bluuebunny/crossref_metadata_2025 huggingface dataset:
Bridge Aesthetics for Broadway Bridge Replacement: Daytona Beach, Florida
Authors: Pielstick Brett H.
Published: April 2007

As the gateway to the beaches of Daytona Beach, Florida, the new Broadway Bridge will be a signature bridge for the community. Mosaic tile murals up to 3 m in height will be incorporated around the columns of the new bridge, as will mosaic panels along the sidewalk handrail. The bridge will also feature ornamental handrail and light fixtures with aesthetic lighting that will display this high-profile structure to the surrounding skyline of Daytona Beach. Additional plantings and fountains will be provided with a grand architectural entrance welcoming visitors to Daytona Beach and onto this signature bridge. The glass tile mosaic art will feature manatees, dolphins, and other nature scenes with species endemic to Florida. Special reviews and approval of the art scenes will be done by the architect of record before fabrication of the large pieces. The Broadway Bridge replacement is being constructed with twin, precast, segmental concrete bridges erected by balanced cantilever construction with an overhead gantry system. The construction includes a cast-in-place, posttensioned flat-slab section on the west end. Each bridge will have a 20-m vertical clearance over the 38-m-wide navigational channel. The bridges will be approximately 918 m in length, with spans varying from 30 to 80 m. The span length variation with structure height will add to the overall aesthetic features of this signature bridge. Graceful lines developed by the segmental design and the additional architectural features provided by the mosaic inlays, lighting, plantings, and fountain make the Broadway Bridge unique and a beautiful addition to the Daytona Beach area.
Design of Semilightweight Bridge Girders: Development-Length Considerations
Authors: Peterman Robert J. , Ramirez Julio A. , Olek Jan
Published: April 2007

In a recent study, 25 development-length tests were conducted on rectangular and T-shaped semilightweight beams having design compressive strengths of 48 MPa (7,000 psi) and 69 MPa (10,000 psi). In the rectangular beam tests, the design moment capacity was exceeded in every case. However, in the tests on T-shaped beams, bond failure occurred in some specimens immediately after the formation of a flexure-shear crack. Additional tests were then conducted on similar T-shaped beams having varying amounts of transverse reinforcement near the point load. These tests showed that bond failure could be prevented by increasing the transverse reinforcement near the point of maximum moment. The study showed that the shift in the tension force that occurs when flexural cracks turn diagonally may lead to bond failure if sufficient anchorage of the strand is not provided. Therefore, the investigators recommend that the current AASHTO requirements for strand development be enforced at a “critical section” located at a distance dp from the point of maximum moment toward the free end of the strand, where dp is the distance from the extreme compression fiber to the centroid of the prestressed reinforcement.
Fatigue Evaluation of Steel and Concrete Bridges
Authors: Szerszen Maria M. , Nowak Andrzej S.
Published: April 2007

The fatigue limit state is one of the important considerations in the design of bridges. Accumulated load cycles can cause cracking or even failure. An approach to evaluation of steel and concrete bridges with regard to fatigue is presented. The method for prediction of the remaining life of a bridge superstructure is based on the load model and the procedure to estimate fatigue degradation of materials. In the case of steel girders, degradation of material is considered using S-N curves. For reinforced concrete beams, degradation of concrete in the compressive zone is described by the rheological fatigue model. Reliability analysis is performed for the fatigue limit state function of flexure. Prediction of the remaining fatigue life for steel and concrete beams is illustrated on examples of existing bridge girders.
Highway Network Bridge Fatigue Damage Potential of Special Truck Configurations
Authors: Laman Jeffrey A. , Ashbaugh John R.
Published: April 2007

A study of the fatigue damage potential of special truck configurations was conducted to facilitate informed decisions by state transportation agencies in considering various truck size and weight and permit policies as well as to provide relative damage information that will be useful in ongoing network damage evaluations. The primary objective was to evaluate 78 existing common and FHWA-proposed truck configurations for relative fatigue damage potential. To accomplish this objective, an analytical fatigue evaluation tool was developed to determine the relative fatigue damage induced in highway network bridges by simulation of a highway fleet mix database crossing actual bridges modeled analytically. Additional objectives were to evaluate the influence of impact values and endurance limits used for a fatigue analysis. The semicontinuum analysis method, the Palmgren-Miner hypothesis, and the rain-flow cycle counting algorithm are incorporated. A 39-bridge database statistically selected as representative of bridges in the United States allowed a network level fatigue analysis of several hundred fatigue-prone details. Seventy-eight special truck configurations were studied, 25 of which were developed by FHWA as part of the comprehensive truck size and weight study. The remaining 53 vehicles were taken from the Turner proposal, Michigan, Pennsylvania, Canada, military, AASHTO, and other sources. It was found that fatigue damage potential is primarily a function of axle weight, spacing, and vehicle length instead of gross vehicle weight.
Design and Performance of Jointless Bridges in Ontario: New Technical and Material Concepts
Authors: Husain Iqbal , Bagnariol Dino
Published: April 2007

It is well recognized that leaking expansion joints at the ends of bridge decks have led to the premature deterioration of bridge components. The elimination of these maintenance-prone joints not only yields immediate economic benefits but also improves the long-term durability of bridges. In Ontario, Canada, “jointless” bridges have been used for many years. Recently, the use of two main types of these bridges has increased dramatically. The first type is an “integral abutment” bridge that comprises an integral deck and abutment system supported on flexible piles. The approach slabs are also continuous with the deck slab. The flexible foundation allows the anticipated deck movements to take place at the end of the approach slab. Control joint details have been developed to allow movements at this location. The second type is a “semi-integral abutment” bridge that also allows expansion joints to be eliminated from the end of the bridge deck. The approach slabs are continuous with the deck slab, and the abutments are supported on rigid foundations (spread footings). The superstructure is not continuous with the abutments, and conventional bearings are used to allow horizontal movements between the deck and the abutments. A control joint is provided at the end of the approach slab that is detailed to slide in between the wing walls. Some of the design methods and construction details that are used in Ontario for integral and semi-integral abutment bridges are summarized. A review of the actual performance of existing bridges is also presented.
Large and Small Incrementally Launched Structures
Authors: Paul Alistair
Published: April 2007

The technology for incrementally launched structures has been known for several decades. It had not been utilized in South Australia until a recent flurry of activity revealed that this method could be economically utilized for both small and large structures. Within 3 years, four structures of various sizes were constructed using the technique. A double-T prestressed concrete recreational jetty was incrementally launched at one of Adelaide’s suburban beaches (Brighton Jetty). Twin single-cell prestressed concrete (PSC) box girders were incrementally launched over eight lanes of traffic at a busy signalized suburban road intersection without disruption to traffic (bridge over Port Wakefield Road). Two incrementally launched major bridges were constructed over the River Murray, Australia’s longest river. The first structure consisted of steel girders composite with a reinforced concrete deck (Berri Bridge, 330 m long), and the other structure was a single PSC box girder (Blanchetown Bridge, 410 m long). All these structures are mentioned, but the focus is on the PSC box girder structures. Construction problems associated with the use of permanent bearings as launch bearings and the sensitivity of box girders to construction tolerances are discussed, and the lessons to be learned are presented. Finally, an unsuccessful attempt to monitor the long-term prestress of the Blanchetown Bridge using state-of-the-art optical fiber technology is discussed, including the reasons for its failure and possible improved future methodology.
Federal Highway Administration’s Horizontally Curved Steel Bridge Research Project: An Update
Authors: Duwadi Sheila Rimal , Grubb Michael A. , Yoo Chai H. , Hartmann Joseph
Published: April 2007

Since 1992, FHWA has had a major concentrated research project in the area of horizontally curved steel bridges, the objective of which is to conduct research to better define the fundamental behavior of such bridges. The project involves theoretical work leading to the development of refined predictor equations and verification of those equations through linear and nonlinear analysis and experimental testing of I-girder components. The overall experimental program involves testing of a series of full-scale bending and shear curved steel I-girder components and subsequently a full-size bridge. The development and refinement of predictor equations are summarized, and the work leading to the first series of experimental tests, which involve testing of full-scale bending components, is described.
Bridge Girders with Corrugated Webs
Authors: Elgaaly Mohamed , Seshadri Anand , Rodriquez Roberto , Ibrahim Sherif
Published: April 2007

In plate girders, the use of corrugated webs permits the use of thin web plates without stiffeners, which reduces the cost of beam fabrication and improves fatigue life. Experimental and analytical studies on the behavior of girders with corrugated webs were conducted that have led to design recommendations. For girders with corrugated webs subjected to shear, it was noted from the experimental as well as the analytical results that failure of the web occurs because of local or global shear buckling, which depends on the corrugation configuration. For girders with corrugated webs subjected to uniform bending, the failure was due to yielding and vertical buckling of the compression flange into the web. The test and analytical results indicate that the web offered negligible contribution to the moment-carrying capacity of the beam, and the ultimate moment capacity may be calculated on the basis of the flange yielding, ignoring any contribution from the web. The behavior of girders with corrugated webs under in-plane compressive edge loads applied directly on the top flange was investigated, and design recommendations are made. Tests to examine the behavior of girders with corrugated webs under repeated loads are few. The results from the available tests are reported and compared with the results from test on conventionally stiffened girders with flat webs.
Enhancing Steel Bridges Through AASHTO/NSBA Steel Bridge Collaboration
Authors: Medlock Ronald D. , Shirolé Arunprakash M.
Published: April 2007

AASHTO and the National Steel Bridge Alliance (NSBA) have a joint effort under way to enhance the quality and value of steel bridge design and construction in the United States. Under this effort, known as the AASHTO/NSBA Collaboration, representatives of the state departments of transportation, FHWA, steel and construction industries, design professionals, and academia have been working together. Issues such as how the Collaboration operates and how, as a comprehensive resource for steel bridges, it works to enhance the state of the art for steel bridges through implementation of technology and exchange of resources among its participants are discussed. Furthermore, standard practices, specifications, guidelines, and details that were developed as a consensus by the Collaboration for steel bridge design, fabrication, and erection are presented.
Low-Volume Road Bridge Alternative
Authors: Phares B. M. , Klaiber F. W. , Wipf T. J.
Published: April 2007

Recent reports indicate that a significant number of the nation’s bridges are either structurally deficient or functionally obsolete. A large number of these bridges are on the secondary road system and fall under the jurisdiction of county engineers with limited budgets and engineering staff. In response to this problem, a bridge replacement system was developed for simple span bridges with minimal to no skew that county engineers can design and build with limited resources. The bridge system involves fabrication of precast units consisting of two steel beams connected with a thin reinforced concrete deck. The precast deck thickness is limited to reduce the weight of the units so that they can be fabricated at one site and then easily transported to the bridge site. Multiple units are then connected on site to give the desired width of bridge, after which a reinforced cast-in-place concrete deck is placed over the entire bridge. Development of the design methodology for the steel beam precast unit bridge consisted of four phases. During the initial phase, small-scale bridge components and a full-scale model bridge were constructed and tested in the Iowa State University Structural Engineering Laboratory. These specimens were tested under a variety of loading configurations under service and ultimate loads. After completion of the laboratory testing, finite-element models of the laboratory bridge were developed and validated with data collected during the first phase. The validated finite-element model was then used to extrapolate analyses of common bridge configurations. The results of the analytical investigation were then combined with classic bridge engineering principles into a design methodology that is easy to use and understand. Although it is not discussed in detail, a demonstration project in which this concept was used has recently been completed and tested.
Structural Identification of a Long-Span Truss Bridge
Authors: Aktan A. , Grimmelsman K. A. , Barrish R. A. , Catbas F. N. , Tsikos C. J.
Published: April 2007

An ongoing research project involving structural identification of the Commodore Barry Bridge, a major long-span truss bridge over the Delaware River, is described. Structural identification is an approach in which a constructed facility and its loading environment are objectively characterized by field observations, measurements, and controlled experiments in conjunction with an analytical model. This process is a necessary precursor to performing health monitoring of the bridge. Long-span bridges have attributes that make utilization of experimental and analytical techniques on them quite different than for short-span bridges. The concept of structural identification and the methods used in applying it to a long-span bridge are presented and discussed. The structural characteristics of the bridge are described and conceptualized. Development of the three-dimensional analytical model and the model characteristics are summarized. Static and dynamic analyses are conducted to help locate anomalies and errors in the model. The experimental techniques necessary for structural identification of a long-span bridge are defined. A limited-scale health-monitoring system, which integrates operational data with structural performance and loading environment data, was designed and installed on the bridge. Mechanical and electrical characteristics of the monitor system and issues related to management of the data from this system are discussed. The monitoring system currently has over 80 channels of different sensor types collecting various data from the bridge. In addition, data from the system can be viewed from a remote location in real time.
The Once and Future Steel Bridge
Authors: Kulicki John M.
Published: April 2007

Some of the highlights of steel bridge design and construction during the 20th century are presented, and some thoughts for the near-term future of steel bridges are developed on the basis of the emergence of new materials and design processes. The “future-oriented” portions of the paper are intended to summarize research during the last decade of the 20th century dealing with the implementation of improved steels. As will be seen, the world community appears to be developing several of the same general concepts for future applications. Some of the ideas presented are speculative at this time, but it will be shown that commercialization is already under way. Finally, some thoughts on needed future developments in specification and design focus are considered.
New Trends in Prestressed Concrete Bridges
Authors: Virlogeux Michel
Published: April 2007

An overview of the recent evolution in the design and construction of prestressed concrete bridges worldwide is provided. Several major trends are evidenced. Certainly those trends that have had greater influences on the industry because of their wide applications are the development of external prestressing, which is now systematically used in some countries for medium-span bridges; the emergence of high-performance concrete, which extends the possibilities at the same time as it improves the durability of concrete structures; and the more frequent association of steel and concrete for composite bridges of different types and composite elements in bridges, allowing the construction of many innovative structures. For more specific applications, cable-stayed bridges, for which interesting developments have been seen in the last 10 years, and the more extensive use of heavy prefabrication in large projects, with elements up to several thousands of metric tons, are also described. Bridge architecture is also discussed in terms of the fact that good structural designs can produce elegant prestressed concrete bridges.
Reliability-Based Criteria for Load and Resistance Factor Design Code for Wood Bridges
Authors: Eamon Chris , Nowak Andrzej S. , Ritter Michael A. , Murphy Joe
Published: April 2007

Recently AASHTO adopted a load and resistance factor design code for highway bridges. The new code provides a rational basis for the design of steel and concrete structures. However, the calibration was not done for wood bridges. Therefore, there is a need to fill this gap. The development of statistical models for wood bridge structures is discussed. Recent test results provided a considerable amount of new data for sawed wood and glulam components. Statistical methods provide a good tool for development of rational models for loads and resistance. Because of the random nature of load and resistance, reliability is a convenient measure of structural performance that also provides a rational basis for comparison of wood and other structural materials. The results of a recent project that led to development of rational design criteria for wood bridges are presented. The structural reliability of selected wooden bridges designed by the AASHTO codes are determined, and inadequacies in load distribution and material resistance in the current specifications are identified.
Evaluation and Field Load Testing of Timber Railroad Bridge
Authors: Wipf Terry J. , Ritter Michael A. , Wood Douglas L.
Published: April 2007

Several spans of a 60-year-old open-deck timber railroad bridge on the Southern Pacific Railroad Line (now the Union Pacific) in Southwest Texas were field tested. The tests were conducted with the sponsorship and cooperation of the Association of American Railroads to determine the vertical live load distribution characteristics of the superstructure. The bridge was originally constructed with Douglas-fir larch solid sawn stringers but was rehabilitated on several occasions to allow comparisons to be made with respect to different rehabilitation options, including the use of a helper stringer and the use of glued laminated timber (glulam) stringers. The test spans measured approximately 4.1 m (13.5 ft) center-to-center of supports and included two closely “packed” chords, each consisting of four timber stringers (one test span included an additional helper stringer added to one chord). One chord was made up of glulam timber and the other was made up of solid sawn timber. The bridge superstructure was generally in satisfactory condition, with some stringer horizontal splitting noted over the bents. The bents were in reasonably good condition, but chord bearing was uneven on bent caps. Static and dynamic deflection load test data were obtained using a special test train. The test results indicate that the glulam chord performed better than the older sawn stringer chord, even when a helper stringer was added. Individual stringers within a chord did not always share the load equally.
Two Test Level 4 Bridge Railing and Transition Systems for Transverse Timber Deck Bridges
Authors: Faller Ronald K. , Ritter Michael A. , Rosson Barry T. , Fowler Michael D. , Duwadi Sheila R.
Published: April 2007

The Midwest Roadside Safety Facility, in cooperation with the Forest Products Laboratory, which is part of the U.S. Department of Agriculture’s Forest Service, and FHWA, designed two bridge railing and approach guardrail transition systems for use on bridges with transverse glue-laminated timber decks. The bridge railing and transition systems were developed and crash tested for use on higher-service-level roadways and evaluated according to the Test Level 4 safety performance criteria presented in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. The first railing system was constructed with glulam timber components, whereas the second railing system was configured with steel hardware. Eight full-scale crash tests were performed, and the bridge railing and transition systems were acceptable according to current safety standards.
Life-Cycle Cost Analysis of a Low-Volume Road Bridge Alternative
Authors: Fagen M. E. , Phares B. M.
Published: April 2007

Life-cycle cost models offer engineers a means to evaluate the anticipated long-term economic performance of prospective design and construction alternatives. Traditionally, only initial investment costs and past experience were used to economically evaluate possible bridge designs. A more logical approach requires that all short- and long-term costs be considered in relation to project location, purpose, and performance specifications. The primary objective of life-cycle cost analysis is to evaluate the total ownership cost of all suitable alternatives. Recent reports indicate that a significant number of the nation’s bridges are either structurally deficient or functionally obsolete. In Iowa, a large portion of these types of bridges are on the secondary road system and fall under the jurisdiction of county engineers. Typically, Iowa county engineers have limited resources. In response to this, a bridge-replacement system was developed that county engineers can design and build with limited staff. The system, which is made up of precast (PC) double T units, involves the fabrication of PC units that consist of two steel beams connected by a thin concrete deck. To illustrate that this bridge system may be an economically viable bridge-replacement alternative for use on low-volume county roads, a life-cycle cost analysis was completed for an actual replacement-repair-rehabilitation project. Various alternatives were economically analyzed and compared with the steel beam PC unit bridge alternative. This analysis indicates that, when lower-cost salvaged steel beams and county work forces are used, the steel beam PC unit bridge can be a viable low-volume road bridge alternative.
Sidney Lanier Bridge, Georgia
Authors: Tang Man-Chung , Jang Dennis , Lee Hohsing
Published: April 2007

The existing Sidney Lanier Bridge crossing the Brunswick River near Brunswick, Georgia, has a lift span of 76.25 m (250 ft), which is deemed too small for the ships that visit the harbor today. The new Sidney Lanier Bridge is a replacement for the existing structure to ensure navigational safety. It will be 2372.9 m (7,780 ft) long with a 381.25-m (1,250-ft) cable-stayed center span, which has a vertical clearance of 56.425 m (185 ft) above the mean high water level. The new bridge will permit the passage of any ship known to exist in the world today. The total width of the bridge deck is 24.71 m (81 ft), which will accommodate two traffic lanes in each direction. The concrete deck girder consists of a concrete slab 27.94 cm (11 in.) thick supported by 1.525-m (5-ft) by 1.45-m (4.75-ft) concrete longitudinal girders at each edge and by transverse floor beams spaced at 8.29 m (27.17 ft). At the two pylons, the superstructure is free to move in the longitudinal direction and restrained in the vertical and transverse directions. The concrete deck is cast monolithically with the two end piers. Each concrete pylon carries two vertical planes of fan-shaped cables anchored to the edge girders.
Forced and Ambient Vibration Tests and Vibration Monitoring of Hakucho Suspension Bridge
Authors: Fujino Yozo , Abe Masato , Shibuya Hajime , Yanagihara Masato , Sato Masashi , Nakamura Shun-Ichi , Sakamoto Yoshifumi
Published: April 2007

Forced and ambient dynamic tests of the Hakucho Bridge were carried out to study the dynamic characteristics of this suspension bridge. Dense-array measurement was employed in order to capture not only natural frequencies and damping, but also the mode shapes of the bridge. The natural frequencies and mode shapes obtained from the forced and ambient vibration tests agreed well with those calculated by a three-dimensional finite element model. A new method that combines the random decrement method with the Ibrahim time domain method is proposed to systematically identify the natural frequencies, damping, and mode shapes. This method is successfully applied to ambient vibration data. It is shown that the natural frequency of the first vertical bending mode decreases noticeably as the wind speed increases. It is also shown that the shape of the first vertical bending mode changes slightly near the towers, depending on the wind velocity; this finding indicates that the change may be associated with friction in the bearings at the towers. Finally, application of the Global Positioning System to measure static displacement of the girder is explained.
Guideline for Evaluation of Scour at Bridges: Proposed ASCE Standard
Authors: Davis Stanley R. , Shea Conor , Pagan-Ortiz Jorge E.
Published: April 2007

The ASCE Water Resources Engineering Division Task Committee on Bridge Management for Scour Safety has prepared a draft ASCE standard entitled Guideline for the Evaluation of Scour at Bridges. The committee plans to submit the draft standard to ASCE for review in 2000. The guideline presents the views of committee members representing federal and state agencies, consultants, and universities with regard to recommended practices and procedures for the evaluation of scour at bridges. The guideline is generally consistent with previous publications on bridge scour evaluation published by AASHTO and FHWA. However, it contains new guidance on a number of issues dealing with the subject of scour evaluation. The guideline stresses the need for an inter-disciplinary team of structural, hydraulic, and geotechnical engineers to work together in the design of bridge foundations.
Prediction of Scour at Bridge Pier Foundations Founded on Rock and Other Earth Materials
Authors: Annandale George W.
Published: April 2007

The erodibility index method, which can be used to predict scour thresholds for rock and other earth materials, is described. The scour threshold is defined by a relationship between the erodibility index and stream power that is based on analysis of field and laboratory data. An explanation of how the method is applied to calculate scour depth is presented, followed by a case study to calculate bridge pier scour.
Maine Builds Longest-Span Precast Segmental Bridge with Unique Design-Build Selection Process
Authors: Phipps Alan R.
Published: April 2007

The Bath-Woolwich Bridge in Maine will have the longest precast balanced cantilever concrete segmental span in America—128 m (420 ft)—when completed. It carries U.S. Route 1 over the Kennebec River between the city of Bath and the town of Woolwich. The bridge is scheduled for completion in July 2000. The bridge designed by the design-build team has a total length of 906 m, with 12 spans at lengths of 56-56-56-80-128-116-101-101-62-50-50-50 m. The 56- and 50-m end spans are cast-in-place concrete box girders. The center spans are precast concrete segmental erected in balanced cantilever. The two-cell box girder superstructure segments vary in depth from 6 m at the piers to 2.8 m at midspan. The Maine Department of Transportation developed a unique procedure to select a design-build team for this project, which included prequalifying four design-build teams to submit proposals; scoring of technical proposals by a diverse group of 19 individuals; and combining scores with price by dividing the price by the score, with the lowest price per score point winning. The Maine Department of Transportation’s design-build selection process assured Maine of the best value for this important project.
Bridge-Condition Assessment and Load Rating Using Nondestructive Evaluation Methods
Authors: Chajes Michael J. , Shenton Harry W. , O’Shea Dennis
Published: April 2007

In most cases, bridge-condition assessment is made according to visual inspections, and bridge-load ratings are determined with fairly simple analytical methods and without site-specific, live-load, bridge-response data. As a result, estimates of bridge load-carrying capacity are often quite conservative. The increased weight of today’s trucks compared with design loads that are used for older bridges, combined with the continued aging and deterioration of our nation’s bridges, has resulted in a significant number of them being classified as structurally deficient. Reliable condition assessments are essential to ensure the safety of the traveling public. Furthermore, because load-carrying capacity is often used to prioritize bridges for repair, rehabilitation, and replacement, and because funds for these actions are limited, it is more important than ever that these estimates be as accurate as possible. To achieve this goal, researchers at the University of Delaware have been working with engineers at the Delaware Department of Transportation to develop methods for improving the accuracy of bridge-capacity evaluation through use of nondestructive evaluation techniques. Among the methods currently used are diagnostic load testing and in-service monitoring. These methods are described, and a detailed case study that illustrates the applied methodologies is discussed.
Load Testing to Collapse Limit State of Barr Creek Bridge
Authors: Haritos Nicholas , Hira Anil , Mendis Priyan , Heywood Rob , Giufre Armando
Published: April 2007

VicRoads, the road authority for the state of Victoria, Australia, has been undertaking extensive research into the load capacity and performance of cast-in-place reinforced concrete flat slab bridges. One of the key objectives of this research is the development of analytical tools that can be used to better determine the performance of these bridges under loadings to the elastic limit and subsequently to failure. The 59-year-old Barr Creek Bridge, a flat slab bridge of four short continuous spans over column piers, was made available to VicRoads in aid of this research. The static testing program executed on this bridge was therefore aimed at providing a comprehensive set of measurements of its response to serviceability level loadings and beyond. This test program was preceded by the performance of a dynamic test (a simplified experimental modal analysis using vehicular excitation) to establish basic structural properties of the bridge (effective flexural rigidity, EI) and the influence of the abutment supports from identification of its dynamic modal characteristics. The dynamic test results enabled a reliably tuned finite element model of the bridge in its in-service condition to be produced for use in conjunction with the static testing program. The results of the static testing program compared well with finite element modeling predictions in both the elastic range (serviceability loadings) and the nonlinear range (load levels taken to incipient collapse). Observed collapse failure modes and corresponding collapse load levels were also found to be predicted well using yield line theory.
Diagnostic Load Tests of a Prestressed Concrete Bridge Damaged by Overheight Vehicle Impact
Authors: Russo Francesco M. , Wipf Terry J. , Klaiber F. Wayne
Published: April 2007

A series of diagnostic load tests performed on two prestressed concrete bridges located in western Iowa are discussed. The bridges are dual prestressed concrete I-beam structures. In June 1996, an overheight vehicle struck the westbound structure and caused significant loss of section and cracking. As a result of the severity of the damage and because of concerns about the remaining capacity and long-term durability of the damaged beams, the Iowa Department of Transportation decided to remove the two most severely damaged beams. The diagnostic load-testing portion of the research program consisted of positioning test vehicles of known weight at predetermined locations along the deck of the damaged westbound and undamaged eastbound bridge. Single-and dual-truck tests were conducted on each bridge. Following replacement of the damaged beams in the westbound structure, additional tests were conducted. The results of these three load tests are compared to determine the effect of the localized beam damage on the overall live load distribution pattern in the bridge. The objective of this research is to determine the effects of damage on the load distribution and the remaining strength of damaged prestressed concrete bridges. Noticeable differences in response were detected in the westbound and eastbound bridges before beam replacement, with the difference essentially disappearing after the repair of the westbound bridge. The research project also involved model bridge testing, along with the repair of the beams that were removed from service and those that were intentionally damaged in the laboratory. The project is now complete.
Durability of Composite Reinforcement for Timber Bridges
Authors: Battles Eoin P. , Dagher Habib J. , Abdel-Magid Beckry
Published: April 2007

Fiber-reinforced polymeric (FRP) composites are materials that are increasing in use in civil engineering applications. Despite the excellent mechanical properties and corrosion resistance offered by these organic matrix materials, their susceptibility to the synergistic effects of stress and environmental weathering hinders their widespread acceptance in civil engineering. The durability of a specific formulation of wood-compatible, pultruded, E-glass–phenolic composite is characterized. This composite is unique because its layered structure and void content make it compatible with standard structural wood adhesives. The durability of this wood-compatible FRP reinforcement cannot be directly determined from published work on the durability of E-glass composites because of its unique design. A durability test matrix was generated according to specifications and test standards from the International Conference of Building Officials Evaluation Service, Inc., and from the California Department of Transportation. Physical and mechanical properties that were used as indicators of degradation mechanisms and that applied to the bridge environment included tensile behavior, interlaminar shear strength, void content, and glass-transition temperature. Environmental testing involved exposure to various storage media, such as moisture, saline solutions, and calcium carbonate, followed by mechanical testing. Other exposure treatments included dry heat, cyclic freeze-thaw, accelerated weathering, and natural weathering. In addition to the strength-retention determination after environmental conditioning, control and exposed specimens were examined visually with optical and scanning electron microscopy to determine surface changes and their effect on failure and fracture modes.
Control of Live Load on Bridges
Authors: Nowak Andrzej S. , Eom Junsik , Sanli Ahmet
Published: April 2007

Application of field testing for an efficient evaluation and control of live-load effects on bridges is described. A system is considered that involves monitoring of various parameters, including vehicle weight, dynamic load component, and load effects (moment, shear force, stress, strain) in bridge components, and verification of the minimum load-carrying capacity of the bridge. Therefore, an important part of the study is development of a procedure for measuring live-load spectra on bridges. Truck weight, including gross vehicle weight, axle loads, and spacing, is measured to determine the statistical parameters of the actual live load. Strain and stress are measured in various components of girder bridges to determine component-specific load. Minimum load-carrying capacity is verified by proof load tests. It has been confirmed that live-load effects are strongly site specific and component specific. The measured strains were relatively low and considerably lower than predicted by analysis. Dynamic load factor decreases with increasing static load effect. For fully loaded trucks, it is lower than the code-specified value. Girder distribution factors observed in the tests are also lower than the values specified by the design code. The proof load test results indicated that the structural response is linear with the absolute value of measured strain considerably lower than expected. Field tests confirmed that the tested bridges are adequate to carry normal truck traffic.
Simplified Load Distribution for Vehicles with Nonstandard Axle Gauges
Authors: Goodrich Brian L. , Puckett Jay A.
Published: April 2007

Several simplified methods have been developed to determine the live-load distribution factors for overweight vehicles on slab-on-girder bridges; however, these methods were developed for vehicles with standard axles. Many vehicles exist with nonstandard axle configurations, such as two-wheel axles that are wider than 6 ft (1.83 m) and four-wheel axles with wheels that are evenly or unevenly spaced. For these vehicles, a rigorous analysis is generally desired but is often deemed uneconomical. Therefore, a simplified method should be an asset to the bridge community and the trucking industry. A simplified method for determining live-load distribution factors for vehicles with nonstandard axle configurations is presented. Distribution factor formulas for moment and shear in interior and exterior girders are given. These formulas account for the transverse axle configurations that compose a vehicle. Several two- and four-wheel axle configurations are considered. The distribution factor formulas for slab-on-girder bridges presented in the AASHTO LRFD Bridge Design Specifications are incorporated into the proposed simplified method. The simplified method formulas were developed to approximate the results from a rigorous finite strip method. Comparisons are presented as verification of the accuracy of the simplified method. The simplified method results are usually conservative and correlate reasonably well with the rigorous results. In general, simplified methods worked better for interior girders than for exterior girders, and moment was better predicted than shear.
Implementation of High Strength-High Performance Concrete in Two Texas Highway Overpass Structures: Critical Comparison
Authors: Gross Shawn P. , Burns Ned H.
Published: April 2007

Two prestressed concrete highway overpass structures, the Louetta Road Overpass and the North Concho River Overpass, were recently constructed in Texas. The structures were built with high strength–high performance concrete (HS-HPC) with nominal strengths of up to 61 MPa (8,800 psi) at release of prestress and 97 MPa (14,000 psi) at 56 days. The use of HS-HPC, in addition to the use of prestressing strands that measured 15 mm (0.6 in.) in diameter, allowed for the accommodation of longer spans and larger girder spacing than are typical for similar designs with conventional concrete. As a result, the structural designs were extremely efficient when compared with the conventional designs. In addition, use of HPC in bridge decks is expected to result in reduced maintenance requirements and a longer service life for each bridge, thereby reducing life-cycle costs. Although HPC is used in both structures to increase structural efficiency and reduce projected life-cycle costs, the structures are quite different and represent unique applications of HPC. Both structures were instrumented as part of an extensive research program, and data were collected on prestress losses, camber and deflections, concrete strains, and concrete temperatures in several actual bridge girders. These data, in combination with observations regarding practical issues such as fabrication, handling, and overall construction costs, are used to compare and contrast the use of HPC in the two bridges. A brief set of recommendations for the use of HPC in future highway bridge projects is also presented.
Design of the Cross Florida Greenway Land Bridge Over I-75 Using Precast Florida U-Beams
Authors: Duggar Charles F. , Corven John A.
Published: April 2007

The Cross Florida Greenway is a multiuse trail that bisects the central region of Florida, an area that was originally set aside for the Cross Florida Barge Canal. After Congress deauthorized the barge canal, the Cross Florida Greenway State Recreational Area was created, and the canal property was turned over to the state. Interstate 75 interrupts the Cross Florida Greenway in Marion County in a north-to-south direction for a distance of about 1829 m (6,000 ft) along the I-75 centerline. No bridges or underpass structures currently exist that connect both sides of the Greenway. Through several years of study, the Florida Department of Transportation and the Florida Department of Environmental Protection developed a land bridge concept for traversing the I-75 right-of-way while continuing the Greenway characteristics across the bridge. The land bridge concept is used internationally and is conducive to wildlife usage. The structure will be 16 m (52.5 ft) wide. It will provide a stabilized section along the center portion of the bridge for bicyclists, pedestrians, and equestrians, as well as earthen berms to support plantings along the outside edges of the structure. The key unique structural elements of the bridge, which is the first precast U-beam superstructure to be constructed in the state, include use of open triangular-shaped median piers, integral abutments, and geosynthetic-reinforced, vegetated approach slopes. The project is expected to attract national and international attention because it may be the first of its kind in the United States and because of its location along the heavily traveled I-75.
Bridge Inspection Decision Making Based on Sequential Hypothesis Testing Methods
Authors: Madanat Samer , Lin Da-Jie
Published: April 2007

A bridge management system (BMS) is a decision support system used by a highway agency in selecting appropriate maintenance and rehabilitation (M&R) activities and in allocating available resources effectively among facilities. BMS decision making is based on the condition of bridge components, their predicted deterioration, and the cost and effectiveness of M&R activities. Traditionally, bridge condition assessments have relied mainly on human inspectors; their results have generally been qualitative and subjective. More detailed inspections requiring some degree of destruction of the bridge, like drilling the deck to inspect for chloride contamination, have also been used. With recent technological developments, methods have been developed to evaluate the condition of bridge structures in a quantitative and objective manner. Associated with the use of these technologies are questions relating to inspection frequency, sample size, and the integration of data from the various technologies and human inspections. The application of a statistical decision-making method, sequential hypothesis testing, to these questions is presented. The mathematical formulation of the sequential hypothesis testing model, the derivation of optimal inspection policies, and the implementation of these policies in the context of bridge component inspection are discussed. A parametric analysis illustrates the sensitivity of the method to the cost structure of the problem, the precision of the technologies used, and the historical information or expert judgment regarding the condition of bridge components.
Cost-Effectiveness of Crack Sealing Materials and Techniques for Asphalt Pavements
Authors: Johnson David R. , Freeman Reed B. , Stevenson James R.
Published: April 2007

Sealing or filling cracked asphalt pavements to prevent the intrusion of water into the pavement structure has long been an accepted practice of the Montana Department of Transportation. Attempts were made to establish the most economical and effective method of sealing pavement cracks for Montana and to better determine crack sealing’s role within Montana’s pavement management system (PvMS). Four experimental test sites were constructed within crack-sealing projects. The test sites included combinations of nine sealant materials and six sealing techniques. Monitoring of the test sites includes visual inspections (for all of the sites) and nondestructive structural readings and surface distress identification under Montana’s PvMS (for one test location). One expectation of the inspections is an estimation of crack sealing’s useful life. Information on project history and project methodology, including the methods used for evaluating the performance of sealed cracks, is presented. Interim conclusions are presented, most of which have been obtained from the two test sites that have been in service for 3 years. Similar performance has been observed for all materials with ASTM D5329 cone penetrations in excess of 90. In general, routing of transverse cracks improved the performance of the sealants. Routing did not appear necessary for centerline longitudinal cracks. Observations from the first year of service for the most recent installation are noted. Notably, router operators appear to prefer the shallow reservoir configuration over square reservoirs. The highest failure rates occur during the coldest period of the year, and much of this distress “heals” after exposure to the summer heat.