joint between the spans. These contradicting requirements and effects in existing replacement concepts for damaged mechanical bridge...... joints are currently unresolved. In the proposed system described in this paper, a ductile cement-based composite section reinforced with Glass Fiber Reinforced Polymers (GFRP) replaces the damaged expansion joint. The combination of this ductile concrete together with corrosion resistant GFRP...

Seismic Retrofit of a Multispan Prestressed Concrete Girder Bridge with Friction Pendulum Devices

Directory of Open Access Journals (Sweden)

Alberto Maria Avossa

2018-01-01

Full Text Available The paper deals with the proposal and application of a procedure for the seismic retrofit of an existing multispan prestressed concrete girder bridge defined explicitly for the use of friction pendulum devices as an isolation system placed between piers top and deck. First, the outcomes of the seismic risk assessment of the existing bridge, performed using an incremental noniterative Nonlinear Static Procedure, based on the Capacity Spectrum Method as well as the Inelastic Demand Response Spectra, are described and discussed. Then, a specific multilevel design process, based on a proper application of the hierarchy of strength considerations and the Direct Displacement-Based Design approach, is adopted to dimension the FPD devices. Furthermore, to assess the impact of the FPD nonlinear behaviour on the bridge seismic response, a device model that reproduces the variation of the normal force and friction coefficient, the bidirectional coupling, and the large deformation effects during nonlinear dynamic analyses was used. Finally, the paper examines the effects of the FPD modelling parameters on the behaviour of the retrofitted bridge and assesses its seismic response with the results pointing out the efficiency of the adopted seismic retrofit solution.

Real-time seismic monitoring of the integrated cape girardeau bridge array and recorded earthquake response

Science.gov (United States)

Celebi, M.

2006-01-01

This paper introduces the state of the art, real-time and broad-band seismic monitoring network implemented for the 1206 m [3956 ft] long, cable-stayed Bill Emerson Memorial Bridge in Cape Girardeau (MO), a new Mississippi River crossing, approximately 80 km from the epicentral region of the 1811-1812 New Madrid earthquakes. The bridge was designed for a strong earthquake (magnitude 7.5 or greater) during the design life of the bridge. The monitoring network comprises a total of 84 channels of accelerometers deployed on the superstructure, pier foundations and at surface and downhole free-field arrays of the bridge. The paper also presents the high quality response data obtained from the network. Such data is aimed to be used by the owner, researchers and engineers to assess the performance of the bridge, to check design parameters, including the comparison of dynamic characteristics with actual response, and to better design future similar bridges. Preliminary analyses of ambient and low amplitude small earthquake data reveal specific response characteristics of the bridge and the free-field. There is evidence of coherent tower, cable, deck interaction that sometimes results in amplified ambient motions. Motions at the lowest tri-axial downhole accelerometers on both MO and IL sides are practically free from any feedback from the bridge. Motions at the mid-level and surface downhole accelerometers are influenced significantly by feedback due to amplified ambient motions of the bridge. Copyright ASCE 2006.

Simulation of the Vacuum Assisted Resin Transfer Molding (VARTM) process and the development of light-weight composite bridging

Science.gov (United States)

Robinson, Marc J.

A continued desire for increased mobility in the aftermath of natural disasters, or on the battlefield, has lead to the need for improved light-weight bridging solutions. This research investigates the development of a carbon/epoxy composite bridging system to meet the needs for light-weight bridging. The research focuses on two main topics. The first topic is that of processing composite structures and the second is the design and testing of these structures. In recent years the Vacuum Assisted Resin Transfer Molding (VARTM) process has become recognized as a low-cost manufacturing alternative for large Fiber Reinforced Polymer (FRP) composite structures for civil, military, and aerospace applications. The success of the VARTM process (complete wet-out) is very sensitive to the resin injection strategy used and the proper placement of flow distribution materials and inlet and vacuum ports. Predicting the flow front pattern, the time required for infusing a part with resin, and the time required to bleed excess resin at the end of filling, is critical to ensure that the part will become completely impregnated and desired fiber volume fractions achieved prior to the resin gelling (initiation of cure). In order to eliminate costly trial and error experiments to determine the optimal infusion strategy, this research presents a simulation model which considers in-plane flow as well as flow through the thickness of the preform. In addition to resin filling, the current model is able to simulate the bleeding of resin at the end of filling to predict the required bleeding time to reach desired fiber volume fractions for the final part. In addition to processing, the second portion of the dissertation investigates the design and testing of composite bridge deck sections which also serve as short-span bridging for gaps up to 4 m in length. The research focuses on the design of a light-weight core material for bridge decking as well as proof loading of short-span bridge

Advanced ground-penetrating, imaging radar for bridge inspection

International Nuclear Information System (INIS)

Warhus, J.P.; Nelson, S.D.; Mast, J.E.; Johansson, E.M.

1994-01-01

During FY-93, the authors continued with development and experimental evaluation of components and system concepts aimed at improving ground-penetrating imaging radar (GPIR) for nondestructive evaluation of bridge decks and other high-value concrete structures. They developed and implemented a laboratory test bed, including features to facilitate component testing antenna system configuration evaluation, and collection of experimental data from realistic test objects. In addition, they developed pulse generators and antennas for evaluation and use in antenna configuration studies. This project was part of a cooperative effort with the Computational Electronics and Electromagnetics and Remote Imaging and Signal Engineering Thrust Areas, which contributed signal- and image-processing algorithm and software development and modeling support

Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

Directory of Open Access Journals (Sweden)

Aneta Krzyżak

2016-01-01

Full Text Available Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

Increasing the Capacity of Existing Bridges by Using Unbonded Prestressing Technology: A Case Study

Directory of Open Access Journals (Sweden)

Antonino Recupero

2014-01-01

Full Text Available External posttensioning or unbonded prestressing was found to be a powerful tool for retrofitting and for increasing the life extension of existing structures. Since the 1950s, this technique of reinforcement was applied with success to bridge structures in many countries, and was found to provide an efficient and economic solution for a wide range of bridge types and conditions. Unbonded prestressing is defined as a system in which the post-tensioning tendons or bars are located outside the concrete cross-section and the prestressing forces are transmitted to the girder through the end anchorages, deviators, or saddles. In response to the demand for a faster and more efficient transportation system, there was a steady increase in the weight and volume of traffic throughout the world. Besides increases in legal vehicle loads, the overloading of vehicles is a common problem and it must also be considered when designing or assessing bridges. As a result, many bridges are now required to carry loads significantly greater than their original design loads; and their deck results still deteriorated by cracking of concrete, corrosion of rebars, snapping of tendons, and so forth. In the following, a case study about a railway bridge retrofitted by external posttensioning technique will be illustrated.

Design and manufacturing of bio-based sandwich structures

CSIR Research Space (South Africa)

John, Maya J

2017-03-01

Full Text Available The aim of this chapter is to discuss the design and manufacturing of bio-based sandwich structures. As the economic advantages of weight reduction have become mandatory for many advanced industries, bio-based sandwich panels have emerged...

Non-destructive inspection protocol for reinforced concrete barriers and bridge railings

Energy Technology Data Exchange (ETDEWEB)

Chintakunta, Satish R. [Engineering and Software Consultants, Inc., 14123 Robert Paris Ct., Chantilly, VA 20151 (United States); Boone, Shane D. [Federal Highway Administration, Turner Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101 (United States)

2014-02-18

Reinforced concrete highway barriers and bridge railings serve to prevent errant vehicles from departing the travel way at grade separations. Despite the important role that they play in maintaining safety and their ubiquitous nature, barrier inspection rarely moves beyond visual inspection. In August 2008, a tractor-trailer fatally departed William Preston Lane, Jr. Memorial Bridge after it dislodged a section of the bridge barrier. Investigations following the accident identified significant corrosion of the anchor bolts attaching the bridge railing to the bridge deck. As a result of the information gathered during its investigation of the accident, the National Transportation Safety Board (NTSB) made recommendations to the Federal Highway Administration concerning Non-Destructive Evaluation (NDE) of concrete bridge railings. The Center for nondestructive evaluation (NDE) at Turner Fairbank Highway Research Center in McLean, VA is currently evaluating feasibility of using four technologies - ground penetrating radar (GPR), ultrasonic pulse-echo, digital radiography and infrared thermal imaging methods to develop bridge inspection methods that augment visual inspections, offer reliable measurement techniques, and are practical, both in terms of time and cost, for field inspection work. Controlled samples containing predefined corrosion levels in reinforcing steel were embedded at barrier connection points for laboratory testing. All four NDE techniques were used in the initial phase I testing. An inspection protocol for detecting and measuring the corrosion of reinforced steel embedded in the anchorage system will be developed as part of phase II research. The identified technologies shall be further developed for field testing utilizing a structure with a barrier in good condition and a structure with a barrier in poor condition.

Non-destructive inspection protocol for reinforced concrete barriers and bridge railings

Science.gov (United States)

Chintakunta, Satish R.; Boone, Shane D.

2014-02-01

Reinforced concrete highway barriers and bridge railings serve to prevent errant vehicles from departing the travel way at grade separations. Despite the important role that they play in maintaining safety and their ubiquitous nature, barrier inspection rarely moves beyond visual inspection. In August 2008, a tractor-trailer fatally departed William Preston Lane, Jr. Memorial Bridge after it dislodged a section of the bridge barrier. Investigations following the accident identified significant corrosion of the anchor bolts attaching the bridge railing to the bridge deck. As a result of the information gathered during its investigation of the accident, the National Transportation Safety Board (NTSB) made recommendations to the Federal Highway Administration concerning Non-Destructive Evaluation (NDE) of concrete bridge railings. The Center for nondestructive evaluation (NDE) at Turner Fairbank Highway Research Center in McLean, VA is currently evaluating feasibility of using four technologies - ground penetrating radar (GPR), ultrasonic pulse-echo, digital radiography and infrared thermal imaging methods to develop bridge inspection methods that augment visual inspections, offer reliable measurement techniques, and are practical, both in terms of time and cost, for field inspection work. Controlled samples containing predefined corrosion levels in reinforcing steel were embedded at barrier connection points for laboratory testing. All four NDE techniques were used in the initial phase I testing. An inspection protocol for detecting and measuring the corrosion of reinforced steel embedded in the anchorage system will be developed as part of phase II research. The identified technologies shall be further developed for field testing utilizing a structure with a barrier in good condition and a structure with a barrier in poor condition.

The sandwich sign | Mahomed | SA Journal of Radiology

African Journals Online (AJOL)

The sandwich sign refers to the sandwiching of mesenteric vessels and fat by enlarged mesenteric nodes on cross-sectional imaging, commonly occurring in lymphoma, but not specific to lymphoma. The sign is radiologically indistinguishable from post-transplant lymphoproliferative disorders. The radiological significance ...

Two-Dimensional Analysis of Cable Stayed Bridge under Wave Loading

Science.gov (United States)

Seeram, Madhuri; Manohar, Y.

2018-06-01

In the present study finite element analysis is performed for a modified fan type cable-stayed bridge using ANSYS Mechanical. A cable stayed bridge with two towers and main deck is considered for the present study. Dynamic analysis is performed to evaluate natural frequencies. The obtained natural frequencies and mode shapes of cable stayed bridge are compared to the existing results. Further studies have been conducted for offshore area application by increasing the pylon/tower height depending upon the water depth. Natural frequencies and mode shapes are evaluated for the cable stayed bridge for offshore area application. The results indicate that the natural periods are higher than the existing results due to the effect of increase in mass of the structure and decrease in stiffness of the pylon/tower. The cable stayed bridge is analyzed under various environmental loads such as dead, live, vehicle, seismic and wave loading. Morison equation is considered to evaluate the wave force. The sum of inertia and drag force is taken as the wave force distribution along the fluid interacting height of the pylon. Airy's wave theory is used to assess water particle kinematics, for the wave periods ranging from 5 to 20 s and unit wave height. The maximum wave force among the different regular waves is considered in the wave load case. The support reactions, moments and deflections for offshore area application are highlighted. It is observed that the maximum support reactions and support moments are obtained due to wave and earthquake loading respectively. Hence, it is concluded that the wave and earthquake forces shall be given significance in the design of cable stayed bridge.

Fluid-structure interaction analysis of a deck structure during a HCDA

International Nuclear Information System (INIS)

Kulak, R.F.

1979-01-01

Presented is an assessment of the structural integrity of the deck structure of a pool-type LMFBR during a Hypothetical Core Disruptive Accident (HCDA). During this accident the sodium above the core is propelled upward until it impacts against the deck structure. This hydrodynamic loading could produce (1) significant structural damage and (2) sodium leak paths. A finite-element model is used to study the deck dynamics during slug impact. By using the symmetry of the system, a sector model which accounts for the salient features of the system is developed. The main radial I-beam, component support I-beam and bottom annular plate are modeled using triangular plate elements. The concrete fill is modeled using hexahedral continuum elements. Using the above finite-element model the dynamics of the deck during a HCDA are investigated

Optimization of wood plastic composite decks

Science.gov (United States)

Ravivarman, S.; Venkatesh, G. S.; Karmarkar, A.; Shivkumar N., D.; Abhilash R., M.

2018-04-01

Wood Plastic Composite (WPC) is a new class of natural fibre based composite material that contains plastic matrix reinforced with wood fibres or wood flour. In the present work, Wood Plastic Composite was prepared with 70-wt% of wood flour reinforced in polypropylene matrix. Mechanical characterization of the composite was done by carrying out laboratory tests such as tensile test and flexural test as per the American Society for Testing and Materials (ASTM) standards. Computer Aided Design (CAD) model of the laboratory test specimen (tensile test) was created and explicit finite element analysis was carried out on the finite element model in non-linear Explicit FE code LS - DYNA. The piecewise linear plasticity (MAT 24) material model was identified as a suitable model in LS-DYNA material library, describing the material behavior of the developed composite. The composite structures for decking application in construction industry were then optimized for cross sectional area and distance between two successive supports (span length) by carrying out various numerical experiments in LS-DYNA. The optimized WPC deck (Elliptical channel-2 E10) has 45% reduced weight than the baseline model (solid cross-section) considered in this study with the load carrying capacity meeting acceptance criterion (allowable deflection & stress) for outdoor decking application.

Feasibility study of a SiC sandwich neutron spectrometer

Energy Technology Data Exchange (ETDEWEB)

Wu, Jian, E-mail: caepwujian@163.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, Sichuan Province (China); Lei, Jiarong, E-mail: jiarong_lei@163.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, Sichuan Province (China); Jiang, Yong; Chen, Yu; Rong, Ru; Zou, Dehui; Fan, Xiaoqiang [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, Sichuan Province (China); Chen, Gang; Li, Li; Bai, Song [Nanjing Electronic Devices Institute, Nanjing 210016 (China)

2013-04-21

Semiconductor sandwich neutron spectrometers are suitable for in-pile measurements of fast reactor spectra thanks to their compact and relatively simple design. We have assembled and tested a sandwich neutron spectrometer based on 4H-silicon carbide (4H-SiC) Schottky diodes. The SiC diodes detect neutrons via neutron-induced charged particles (tritons and alpha particles) produced by {sup 6}Li(n,α){sup 3}H reaction. {sup 6}LiF neutron converter layers are deposited on the front surface of Schottky diodes by magnetron sputtering. The responses of SiC diodes to charged particles were investigated with an {sup 241}Am alpha source. A sandwich neutron spectrometer was assembled with two SiC Schottky diodes selected based on the charged-particle-response experimental results. The low-energy neutron response of the sandwich spectrometer was measured in the neutron field of the Chinese Fast Burst Reactor-II (CFBR-II). Spectra of alpha particles and tritons from {sup 6}Li(n,α){sup 3}H reaction were obtained with two well-resolved peaks. The energy resolution of the sum spectrum was 8.8%. The primary experimental results confirmed the 4H-SiC sandwich neutron spectrometer's feasibility. -- Highlights: ► Sandwich neutron spectrometer employing 4H-SiC as a detecting material has been developed for the first time. ► {sup 6}LiF neutron converter has been deposited on the surface of 4H-SiC Schottky diode. ► Preliminary testing results obtained with the 4H-SiC sandwich neutron spectrometer are presented.

Optimization of composite sandwich cover panels subjected to compressive loadings

Science.gov (United States)

Cruz, Juan R.

1991-01-01

An analysis and design method is presented for the design of composite sandwich cover panels that include the transverse shear effects and damage tolerance considerations. This method is incorporated into a sandwich optimization computer program entitled SANDOP. As a demonstration of its capabilities, SANDOP is used in the present study to design optimized composite sandwich cover panels for for transport aircraft wing applications. The results of this design study indicate that optimized composite sandwich cover panels have approximately the same structural efficiency as stiffened composite cover panels designed to satisfy individual constraints. The results also indicate that inplane stiffness requirements have a large effect on the weight of these composite sandwich cover panels at higher load levels. Increasing the maximum allowable strain and the upper percentage limit of the 0 degree and +/- 45 degree plies can yield significant weight savings. The results show that the structural efficiency of these optimized composite sandwich cover panels is relatively insensitive to changes in core density. Thus, core density should be chosen by criteria other than minimum weight (e.g., damage tolerance, ease of manufacture, etc.).

Pilot Study for Investigating the Cyclic Response of the Recentering Bridge Bearing System Combined with the Friction Damper

Directory of Open Access Journals (Sweden)

Jong Wan Hu

2016-01-01

Full Text Available The bridge bearing is one of the component members which provide resting supports between piers and decks. The bridge bearing is intended to control longitudinal movement caused by traffic flow and thermal expansion, thereby reducing stress concentration. In high seismicity area, the bridge bearing has been utilized as the base isolation system to mitigate acceleration transferred from the ground. Although the existing bridge bearing installed between superstructure and substructure provides extra flexibility to the base of the entire structure, considerable permanent deformation occurs due to lack of recentering capacity after earthquake. It is required to spend extra cost for repairing impaired parts. The bridge bearings integrated with superelastic shape memory alloy (SMA devices used for upgrading the recentering effect into the friction damper are proposed in this study. The refined finite element (FE analyses are introduced to reproduce the response of such new structures under cyclic loading condition. The bridge bearing systems that maintain uniform recentering capability are designed with various friction coefficients so as to examine energy dissipation and residual deformation through FE analyses. After observing FE analysis results, optimal design for the recentering bridge bearing system will be proposed to take advantage of energy dissipation and self-centering capacity.

29 CFR 1915.73 - Guarding of deck openings and edges.

Science.gov (United States)

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Guarding of deck openings and edges. 1915.73 Section 1915.73 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION..., Ladders and Other Working Surfaces § 1915.73 Guarding of deck openings and edges. (a) The provisions of...

Mechanical properties of superelastic Cu–Al–Be wires at cold temperatures for the seismic protection of bridges

International Nuclear Information System (INIS)

Zhang Yunfeng; Zhu Songye; Camilleri, Joseph A

2008-01-01

This paper examines the suitability of superelastic copper–aluminum–beryllium (Cu–Al–Be) alloy wires for the seismic protection of bridges in cold regions. Experimental results for the mechanical properties of superelastic Cu–Al–Be alloy wires at a variety of temperatures and loading rates are presented. This research is motivated by the recent use of shape memory alloys for bridge restrainers subject to harsh winter conditions, especially in cold regions. Bridge restrainers made of superelastic Cu–Al–Be wire strands are expected to be used for protecting bridge decks from excessive displacement when subjected to strong earthquakes. Using a temperature chamber, superelastic Cu–Al–Be wires with a diameter of 1.4 mm were tested under uniaxial cyclic loading at various loading rates and cold temperatures. The test results from 23 to −50 °C demonstrate that Cu–Al–Be exhibits superelastic behavior at cold temperatures down to −85 °C. It is also found that with decreasing temperature the transformation plateau stress is reduced while its fatigue life increases under cyclic testing

Analysis of structural diseases in widened structure due to the shrinkage and creep difference of new bridge

Science.gov (United States)

Wu, Wenqing; Zhang, Hui

2018-03-01

In order to investigate the possible structural diseases brought to the top flange of existing prestressed concrete box girder bridge due to the shrinkage and creep difference between new and old bridge, the stress state of the existing box girder before and after widening and the mechanisms of potential structural diseases were analyzed using finite element method in this paper. Results showed that the inner flange of the old box girder were generally in the state of large tensile stress, the main reason for which was the shrinkage and creep effect difference of the new and old bridge. And the tensile stress was larger than tensile strength of C50 concrete, which would most likely cause crack in the deck plate of box girder. Hence, reinforcement measures are needed to be designed carefully. Meanwhile, the transverse deformation of widened structure had exceeded the distance between the anti-seismic block and the web of box girder at the end cross section, which would squeeze anti-seismic block severely. Therefore, it is necessary to limit the length of continuous bridge in need of widening.

Investigating extreme event loading on coastal bridges using wireless sensor technology

Science.gov (United States)

Gelineau, Douglas A.; Davis, Justin R.; Rice, Jennifer A.

2017-04-01

Coastal infrastructure, such as bridges, are susceptible to many forms of coastal hazards: particularly hurricane surge and wave loading. These two forms of loading can cause catastrophic damage to aging highway infrastructure. It is estimated that storm damage costs the United States about $50 Billion per year. In light of this, it is crucial that we understand the damaging forces placed on infrastructure during storm events so that we can develop safer and more resilient coastal structures. This paper presents the ongoing research to enable the efficient collection of extreme event loads acting on both the substructure and superstructure of low clearance, simple span, reinforced concrete bridges. Bridges of this type were commonly constructed during the 1950's and 60's and are particularly susceptible to deck unseating caused by hurricane surge and wave loading. The sensing technology used to capture this data must be ruggedized to survive in an extremely challenging environment, be designed to allow for redundancy in the event of sensors or other network components being lost in the storm, and be relatively low cost to allow for more bridges to be instrumented per storm event. The prototype system described in this paper includes wireless technology, rapid data transmission, and, for the sensors, self-contained power. While this specific application focuses on hurricane hazards, the framework can be extended to include other natural hazards.

Theoretical and Experimental Studies of Wave Impact underneath Decks of Offshore Platforms

Energy Technology Data Exchange (ETDEWEB)

Baarholm, Rolf Jarle

2001-07-01

The main objective of this thesis has been to study the phenomenon of water impact underneath the decks of offshore platforms due to propagating waves. The emphasis has been on the impact loads. Two theoretical methods based on two-dimensional potential theory have been developed, a Wagner based method (WBM) and a nonlinear boundary element method (BEM). A procedure to account for three-dimensional effects is suggested. The deck is assumed to be rigid. Initial studies of the importance of hydroelasticity for wave loads on an existing deck structure have been performed. For a given design wave, the local structural responses were found to behave quasi-static. Global structural response has not been studied. In the Wagner based method gravity is neglected and a linear spatial distribution of the relative impact velocity along the deck is assumed. The resulting boundary value problem is solved analytically for each time step. A numerical scheme for stepping the wetted deck area in time is presented. The nonlinear boundary element method includes gravity, and the exact impact velocity is considered. The incident wave velocity potential is given a priori, and a boundary value problem for the perturbation velocity potential associated with the impact is defined. The boundary value problem is solved for each time step by applying Green's second identity. The exact boundary conditions are imposed on the exact boundaries. A Kutta condition is introduced as the fluid flow reaches the downstream end of the deck. At present, the BEM is only applicable for fixed platform decks. To validate the theories, experiments have been carried out in a wave flume. The experiments were performed in two-dimensional flow condition with a fixed horizontal deck at different vertical levels above the mean free surface. The vertical force on the deck and the wetting of the deck were the primary parameters measured. Only regular propagating waves were applied. When a wave hits the deck, the

Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

OpenAIRE

Chon W.; Amano R. S.

2005-01-01

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a 1.1m wide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Do...

Dynamic Response of Functionally Graded Carbon Nanotube Reinforced Sandwich Plate

Science.gov (United States)

Mehar, Kulmani; Panda, Subrata Kumar

2018-03-01

In this article, the dynamic response of the carbon nanotube-reinforced functionally graded sandwich composite plate has been studied numerically with the help of finite element method. The face sheets of the sandwich composite plate are made of carbon nanotube- reinforced composite for two different grading patterns whereas the core phase is taken as isotropic material. The final properties of the structure are calculated using the rule of mixture. The geometrical model of the sandwich plate is developed and discretized suitably with the help of available shell element in ANSYS library. Subsequently, the corresponding numerical dynamic responses computed via batch input technique (parametric design language code in ANSYS) of ANSYS including Newmark’s integration scheme. The stability of the sandwich structural numerical model is established through the proper convergence study. Further, the reliability of the sandwich model is checked by comparison study between present and available results from references. As a final point, some numerical problems have been solved to examine the effect of different design constraints (carbon nanotube distribution pattern, core to face thickness ratio, volume fractions of the nanotube, length to thickness ratio, aspect ratio and constraints at edges) on the time-responses of sandwich plate.

Full-scale measurements and system identification on Sutong cable-stayed bridge during Typhoon Fung-Wong.

Science.gov (United States)

Wang, Hao; Tao, Tianyou; Guo, Tong; Li, Jian; Li, Aiqun

2014-01-01

The structural health monitoring system (SHMS) provides an effective tool to conduct full-scale measurements on existing bridges for essential research on bridge wind engineering. In July 2008, Typhoon Fung-Wong lashed China and hit Sutong cable-stayed bridge (SCB) in China. During typhoon period, full-scale measurements were conducted to record the wind data and the structural vibration responses were collected by the SHMS installed on SCB. Based on the statistical method and the spectral analysis technique, the measured data are analyzed to obtain the typical parameters and characteristics. Furthermore, this paper analyzed the measured structural vibration responses and indicated the vibration characteristics of the stay cable and the deck, the relationship between structural vibrations and wind speed, the comparison of upstream and downstream cable vibrations, the effectiveness of cable dampers, and so forth. Considering the significance of damping ratio in vibration mitigation, the modal damping ratios of the SCB are identified based on the Hilbert-Huang transform (HHT) combined with the random decrement technique (RDT). The analysis results can be used to validate the current dynamic characteristic analysis methods, buffeting calculation methods, and wind tunnel test results of the long-span cable-stayed bridges.

Full-Scale Measurements and System Identification on Sutong Cable-Stayed Bridge during Typhoon Fung-Wong

Directory of Open Access Journals (Sweden)

Hao Wang

2014-01-01

Full Text Available The structural health monitoring system (SHMS provides an effective tool to conduct full-scale measurements on existing bridges for essential research on bridge wind engineering. In July 2008, Typhoon Fung-Wong lashed China and hit Sutong cable-stayed bridge (SCB in China. During typhoon period, full-scale measurements were conducted to record the wind data and the structural vibration responses were collected by the SHMS installed on SCB. Based on the statistical method and the spectral analysis technique, the measured data are analyzed to obtain the typical parameters and characteristics. Furthermore, this paper analyzed the measured structural vibration responses and indicated the vibration characteristics of the stay cable and the deck, the relationship between structural vibrations and wind speed, the comparison of upstream and downstream cable vibrations, the effectiveness of cable dampers, and so forth. Considering the significance of damping ratio in vibration mitigation, the modal damping ratios of the SCB are identified based on the Hilbert-Huang transform (HHT combined with the random decrement technique (RDT. The analysis results can be used to validate the current dynamic characteristic analysis methods, buffeting calculation methods, and wind tunnel test results of the long-span cable-stayed bridges.

Flight Deck I-Glasses, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Flight Deck i-Glasses is a color, stereoscopic 3-D display mounted on consumer style eye glass frames that will enhance operator performance and multi-modal...

Fracture Analysis of Debonded Sandwich Columns Under Axial Compression

DEFF Research Database (Denmark)

May, A.; Avilés, F.; Berggreen, Christian

A sandwich structure consists of two strong and stiff face sheets bonded to a weak low density core. The large separation between the face sheets provides increased bending rigidity and strength at low weight cost. Thus, sandwich structures frequently present better mechanical properties than...... monolithic structures of the same weight. The vast range of applications of such materials includes wind turbines, marine, and aerospace industries. In this work, geometrically nonlinear finite element analysis is conducted to investigate the fracture parameters and debond propagation of sandwich columns...

Porous Sandwiched Graphene/Silicon Anodes for Lithium Storage

International Nuclear Information System (INIS)

Wei, Liangming; Hou, Zhongyu; Wei, Hao

2017-01-01

Highlights: • In situ hydrolysis of tetraethoxysilane within the confined galleries region of graphite oxide. • New porous sandwiched graphene/Si nanocomposites were prepared by magnesium thermal reduction. • The Si nanostructure was compactly sandwiched between two neighboring graphenes. • The Si/graphene anodes deliver large reversible capacity with excellent cycling stability. - Abstract: Porous sandwiched graphene/Si nanocomposites (PG-Si) are prepared by in situ hydrolysis of tetraethoxysilane within the confined gallery region of graphite oxide, and then magnesium thermal reduction of the intra-gallery SiO 2 to Si nanocrystals. The Si nanostructures are in situ formed within the confined gallery region of graphite, and they are compactly sandwiched between two neighboring graphene sheets. This compactly sandwiched structure affords enhanced electron conductivity, and prevents Si nanoparticles from aggregation. Meanwhile, the free voids between neighboring Si nanocrystals alleviate the volume change of Si during cycling. As a consequence, the resulting PG-Si nanocomposites are high-performance anode materials for lithium-ion batteries which show long cycle life (>500 cycles) and high specific charge capacity (1464 mAh g −1 at a current density of 200 mA/g, 920 mAh g −1 at a current density of 1.68A/g after 500 cycles). The Li + diffusion kinetics in PG-Si is also discussed.

Comparison of deck- and trial-based approaches to advantageous decision making on the Iowa Gambling Task.

Science.gov (United States)

Visagan, Ravindran; Xiang, Ally; Lamar, Melissa

2012-06-01

We compared the original deck-based model of advantageous decision making assessed with the Iowa Gambling Task (IGT) with a trial-based approach across behavioral and physiological outcomes in 33 younger adults (15 men, 18 women; 22.2 ± 3.7 years of age). One administration of the IGT with simultaneous measurement of skin conductance responses (SCRs) was performed and the two methods applied: (a) the original approach of subtracting disadvantageous picks of Decks A and B from advantageous picks of Decks C and D and (b) a trial-based approach focused on the financial outcome for each deck leading up to the trial in question. When directly compared, the deck-based approach resulted in a more advantageous behavioral profile than did the trial-based approach. Analysis of SCR data revealed no significant differences between methods for physiological measurements of SCR fluctuations or anticipatory responses to disadvantageous picks. Post hoc investigation of the trial-based method revealed Deck B contributed to both advantageous and disadvantageous decision making for the majority of participants. When divided by blocks of 20, the number of advantageous to disadvantageous choices reversed as the task progressed despite the total number of picks from Deck B remaining high. SCR fluctuations for Deck B, although not significantly different from the other decks, did show a sharp decline after the first block of 20 and remained below levels for Decks C and D toward the end of the task, suggesting that participants may have gained knowledge of the frequency of loss for this deck. (c) 2012 APA, all rights reserved

Aircraft Carrier Flight and Hangar Deck Fire Protection: History and Current Status

National Research Council Canada - National Science Library

Darwin, Robert L; Bowman, Howard L; Hunstad, Mary; Leach, William B; Williams, Frederick W

2005-01-01

.... Next, a review of firefighting systems, including the firefighting agents currently in use, as well as the current tactics for fighting fires on the flight deck and the hangar deck, is provided...

AA, sandwich line with magnetic horn

CERN Multimedia

CERN PhotoLab

1980-01-01

The magnetic horn, focusing the antiprotons emanating from the target, was affixed to a sandwich line through which the 150 kA pulses were supplied. Expecting to have to change from time to time the fragile horn (inner conductor only 0.7 mm thick), the assembly was designed for quick exchange. At the lower end of the sandwich line we see the connectors for the high-current cables, at the upper end the magnet horn. It has just been lifted from the V-supports which held it aligned downstream of the target. Continue with 8010293.

Buckling driven debonding in sandwich columns

DEFF Research Database (Denmark)

Østergaard, Rasmus Christian

2008-01-01

results from two mechanisms: (a) interaction of local debond buckling and global buckling and (b) the development of a damaged zone at the debond crack tip. Based on the pronounced imperfection sensitivity, the author predicts that an experimental measurement of the strength of sandwich structures may......A compression loaded sandwich column that contains a debond is analyzed using a geometrically non-linear finite element model. The model includes a cohesive zone along one face sheet/core interface whereby the debond can extend by interface crack growth. Two geometrical imperfections are introduced...

Measuring Cohesive Laws for Interfaces in Sandwich Structures

DEFF Research Database (Denmark)

Lundsgaard-Larsen, Christian; Sørensen, Bent F.; Berggreen, Carl Christian

2006-01-01

mixities. The sandwich specimens consists of glass fiber faces and Divinycell H200 foam core with a pre-crack between face and core made with teflon film. Arbitrary stiffening of the sandwich faces with steel bars adhered to the faces reduces rotations and ensures that the method is useable for a wide...

Effect of nanomodified polyester resin on hybrid sandwich laminates

International Nuclear Information System (INIS)

Anbusagar, NRR.; Giridharan, P.K.; Palanikumar, K.

2014-01-01

Highlights: • Effect of nanomodified polyester resin on hybrid sandwich laminates is evaluated. • The hybrid sandwich laminates are fabricated with varying wt% of nanoclay. • Flexural, impact and moisture absorbtion properties are evaluated for hybrid composites. • Scanning electron microscopy is utilized to analyze the dispersion of clay and fractured surfaces of the nanocomposites. - Abstract: Effect of nanoclay modified polyester resin on flexural, impact, hardness and water absorption properties of untreated woven jute and glass fabric hybrid sandwich laminates have been investigated experimentally. The hybrid sandwich laminates are prepared by hand lay-up manufacturing technique (HL) for investigation. All hybrid sandwich laminates are fabricated with a total of 10 layers, by varying the extreme layers and wt% of nanoclay in polyester resin so as to obtain four different combinations of hybrid sandwich laminates. For comparison of the composite with hybrid composite, jute fiber reinforced composite laminate also fabricated. X-ray diffraction (XRD) results obtained from samples with nanoclay indicated that intergallery spacing of the layered clay increases with matrix. Scanning electron microscopy (SEM) gave a morphological picture of the cross-sections and energy dispersive X-ray spectroscopy (EDS) allowed investigating the elemental composition of matrix in composites. The testing results indicated that the flexural properties are greatly increased at 4% of nanoclay loading while impact, hardness and water absorption properties are increased at 6% of nanoclay loading. A plausible explanation for high increase of properties has also been discussed

46 CFR 108.133 - Hull superstructure, structural bulkheads, decks, and deckhouses.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Hull superstructure, structural bulkheads, decks, and deckhouses. 108.133 Section 108.133 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A... Protection § 108.133 Hull superstructure, structural bulkheads, decks, and deckhouses. Each hull...

Super-light SL-Deck elements with fixed end connections

DEFF Research Database (Denmark)

Hertz, Kristian Dahl

2015-01-01

Super-light structures combining light and strong concrete are invented by the author at the Technical University of Denmark and commercialized by the spin-out company Abeo Ltd. The first product is the SL-Deck element that represents a number of strong improvements to the building industry among...... to low weight and due to possibilities of continuous elements and fixed end connections. A new machine is constructed producing the elements and BIM software is developed optimizing the structures, the production, and the logistics and running the machine. New production lines are established...... building projects leading to considerable savings of time and costs and opening up new possibilities for architects and users. Furthermore, the paper describes full-scale test results with new fixed end connections between decks and walls and between decks and columns in facades giving more possibilities...

Numerical Analysis of Heat Storage and Heat Conductivity in the Concrete Hollow Core Deck Element

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

2011-01-01

extent these simplified models estimate the heat storage potential of precast hollow-core concrete decks correctly. This study investigates various approaches on how to model the heat transfer within the air void in the deck. Furthermore, it is analysed how different heat transfer models influence...... the overall heat transfer and heat storage in the hollow-core decks. The presented results allow comparison between detailed results from 2D-COMSOL simulations and simple 1D calculations from the whole building simulation tool such as BSim program and moreover, it is possible to validate the calculation...... method in BSim for the concrete deck element with air voids. Finally, this paper presents a comparison of the calculated heat conductivity of the hollow-core concrete deck and the measured heat conductivity for the same deck by using hot box apparatus....

A Debonded Sandwich Specimen Under Mixed Mode Bending (MMB)

DEFF Research Database (Denmark)

Quispitupa, Amilcar; Berggreen, Christian; Carlsson, Leif A.

2008-01-01

Face/core interface crack propagation in sandwich specimens is analyzed. A thorough analysis of the typical failure modes in sandwich composites was performed in order to design the MMB specimen to promote face/core debond fracture. Displacement, compliance and energy release rate expressions...... for the MMB specimen were derived from a superposition analysis. An experimental verification of the methodology proposed was performed using MMB sandwich specimens with H100 PVC foam core and E-glass/polyester non-crimp quadro-axial [0/45/90/-45]s DBLT-850 faces. Different mixed mode loadings were applied...

Mechanical evaluation with fe analysis of sandwich panels for wind turbine blade

Energy Technology Data Exchange (ETDEWEB)

Yasaswi, M.; Naveen, P.N.E.; Prasad, R.V. [GIET. Dept. of Mechanical Engineering, Rajahmundry (India)

2012-07-01

Sandwich panels are notable for their structural efficiency and are used as load bearing components in various branches of engineering, especially in aerospace and marine industries. The objective of the present work is to perform computer-aided analysis on sandwich panels. The analysis of sandwich panel with truss core are compared with other four types of sandwich panel with continuous corrugated core, top hat core, zed core and channel core. The basic reason to use sandwich structure is to save weight, however smooth skins and excellent fatigue resistance are also attributes of a sandwich structure. A sandwich is comprised of two layered composite materials formed by bonding two or more thin facings or face sheets to relatively thick core materials. In this type of construction the facings resist nearly all of the in-plane loads and out-of-plane bending moments. The thin facings provide nearly all of the bending stiffness because they are generally of a much higher modulus material is located at a greatest distance from the neutral axis of the component. The basic concept of sandwich panel is that the facings carry the bending loads and the core carries the shear loads. The main function of the core material is to distribute local loads and stresses over large areas. From all this analysis it is concluded that the truss core Sandwich panels can be used in wind turbine blade design. (Author)

STOCHASTIC ASSESSMENT OF NIGERIAN STOCHASTIC ...

African Journals Online (AJOL)

eobe

STOCHASTIC ASSESSMENT OF NIGERIAN WOOD FOR BRIDGE DECKS ... abandoned bridges with defects only in their decks in both rural and urban locations can be effectively .... which can be seen as the detection of rare physical.

A vibration powered wireless mote on the Forth Road Bridge

International Nuclear Information System (INIS)

Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A

2015-01-01

The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm 3 , was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent. (paper)

A vibration powered wireless mote on the Forth Road Bridge

Science.gov (United States)

Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A.

2015-12-01

The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm3, was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent.

Design of bridges against large tectonic deformation

Science.gov (United States)

Anastasopoulos, I.; Gazetas, G.; Drosos, V.; Georgarakos, T.; Kourkoulis, R.

2008-12-01

The engineering community has devoted much effort to understanding the response of soil-structure systems to seismic ground motions, but little attention to the effects of an outcropping fault offset. The 1999 earthquakes of Turkey and Taiwan, offering a variety of case histories of structural damage due to faulting, have (re)fueled the interest on the subject. This paper presents a methodology for design of bridges against tectonic deformation. The problem is decoupled in two analysis steps: the first (at the local level) deals with the response of a single pier and its foundation to fault rupture propagating through the soil, and the superstructure is modeled in a simplified manner; and the second (at the global level) investigates detailed models of the superstructure subjected to the support (differential) displacements of Step 1. A parametric study investigates typical models of viaduct and overpass bridges, founded on piles or caissons. Fixed-head piled foundations are shown to be rather vulnerable to faulting-induced deformation. End-bearing piles in particular are unable to survive bedrock offsets exceeding 10 cm. Floating piles perform better, and if combined with hinged pile-to-cap connections, they could survive much larger offsets. Soil resilience is beneficial in reducing pile distress. Caisson foundations are almost invariably successful. Statically-indeterminate superstructures are quite vulnerable, while statically-determinate are insensitive (allowing differential displacements and rotations without suffering any distress). For large-span cantilever-construction bridges, where a statically determinate system is hardly an option, inserting resilient seismic isolation bearings is advantageous as long as ample seating can prevent the deck from falling off the supports. An actual application of the developed method is presented for a major bridge, demonstrating the feasibility of design against tectonic deformation.

Towards a characterization of information automation systems on the flight deck

Science.gov (United States)

Dudley, Rachel Feddersen

This thesis summarizes research to investigate the characteristics that define information automation systems used on aircraft flight decks and the significant impacts that these characteristics have on pilot performance. Major accomplishments of the work include the development of a set of characteristics that describe information automation systems on the flight deck and an experiment designed to study a subset of these characteristics. Information automation systems on the flight deck are responsible for the collection, processing, analysis, and presentation of data to the flightcrew. These systems pose human factors issues and challenges that must be considered by designers of these systems. Based on a previously developed formal definition of information automation for aircraft flight deck systems, an analysis process was developed and conducted to reach a refined set of information automation characteristics. In this work, characteristics are defined as a set of properties or attributes that describe an information automation system's operation or behavior, which can be used to identify and assess potential human factors issues. Hypotheses were formed for a subset of the characteristics: Automation Visibility, Information Quality, and Display Complexity. An experimental investigation was developed to measure performance impacts related to these characteristics, which showed mixed results of expected and surprising findings, with many interactions. A set of recommendations were then developed based on the experimental observations. Ensuring that the right information is presented to pilots at the right time and in the appropriate manner is the job of flight deck system designers. This work provides a foundation for developing recommendations and guidelines specific to information automation on the flight deck with the goal of improving the design and evaluation of information automation systems before they are implemented.

Disadvantageous Deck Selection in the Iowa Gambling Task: The Effect of Cognitive Load

Directory of Open Access Journals (Sweden)

Melissa J. Hawthorne

2015-05-01

Full Text Available Research has shown that cognitive load affects overall Iowa Gambling Task (IGT performance, but it is unknown whether such load impacts the selection of the individual decks that correspond to gains or losses. Here, participants performed the IGT either in a full attention condition or while engaged in a number monitoring task to divide attention. Results showed that the full attention group was more aware of the magnitude of gains or losses for each draw (i.e., payoff awareness than was the divided attention group. However, the divided attention group was more sensitive to the frequency of the losses (i.e., frequency awareness, as evidenced by their increased preference for Deck B, which is the large but infrequent loss deck. An analysis across blocks showed that the number monitoring group was consistently more aware of loss frequency, whereas the full attention group shifted between awareness of loss frequency and awareness of payoff amount. Furthermore, the full attention group was better able to weigh loss frequency and payoff amount when making deck selections. These findings support the notion that diminished cognitive resources may result in greater selection of Deck B, otherwise known as the prominent Deck B phenomenon.

Adhesion aspects of polyurethane foam sandwich panels.

OpenAIRE

Ng, Simon L.

2016-01-01

Sandwich panels, polyurethane foam sandwiched between two sheets of steel, form the walls and roofs in the construction of buildings. ArcelorMittal is a manufacturer of the steel as well as these finished panels. For this project they combined with a supplier of the polyurethane foams, Huntsman Polyurethanes, to joint-fund a research project investigating the fundamental mechanisms of adhesion, as well as the causes of failures in the product which manifests primarily in two different ways...

Application Side Casing on Open Deck RoRo to Improve Ship Stability

Science.gov (United States)

Hasanudin; K. A. P Utama, I.; Chen, Jeng-Horng

2018-03-01

RoRo is a vessel that can transport passengers, cargo, container and cars. Open Car Deck is favourite RoRo Vessel in developing countries due to its small GT, small tax and spacious car deck, but it has poor survival of stability. Many accident involve Open Car Deck RoRo which cause fatalities and victim. In order to ensure the safety of the ship, IMO had applied intact stability criteria IS Code 2008 which adapted from Rahola’s Research, but since 2008 IMO improved criteria become probabilistic damage stability SOLAS 2009. The RoRo type Open Car Deck has wide Breadth (B), small Draft (D) and small freeboard. It has difficulties to satisfy the ship’s stability criteria. Side Casings which has been applied in some RoRo have be known reduce freeboard or improve ship’s safety. In this paper investigated the effect side casings to survival of intact dan damage ship’s stability. Calculation has been conducted for four ships without, existing and full side casings. The investigation results shows that defect stability of Open Deck RoRo can be reduce with fitting side casing.

Behavior of sandwich panels in a fire

Science.gov (United States)

Chelekova, Eugenia

2018-03-01

For the last decades there emerged a vast number of buildings and structures erected with the use of sandwich panels. The field of application for this construction material is manifold, especially in the construction of fire and explosion hazardous buildings. In advanced evacu-ation time calculation methods the coefficient of heat losses is defined with dire regard to fire load features, but without account to thermal and physical characteristics of building envelopes, or, to be exact, it is defined for brick and concrete walls with gross heat capacity. That is why the application of the heat loss coefficient expression obtained for buildings of sandwich panels is impossible because of different heat capacity of these panels from the heat capacities of brick and concrete building envelopes. The article conducts an analysis and calculation of the heal loss coefficient for buildings and structures of three layer sandwich panels as building envelopes.

Sandwich mapping of schistosomiasis risk in Anhui Province, China.

Science.gov (United States)

Hu, Yi; Bergquist, Robert; Lynn, Henry; Gao, Fenghua; Wang, Qizhi; Zhang, Shiqing; Li, Rui; Sun, Liqian; Xia, Congcong; Xiong, Chenglong; Zhang, Zhijie; Jiang, Qingwu

2015-06-03

Schistosomiasis mapping using data obtained from parasitological surveys is frequently used in planning and evaluation of disease control strategies. The available geostatistical approaches are, however, subject to the assumption of stationarity, a stochastic process whose joint probability distribution does not change when shifted in time. As this is impractical for large areas, we introduce here the sandwich method, the basic idea of which is to divide the study area (with its attributes) into homogeneous subareas and estimate the values for the reporting units using spatial stratified sampling. The sandwich method was applied to map the county-level prevalence of schistosomiasis japonica in Anhui Province, China based on parasitological data collected from sample villages and land use data. We first mapped the county-level prevalence using the sandwich method, then compared our findings with block Kriging. The sandwich estimates ranged from 0.17 to 0.21% with a lower level of uncertainty, while the Kriging estimates varied from 0 to 0.97% with a higher level of uncertainty, indicating that the former is more smoothed and stable compared to latter. Aside from various forms of reporting units, the sandwich method has the particular merit of simple model assumption coupled with full utilization of sample data. It performs well when a disease presents stratified heterogeneity over space.

Organic Functional Group Playing Card Deck

Science.gov (United States)

Welsh, Michael J.

2003-04-01

The recognition and identification of organic functional groups, while essential for chemistry and biology majors, is also very useful for non-science majors in the study of molecules in art and life. In order to make this task more palatable for the non-science major (art and communications students), the images of a traditional playing deck of cards (heart, spade, diamond, and club) have been replaced with four representations of common organic functional groups. The hierarchy rules for naming two groups in a molecule is loosely incorporated to represent the sequence (King, Queen, Jack, ?, Ace) of the deck. Students practice recognizing and identifying organic groups by playing simple card games of "Old Maid" and "Go Fish". To play games like "Poker" or "Gin", a student must not only recognize the functional groups, but also master a naming hierarchy for the organic groups.

Full Scale Investigation of the Dynamic Heat Storage of Concrete Decks with PCM and Enhanced Heat Transfer Surface Area

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

2013-01-01

The paper presents the full-scale experimental investigation of the dynamic heat storage potential of the prefabricated hollow core deck elements with and without phase change material (PCM) and with and without increased bottom surface area of the decks. In the presented investigation five types...... of hollow core decks with different surfaces on the bottom are investigated: reference deck made of standard concrete and flat surface, deck with special mortar grooved tiles, deck with flat mortar tiles, deck with grooved mortar and phase change material tiles, deck with flat mortar and phase change...... material tiles. The experimental investigation presented in the paper is performed in the specially designed modified hot box apparatus that allows maintaining periodic steady-state tests with the full-scale concrete deck elements. The presented research investigates if the extended surface area and PCM...

46 CFR 45.135 - Hull openings at or below freeboard deck.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Hull openings at or below freeboard deck. 45.135 Section 45.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.135 Hull openings at or below freeboard deck. Closures for hull...

Analysis of syntactic foam – GFRP sandwich composites for flexural loads

Science.gov (United States)

Paul, Daniel; Velmurugan, R.; Jayaganthan, R.; Gupta, N. K.; Manzhirov, A. V.

2018-04-01

The use of glass microballoon (GMB) — epoxy syntactic foams as a sandwich core material is studied. The skins and foam core are fabricated and joined instantaneously unlike the procedures followed in the previous studies. Each successive layer of the sandwich is fabricated when the previous layer is in a semi-gelled state. These sandwich samples are characterized for their properties under flexural loading. The failure modes and mechanical properties are carefully investigated. The change in fabrication technique results in a significant increase in the load bearing pattern of the sandwich. In earlier studies, debonding was found to occur prematurely since the bonding between the skins and core is the weakest plane. Using the current technique, core cracking occurs first, followed by skin fiber breaking and debonding happens at the end. This ensures that the load carrying phase of the structure is extended considerably. The sandwich is also analytically studied using Reddy’s higher order shear deformation theory. A higher order theory is selected as the sandwich can no longer be considered as a thin beam and thus shear effects also need to be considered in addition to bending effects.

Behavior of Epoxy-Coated Textured Reinforcing Bars

Science.gov (United States)

2018-04-01

Cracking in bridge decks is a common but difficult problem to control. Both research and experience show that the use of epoxy-coated reinforcement, which is mandated by most state departments of transportation (DOTs) for bridge decks, increases c...

Failure of riprap protection : phase II (final report).

Science.gov (United States)

2008-06-01

Riprap rundowns are often used by the New Mexico Department of Transportation (NMDOT) to : capture and drain the runoff approaching or leaving bridge decks. Rundowns are generally located at : the ends of a bridge deck to transport the water down the...

Durability of lightweight concrete : Phase I : concrete temperature study.

Science.gov (United States)

1968-08-01

This report describes a study conducted to determine the temperature gradient throughout the depth of a six inch concrete bridge deck. The bridge deck selected for study was constructed using lightweight concrete for the center spans and sand and gra...

Sandwich mapping of schistosomiasis risk in Anhui Province, China

Directory of Open Access Journals (Sweden)

Yi Hu

2015-06-01

Full Text Available Schistosomiasis mapping using data obtained from parasitological surveys is frequently used in planning and evaluation of disease control strategies. The available geostatistical approaches are, however, subject to the assumption of stationarity, a stochastic process whose joint probability distribution does not change when shifted in time. As this is impractical for large areas, we introduce here the sandwich method, the basic idea of which is to divide the study area (with its attributes into homogeneous subareas and estimate the values for the reporting units using spatial stratified sampling. The sandwich method was applied to map the county-level prevalence of schistosomiasis japonica in Anhui Province, China based on parasitological data collected from sample villages and land use data. We first mapped the county-level prevalence using the sandwich method, then compared our findings with block Kriging. The sandwich estimates ranged from 0.17 to 0.21% with a lower level of uncertainty, while the Kriging estimates varied from 0 to 0.97% with a higher level of uncertainty, indicating that the former is more smoothed and stable compared to latter. Aside from various forms of reporting units, the sandwich method has the particular merit of simple model assumption coupled with full utilization of sample data. It performs well when a disease presents stratified heterogeneity over space.

Effect of vertical ground motion on earthquake-induced derailment of railway vehicles over simply-supported bridges

Science.gov (United States)

Jin, Zhibin; Pei, Shiling; Li, Xiaozhen; Liu, Hongyan; Qiang, Shizhong

2016-11-01

The running safety of railway vehicles on bridges can be negatively affected by earthquake events. This phenomenon has traditionally been investigated with only the lateral ground excitation component considered. This paper presented results from a numerical investigation on the contribution of vertical ground motion component to the derailment of vehicles on simply-supported bridges. A full nonlinear wheel-rail contact model was used in the investigation together with the Hertzian contact theory and nonlinear creepage theory, which allows the wheel to jump vertically and separate from the rail. The wheel-rail relative displacement was used as the criterion for derailment events. A total of 18 ground motion records were used in the analysis to account for the uncertainty of ground motions. The results showed that inclusion of vertical ground motion will likely increase the chance of derailment. It is recommended to include vertical ground motion component in earthquake induced derailment analysis to ensure conservative estimations. The derailment event on bridges was found to be more closely related to the deck acceleration rather than the ground acceleration.

Aerodynamic stability study of a long-span prestressed concrete cable-stayed bridge. Aerodynamic behavior of edge box girder under uniform flow; Chodai PC shachokyo no taifu anteisei ni kansuru kenkyu. Ichiyoryuchu ni okeru edge girder keishiki no kuriki tokusei

Energy Technology Data Exchange (ETDEWEB)

Nomura, T. [Obayashi Corp., Tokyo (Japan)

1999-01-10

In recent years, the construction of long-span bridges is on the increase. Prestressed concrete cable-stayed bridges are dynamically very efficient structures of relatively low cost that blend in well with the landscape. Maintenance is also easy. Consequently, the adoption of edge box girders for cable-stayed bridges is increasing worldwide, but problems related to the aerodynamic stability of the structure have emerged. The aerodynamic stability of edge box girders for a prestressed concrete cable-stayed bridge was investigated under uniform flow conditions by conducting several wind tunnel experiments. As a result, the section of the bridge deck was optimized to prevent torsional flutter within an angle of attack varying from -5 to +5 degrees. It is therefore possible to guarantee the aerodynamic stability of long-span prestressed concrete cable-stayed bridges. (author)

Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

Directory of Open Access Journals (Sweden)

Chon W.

2005-01-01

Full Text Available When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a 1.1m wide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

Live-Load Testing Application Using a Wireless Sensor System and Finite-Element Model Analysis of an Integral Abutment Concrete Girder Bridge

Directory of Open Access Journals (Sweden)

Robert W. Fausett

2014-01-01

Full Text Available As part of an investigation on the performance of integral abutment bridges, a single-span, integral abutment, prestressed concrete girder bridge near Perry, Utah was instrumented for live-load testing. The live-load test included driving trucks at 2.24 m/s (5 mph along predetermined load paths and measuring the corresponding strain and deflection. The measured data was used to validate a finite-element model (FEM of the bridge. The model showed that the integral abutments were behaving as 94% of a fixed-fixed support. Live-load distribution factors were obtained using this validated model and compared to those calculated in accordance to recommended procedures provided in the AASHTO LRFD Bridge Design Specifications (2010. The results indicated that if the bridge was considered simply supported, the AASHTO LRFD Specification distribution factors were conservative (in comparison to the FEM results. These conservative distribution factors, along with the initial simply supported design assumption resulted in a very conservative bridge design. In addition, a parametric study was conducted by modifying various bridge properties of the validated bridge model, one at a time, in order to investigate the influence that individual changes in span length, deck thickness, edge distance, skew, and fixity had on live-load distribution. The results showed that the bridge properties with the largest influence on bridge live-load distribution were fixity, skew, and changes in edge distance.

Salads, Sandwiches and Desserts.

Science.gov (United States)

Marine Corps Inst., Washington, DC.

Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on salads, sandwiches, and desserts is designed to provide Marine food service personnel with a general background in the proper techniques for the preparation of these items. Introductory materials include specific information for MCI students and a…

3D Energy Absorption Diagram Construction of Paper Honeycomb Sandwich Panel

Directory of Open Access Journals (Sweden)

Dongmei Wang

2018-01-01

Full Text Available Paper honeycomb sandwich panel is an environment-sensitive material. Its cushioning property is closely related to its structural factors, the temperature and humidity, random shocks, and vibration events in the logistics environment. In order to visually characterize the cushioning property of paper honeycomb sandwich panel in different logistics conditions, the energy absorption equation of per unit volume of paper honeycomb sandwich panel was constructed by piecewise function. The three-dimensional (3D energy absorption diagram of paper honeycomb sandwich panel was constructed by connecting the inflexion of energy absorption curve. It takes into account the temperature, humidity, strain rate, and characteristics of the honeycomb structure. On the one hand, this diagram breaks through the limitation of the static compression curve of paper honeycomb sandwich panel, which depends on the test specimen and is applicable only to the standard condition. On the other hand, it breaks through the limitation of the conventional 2D energy absorption diagram which has less information. Elastic modulus was used to normalize the plateau stress and energy absorption per unit volume. This makes the 3D energy absorption diagram universal for different material sandwich panels. It provides a new theoretical basis for packaging optimized design.

Finite element simulation of low velocity impact loading on a sandwich composite

Directory of Open Access Journals (Sweden)

Vishwas M.

2018-01-01

Full Text Available Sandwich structure offer more advantage in bringing flexural stiffness and energy absorption capabilities in the application of automobile and aerospace components. This paper presents comparison study and analysis of two types of composite sandwich structures, one having Jute Epoxy skins with rubber core and the other having Glass Epoxy skins with rubber core subjected to low velocity normal impact loading. The behaviour of sandwich structure with various parameters such as energy absorption, peak load developed, deformation and von Mises stress and strain, are analyzed using commercially available analysis software. The results confirm that sandwich composite with jute epoxy skin absorbs approximately 20% more energy than glass epoxy skin. The contact force developed in jute epoxy skin is approximately 2.3 times less when compared to glass epoxy skin. von Mises stress developed is less in case of jute epoxy. The sandwich with jute epoxy skin deforms approximately 1.6 times more than that of same geometry of sandwich with glass epoxy skin. Thus exhibiting its elastic nature and making it potential candidate for low velocity impact application.

Non-linear vehicle-bridge-wind interaction model for running safety assessment of high-speed trains over a high-pier viaduct

Science.gov (United States)

Olmos, José M.; Astiz, Miguel Á.

2018-04-01

In order to properly study the high-speed traffic safety on a high-pier viaduct subject to episodes of lateral turbulent winds, an efficient dynamic interaction train-bridge-wind model has been developed and experimentally validated. This model considers the full wheel and rail profiles, the friction between these two bodies in contact, and the piers P-Delta effect. The model has been used to determine the critical train and wind velocities from which the trains cannot travel safely over the O'Eixo Bridge. The dynamic simulations carried out and the results obtained in the time domain show that traffic safety rates exceed the allowed limits for turbulent winds with mean velocities at the deck higher than 25 m/s.

Nonlinear Analysis of Cable Vibration of a Multispan Cable-Stayed Bridge under Transverse Excitation

Directory of Open Access Journals (Sweden)

Kun Lin

2014-01-01

Full Text Available The nonlinear vibrations of cable in a multispan cable-stayed bridge subjected to transverse excitation are investigated. The MECS (multielements cable system model, where multielements per cable stay are used, is built up and used to analyze the model properties of the multispan cable-stayed bridges. Then, a simplified two-degrees-of-freedom (2-DOFs model, where the tower or the deck is reduced to a beam, is proposed to analyze the nonlinear dynamic behaviors of the beam and cable. The results of MECS model analysis show that the main tower in the multispan cable-stayed bridge is prone to the transverse vibration, and the local vibration of cables only has a little impact on the frequency values of the global modes. The results of simplified model analysis show that the energy can be transformed between the modes of the beam and cable when the nature frequencies of them are very close. On the other hand, with the transverse excitation changing, the cable can exhibit richer quasi-periodic or chaotic motions due to the nonlinear terms caused by the coupled mode between the beam and cable.

Deck41 Surficial Seafloor Sediment Description Database

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Deck41 is a digital summary of surficial sediment composition for 36,401 seafloor samples worldwide. Data include collecting source, ship, cruise, sample id,...

Concept design and alternate arrangements of orbiter mid-deck habitability features

Science.gov (United States)

Church, R. A.; Ciciora, J. A.; Porter, K. L.; Stevenson, G. E.

1976-01-01

The evaluations and recommendations for habitability features in the space shuttle orbiter mid-deck are summarized. The orbiter mission plans, the mid-deck dimensions and baseline arrangements along with crew compliments and typical activities were defined. Female and male anthropometric data based on zero-g operations were also defined. Evaluations of baseline and alternate feasible concepts provided several recommendations which are discussed.

Investigation on Wall Panel Sandwiched With Lightweight Concrete

Science.gov (United States)

Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

2017-08-01

The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

Acoustic wave spread in superconducting-normal-superconducting sandwich

International Nuclear Information System (INIS)

Urushadze, G.I.

2004-01-01

The acoustic wave spread, perpendicular to the boundaries between superconducting and normal metals in superconducting-normal-superconducting (SNS) sandwich has been considered. The alternate current flow sound induced by the Green function method has been found and the coefficient of the acoustic wave transmission through the junction γ=(S 1 -S 2 )/S 1 , (where S 1 and S 2 are average energy flows formed on the first and second boundaries) as a function of the phase difference between superconductors has been investigated. It is shown that while the SNS sandwich is almost transparent for acoustic waves (γ 0 /τ), n=0,1,2, ... (where τ 0 /τ is the ratio of the broadening of the quasiparticle energy levels in impurity normal metal as a result of scattering of the carriers by impurities 1/τ to the spacing between energy levels 1/τ 0 ), γ=2, (S 2 =-S 1 ), which corresponds to the full reflection of the acoustic wave from SNS sandwich. This result is valid for the limit of a pure normal metal but in the main impurity case there are two amplification and reflection regions for acoustic waves. The result obtained shows promise for the SNS sandwich as an ideal mirror for acoustic wave reflection

A Novel Concrete-Based Sensor for Detection of Ice and Water on Roads and Bridges.

Science.gov (United States)

Tabatabai, Habib; Aljuboori, Mohammed

2017-12-14

Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry, and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists of a 102-mm-diameter, 38-mm-high, concrete cylinder. Laboratory results indicate that the proposed sensor can effectively detect surface ice and wet conditions even in the presence of deicing chlorides and rubber residue. This sensor can further distinguish black ice from ice that may exist within concrete pores.

A nano-sandwich construct built with graphene nanosheets and carbon nanotubes enhances mechanical properties of hydroxyapatite-polyetheretherketone scaffolds.

Science.gov (United States)

Feng, Pei; Peng, Shuping; Wu, Ping; Gao, Chengde; Huang, Wei; Deng, Youwen; Xiao, Tao; Shuai, Cijun

2016-01-01

A nano-sandwich construct was built by combining two-dimensional graphene nanosheets (GNSs) and one-dimensional carbon nanotubes (CNTs) to improve the mechanical properties of hydroxyapatite-polyetheretherketone (HAP-PEEK) scaffolds for bone tissue engineering. In this nano-sandwich construct, the long tubular CNTs penetrated the interlayers of graphene and prevented their aggregation, increasing the effective contact area between the construct and matrix. The combination of GNSs and CNTs in a weight ratio of 2:8 facilitated the dispersion of each other and provided a synergetic effect in enhancing the mechanical properties. The compressive strength and modulus of the scaffolds were increased by 63.58% and 56.54% at this time compared with those of HAP-PEEK scaffolds, respectively. The carbon-based fillers, pulling out and bridging, were also clearly observed in the matrix. Moreover, the dangling of CNTs and their entangling with GNSs further reinforced the mechanical properties. Furthermore, apatite layer formed on the scaffold surface after immersing in simulated body fluid, and the cells attached and spread well on the surface of the scaffolds and displayed good viability, proliferation, and differentiation. These evidence indicate that the HAP-PEEK scaffolds enhanced by GNSs and CNTs are a promising alternative for bone tissue engineering.

Design Analysis of the Mixed Mode Bending Sandwich Specimen

DEFF Research Database (Denmark)

Quispitupa, Amilcar; Berggreen, Christian; Carlsson, Leif A.

2010-01-01

A design analysis of the mixed mode bending (MMB) sandwich specimen for face–core interface fracture characterization is presented. An analysis of the competing failure modes in the foam cored sandwich specimens is performed in order to achieve face–core debond fracture prior to other failure modes...... for the chosen geometries and mixed mode loading conditions....

Two dimensional dynamic analysis of sandwich plates with gradient foam cores

Energy Technology Data Exchange (ETDEWEB)

Mu, Lin; Xiao, Deng Bao; Zhao, Guiping [State Key Laboratory for Mechanical structure Strength and Vibration, School of AerospaceXi' an Jiaotong University, Xi' an (China); Cho, Chong Du [Dept. of Mechanical Engineering, Inha University, Inchon (Korea, Republic of)

2016-09-15

Present investigation is concerned about dynamic response of composite sandwich plates with the functionally gradient foam cores under time-dependent impulse. The analysis is based on a model of the gradient sandwich plate, in which the face sheets and the core adopt the Kirchhoff theory and a [2, 1]-order theory, respectively. The material properties of the gradient foam core vary continuously along the thickness direction. The gradient plate model is validated with the finite element code ABAQUS®. And the results show that the proposed model can predict well the free vibration of composite sandwich plates with gradient foam cores. The influences of gradient foam cores on the natural frequency, deflection and energy absorbing of the sandwich plates are also investigated.

Critique of the Reggeized deck model

International Nuclear Information System (INIS)

Berger, E.L.

1975-01-01

A detailed analysis is presented of the Reggeized pion exchange Deck model for processes of the type ap → A*N → (a*π)N, where a = π, K, or nucleon and a* = rho, K*, N or Δ. Predictions of the model for both production and decay properties of the low mass system A* → (a*π) are derived and contrasted with data. Diffractive as well as charge exchange reactions are treated. The role of pion exchange in generating (a*π) enhancements near threshold and their properties is examined from several points of view. Characteristic exchange effects and quantum number properties (e.g., cross-overs) of the pion exchange Deck graph are shown to be verified in the data, but this graph alone is inadequate. The failures all point to the need for a second graph, having a* exchange properties. The contribution of a* exchange is roughly equal to that of the π exchange graph. (U.S.)

Magnetic properties of sandwiches based on Nd-Co and Y-Co amorphous alloys

International Nuclear Information System (INIS)

Ndjaka, J.M.B.; Givord, D.

1996-01-01

Y-Co/Nd-Co/Y-Co and Nd-Co/Y-Co/Nd-Co amorphous sandwiches have been prepared by d.c. triode sputtering. The chemical composition of the constituent layers is R 0.33 Co 0.67 (R=Y, Nd). In such systems, the Co moments are coupled parallel through the whole sandwich thickness by strong positive 3d-3d exchange interactions. But, the coercive fields of the constituent layers taken separately differ. In the sandwiches as well, the reversal of magnetization in the different layers occurs at different values of the applied magnetic field. This phenomenon has been analysed qualitatively in terms of creation and annihilation of walls at the interfaces between layers for sandwiches where the thicknesses of the constituent layers are about 1000 A. In sandwiches where the thickness of the constituent layers is 100 A, the wall width available is very weak and the value of the applied magnetic field necessary for the creation of such a wall is higher than the coercive field of the entire sandwich system. As a result, the magnetization of the sandwich system reverses as a whole like in homogeneous systems. (orig.)

Sandwich design for ships and railway wagons

Energy Technology Data Exchange (ETDEWEB)

Olsson, K.-A. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Aeronautics

2000-07-01

In Sweden we have long experience of different types of vehicles and ships in sandwich construction, especially for Navy ships, such as minesweepers, mine-counter-measure-vessels and corvettes. As face materials mostly GRP and FRP have been used, but also metallic materials of Al-alloys, coated carbon steel and stainless steel. Core materials have usually been cellular plastic foams of cross-linked PVC, but also extruded PS, PUR, PEI and PMI. A lot of different continuous and discontinuous manufacturing processes are used. Vacuum assisted infusion is used in the last years, because it is a closed process, gives high fibre content and a good quality of the laminates. Sandwich design has mainly been used in the transportation area, where lightweight design is needed to give higher performance and load bearing capacity. The use of sandwich will give high stiffness- and strength-to weight ratio. These are in most cases not enough from economic point of view, but even other integrated functions must be considered, i.e. insulation, energy consumption, damping, less components, lower manufacturing costs, low maintenance, signature effects (military) etc. (orig.)

Study on the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration

International Nuclear Information System (INIS)

Lin Shuyu; Tian Hua

2008-01-01

A sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is studied. The transducer consists of front and back metal masses, and coaxially segmented, thickness polarized piezoelectric ceramic thin rings. For this kind of sandwich piezoelectric transducers in thickness vibration, it is required that the lateral dimension of the transducer is sufficiently large compared with its longitudinal dimension so that no lateral displacements in the transducer can occur (laterally clamped). In this paper, the thickness vibration of the piezoelectric ceramic stack consisting of a number of identical piezoelectric ceramic thin rings is analysed and its electro-mechanical equivalent circuit is obtained. The resonance frequency equation for the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is derived. Based on the frequency equation, two sandwich piezoelectric ceramic ultrasonic transducers are designed and manufactured, and their resonance frequencies are measured. It is shown that the measured resonance frequencies are in good agreement with the theoretical results. This kind of sandwich piezoelectric ultrasonic transducer is expected to be used in megasonic ultrasonic cleaning and sonochemistry where high power and high frequency ultrasound is needed

Insert Design and Manufacturing for Foam-Core Composite Sandwich Structures

Science.gov (United States)

Lares, Alan

Sandwich structures have been used in the aerospace industry for many years. The high strength to weight ratios that are possible with sandwich constructions makes them desirable for airframe applications. While sandwich structures are effective at handling distributed loads such as aerodynamic forces, they are prone to damage from concentrated loads at joints or due to impact. This is due to the relatively thin face-sheets and soft core materials typically found in sandwich structures. Carleton University's Uninhabited Aerial Vehicle (UAV) Project Team has designed and manufactured a UAV (GeoSury II Prototype) which features an all composite sandwich structure fuselage structure. The purpose of the aircraft is to conduct geomagnetic surveys. The GeoSury II Prototype serves as the test bed for many areas of research in advancing UAV technologies. Those areas of research include: low cost composite materials manufacturing, geomagnetic data acquisition, obstacle detection, autonomous operations and magnetic signature control. In this thesis work a methodology for designing and manufacturing inserts for foam-core sandwich structures was developed. The results of this research work enables a designer wishing to design a foam-core sandwich airframe structure, a means of quickly manufacturing optimized inserts for the safe introduction of discrete loads into the airframe. The previous GeoSury II Prototype insert designs (v.1 & v.2) were performance tested to establish a benchmark with which to compare future insert designs. Several designs and materials were considered for the new v.3 inserts. A plug and sleeve design was selected, due to its ability to effectively transfer the required loads to the sandwich structure. The insert material was chosen to be epoxy, reinforced with chopped carbon fibre. This material was chosen for its combination of strength, low mass and also compatibility with the face-sheet material. The v.3 insert assembly is 60% lighter than the

Vědecké osobnosti a vedení ve vědě

Czech Academy of Sciences Publication Activity Database

Wiedermann, Jiří

č. 3 (2005), s. 14-17 ISSN 1210-9525 Institutional research plan: CEZ:AV0Z10300504 Keywords : vědecké osobnosti * talent * grantový systém * vědecká excelence Subject RIV: AM - Education http://abicko.avcr.cz/archiv/2005/3/obsah/vedecke-osobnosti-a-vedeni-ve-vede.html

A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel PART I : Proposal of a heat source model

Directory of Open Access Journals (Sweden)

Jae Woong Kim

2013-09-01

Full Text Available The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power CO2 laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

Nanocrystalline Aluminum Truss Cores for Lightweight Sandwich Structures

Science.gov (United States)

Schaedler, Tobias A.; Chan, Lisa J.; Clough, Eric C.; Stilke, Morgan A.; Hundley, Jacob M.; Masur, Lawrence J.

2017-12-01

Substitution of conventional honeycomb composite sandwich structures with lighter alternatives has the potential to reduce the mass of future vehicles. Here we demonstrate nanocrystalline aluminum-manganese truss cores that achieve 2-4 times higher strength than aluminum alloy 5056 honeycombs of the same density. The scalable fabrication approach starts with additive manufacturing of polymer templates, followed by electrodeposition of nanocrystalline Al-Mn alloy, removal of the polymer, and facesheet integration. This facilitates curved and net-shaped sandwich structures, as well as co-curing of the facesheets, which eliminates the need for extra adhesive. The nanocrystalline Al-Mn alloy thin-film material exhibits high strength and ductility and can be converted into a three-dimensional hollow truss structure with this approach. Ultra-lightweight sandwich structures are of interest for a range of applications in aerospace, such as fairings, wings, and flaps, as well as for the automotive and sports industries.

Blast-Resistant Improvement of Sandwich Armor Structure with Aluminum Foam Composite

OpenAIRE

Yang, Shu; Qi, Chang

2013-01-01

Sandwich armor structures with aluminum foam can be utilized to protect a military vehicle from harmful blast load such as a landmine explosion. In this paper, a system-level dynamic finite element model is developed to simulate the blast event and to evaluate the blast-resistant performance of the sandwich armor structure. It is found that a sandwich armor structure with only aluminum foam is capable of mitigating crew injuries under a moderate blast load. However, a severe blast load causes...

Analysis and Behaviour of Sandwich Panels with Profiled Metal Facings under Transverse Load

Directory of Open Access Journals (Sweden)

M. Budescu

2004-01-01

Full Text Available Sandwich panels with thin steel facings and polyurethane core combine the load-carrying capacity of metal facings and protection functions with core properties. The core separates the two facings and keeps them in a stable condition, transmits shear between external layers, provides most of the shear rigidity and occasionally makes of useful contribution to the bending stiffness of the sandwich construction as a whole [1]. An experimental program on sandwich panels has been organized to prove that the mechanical properties of core and interface satisfy the load-carrying requirements for structural sandwich panels. The analysis of sandwich panels with deep profiles facings for cladding elements, respectively the roof constructions, has been carried out according to the European design norms [1], [5].

Heat Storage Performance of the Prefabricated Hollow Core Concrete Deck Element with Integrated Microencapsulated Phase Change Material

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

2012-01-01

The paper presents the numerically calculated dynamic heat storage capacity of the prefabricated hollow core concrete deck element with and without microencapsulated phase change material (PCM). The reference deck is the ordinary deck made of standard concrete material and that is broadly used...

Effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure

Directory of Open Access Journals (Sweden)

Zaid N.Z.M.

2017-01-01

Full Text Available Sandwich structure is an attractive alternative that increasingly used in the transportation and aerospace industry. Corrugated-core with trapezoidal shape allows enhancing the damage resistance to the sandwich structure, but on the other hand, it changes the structural response of the sandwich structure. The aim of this paper is to study the effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure under compression loading. The corrugated-core specimen was fabricated using press technique, following the shape of trapezoidal shape. Two different materials were used in the study, glass fibre reinforced plastic (GFRP and carbon fibre reinforced plastic (CFRP. The result shows that the mechanical properties of the core in compression loading are sensitive to the variation of a number of unit cells and the core thickness.

Long sandwich modules for photon veto detectors

International Nuclear Information System (INIS)

Yershov, N.; Khabibullin, M.; Kudenko, Yu.; Littenberg, L.; Mayatski, V.; Mineev, O.

2005-01-01

Long lead-scintillator sandwich modules developed for the BNL experiment KOPIO are described. The individual 4 m long module consists of 15 layers of 7 mm thick extruded scintillator and 15 layers of 1 mm lead absorber. Readout is implemented via WLS fibers glued into grooves in a scintillator with 7 mm spacing and viewed from both ends by the phototubes. Time resolution of 300 ps for cosmic MIPs was obtained. Light output stability monitored for 2 years shows no degradation beyond the measurement errors. A 4 m long C-bent sandwich module was also manufactured and tested

Application of fibre reinforced plastic sandwich structures for automotive crashworthiness applications

NARCIS (Netherlands)

Lukaszewicz, D.; Blok, L.G.; Kratz, J.; Ward, C.; Kassapoglou, C.; Elmarakbi, A.; Araújo, A.L.

2016-01-01

In this work the application of fibre reinforced plastic (FRP) sandwich
structures, with particular focus on aramid fibre tufted sandwiches is being studied for
automotive crashworthiness applications using impact testing and numerical simulation.

Application of Load Carrying Sandwich Elements in Wind Turbine Blades

DEFF Research Database (Denmark)

Jensen, Jacob Fisker; Schultz, Jacob Pagh; Berggreen, Carl Christian

2005-01-01

The present work investigates the possibilities and drawbacks when applying sandwich as opposed to single skin composites in the flanges of the load carrying spar in a future 180 m wind turbine rotor. FEA is applied to investigate two basic designs with single skin and sandwich flanges respectively...

Compressive Behaviour and Energy Absorption of Aluminium Foam Sandwich

Science.gov (United States)

Endut, N. A.; Hazza, M. H. F. Al; Sidek, A. A.; Adesta, E. T. Y.; Ibrahim, N. A.

2018-01-01

Development of materials in automotive industries plays an important role in order to retain the safety, performance and cost. Metal foams are one of the idea to evolve new material in automotive industries since it can absorb energy when it deformed and good for crash management. Recently, new technology had been introduced to replace metallic foam by using aluminium foam sandwich (AFS) due to lightweight and high energy absorption behaviour. Therefore, this paper provides reliable data that can be used to analyze the energy absorption behaviour of aluminium foam sandwich by conducting experimental work which is compression test. Six experiments of the compression test were carried out to analyze the stress-strain relationship in terms of energy absorption behavior. The effects of input variables include varying the thickness of aluminium foam core and aluminium sheets on energy absorption behavior were evaluated comprehensively. Stress-strain relationship curves was used for energy absorption of aluminium foam sandwich calculation. The result highlights that the energy absorption of aluminium foam sandwich increases from 12.74 J to 64.42 J respectively with increasing the foam and skin thickness.

Sandwiched Rényi divergence satisfies data processing inequality

International Nuclear Information System (INIS)

Beigi, Salman

2013-01-01

Sandwiched (quantum) α-Rényi divergence has been recently defined in the independent works of Wilde et al. [“Strong converse for the classical capacity of entanglement-breaking channels,” preprint http://arxiv.org/abs/arXiv:1306.1586 (2013)] and Müller-Lennert et al. [“On quantum Rényi entropies: a new definition, some properties and several conjectures,” preprint http://arxiv.org/abs/arXiv:1306.3142v1 (2013)]. This new quantum divergence has already found applications in quantum information theory. Here we further investigate properties of this new quantum divergence. In particular, we show that sandwiched α-Rényi divergence satisfies the data processing inequality for all values of α > 1. Moreover we prove that α-Holevo information, a variant of Holevo information defined in terms of sandwiched α-Rényi divergence, is super-additive. Our results are based on Hölder's inequality, the Riesz-Thorin theorem and ideas from the theory of complex interpolation. We also employ Sion's minimax theorem

Applications of Non-destructive methods (GPR and 3D Laser Scanner) in Historic Masonry Arch Bridge Assessment

Science.gov (United States)

Alani, Amir; Banks, Kevin

2014-05-01

There exist approximately 70,000 masonry arch bridge spans (brick and stone) in the UK with tens of thousands more throughout Europe. A significant number of these bridges are still in operation and form part of the road and rail network systems in many countries. A great majority of these bridges are in desperate need of repair and maintenance. Applications of non-destructive testing methods such as ground penetrating radar (GPR), 3D laser scanning, accelerometer sensors and vibration detecting sensors amongst many others have been used to assess and monitor such structures in the past few years. This presentation provides results of the applications of a 2GHz GPR antenna system and a 3D laser scanner on a historic masonry arch bridge (the Old Bridge, Aylesford) located in Kent, in the south east of England. The older part of the bridge (the mid-span) is 860 years old. The bridge was the subject of a major alteration in 1811. This presentation forms part of a larger ongoing study which is using the two above mentioned non-destructive methods for long-term monitoring of the bridge. The adopted survey planning strategy and technique, data acquisition and processing as well as challenges encountered during actual survey and fieldworks have been discussed in this presentation. As a result of this study the position of different layers of the deck structure has been established with the identification of the original stone base of the bridge. This information in addition to the location of a number of structural ties (anchors - remedial work carried out previously) in the absence of reliable and accurate design details proved to be extremely useful for the modelling of the bridge using the finite element method. Results of the 3D laser scanning of the bridge have also been presented which have provided invaluable data essential for the accurate modelling of the bridge as well as the long term monitoring of the bridge. 2014 EGU-GA GI3.1 Session, organised by COST Action

Multi-objective optimal design of sandwich panels using a genetic algorithm

Science.gov (United States)

Xu, Xiaomei; Jiang, Yiping; Pueh Lee, Heow

2017-10-01

In this study, an optimization problem concerning sandwich panels is investigated by simultaneously considering the two objectives of minimizing the panel mass and maximizing the sound insulation performance. First of all, the acoustic model of sandwich panels is discussed, which provides a foundation to model the acoustic objective function. Then the optimization problem is formulated as a bi-objective programming model, and a solution algorithm based on the non-dominated sorting genetic algorithm II (NSGA-II) is provided to solve the proposed model. Finally, taking an example of a sandwich panel that is expected to be used as an automotive roof panel, numerical experiments are carried out to verify the effectiveness of the proposed model and solution algorithm. Numerical results demonstrate in detail how the core material, geometric constraints and mechanical constraints impact the optimal designs of sandwich panels.

effect of uncertainty on the fatigue reliability of reinforced concrete ...

African Journals Online (AJOL)

In this paper, a reliability time-variant fatigue analysis and uncertainty effect on the serviceability of reinforced concrete bridge deck was carried out. A simply supported 15m bridge deck was specifically used for the investigation. Mathematical models were developed and the uncertainties in structural resistance, applied ...

A Novel Concrete-Based Sensor for Detection of Ice and Water on Roads and Bridges

Directory of Open Access Journals (Sweden)

Habib Tabatabai

2017-12-01

Full Text Available Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry, and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists of a 102-mm-diameter, 38-mm-high, concrete cylinder. Laboratory results indicate that the proposed sensor can effectively detect surface ice and wet conditions even in the presence of deicing chlorides and rubber residue. This sensor can further distinguish black ice from ice that may exist within concrete pores.

Design Considerations for Thermally Insulating Structural Sandwich Panels for Hypersonic Vehicles

Science.gov (United States)

Blosser, Max L.

2016-01-01

Simplified thermal/structural sizing equations were derived for the in-plane loading of a thermally insulating structural sandwich panel. Equations were developed for the strain in the inner and outer face sheets of a sandwich subjected to uniaxial mechanical loads and differences in face sheet temperatures. Simple equations describing situations with no viable solution were developed. Key design parameters, material properties, and design principles are identified. A numerical example illustrates using the equations for a preliminary feasibility assessment of various material combinations and an initial sizing for minimum mass of a sandwich panel.

The Planar Sandwich and Other 1D Planar Heat Flow Test Problems in ExactPack

Energy Technology Data Exchange (ETDEWEB)

Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-24

This report documents the implementation of several related 1D heat flow problems in the verification package ExactPack [1]. In particular, the planar sandwich class defined in Ref. [2], as well as the classes PlanarSandwichHot, PlanarSandwichHalf, and other generalizations of the planar sandwich problem, are defined and documented here. A rather general treatment of 1D heat flow is presented, whose main results have been implemented in the class Rod1D. All planar sandwich classes are derived from the parent class Rod1D.

Photocatalytic perfermance of sandwich-like BiVO_4 sheets by microwave assisted synthesis

International Nuclear Information System (INIS)

Liu, Suqin; Tang, Huiling; Zhou, Huan; Dai, Gaopeng; Wang, Wanqiang

2017-01-01

Graphical abstract: Sandwich-like BiVO_4 sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO_4 sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO_4. • The sandwich-like BiVO_4 sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO_4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N_2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO_4 sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO_4 sheets can be attributed to its large surface area over the irregular BiVO_4 particles.

Flexural Behavior of Aluminum Honeycomb Core Sandwich Structure

Science.gov (United States)

Matta, Vidyasagar; Kumar, J. Suresh; Venkataraviteja, Duddu; Reddy, Guggulla Bharath Kumar

2017-05-01

This project is concerned with the fabrication and flexural testing of aluminium honey comb sandwich structure which is a special case of composite materials that is fabricated by attaching two thin but stiff skins to a light weight but thick core. The core material is normally low density material but its high thickness provide the sandwich composite with high bonding stiffness. Honeycomb core are classified into two types based on the materials and structures. Hexagonal shape has a unique properties i.e has more bonding strength and less formation time based on the cell size and sheet thickness. Sandwich structure exhibit different properties such as high load bearing capacity at low weight and has excellent thermal insulation. By considering the above properties it has tendency to minimize the structural problem. So honey comb sandwich structure is choosed. The core structure has a different applications such as aircraft, ship interiors, construction industries. As there is no proper research on strength characteristics of sandwich structure. So, we use light weight material to desire the strength. There are different parameters involved in this structure i.e cell size, sheet thickness and core height. In this project we considered 3 level of comparison among the 3 different parameters cell size of 4, 6 and 8 mm, sheet thickness of 0.3, 0.5 and 0.7 mm, and core height of 20,25 and 30 mm. In order to reduce the number of experiment we use taguchi design of experiment, and we select the L8 orthogonal array is the best array for this type of situation, which clearly identifies the parameters by independent of material weight to support this we add the minitab software, to identify the main effective plots and regression equation which involves the individual response and corresponding parameters. Aluminium material is used for the fabrication of Honeycomb sandwich structure among the various grades of aluminium we consider the AL6061 which is light weight material

Robotics and Automation for Flight Deck Aircraft Servicing

Energy Technology Data Exchange (ETDEWEB)

Chesser, J.B.; Draper, J.V.; Pin, F.G.

1999-03-01

One of the missions of the Future Aircraft Carriers Program is to investigate methods that would improve aircraft turnaround servicing activities on carrier decks. The major objectives and criteria for evaluating alternative aircraft servicing methods are to reduce workload requirements, turnaround times (TAT), and life-cycle costs (LCC). Technologies in the field of Robotics and Automation (R and A) have the potential to significantly contribute to these objectives. The objective of this study was to investigate aircraft servicing functions on carrier decks which would offer the potentially most significant payoff if improved by various R and A technologies. Improvement in this case means reducing workload, time and LCC. This objective was accomplished using a ''bottom-up'' formalized approach as described in the following.

Hydrothermal synthesis and structural characterization of an organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en)2(H2O)]4[Cu(en)2(H2O)2][Cu2Na4(α-SbW9O33)2]·6H2O

International Nuclear Information System (INIS)

Liu, Yingjie; Cao, Jing; Wang, Yujie; Li, Yanzhou; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

2014-01-01

An organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu(en) 2 (H 2 O) 2 ][Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ]·6H 2 O (1) has been synthesized by reaction of Sb 2 O 3 , Na 2 WO 4 ·2H 2 O, CuCl 2 ·2H 2 O with en (en=ethanediamine) under hydrothermal conditions and structurally characterized by elemental analysis, inductively coupled plasma atomic emission spectrometry, IR spectrum and single-crystal X-ray diffraction. 1 displays a centric dimeric structure formed by two equivalent trivacant Keggin [α-SbW 9 O 33 ] 9− subunits sandwiching a hexagonal (Cu 2 Na 4 ) cluster. Moreover, those related hexagonal hexa-metal cluster sandwiched tungstoantimonates have been also summarized and compared. The variable-temperature magnetic measurements of 1 exhibit the weak ferromagnetic exchange interactions within the hexagonal (Cu 2 Na 4 ) cluster mediated by the oxygen bridges. - Graphical abstract: An organic–inorganic hybrid (Cu 2 Na 4 ) sandwiched tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu (en) 2 (H 2 O) 2 ][Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ]·6H 2 O was synthesized and magnetic properties was investigated. Display Omitted - Highlights: • Organic–inorganic hybrid sandwich-type tungstoantimonate. • (Cu 2 Na 4 sandwiched) tungstoantimonate [Cu 2 Na 4 (α-SbW 9 O 33 ) 2 ] 10− . • Ferromagnetic tungstoantimonate

Experimental and Computational Investigation of Triple-rotating Blades in a Mower Deck

Science.gov (United States)

Chon, Woochong; Amano, Ryoichi S.

Experimental and computational studies were performed on the 1.27m wide three-spindle lawn mower deck with side discharge arrangement. Laser Doppler Velocimetry was used to measure the air velocity at 12 different sections under the mower deck. The high-speed video camera test provided valuable visual evidence of airflow and grass discharge patterns. The strain gages were attached at several predetermined locations of the mower blades to measure the strain. In computational fluid dynamics work, computer based analytical studies were performed. During this phase of work, two different trials were attempted. First, two-dimensional blade shapes at several arbitrary radial sections were selected for flow computations around the blade model. Finally, a three-dimensional full deck model was developed and compared with the experimental results.

Buckling Analysis of Edge Cracked Sandwich Plate

Directory of Open Access Journals (Sweden)

Rasha Mohammed Hussein

2016-07-01

Full Text Available This work presents mainly the buckling load of sandwich plates with or without crack for different cases. The buckling loads are analyzed experimentally and numerically by using ANSYS 15. The experimental investigation was to fabricate the cracked sandwich plate from stainless steel and PVC to find mechanical properties of stainless steel and PVC such as young modulus. The buckling load for different aspect ratio, crack length, cracked location and plate without crack found. The experimental results were compared with that found from ANSYS program. Present of crack is decreased the buckling load and that depends on crack size, crack location and aspect ratio.

Behavior of composite sandwich panels with several core designs at different impact velocities

Science.gov (United States)

Jiga, Gabriel; Stamin, Ştefan; Dinu, Gabriela

2018-02-01

A sandwich composite represents a special class of composite materials that is manufactured by bonding two thin but stiff faces to a low density and low strength but thick core. The distance between the skins given by the core increases the flexural modulus of the panel with a low mass increase, producing an efficient structure able to resist at flexural and buckling loads. The strength of sandwich panels depends on the size of the panel, skins material and number or density of the cells within it. Sandwich composites are used widely in several industries, such as aerospace, automotive, medical and leisure industries. The behavior of composite sandwich panels with different core designs under different impact velocities are analyzed in this paper by numerical simulations performed on sandwich panels. The modeling was done in ANSYS and the analysis was performed through LS-DYNA.

Ultra-high performance fiber-reinforced concrete (UHPFRC) for infrastructure rehabilitation Volume II : behavior of ultra-high strength concrete bridge deck panels compared to conventional stay-in-place deck panels

Science.gov (United States)

2017-08-01

The remarkable features of ultra-high performance concrete (UHPC) have been reported. Its application in bridge construction has been an active research area in recent years, attributed to its higher compressive strength, higher ductility and reduced...

Preparation of Input Deck to analyze the Nuclear Power Plant for the Use of Regulatory Verification

International Nuclear Information System (INIS)

Kang, Doo Hyuk; Kim, Hyung Seok; Suh, Jae Seung; Ahn, Seung Hoon

2009-01-01

The objectives of this paper are to make out the input deck that analyzes a nuclear power plant for the use of regulatory verification and to produce its calculation note. We have been maintained the input deck of T/H safety codes used in existing domestic reactors to ensure independent and accurate regulatory verification for the thermal-hydraulic safety analysis in domestic NPPs. This paper is mainly divided into two steps: first step is to compare existing input deck to the calculation note in order to verify the consistency. Next step is to model 3-dimensional reactor pressure vessel using MULTID component instead of the 1D existing input deck

Demonstration and Validation of a Lightweight Composite Bridge Deck Technology as an Alternative to Reinforced Concrete

Science.gov (United States)

2016-08-01

Examples of the sensor placement are shown in Fig- ure 58 through Figure 60. A fully loaded dump truck weighing 78,660 lb was driven across the bridge at...release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and...environmental challenges. ERDC develops innovative solutions in civil and military engineering , geospatial sciences, water resources, and

Effect of microencapsulated phase change material in sandwich panels

Energy Technology Data Exchange (ETDEWEB)

Castellon, Cecilia; Medrano, Marc; Roca, Joan; Cabeza, Luisa F. [GREA Innovacio Concurrent, Edifici CREA, Universitat de Lleida, Pere de Cabrera s/n, 25001 Lleida (Spain); Navarro, Maria E.; Fernandez, Ana I. [Departamento de Ciencias de los Materiales e Ingenieria Metalurgica, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Lazaro, Ana; Zalba, Belen [Instituto de Investigacion en Ingenieria de Aragon, I3A, Grupo de Ingenieria Termica y Sistemas Energeticos (GITSE), Dpto. Ingenieria Mecanica, Area de Maquinas y Motores Termicos, Universidad de Zaragoza, Campus Politecnico Rio Ebro, Edificio ' ' Agustin de Betancourt,' ' Maria de Luna s/n, 50018 Zaragoza (Spain)

2010-10-15

Sandwich panels are a good option as building materials, as they offer excellent characteristics in a modular system. The goal of this study was to demonstrate the feasibility of using the microencapsulated PCM (Micronal BASF) in sandwich panels to increase their thermal inertia and to reduce the energy demand of the final buildings. In this paper, to manufacture the sandwich panel with microencapsulated PCM three different methods were tested. In case 1, the PCM was added mixing the microencapsulated PCM with one of the components of the polyurethane. In the other two cases, the PCM was added either a step before (case 2) or a step after (case 3) to the addition of the polyurethane to the metal sheets. The results show that in case 1 the effect of PCM was overlapped by a possible increase in thermal conductivity, but an increase of thermal inertia was found in case 3. In case 2, different results were obtained due to the poor distribution of the PCM. Some samples showed the effect of the PCM (higher thermal inertia), and other samples results were similar to the conventional sandwich panel. In both cases (2 and 3), it is required to industrialize the process to improve the results. (author)

Parametric study on nonlinear vibration of composite truss core sandwich plate with internal resonance

Energy Technology Data Exchange (ETDEWEB)

Chen, Jia Nen; Liu, Jun [Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System, Tianjin University of Technology, Tianjin (China); Zhang, Wei; Yao, Ming Hui [College of Mechanical Engineering, Beijing University of Technology, Beijing (China); Sun, Min [School of Science, Tianjin Chengjian University, Tianjin (China)

2016-09-15

Nonlinear vibrations of carbon fiber reinforced composite sandwich plate with pyramidal truss core are investigated. The governing equation of motion for the sandwich plate is derived by using a Zig-Zag theory under consideration of geometrically nonlinear. The natural frequencies of sandwich plates with different dimensions are calculated and compared with those obtained from the classic laminated plate theory and Reddy's third-order shear deformation plate theory. The frequency responses and waveforms of the sandwich plate when 1:3 internal resonance occurs are obtained, and the characteristics of the internal resonance are discussed. The influences of layer number of face sheet, strut radius, core height and inclination angle on the nonlinear responses of the sandwich plate are analyzed. The results demonstrate that the strut radius and inclination angle mainly affect the resonance frequency band of the sandwich plate, and the layer number and core height not only influence the resonance frequency band but also significantly affect the response amplitude.

ABC deck panel testing.

Science.gov (United States)

2013-09-01

Accelerated Bridge Construction techniques have resulted in innovative options that : save time and money during the construction of bridges. One such group of techniques : that has generated considerable interest is the usage of individual precast c...

STS-37 Commander Nagel in commanders seat on OV-104's flight deck

Science.gov (United States)

1991-01-01

STS-37 Commander Steven R. Nagel, wearing launch and entry suit (LES), sits at commanders station on the forward flight deck of Atlantis, Orbiter Vehicle (OV) 104. Surrounding Nagel are the seat headrest, control panels, checklists, forward flight deck windows, and three drinking water containers with straws attached to forward panel F2.

Study of the action of blast deck charge in rocky soils

Directory of Open Access Journals (Sweden)

Boiko V.V.

2017-04-01

Full Text Available Blasting (B in the industry, including the mining extraction of minerals, are carried out mostly with the use of blasthole charges that systematically distributed on the block that is undermined, by individual groups. The latter are blasted according to the scheme of short-delay firing (SDF through the intervals that are accepted not less than 20 Ms. Thus, the seismic effect of group charge explosion, consisting of individual blasthole charges and that actually is a group located charge determined by the formula of concentrated charge. Blast deck charges are effectively used in the driving of the trenches in the mining, formation of screens and cracks near the security objects. Only this method of performing blasting allows to define seismic effect in the transition from one diameter of a charge to another, as well as to determine the actual number of detonated charges in one group, which may differ from the calculated in drilling and blasting project. The work analyzes the physical essence of processes happened while blasting of blast deck charges. The effect of the orientation of the seismic action of blasting of blast deck charges towards the allocation line of charges is investigated. The results of generalized dependence of the speed of the displacement of the ground by the blast parameters and epicentral distance are obtained. We demonstrate with specific examples that blast deck charges that blasting simultaneously make a major chain of the career massive explosions at mining. Keywords: seismic fluctuations; the number of charges; the interaction of charges; the distance between the charges; the coefficients of the seismicity and the attenuation of the intensity of the waves; the unit charge; blast deck and blasthole charges; phase shifting; effective charge.

Failure Investigation of Debonded Sandwich Columns: An Experimental and Numerical Study

DEFF Research Database (Denmark)

Moslemian, Ramin; Berggreen, Christian; Carlsson, Leif A.

2009-01-01

Failure of compression loaded sandwich columns with an implanted through-width face/core debond is examined. Compression tests were conducted on sandwich columns containing implemented face/core debonds. The strains and out-of-plane displacements of the debonded region were monitored using the di...

Deck Yourself with Flu Protection Song

Centers for Disease Control (CDC) Podcasts

2009-12-22

This song (sung to the tune of Deck the Halls) describes actions you can take to protect yourself and others from the flu. Sing along!  Created: 12/22/2009 by National Center for Preparedness, Detection, and Control of Infectious Diseases (NCPDCID), Division of Global Migration and Quarantine (DGMQ).   Date Released: 12/22/2009.

Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites.

Science.gov (United States)

Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

2012-01-01

Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades.

Flexural wave attenuation in a sandwich beam with viscoelastic periodic cores

Science.gov (United States)

Guo, Zhiwei; Sheng, Meiping; Pan, Jie

2017-07-01

The flexural-wave attenuation performance of traditional constraint-layer damping in a sandwich beam is improved by using periodic constrained-layer damping (PCLD), where the monolithic viscoelastic core is replaced with two periodically alternating viscoelastic cores. Closed-form solutions of the wave propagation constants of the infinite periodic sandwich beam and the forced response of the corresponding finite sandwich structure are theoretically derived, providing computational support on the analysis of attenuation characteristics. In a sandwich beam with PCLD, the flexural waves can be attenuated by both Bragg scattering effect and damping effect, where the attenuation level is mainly dominated by Bragg scattering in the band-gaps and by damping in the pass-bands. Affected by these two effects, when the parameters of periodic cores are properly selected, a sandwich beam with PCLD can effectively reduce vibrations of much lower frequencies than that with traditional constrained-layer damping. The effects of the parameters of viscoelastic periodic cores on band-gap properties are also discussed, showing that the average attenuation in the desired frequency band can be maximized by tuning the length ratio and core thickness to proper values. The research in this paper could possibly provide useful information for the researches and engineers to design damping structures.

Robust and Air-Stable Sandwiched Organo-Lead Halide Perovskites for Photodetector Applications

KAUST Repository

Mohammed, Omar F.; Banavoth, Murali; Saidaminov, Makhsud I.; Abdelhady, Ahmed L.; Pan, Jun; Liu, Jiakai; Peng, Wei; Bakr, Osman

2016-01-01

We report the simplest possible method to date for fabricating robust, air-stable, sandwiched perovskite photodetectors. Our proposed sandwiched structure is devoid of electron or hole transporting layers and also the expensive electrodes

Interfacial Crack Arrest in Sandwich Panels with Embedded Crack Stoppers Subjected to Fatigue Loading

DEFF Research Database (Denmark)

Martakos, G.; Andreasen, J. H.; Berggreen, Christian

2017-01-01

A novel crack arresting device has been implemented in sandwich panels and tested using a special rig to apply out-of-plane loading on the sandwich panel face-sheets. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect o...

Seismic Analysis for a Crane System

Energy Technology Data Exchange (ETDEWEB)

Kim, Kang Soo; Lee, Chung Young; Ryu, Jeong Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

The operation bridge used for an open-pool type research reactor is a crane system with a working deck for the handling of in-pool parts such as fuels, reactor components and reactor utilization facilities. The operation bridge allows operators to access the top of the reactor in the reactor pool and the fuel storage racks in the service pool. The operation bridge contains an operating platform mounted on a truck travelling on rails. Upright members are mounted on the truck to support the upper structure and two hoist monorails. The operation bridge consists of two hoists, upper girder frames, legs, cables, saddle frames, upper deck frames, lower deck frames, and the ladder. Static and dynamic analyses are performed to evaluate the structural integrity for the operation bridge for the required design loadings. The response spectrum analysis is employed as a dynamic analysis method

Seismic Analysis for a Crane System

International Nuclear Information System (INIS)

Kim, Kang Soo; Lee, Chung Young; Ryu, Jeong Soo

2012-01-01

The operation bridge used for an open-pool type research reactor is a crane system with a working deck for the handling of in-pool parts such as fuels, reactor components and reactor utilization facilities. The operation bridge allows operators to access the top of the reactor in the reactor pool and the fuel storage racks in the service pool. The operation bridge contains an operating platform mounted on a truck travelling on rails. Upright members are mounted on the truck to support the upper structure and two hoist monorails. The operation bridge consists of two hoists, upper girder frames, legs, cables, saddle frames, upper deck frames, lower deck frames, and the ladder. Static and dynamic analyses are performed to evaluate the structural integrity for the operation bridge for the required design loadings. The response spectrum analysis is employed as a dynamic analysis method

Radar-based dynamic testing of the cable-suspended bridge crossing the Ebro River at Amposta, Spain

Energy Technology Data Exchange (ETDEWEB)

Gentile, Carmelo [Politecnico di Milano, Dept. of Architecture, Built environment and Construction engineering (ABC), Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Luzi, Guido [Centre Tecnòlogic de Telecomunicacions de Catalunya (CTTC), Division of Geomatics, Av. Gauss, 7 E-08860 Castelldefels (Barcelona) (Spain)

2014-05-27

Microwave remote sensing is the most recent experimental methodology suitable to the non-contact measurement of deflections on large structures, in static or dynamic conditions. After a brief description of the radar measurement system, the paper addresses the application of microwave remote sensing to ambient vibration testing of a cable-suspended bridge. The investigated bridge crosses the Ebro River at Amposta, Spain and consists of two steel stiffening trusses and a series of equally spaced steel floor beams; the main span is supported by inclined stay cables and two series of 8 suspension cables. The dynamic tests were performed in operational conditions, with the sensor being placed in two different positions so that the response of both the steel deck and the arrays of suspension elements was measured. The experimental investigation confirms the simplicity of use of the radar and the accuracy of the results provided by the microwave remote sensing as well as the issues often met in the clear localization of measurement points.

Wind effects on long-span bridges: Probabilistic wind data format for buffeting and VIV load assessments

Science.gov (United States)

Hoffmann, K.; Srouji, R. G.; Hansen, S. O.

2017-12-01

The technology development within the structural design of long-span bridges in Norwegian fjords has created a need for reformulating the calculation format and the physical quantities used to describe the properties of wind and the associated wind-induced effects on bridge decks. Parts of a new probabilistic format describing the incoming, undisturbed wind is presented. It is expected that a fixed probabilistic format will facilitate a more physically consistent and precise description of the wind conditions, which in turn increase the accuracy and considerably reduce uncertainties in wind load assessments. Because the format is probabilistic, a quantification of the level of safety and uncertainty in predicted wind loads is readily accessible. A simple buffeting response calculation demonstrates the use of probabilistic wind data in the assessment of wind loads and responses. Furthermore, vortex-induced fatigue damage is discussed in relation to probabilistic wind turbulence data and response measurements from wind tunnel tests.

Radar-based dynamic testing of the cable-suspended bridge crossing the Ebro River at Amposta, Spain

International Nuclear Information System (INIS)

Gentile, Carmelo; Luzi, Guido

2014-01-01

Microwave remote sensing is the most recent experimental methodology suitable to the non-contact measurement of deflections on large structures, in static or dynamic conditions. After a brief description of the radar measurement system, the paper addresses the application of microwave remote sensing to ambient vibration testing of a cable-suspended bridge. The investigated bridge crosses the Ebro River at Amposta, Spain and consists of two steel stiffening trusses and a series of equally spaced steel floor beams; the main span is supported by inclined stay cables and two series of 8 suspension cables. The dynamic tests were performed in operational conditions, with the sensor being placed in two different positions so that the response of both the steel deck and the arrays of suspension elements was measured. The experimental investigation confirms the simplicity of use of the radar and the accuracy of the results provided by the microwave remote sensing as well as the issues often met in the clear localization of measurement points

Tailoring Sandwich Face/Core Interfaces for Improved Damage Tolerance

DEFF Research Database (Denmark)

Lundsgaard-Larsen, Christian; Berggreen, Christian; Carlsson, Leif A.

2010-01-01

A face/core debond in a sandwich structure may propagate in the interface or kink into either the face or core. It is found that certain modifications of the face/core interface region influence the kinking behavior, which is studied experimentally in the present paper. A sandwich double cantilever....... The transition points where the crack kinks are identified and the influence of four various interface design modifications on the propagation path and fracture resistance are investigated....

Effect of Different Concentration of Sodium Hydroxide [NaOH] on Kenaf Sandwich Structures

Science.gov (United States)

Aziz, M.; Halim, Z.; Othman, M.

2018-01-01

Sandwich panels are structures that made of three layers, low-density core inserted in between thin skin layers. This structures allow the achievement of excellent mechanical performance with low weight, thus this characteristic fulfil requirement to be use in aircraft application. In recent time, sandwich structures have been studied due to it has multifunction properties and lightweight. The aim of this study is to fabricate a composite sandwich structures with biodegradable material for face sheet [skin] where the fibre being treat with different concentration of sodium hydroxide [NaOH] with 10 and 20 hours of soaking time. Kenaf fibre [treated] reinforced epoxy will be used as skins and Nomex honeycomb is chosen to perform as core for this sandwich composite structure. The mechanical properties that are evaluated such as flexural strength and impact energy of kenaf fibre-reinforced epoxy sandwich structures. For flexural test, the optimum flexural strength is 13.4 MPa and impact strength is 18.3 J.

GFRP seismic strengthening and structural heath monitoring of Portage Creek Bridge concrete columns

International Nuclear Information System (INIS)

Huffman, S.; Bagchi, A.; Mufti, A.; Neale, K.; Sargent, D.; Rivera, E.

2006-01-01

Located in Victoria British Columbia (BC), Canada, the Portage Creek Bridge is a 124m long, three-span structure with a reinforced concrete piers and abutments on H piles. The bridge was designed prior to the introduction of current bridge seismic design codes and construction practices. Therefore it was not designed to resist the earthquake forces as required by today's standards. The bridge is on a route classified as a Municipal Disaster Route scheduled to be retrofitted to prevent collapse during a design seismic event, with a return period of 475 years (i.e., an event with 105 probability of exceedance in 50 years). Conventional materials and methods were used to retrofit most of the bridge. The dynamic analysis of the bridge predicted the two tall columns of Pier No. 1 will form plastic hinges under an earthquake resulting an additional shear to the short columns of Pier No. 2. A non-liner static pushover analysis indicated the short columns will not be able to form plastic hinges prior to failure in shear. The innovative solution of Fiber Reinforced Polymer wraps (FRPs) was chosen to strengthen the short columns for shear without increasing the moment capacity. The FRP wraps and the bridge were instrumented as one of 36 demonstration projects across Canada sponsored by ISIS (Intelligent Sensing for Innovative Structure) Canada, federally funded Network of Centers of Excellence, to access the performance of FRP and the use of FOS (Fiber Optic Sensors) for Structural Health Monitoring (SHM). The two columns of the bridge pier were strengthened with GFRP (Glass Fiber Reinforced Polymer) wraps with eight bi-directional rosette type strain gauges and four long gauge fiber optic sensors attached to the outer layer of the wraps. In addition, two 3-D Crossbow accelerometers are installed on the pier cap above the columns and a traffic web-cam mounted above the deck at the pier location. The data is collected through high sped internet line to an interactive web page

Dynamic Heat Storage and Cooling Capacity of a Concrete Deck with PCM and Thermally Activated Building System

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

2012-01-01

This paper presents a heat storage and cooling concept that utilizes a phase change material (PCM) and a thermally activated building system (TABS) implemented in a hollow core concrete deck. Numerical calculations of the dynamic heat storage capacity of the hollow core concrete deck element...... in the article highlight the potential of using TABS and PCM in a prefabricated concrete deck element....

Tuning electron transport through a single molecular junction by bridge modification

International Nuclear Information System (INIS)

Li, Xiao-Fei; Qiu, Qi; Luo, Yi

2014-01-01

The possibility of controlling electron transport in a single molecular junction represents the ultimate goal of molecular electronics. Here, we report that the modification of bridging group makes it possible to improve the performance and obtain new functions in a single cross-conjugated molecular junction, designed from a recently synthesized bipolar molecule bithiophene naphthalene diimide. Our first principles results show that the bipolar characteristic remains after the molecule was modified and sandwiched between two metal electrodes. Rectifying is the intrinsic characteristic of the molecular junction and its performance can be enhanced by replacing the saturated bridging group with an unsaturated group. A further improvement of the rectifying and a robust negative differential resistance (NDR) behavior can be achieved by the modification of unsaturated bridge. It is revealed that the modification can induce a deviation angle about 4° between the donor and the acceptor π-conjugations, making it possible to enhance the communication between the two π systems. Meanwhile, the low energy frontier orbitals of the junction can move close to the Fermi level and encounter in energy at certain biases, thus a transport channel with a considerable transmission can be formed near the Fermi level only at a narrow bias regime, resulting in the improvement of rectifying and the robust NDR behavior. This finding could be useful for the design of single molecular devices.

Fracture Behaviours in Compression-loaded Triangular Corrugated Core Sandwich Panels

Directory of Open Access Journals (Sweden)

Zaid N.Z.M.

2016-01-01

Full Text Available The failure modes occurring in sandwich panels based on the corrugations of aluminium alloy, carbon fibre-reinforced plastic (CFRP and glass fibre-reinforced plastic (GFRP are analysed in this work. The fracture behaviour of these sandwich panels under compressive stresses is determined through a series of uniform lateral compression performed on samples with different cell wall thicknesses. Compression test on the corrugated-core sandwich panels were conducted using an Instron series 4505 testing machine. The post-failure examinations of the corrugated-core in different cell wall thickness were conducted using optical microscope. Load-displacement graphs of aluminium alloy, GFRP and CFRP specimens were plotted to show progressive damage development with five unit cells. Four modes of failure were described in the results: buckling, hinges, delamination and debonding. Each of these failure modes may dominate under different cell wall thickness or loading condition, and they may act in combination. The results indicate that thicker composites corrugated-core panels tend can recover more stress and retain more stiffness. This analysis provides a valuable insight into the mechanical behaviour of corrugated-core sandwich panels for use in lightweight engineering applications.

Delamination Detection of Reinforced Concrete Decks Using Modal Identification

Directory of Open Access Journals (Sweden)

Shutao Xing

2012-01-01

Full Text Available This study addressed delamination detection of concrete slabs by analyzing global dynamic responses of structures. Both numerical and experimental studies are presented. In the numerical examples, delaminations with different sizes and locations were introduced into a concrete slab; the effects of presence, sizes, and locations of delaminations on the modal frequencies and mode shapes of the concrete slab under various support conditions were studied. In the experimental study, four concrete deck specimens with different delamination sizes were constructed, and experimental tests were conducted. Traditional peak-picking, frequency domain decomposition, and stochastic subspace identification methods were applied to the modal identification from dynamic response measurements. The modal parameters identified by these three methods correlated well. The changes in modal frequencies, damping ratios, and mode shapes that were extracted from the dynamic measurements were investigated and correlated to the actual delaminations and can indicate presence and severity of delamination. Finite element (FE models of reinforced concrete decks with different delamination sizes and locations were established. The modal parameters computed from the FE models were compared to those obtained from the laboratory specimens, and the FE models were validated. The delamination detection approach was proved to be effective for concrete decks on beams.

Numerical simulation of the hole-flanging process for steel-polymer sandwich sheets

Science.gov (United States)

Griesel, Dominic; Keller, Marco C.; Groche, Peter

2018-05-01

In light of increasing demand for lightweight structures, hybrid materials are frequently used in load-optimized parts. Sandwich structures like metal-polymer sandwich sheets provide equal bending stiffness as their monolithic counterparts at a drastically reduced weight. In addition, sandwich sheets have noise-damping properties, thus they are well-suited for a large variety of parts, e.g. façade and car body panels, but also load-carrying components. However, due to the creep tendency and low heat resistance of the polymer cores, conventional joining technologies are only applicable to a limited degree. Through hole-flanging it is possible to create branches in sandwich sheets to be used as reinforced joints. While it is state of the art for monolithic materials, hole-flanging of sandwich sheets has not been investigated yet. In order to simulate this process for different material combinations and tool geometries, an axisymmetric model has been developed in the FE software Abaqus/CAE. In the present paper, various modeling strategies for steel-polymer sandwich sheets are examined, including volume elements, shell elements and combinations thereof. Different methods for joining the distinct layers in the FE model are discussed. By comparison with CT scans and optical 3D measurements of experimentally produced hole-flanges, the feasibility of the presented models is evaluated. Although a good agreement of the numerical and experimental results has been achieved, it becomes clear that the classical forming limit diagram (FLD) does not adequately predict failure of the steel skins.

Parametric Analyses of Dynamic Characteristic of the Cable-Stayed Pedestrian Bridge

Directory of Open Access Journals (Sweden)

Pańtak Marek

2017-12-01

Full Text Available The paper presents characteristics of the structural system and results of dynamic field tests and numerical parametric analyses of three-span, two-pylon, cable-stayed pedestrian bridge with steel-concrete composite deck and spans of 25.5 + 60.0 + 25.5 m. The footbridge is characterized by increased dynamic susceptibility of the elements of the suspension system observed during the everyday operation of the structure. The analyses have shown that the high amplitude vibrations of the pylon back-stay cables change the parameters of the structural system and consequently change the value of the natural vibration frequencies of the structure. In the paper, the selection methodology of parameters of the computational model which allows to correctly determine the natural vibration frequencies of the footbridge has been presented.

Identification of moving vehicle forces on bridge structures via moving average Tikhonov regularization

Science.gov (United States)

Pan, Chu-Dong; Yu, Ling; Liu, Huan-Lin

2017-08-01

Traffic-induced moving force identification (MFI) is a typical inverse problem in the field of bridge structural health monitoring. Lots of regularization-based methods have been proposed for MFI. However, the MFI accuracy obtained from the existing methods is low when the moving forces enter into and exit a bridge deck due to low sensitivity of structural responses to the forces at these zones. To overcome this shortcoming, a novel moving average Tikhonov regularization method is proposed for MFI by combining with the moving average concepts. Firstly, the bridge-vehicle interaction moving force is assumed as a discrete finite signal with stable average value (DFS-SAV). Secondly, the reasonable signal feature of DFS-SAV is quantified and introduced for improving the penalty function (∣∣x∣∣2 2) defined in the classical Tikhonov regularization. Then, a feasible two-step strategy is proposed for selecting regularization parameter and balance coefficient defined in the improved penalty function. Finally, both numerical simulations on a simply-supported beam and laboratory experiments on a hollow tube beam are performed for assessing the accuracy and the feasibility of the proposed method. The illustrated results show that the moving forces can be accurately identified with a strong robustness. Some related issues, such as selection of moving window length, effect of different penalty functions, and effect of different car speeds, are discussed as well.

STS-27 crew poses for inflight portrait on forward flight deck with football

Science.gov (United States)

1988-01-01

With WILSON NFL football freefloating in front of them, STS-27 astronauts pose on Atlantis', Orbiter Vehicle (OV) 104's, forward flight deck for inflight crew portrait. Crewmembers, wearing blue mission t-shirts, are (left to right) Commander Robert L. Gibson, Mission Specialist (MS) Richard M. Mullane, MS Jerry L. Ross, MS William M. Shepherd, and Pilot Guy S. Gardner. Forward flight deck overhead control panels are visible above crewmembers, commanders and pilots seats in front of them, and forward windows behind them. An auto-set 35mm camera mounted on the aft flight deck was used to take this photo. The football was later presented to the National Football League (NFL) at halftime of the Super Bowl in Miami.

Gravity sag of sandwich panel assemblies as applied to precision cathode strip chamber structural design

International Nuclear Information System (INIS)

Horvath, J.

1993-01-01

The relationship between gravity sag of a precision cathode strip chamber and its sandwich panel structural design is explored parametrically. An algorithm for estimating the dominant component of gravity sag is defined. Graphs of normalized gravity sag as a function of gap frame width and material, sandwich core edge filler width and material, panel skin thickness, gap height, and support location are calculated using the gravity sag algorithm. The structural importance of the sandwich-to-sandwich ''gap frame'' connection is explained

Functional grading of metal foam cores for yield-limited lightweight sandwich beams

International Nuclear Information System (INIS)

Conde, Yves; Pollien, Arnaud; Mortensen, Andreas

2006-01-01

We show that grading the porosity in a bent metal skin/metal foam core sandwich can generate significant weight savings in yield-limited design when, and only when, there is a gradient in the applied moment along the sandwich beam

Behaviour of glued fibre composite sandwich structure in flexure: Experiment and Fibre Model Analysis

International Nuclear Information System (INIS)

Manalo, Allan; Aravinthan, Thiru

2012-01-01

Highlights: ► Fibre Model Analysis is used to examine the flexural behaviour of sandwich beams. ► Theoretical prediction using FMA is in good agreement with the experiment. ► Using the constituent materials in FMA predicted accurately the beam’s behaviour. ► FMA can be used for analysing sandwich beams with high-strength core in flexure. -- Abstract: The behaviour of glued composite sandwich beams in flexure was investigated with a view of using this material for structural and civil engineering applications. The building block of this glue-laminated beam is a new generation composite sandwich structure made up of glass fibre reinforced polymer skins and a high strength phenolic core material. A simplified Fibre Model Analysis (FMA) usually used to analyse a concrete beam section is adopted to theoretically describe the flexural behaviour of the innovative sandwich beam structure. The analysis included the flexural behaviour of the glued sandwich beams in the flatwise and the edgewise positions. The FMA accounted for the non-linear behaviour of the phenolic core in compression, the cracking of the core in tension and the linear elastic behaviour of the fibre composite skin. The results of the FMA showed a good agreement with the experimental data showing the efficiency and practical applications of the simplified FMA in analysing and designing sandwich structures with high strength core material.

Upper Mississippi River System, Environment Management Program, Definite Project Report with Integrated Environmental Assessment (R-8). Bay Island, Missouri Rehabilitation and Enhancement. Pool 22, Mississippi River Miles 311 through 312, Marion County, Missouri

Science.gov (United States)

1990-03-01

work under- taken by the drainage district. The new bridge will have a prefabricated deck set on concrete abutments . The span length will be 42 feet...FaciLities & Sanctuaries (Access Road Bridge) 06.3.C.9 Prefabricated Deck & Wearing Surface I LS 20,000.00 20,000 5,000 06.3.C.0 Structural Concrete 54... abutments with wing walls. The existing bridge abutments will remain in place. Installation of the pump station will involve site preparation using

Modification of Displacement Coefficient Method in Estimation of Target Displacement for Regular Concrete Bridges Based on ASCE 41-06 Standard

Directory of Open Access Journals (Sweden)

Seyed Bahram Beheshti-Aval

2015-06-01

Full Text Available Displacement Coefficient Method (DCM stipulated in the ASCE 41-06 standard is becoming the preferred method for seismic rehabilitation of buildings in many high-seismic-hazard countries. Applications of the method for non-building constructions such as bridges are beyond the scope of this standard. Thus its application to this kind of structure should be approached with care. Target displacement has reasonable accuracy for buildings with strong columns and weak beams, where there is the development of plastic hinges. Due to high stiffness and strength of the deck relative to the piers in most bridges, this mechanism does not occur, and it is necessary to evaluate the accuracy of DCM for such structures. In this research, an attempt is made to evaluate the credibility of DCM in the ASCE/SEI 41-06 standard for estimating target drifts in concrete regular bridges under strong ground motions. To apply the extension of the method to bridge structures, the definition of new correction factor CB, which should be multiplied to previous coefficients, is required. This novel coefficient can improve the accuracy of the mentioned method in accessing seismic displacement demands. The coefficient is presented for soil types A to D based on NEHRP soil classification. The validity of the modified DCM is examined for several bridges with use of nonlinear dynamic analysis. Good correlation is found between both procedures.

Applications of thin-film sandwich crystallization platforms

Energy Technology Data Exchange (ETDEWEB)

Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

2016-03-24

Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

Structural Loading of Cross Deck Connections for Trimaran Vessels

National Research Council Canada - National Science Library

Rhoads, Jason

2004-01-01

...: longitudinal bending, transverse bending, torsional bending, spreading and squeezing of hulls, inner and outer hull slam pressures, wet deck slam pressures, loading from ship's motions, and whipping of slender hulls...

High performance sandwich structured Si thin film anodes with LiPON coating

Science.gov (United States)

Luo, Xinyi; Lang, Jialiang; Lv, Shasha; Li, Zhengcao

2018-04-01

The sandwich structured silicon thin film anodes with lithium phosphorus oxynitride (LiPON) coating are synthesized via the radio frequency magnetron sputtering method, whereas the thicknesses of both layers are in the nanometer range, i.e. between 50 and 200 nm. In this sandwich structure, the separator simultaneously functions as a flexible substrate, while the LiPON layer is regarded as a protective layer. This sandwich structure combines the advantages of flexible substrate, which can help silicon release the compressive stress, and the LiPON coating, which can provide a stable artificial solidelectrolyte interphase (SEI) film on the electrode. As a result, the silicon anodes are protected well, and the cells exhibit high reversible capacity, excellent cycling stability and good rate capability. All the results demonstrate that this sandwich structure can be a promising option for high performance Si thin film lithium ion batteries.

Photocatalytic perfermance of sandwich-like BiVO{sub 4} sheets by microwave assisted synthesis

Energy Technology Data Exchange (ETDEWEB)

Liu, Suqin, E-mail: liusuqin888@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Xiangyang 441053 (China); Tang, Huiling; Zhou, Huan [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Dai, Gaopeng, E-mail: dgp2000@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Wang, Wanqiang [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China)

2017-01-01

Graphical abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO{sub 4} sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO{sub 4}. • The sandwich-like BiVO{sub 4} sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N{sub 2} adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO{sub 4} sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO{sub 4} sheets can be attributed to its large surface area over the irregular BiVO{sub 4} particles.

High renewable content sandwich structures based on flax-basalt hybrids and biobased epoxy polymers

Science.gov (United States)

Colomina, S.; Boronat, T.; Fenollar, O.; Sánchez-Nacher, L.; Balart, R.

2014-05-01

In the last years, a growing interest in the development of high environmental efficiency materials has been detected and this situation is more accentuated in the field of polymers and polymer composites. In this work, green composite sandwich structures with high renewable content have been developed with core cork materials. The base resin for composites was a biobased epoxy resin derived from epoxidized vegetable oils. Hybrid basalt-flax fabrics have been used as reinforcements for composites and the influence of the stacking sequence has been evaluated in order to optimize the appropriate laminate structure for the sandwich bases. Core cork materials with different thickness have been used to evaluate performance of sandwich structures thus leading to high renewable content composite sandwich structures. Results show that position of basalt fabrics plays a key role in flexural fracture of sandwich structures due to differences in stiffness between flax and basalt fibers.

Combined-load buckling behavior of metal-matrix composite sandwich panels under different thermal environments

Science.gov (United States)

Ko, William L.; Jackson, Raymond H.

1991-01-01

Combined compressive and shear buckling analysis was conducted on flat rectangular sandwich panels with the consideration of transverse shear effects of the core. The sandwich panel is fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that the square panel has the highest combined load buckling strength, and that the buckling strength decreases sharply with the increases of both temperature and panel aspect ratio. The effect of layup (fiber orientation) on the buckling strength of the panels was studied in detail. The metal matrix composite sandwich panel was much more efficient than the sandwich panel with nonreinforced face sheets and had the same specific weight.

Load test of the 277W Building high bay roof deck and support structure

International Nuclear Information System (INIS)

McCoy, R.M.

1994-01-01

The 277W Building high bay roof area was load tested according to the approved load-test procedure, WHC-SD-GN-TP-30015, Revision 1. The 277W Building is located in the 200 West Area of the Hanford Site and has the following characteristics: roof deck -- wood decking supported by 4 x 14 timber purlins; roof membrane -- tar and gravel; roof slope -- flat (<10 deg); and roof elevation -- maximum height of about 63 ft. The 227W Building was visited in March 1994 for a visual inspection. During this inspection, cracked areas were visible in the decking, but it was not possible to determine whether these cracks extended completely through the decking, which is 2-in. thick. The building was revisited in March 1994 for the purpose of writing this test report. Because the roof requires personnel access, a test was determined to be the best way to qualify the roof. The conclusions are that the roof has been qualified for 500-lb total roof load and that the ''No Roof Access'' signs can be changed to ''Roof Access Restricted'' signs

Identification of material properties of sandwich structure with piezoelectric patches

Directory of Open Access Journals (Sweden)

Zemčík R.

2008-11-01

Full Text Available The work focuses on light-weight sandwich structures made of carbon-epoxy skins and foam core which have unique bending stiffness compared to conventional materials. The skins are manufactured by vacuum autoclave technology from unidirectional prepregs and the sandwich is then glued together. The resulting material properties of the structure usually differ from those provided by manufacturer or even those obtained from experimental tests on separate materials, which makes computational models unreliable. Therefore, the properties are identified using the combination of experimental analysis of the sandwich with attached piezoelectric transducer and corresponding static and modal finite element analyses. Simple mathematical optimization with repetitive finite element solution is used. The model is then verified by transient analysis when the piezoelectric patch is excited by harmonic signals covering the first two eigen-frequencies and the induced oscillations are measured by laser sensor.

Natural fabric sandwich laminate composites: development and ...

Indian Academy of Sciences (India)

3Department of Production Technology, MIT Campus, Anna University, Chennai 600044, India. MS received ... In this work, eco-friendly natural fabric sandwich laminate (NFSL) composites are formulated using ... and eco-friendly quality [22].

Numerical Study on the Projectile Impact Resistance of Multi-Layer Sandwich Panels with Cellular Cores

Directory of Open Access Journals (Sweden)

Liming Chen

Full Text Available Abstract The projectile impact resistance of sandwich panels with cellular cores with different layer numbers has been numerically investigated by perpendicular impact of rigid blunt projectile in ABAQUS/Explicit. These panels with corrugation, hexagonal honeycomb and pyramidal truss cores are impacted at velocities between 50 m/s and 202 m/s while the relative density ranges from 0.001 to 0.15 The effects of core configuration and layer number on projectile impact resistance of sandwich panels with cellular cores are studied. At low impact velocity, sandwich panels with cellular cores outperform the corresponding solid ones and non-montonicity between relative density and projectile resistance of sandwich panels is found and analyzed. Multiplying layer can reduce the maximum central deflection of back face sheet of the above three sandwich panels except pyramidal truss ones in high relative density. Hexagonal honeycomb sandwich panel is beneficial to increasing layer numbers in lowering the contact force and prolonging the interaction time. At high impact velocity, though corrugation and honeycomb sandwich panels are inferior to the equal-weighted solid panels, pyramidal truss ones with high relative density outperform the corresponding solid panels. Multiplying layer is not the desirable way to improve high-velocity projectile resistance.

A materials selection procedure for sandwiched beams via parametric optimization with applications in automotive industry

International Nuclear Information System (INIS)

Aly, Mohamed F.; Hamza, Karim T.; Farag, Mahmoud M.

2014-01-01

Highlights: • Sandwich panels optimization model. • Sandwich panels design procedure. • Study of sandwich panels for automotive vehicle flooring. • Study of sandwich panels for truck cabin exterior. - Abstract: The future of automotive industry faces many challenges in meeting increasingly strict restrictions on emissions, energy usage and recyclability of components alongside the need to maintain cost competiveness. Weight reduction through innovative design of components and proper material selection can have profound impact towards attaining such goals since most of the lifecycle energy usage occurs during the operation phase of a vehicle. In electric and hybrid vehicles, weight reduction has another important effect of extending the electric mode driving range between stops or gasoline mode. This paper adopts parametric models for design optimization and material selection of sandwich panels with the objective of weight and cost minimization subject to structural integrity constraints such as strength, stiffness and buckling resistance. The proposed design procedure employs a pre-compiled library of candidate sandwich panel material combinations, for which optimization of the layered thicknesses is conducted and the best one is reported. Example demonstration studies from the automotive industry are presented for the replacement of Aluminum and Steel panels with polypropylene-filled sandwich panel alternatives

A quantitative exposure model simulating human norovirus transmission during preparation of deli sandwiches.

Science.gov (United States)

Stals, Ambroos; Jacxsens, Liesbeth; Baert, Leen; Van Coillie, Els; Uyttendaele, Mieke

2015-03-02

Human noroviruses (HuNoVs) are a major cause of food borne gastroenteritis worldwide. They are often transmitted via infected and shedding food handlers manipulating foods such as deli sandwiches. The presented study aimed to simulate HuNoV transmission during the preparation of deli sandwiches in a sandwich bar. A quantitative exposure model was developed by combining the GoldSim® and @Risk® software packages. Input data were collected from scientific literature and from a two week observational study performed at two sandwich bars. The model included three food handlers working during a three hour shift on a shared working surface where deli sandwiches are prepared. The model consisted of three components. The first component simulated the preparation of the deli sandwiches and contained the HuNoV reservoirs, locations within the model allowing the accumulation of NoV and the working of intervention measures. The second component covered the contamination sources being (1) the initial HuNoV contaminated lettuce used on the sandwiches and (2) HuNoV originating from a shedding food handler. The third component included four possible intervention measures to reduce HuNoV transmission: hand and surface disinfection during preparation of the sandwiches, hand gloving and hand washing after a restroom visit. A single HuNoV shedding food handler could cause mean levels of 43±18, 81±37 and 18±7 HuNoV particles present on the deli sandwiches, hands and working surfaces, respectively. Introduction of contaminated lettuce as the only source of HuNoV resulted in the presence of 6.4±0.8 and 4.3±0.4 HuNoV on the food and hand reservoirs. The inclusion of hand and surface disinfection and hand gloving as a single intervention measure was not effective in the model as only marginal reductions of HuNoV levels were noticeable in the different reservoirs. High compliance of hand washing after a restroom visit did reduce HuNoV presence substantially on all reservoirs. The