bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Cross-Frame Connection Details for Steel Bridges with Skewed Supports
Authors: Quadrato Craig , Battistini Anthony , Frank Karl , Helwig Todd , Engelhardt Michael
Published: December 2010

Cross frames and diaphragms play an important role in stabilizing straight steel girders. Commonly used connections between these braces and the steel girders can introduce flexibility, which can have detrimental effects on the bracing behavior, particularly on bridges with skewed supports. This paper documents a research investigation sponsored by the Texas Department of Transportation on connection details for stability bracing in steel bridges with skewed supports. One goal of the study is to propose an improved connection method. One detail being investigated is a round half-pipe stiffener connected to the top and bottom flanges. The round stiffener allows perpendicular connections to the cross-frame connection tab, regardless of the skew angle. Additionally, there are substantial structural improvements when the tubular stiffener is used. Fastening the tubular stiffener to the flanges provides a significant increase in the warping stiffness of the cross section at the support. Finite element modeling has predicted increases in buckling capacity as high as 80% because of this warping restraint. As a result, in the vicinity of the half-pipe stiffener, the brace spacing can likely be increased. The increased spacing in these regions will simplify fabrication and reduce the number of fatigue-sensitive details in the congested support region. This paper describes a method to calculate the increase in girder buckling capacity due to the warping restraint provided by the pipe stiffener as well as the size of pipe for a required buckling capacity or unbraced length with design tools already widely used by structural engineers.
Load Testing a Double-Composite Steel Box Girder Bridge
Authors: Stroh Steven L. , Sen Rajan , Ansley Marcus
Published: December 2010

This paper describes the load testing and results of a full-scale double-composite steel box bridge girder tested in a cooperative research study by the University of South Florida, the URS Corporation, and the Florida Department of Transportation to develop design rules for double-composite steel bridges. The section modeled is a 53-ft-long, 4-ft-deep trapezoidal double-composite steel box girder that replicates the negative moment region of a continuous steel box girder bridge. The specimen was tested to evaluate fatigue, service, and ultimate design provisions. After 5.6 million cycles of fatigue loading, there was a 17% loss in stiffness. The service tests showed that 1% reinforcement for the top slab was adequate. The specimen failed because of crushing of the bottom concrete slab and buckling of the bottom steel flange in the final service test. Finite element analysis was used to simulate the failure and showed that the bottom flange buckles at relatively low loads, but because of composite action with concrete at shear stud locations it can still effectively carry additional compressive load until the bottom flange yields from plastic buckling. The concrete bottom slab carries all additional load until it crushes. Supplementary provisions are proposed for designing double-composite members. They limit the maximum compressive stress in the bottom slab to 0.6 fc′ and set a requirement for the location of the neutral axis to ensure ductility. Because of the strain limit on the concrete bottom slab, it may not be possible to achieve net section plastic capacity.
User-Friendly Finite Element Analysis Software for Analysis of Curved-Steel I-Girder Bridges
Authors: Stith Jason , Petruzzi Brian , Kim Hyeong Jun , Helwig Todd , Williamson Eric , Frank Karl , Engelhardt Michael
Published: December 2010

The design of curved I-girders is complicated because of the many performance stages that must be evaluated, including erection, construction, and in service. Evaluation of girder stability during early stages of construction is particularly complicated because of the limited presence of bracing. In addition to stability issues during girder lifting, guidelines for the necessity of shore towers during erection are not available. The Texas Department of Transportation funded a research project to investigate girder stability during early stages of construction. Results from this project will be used to develop guidelines for evaluating girder stability during early construction stages as well as to proportion the girder cross sections for safe and economic construction. The research includes field monitoring, a parametric study using finite element analysis (FEA), and development of user-friendly finite element analytic software that will serve as a tool for designers. This paper summarizes the development of an analysis tool as part of the UT Bridge research project, which provides engineers with a three-dimensional FEA of plate girder bridges during erection and concrete deck placement. The software provides a user-friendly preprocessor to guide input and a three-dimensional visual postprocessor output. UT Bridge performs a linear elastic or eigenvalue buckling analysis for a curved or straight bridge's defined construction procedure and is available free from the website of the University of Texas at Austin Ferguson Structural Engineering Laboratory.
Experience of the Texas Department of Transportation in Repair of Steel Bridge Fatigue
Authors: Zhao Yuan , Yang Dingyi , Freeby Gregg A. , Holt John M. , Kowalik Alan , Flournoy Leon B. , Rummel Thomas E. , Pruski Kevin , Wolf Lloyd M.
Published: December 2010

Although steel bridges of the Texas Department of Transportation (DOT) generally exhibit satisfactory fatigue performance, several structures have developed fatigue cracks at various welded attachments because of the previous use of fatigue-prone details. These bridges were typically constructed between the 1950s and 1980s, before the knowledge base of steel bridge fatigue and fracture was well established. Some bridges were not designed to carry the increasing traffic volume experienced today. Cracks occurred primarily at details that were not sufficiently addressed in the previous AASHTO design specifications, in particular at locations subjected to out-of-plane distortion. This paper provides an overview of Texas DOT practice in the repair of steel bridge fatigue cracking, including Texas DOT–sponsored research studies and their successful implementation in bridge rehabilitation. Case studies presented in this paper include the Fair Park bridges in Dallas, the IH-20 bridges in Midland County, the SH-225 bridges at Sims Bayou, the Intracoastal Canal Bridge in Jefferson County, and the IH-345 bridges in Dallas.
Calibration of Load and Resistance Factor Rating Methodology in New York State
Authors: Ghosn Michel , Sivakumar Bala , Miao Feng
Published: December 2010

In 2003, AASHTO adopted the Guide Manual for Condition Evaluation and Load and Resistance Factor Rating (LRFR) of Highway Bridges, which was calibrated to provide uniform reliability levels represented by a target reliability index β = 3.5 for inventory ratings and β = 2.5 for operating ratings. These target values were selected to remain consistent with the AASHTO load and resistance factor bridge design specifications and provide average reliability levels similar to those of the allowable stress operating ratings and load factor ratings (LFR). The calibration process was based on a generic live load database considered to be representative of truck weight and traffic spectra at typical U.S. bridge sites. Recognizing the limitations of this generic data set, the LRFR provides sufficient flexibility and allows state agencies to adjust the LRFR load factors on the basis of their individual conditions and site-specific or state-specific information. A reliability-based procedure was developed for calibrating a state-specific NYS-LRFR that would reflect current bridge loading conditions in the state of New York, including the intensity and shape of the truck weight spectra as well as measured truck traffic data. The proposed calibration would lead to bridge ratings consistent with the current practice of the New York State Department of Transportation and provide uniform and consistent levels of bridge safety and reliability. The methodology can be easily adapted by other states on the basis of their unique truck loads and traffic conditions.
Structure Identification and Load Capacity Rating of Veteran's Memorial Curved Steel Box Girder Bridge
Authors: Huang Dongzhou
Published: December 2010

Veteran's Memorial Bridge is a curved steel box girder bridge located in Tallahassee, Florida. A structural system identification procedure through field test and analysis was developed for the bridge. A bridge capacity rating is included. The tests include a bending test, a shear test, and a structural system test. Test and analytical results indicate (a) nearly all concrete areas of the bridge deck and barriers are composite with the steel box girders and effectively resist both bending and shear forces, (b) the shear capacity at the end abutment is much higher than that predicted by current AASHTO Guide Specifications for Horizontally Curved Highway Bridges, and (c) the bridge behaves predictably. On the basis of test and theoretical results, a reliable analytic model was developed. Load ratings for 13 types of trucks permitted in Florida were performed according to the identified analytical model. Rating results show that the operating rating loads evaluated on the basis of the identified model are greater by approximately 43% than those obtained on the basis of current AASHTO guide specifications. The operating rating factor for the HS20–44 vehicle based on the identified model is 38% greater than that obtained in 1997. The rating procedures presented are instructive and can be used in bridge load-rating activities.
Full-Scale Destructive Bridge Test Allows Prediction of Ultimate Capacity
Authors: Chajes Michael J. , McConnell Jennifer Righman , Shenton Harry W. , Michaud Kervin , Ross Justin , Russo Chris
Published: December 2010

Contemporary bridge design is generally based on designing individual members for the maximum force effect that each member may experience. This approach ignores the system-level interactions of these individual members, which may greatly increase the ultimate strength of the complete structure. In an attempt to understand better the load redistribution mechanisms that lead to this increase in ultimate strength, the destructive testing of a skewed steel I-girder bridge was planned and executed. However, because of the enormous system-level reserve capacity of the structure, the structure generally responded elastically, despite being loaded with the equivalent of 17 HS-20 design vehicles. Thus, a validated finite element analysis (FEA) approach was used to predict the ultimate capacity of this structure and to analyze the force redistribution as the bridge's elastic limit was exceeded. The FEA results predicted that the equivalent of 41 HS-20 vehicles was needed to plastify fully the four girders of the subject bridge and show the significant amount of yielding that occurs in the cross-frames when the ultimate capacity of the girders is achieved.
Experimental Evaluation of In-Span Hinge Details in Reinforced Concrete Box Girder Bridges
Authors: Hube M. A. , Mosalam K. M.
Published: December 2010

During the past three decades, considerable research efforts have sought to improve the seismic design of California highway bridges. However, the in-span hinge (ISH) regions of concrete box girders have not been studied adequately. ISHs are classified as disturbed regions caused by the concentrated bearing loads and the possible existence of utility and maintenance openings, which induce a complicated three-dimensional stress state. Nevertheless, ISHs are commonly designed as two-dimensional short cantilevers following standard procedures. These designs typically lead to congested reinforcement causing constructability concerns from practical and economical aspects. The behavior and the strength of ISHs were assessed with five one-third–scale specimens that were tested at the University of California, Berkeley. The first two specimens represent the as-built conditions of typical ISHs of California box girder bridges. These specimens were detailed identically, but with one, utility openings were considered to study their influence on the behavior and strength of ISHs. The typical ISH characteristics were obtained from a survey of eight projects in California. The other three specimens represent new ISH designs, aimed at reducing the steel congestion and improving the structural performance of ISHs. Findings from the experimental results revealed that as-built ISHs fail with a combination of three failure modes: (a) beam shear, (b) two-dimensional strut and tie, and (c) punching shear. On the basis of the observed failure modes, it was concluded that the current ISH design could be optimized to reduce steel congestion and improve constructability.
Experimental Study of Reversed Cyclic Loading Test for Pile-to-Slab Bridge Connections
Authors: Ayoub Mohamed I. , Sanders David H.
Published: December 2010

Slab bridge connections have not been as extensively discussed and tested as column-to-box-girder bridge connections have been. In a typical bridge configuration, multiple piles extend into the slab along the bent centerline. An interior pile-to-slab connection performs like a T-connection. Two full-scale, 24-in.-diameter pile-to-slab connections were tested. The first was designed on the basis of California Department of Transportation (Caltrans) criteria, which are based on box girder connection details. Current Caltrans standard pile connection details do not apply to 24-in.-diameter piles. The specimen had a flat slab and showed failure in the slab instead of the pile. The first problem with current joint design methods was the lack of longitudinal reinforcement in the slab near the pile. A second problem was the absence of any vertical stirrups or J-dowels into the joint to transfer force from the longitudinal reinforcement of the pile to the top mat of the slab reinforcement. The third problem was the limited number of vertical stirrups, because the stirrups were too far from the pile. A second T-connection specimen was tested with modified details. The new design specimen showed very good performance compared with the first specimen. The new details were developed using the strut-and-tie model and examining the specimen performance.
Comparative Analysis of Design Codes for Timber Bridges in Canada, the United States, and Europe
Authors: Wacker James P. , (Scott)Groenier James
Published: December 2010

The United States recently completed its transition from the allowable stress design code to the load and resistance factor design (LRFD) reliability-based code for the design of most highway bridges. For an international perspective on the LRFD-based bridge codes, a comparative analysis is presented: a study addressed national codes of the United States, Canada, and Europe. The study focused on codes related to timber bridges and involved the following parameters: organization format, superstructure types, loads, materials, design for bending, design for shear, deflection criteria, and durability requirements. The investigation found many similarities and some distinctive differences between the three bridge codes. Although the United States and Canada have different design load configurations, these result in similar bending moments and shear effects over a typical span range. However, the design load configuration in the European code produces bending moment and shear effects that are two to three times greater than the U.S. and Canadian levels. The comparative design of a glulam girder bridge revealed that the smallest beam size was required by the Canadian code and the largest was required by the European code.
Jet Grouting to Provide Scour Protection
Authors: Carvajal Gabriel , Arora Sunil
Published: December 2010

The San Juan Creek Bridge near Antonio Parkway in Orange County, California, was slated for improvement as part of the widening of Ortega Highway (SR-74) into four lanes to relieve traffic congestion and accommodate planned growth in the region. To provide scour protection for the existing and new bridge piles, soilcrete (soil–cement) columns were constructed around the pile locations by using jet grouting, an in situ ground modification system. The Super Jet system of jet grouting was used. Headroom under the existing bridge was 10 ft. One hundred fifty-eight overlapping soilcrete columns were constructed around the planned piles. These columns were installed to the top of the San Juan Capistrano formation or to the designed scour depth. The specified minimum unconfined compressive strength (UCS) was 600 psi, and the required average strength was 750 psi. A test section was used to confirm the geometry and strength of the soilcrete columns. UCS tests were performed on wet grab samples and core samples. State-of-the-art quality control measures were implemented throughout the project. The design, construction, and quality control measures undertaken by the geotechnical contractor are discussed.
Multiple Complementary Nondestructive Evaluation Technologies for Condition Assessment of Concrete Bridge Decks
Authors: Gucunski Nenad , Romero Francisco , Kruschwitz Sabine , Feldmann Ruediger , Abu-Hawash Ahmad , Dunn Mark
Published: December 2010

Reinforced concrete bridge decks are exposed to several types of deterioration processes: corrosion, alkali–silica reaction, carbonation, shrinkage, freeze–thaw actions, and so forth. The most commonly found problem is corrosion-induced bridge deck delamination. Previous studies have shown that surveys of bridges relying on a single nondestructive evaluation (NDE) technology provide limited information about the condition of concrete bridge decks. To overcome limitations of individual technologies, a complementary approach using several NDE technologies should be used in bridge deck evaluation. The presented approach utilizes a suite of NDE technologies, namely, impact echo (IE), ultrasonic surface waves (USW), ground-penetrating radar (GPR), half-cell potential (HCP), and electrical resistivity (ER). The suite of NDE technologies was implemented in the evaluation of bridge decks on nine bridges in Iowa. The NDE was complemented by ground-truth measurements on the cores extracted from all nine bridge decks. Condition assessment with the five NDE technologies has clearly shown their advantages and limitations. For example, the GPR surveys provided assessment of concrete deterioration at relatively high speeds of data collection. In contrast, IE provided high accuracy in detection and characterization of delaminations in the deck but at a lower testing speed. HCP and ER tests provided assessment of the likelihood of corrosion, whereas the USW test provided accurate assessment of the effects of deterioration processes and defects on mechanical properties, primarily the degradation of the elastic modulus. Most important, the survey showed the advantages of use of multimodal NDE surveys in the comprehensiveness of condition assessment of concrete bridge decks.
Ultimate Limit State of Deep-Corrugated Large-Span Box Culvert
Authors: Brachman R. W. I. , Moore I. D. , Mak A. C.
Published: December 2010

Limit state design requires independent assessment of both load and resistance. Although much is known about the live and dead loads that may act on box culverts, there is no known measurement of the resistance (or capacity) at the ultimate limit state. The objective of this study is to present results from a full-scale experiment conducted on a buried, deep-corrugated, large-span box culvert under controlled laboratory conditions—the first conducted to its ultimate limit state. The box culvert had a 2.4-m rise and 10-m span (7.9 × 32.8 ft) and was fabricated from steel plate 6 mm thick with corrugations 150 mm deep at a 400-mm pitch (0.24 × 6 × 16 in.). The box culvert was backfilled to a minimum cover depth of 0.45 m (1.5 ft) with densely compacted well-graded sand and gravel. Tandem-axle loading was then applied by an actuator until an ultimate limit state was attained. The ultimate limit state of the box culvert involved the formation of plastic hinges at the crown and shoulders at a total applied force of 1,100 kN (250 kips). The force required to reach the ultimate limit state was 1.8 times larger than the factored design tandem-axle load from the AASHTO bridge design specifications. Similarly, the factored resistance at the ultimate limit state was 1.7 times larger than the factored CL-625-ONT tandem-axle load from the Canadian highway bridge design code.
Seismic Analysis of Integral Abutment Bridge in Tennessee, Including Soil–Structure Interaction
Authors: Vasheghani-Farahani Reza , Zhao Qiuhong , Burdette Edwin G.
Published: December 2010

Integral abutment bridges are jointless bridges in which the deck is continuous and connected monolithically with the abutment walls, supported typically by a single row of piles. Part of the research results from an ongoing project focus on the effects of two major parameters on the seismic behavior of an integral abutment bridge in Tennessee. The soil–structure interaction around the piles and in back of the abutments is considered, namely, clay stiffness (medium versus hard) around the piles and level of compaction (loose versus dense) of the abutment wall backfilling. Modal and nonlinear time-history analyses were performed on a three-dimensional detailed bridge model with the commercial software SAP2000. These analyses clearly showed that (a) compacting the backfilling of the abutment wall will increase the dominant bridge longitudinal natural frequency considerably more than increasing the foundation clay stiffness; (b) the maximum deflection and bending moment in the piles under seismic loading will occur at the pile–abutment interface; (c) under seismic loading, densely compacted backfilling of the abutment wall is generally recommended because it will reduce the pile moments considerably, the pile deflection, the abutment displacement, and the moments in the steel girder, except for girder moments at the abutments when the piles are in medium clay; and (d) under seismic loading, when the abutment backfilling is loosely compacted, steel girder moments at the abutments will increase considerably with the foundation clay stiffness.
Seismic Retrofit of California's Auburn–Foresthill Bridge
Authors: Reno Mark L. , Pohll Martin N.
Published: December 2010

The Auburn–Foresthill Bridge in California was built by the Bureau of Reclamation in 1973. The 2,428-ft-long bridge is made up of three spans—639 ft, 862 ft, 639 ft—and sits 730 ft above the north fork of the American River; it would have spanned the reservoir created by the proposed, but never constructed, Auburn Dam. The superstructure is a parabolic haunched deck truss bridge that has fracture-critical, high-strength steel (100 ksi) main members. As part of the Local Agency Seismic Retrofit Program, Placer County, California, embarked on the seismic retrofit design of this bridge. This project expanded on the concepts and design methodologies that were developed during the retrofits of the California Toll Bridge Program. Strain-based design criteria were developed for all concrete and steel members of the bridge. The project-specific design criteria may serve as the “next generation” for complex steel seismic retrofit projects. The time history model incorporated material and geometric nonlinearity components and was capable of capturing the global buckling of steel members and reporting member strains. The gusset plates were evaluated to ensure that any ductile behavior was limited to the members themselves and not the connections. The project incorporated the use of large buckling restrained braces (BRBs) to improve the performance of the bridge during large seismic events. BRBs are simple, low-maintenance devices that dissipate energy and improve the seismic behavior of steel structures. This paper summarizes the innovative design concepts and their application throughout the project.
Assessment and Rehabilitation of Corpus Christi Harbor Bridge, Texas
Authors: Bachman Patrick , Hohmann David , Bunner Matthew
Published: December 2010

The Corpus Christi Harbor Bridge carries US Route 181 over the Port of Corpus Christi, Texas, ship channel entrance. The topic of this paper is the five-span 1,788-ft truss portion of the bridge. It is a vital element of the Corpus Christi road system and provides the main link between the city of Corpus Christi and industry and recreation to the north. The six-lane bridge was opened to traffic in October 1959. A wider replacement bridge, with greater vertical clearance to accommodate modern maritime traffic and more desirable approach geometry, has been studied for several years, but the anticipated cost exceeds $700 million. Because of the cost, the Texas Department of Transportation (DOT) has elected to rehabilitate the existing bridge and gain another 20 years of service life for a projected cost of $20 million. Texas DOT chose to take a three-phase approach to the assessment and rehabilitation of the truss. The first phase was a detailed inspection and condition evaluation, the second phase included analyses and load ratings of the original and deteriorated conditions, and the third phase was to produce detailed plans, specifications, and estimates for the truss rehabilitation. All phases of work were conducted by HDR Engineering, Inc., during a 10-month period. This paper focuses on the fast-track schedule, the approach to managing voluminous amounts of analysis data, innovative repair methods conducted while maintaining vehicular and maritime traffic, and the way the plans and specifications were presented to generate solid competitive bids.
Design–Build Replacement of US-90 Bridge over Bay St. Louis, Mississippi
Authors: Blakemore Frank P. , Konda Travis F.
Published: December 2010

As part of the rebuilding efforts after Hurricane Katrina, the Mississippi Department of Transportation awarded a design–build contract for the replacement of the 2.1-mi-long US-90 bridge spanning Bay St. Louis. With a January 25, 2006, start date, the deadline for opening two lanes of traffic was May 16, 2007, followed by a February 15, 2008, deadline for opening the entire bridge. The bridge was constructed as two separate structures except for the navigation unit, where the deck and substructure are continuous between the eastbound and westbound structures. To allow for such an aggressive construction schedule, several concepts were used. Plans were delivered in stages to allow construction to proceed before the final submittal. The use of precast components including girders, piles, and capbeams was maximized. Pile bents to a height of 75 ft above fixity were used, with no battered piles. The pile and girder sections were varied to allow for utilization of more precast fabricators. Precast, prestressed piles, ranging in length from 50 to 164 ft, form the bridge foundations of the pile bents (24- and 36-in. piles) and waterline footings (30-in. piles). Typical superstructure elements consist of BT-78 girders (maximum span of 154 ft) and AASHTO Type IV girders (maximum span of 112 ft). A spliced haunch girder system with a 250-tt main span and 200-ft end spans was implemented at the navigational channel to satisfy the vertical and horizontal clearances.
Sanhao Bridge, Shenyang, China
Authors: Tang Man-Chung
Published: December 2010

Sanhao Bridge is the first bridge with design based on the concept of the partially cable-supported girder bridge. It has a curved steel tower and a prestressed concrete box girder. This design concept fully utilizes the capacities of the girder and the cable supporting system, thus achieving good economy. It is a beautiful bridge that has become a signature of the city.
Evaluation of Wireless Devices for Monitoring Fracture-Critical Steel Bridges
Authors: Fasl Jeremiah , Helwig Todd , Wood Sharon L. , Samaras Vasilis , Potter David , Lindenberg Richard , Frank Karl
Published: December 2010

Highway bridges are vital links in the U.S. transportation network, providing the public with routes for daily commutes and businesses with the infrastructure needed to supply goods and services. Identifying possible safety problems in the approximately 600,000 bridges across the country generally is accomplished through labor-intensive visual inspections. The National Bridge Inspection Program requires that bridges be inspected at least once every 2 years. Pending legislation spurred by the collapse of the I-35W steel truss bridge in Minneapolis, Minnesota, would increase the inspections for fracture-critical bridges to once a year and likely strain department of transportation resources that are already stretched to the limit. This paper outlines ongoing research sponsored by the National Institute of Standards and Technology that seeks to improve inspection practices by providing the technology and methodology for real-time monitoring of steel bridges. The first generation of two wireless systems (one based on IEEE 802.11 and another on IEEE 802.15.4) from National Instruments has been evaluated in field conditions. This paper presents results of a study to characterize wireless communication in steel box girders and I-girders. In addition, enhancements to be made in the second generation are discussed.
Reliability of Pile Driving Analyzer for Determination of Axial Capacity of Large-Diameter Cylindrical Pile
Authors: Mankbadi Raymond , Ramakrishna Aravinda , Yang Kuang-Yu
Published: December 2010

A case history involving the design and construction of the water pier foundations for a fixed high-level precast segmental bridge over the Shrewsbury River in Monmouth County, New Jersey, is presented. The water pier foundations are supported on 54-in. prestressed open-ended concrete cylindrical piles with a 6.0-in. wall thickness. Design concepts for cylindrical piles are outlined. Results of the pile load testing program on one pile are presented. The reliability of the pile driving analyzer and case pile wave analysis program data are evaluated based on the result of the static load test. Installation procedures and load-testing programs of the open-ended cylindrical piles are discussed. A comparison of case histories of large-diameter cylindrical piles is presented, drawing from a similar experience of a former project. Recommendations for design, construction, and dynamic testing of large-diameter cylindrical piles are made.
Fast-Track Installation of Micropiles to Resupport Settled Florida SR-60 Bridge End Bents
Authors: Hussin James , Cook Curtis
Published: December 2010

The end bents of an existing bridge located west of Lake Wales, Florida, experienced significant settlement, leading to concern about its stability. A detailed foundation inspection attributed the settlement to deterioration of the existing timber piles. The bridge was closed to traffic until both end bents could be remediated. An adjacent bridge handled both directions of traffic during the closure. The geotechnical contractor proposed a solution of micropiles installed through both end bents to restore the bridge's capacity. Timing was a critical component of the remediation work. The micropile program consisted of the use of rotary drilling techniques to install 20 micropiles through the end bents to a depth of 30 ft. The tops of the micropiles were bonded to the end bent pile caps. A load test was performed on a test pile installed adjacent to the existing bridge.
Low-Cracking, High-Performance Concrete Bridge Decks
Authors: Darwin David , Browning Joann , Lindquist Will , McLeod Heather A. K. , Yuan Jiqiu , Toledo Miriam , Reynolds Diane
Published: December 2010

Cracks in concrete bridge decks provide easy access for water and deicing chemicals that shorten the life of the deck, and field surveys show that the problem has become progressively more severe since at least the 1980s. A two-phase, 10-year Pooled Fund study to minimize cracking in bridge decks is now under way. Twenty bridge decks have been constructed in the program to date. Comparison with conventional decks shows that the techniques embodied in low-cracking, high-performance concrete (LC-HPC) bridge deck specifications have been highly successful in reducing cracking in bridge decks. The results also show that high-slump high-strength concretes result in greater cracking in bridge decks than low-slump, moderate-strength concretes and that concrete temperature control and early application of curing counteract the negative effects of casting concrete under high-temperature conditions. Early owner and contractor buy-in is needed for successful LC-HPC bridge deck construction, and top performance requires the adherence to all aspects of the specifications.
Response Sensitivity for Probabilistic Damage Assessment of Coastal Bridges under Surge and Wave Loading
Authors: Ataei Navid , Stearns Matthew , Padgett Jamie E.
Published: December 2010

The susceptibility of coastal bridges to damage during hurricane-induced storm surge has been illustrated along the U.S. Gulf Coast in several hurricane events. This factor poses a significant threat to the safety of nationwide transportation systems, effectiveness of postevent emergency response and recovery activities, and socioeconomic stability further afforded by functioning transportation infrastructure. Nationwide risk and loss assessment packages currently lack any reliable input models of bridge fragility to assess the risk to the transportation infrastructure posed by hurricane-induced storm surge and wave. However, these tools are essential for comparing the vulnerability of different bridge types, conducting regional risk assessment or loss estimates, and supporting decision making on risk mitigation activities. As a first step in the development of probabilistic models of bridge vulnerability subjected to hurricane scenarios, sensitivity studies are conducted to assess the significance of varying hazard and bridge parameters on the dynamic response of coastal bridges. Three-dimensional nonlinear finite element models are used to assess these demands under varying input modeling parameters, and an analysis of variance is conducted to evaluate the significance of each parameter. The sensitivity study reveals that the potential variation in wave parameters has the most statistically significant impact on the response of the bridge. Additionally, a second-level sensitivity study reveals that the most critical structural parameter is the deck mass followed by connection modeling parameters. The results of this study provide insight into modeling parameters that should receive careful treatment in probabilistic analysis of bridge vulnerability.
Development of User-Friendly Software Application for Extracting Information from National Bridge Inventory Source Files
Authors: McClure Scott , Daniell Keli
Published: December 2010

The nation is facing enormous repair, maintenance, and replacement costs for its aging bridge infrastructure, and this issue is of concern to a broad cross section of public and private interests. A simple-to-use bridge information system is needed by technical and nontechnical users who would like to review detailed information on the condition of the nation's public bridges without recourse to access-restricted and cost-prohibitive proprietary software. The annual National Bridge Inventory (NBI) text files collected from the states over consecutive years and maintained by FHWA constitute a wealth of information on approximately 600,000 public bridges throughout the United States, including information on condition and load ratings, geometry, sufficiency, age, location, functional classification, average daily traffic, improvement costs, inspection frequency, material and design types, historical significance, structural deficiency, and functional obsolescence. This information is of potential significance to a wide variety of end users, including bridge design and maintenance personnel, departments of transportation executive management, cultural and environmental specialists, economic forecasting and financial personnel, and media, commercial interest, and public information officers. As a supplement to a proprietary bridge management system, the New Mexico Department of Transportation developed an independent bridge information software application to process NBI source files and to produce commonly requested formatted reports on various categories of bridge information, including structural deficiency, age, improvement costs, historical significance, and several others. Because the NBI text files are processed into a common database format, custom reports may be easily generated by using simple query tools.
Optimization of Bridge Management under Budget Constraints
Authors: Orcesi André D. , Frangopol Dan M.
Published: December 2010

Bridge management is a complex engineering issue with public safety and financial implications. It is a challenge to provide efficient bridge management systems, taking into account uncertainties in the structural degradation process, the loads and resistance of the structure, the decisions that are made concerning assessment strategies—such as inspections or structural health monitoring (SHM)—and maintenance and rehabilitation strategies. It is important to determine optimal management strategies that satisfy budget constraints, because efficient use of available financial funds is a primary objective of stakeholders. The purpose of this paper is to provide a probabilistic framework based on SHM results for optimization of management strategies under multiple criteria, including budget availability. To take into account uncertainties in the decision process, an event tree–based approach is used. This enables quantification of the expected inspection, SHM, maintenance and failure costs, and accuracy of the decision process according to the occurrence and duration of future SHM programs. To include budget constraints, the probability distribution of management cost—defined as the sum of inspection, SHM, and maintenance costs—is determined at each decision time and compared with an ideal budget distribution. The proposed approach is applied to an existing bridge.
Bridge Management to the Year 2020 and Beyond
Authors: Shirolé Arunprakash M.
Published: December 2010

During the past three decades, the art and science of bridge management has experienced significant milestones in its development and implementation. Bridge management systems (BMSs) are now entering into the mainstream of comprehensive transportation asset management. This paper is a successor to “Bridge Management to the Year 2000 and Beyond,” which was published in the proceedings of the 1993 TRB International Conference on Bridge Management. It reviewed the progression of BMS development activities through the 1980s and the early 1990s and then envisioned these systems transitioning into real-life application. This paper reviews subsequent enhancements to the state of the art of bridge life-cycle management in view of the galloping advances in automation and communications technologies that have made, and will continue to make, an enormous impact on the potential and tools available for advancing capabilities of BMSs. Recent emergence of cradle-to-grave, integrated, and comprehensive approaches through bridge information modeling has opened up new horizons for the future of bridge management. This paper examines and projects, to the year 2020 and beyond, the substantive impact of this innovative concept on the coordinated management of the various distinct phases in the bridge life cycle, starting with preliminary and final design and proceeding through construction, day-to-day operations, and project- and network-level planning and capital programming. Further, the paper discusses potential hurdles bridge management practitioners are likely to face and potential successes they are likely to experience.
Structural Fuse Concept for Bridges
Authors: El-Bahey Samer , Bruneau Michel
Published: December 2010

The concept of designing sacrificial elements to dissipate seismic energy while preserving the integrity of the structure's other main components is known as the structural fuse concept. Few implementations of this concept have been rigorous in emphasizing replaceability of the sacrificial elements and absence of damage to the primary load-resisting structural system. Here the concept is applied to an innovative multicolumn accelerated bridge construction (ABC) pier concept. Different types of structural fuses are investigated to compare the effect of each on ABC bridge bents. A three-span continuous bridge prototype having two twin-column pier bents with fixed base spaced at 36 m (120 ft) and 9 m (30 ft) tall was designed according to AASHTO load and resistance factor design specifications. Its piers were designed with double-composite rectangular columns using Bi-Steel panels and structural fuses. Two corresponding ⅔-scale models were developed and tested. The two specimens were designed for a maximum horizontal force of 1,777 kN (400 kips). Three quasi-static tests were performed. For the first specimen, steel plate shear links were installed between the columns as a series of structural fuses. Testing was performed up to a drift corresponding to the onset of column yielding to investigate the effectiveness of adding the fuses in dissipating the seismic energy, then testing continued until column failure. Then, the other specimen was installed and tested utilizing buckling restrained braces (BRBs) as a series of structural fuses. The BRBs were then removed and a bare frame cyclic test was performed until column failure.
Analytical Fragility Curves for Multispan Continuous Steel Girder Bridges in Moderate Seismic Zones
Authors: Ramanathan Karthik , Desroches Reginald , Padgett Jamie Ellen
Published: December 2010

Multispan continuous steel girder bridges are one of the most common bridge types in the central and southeastern United States. Seismic fragility curves for these highway bridges are essential for risk assessment of highway transportation networks exposed to seismic hazards. This study focuses on developing and comparing fragility curves for seismically and nonseismically designed bridges that are common in this region. The primary differences between seismically and nonseismically designed bridges are the column details and bridge bearings. Detailed three-dimensional (3-D) nonlinear analytical models, which account for the nonlinear behavior of the column, girders, and abutments, are developed with the use of the OpenSees platform. The fragility curves are developed with a suite of ground motions representative of the seismic hazard in the region. Unlike most previous studies, the fragility curves are developed with geometric variations such as column height, deck width, and length considered to study the effect of these variations on the fragility curves within the same class of bridges. The results provide insight into the level of uncertainty introduced in the analysis of fragility curves for portfolios of bridges with the use of 3-D analytical models and nonlinear time–history analyses. Component and system fragility curves are obtained and are compared for the case of nonseismically and seismically designed bridges.
Seismic Analysis and Design of Pile Group Bridge Foundations in Soft and Liquefied Soil
Authors: Malek Amir M. , Islam Mohammed S.
Published: December 2010

A pile group foundation is a highly indeterminate system with non-linearities caused by soils and pile and cap materials. The cap footing is often sufficiently rigid to develop a linear variation in the pile axial forces induced by the imposed moments. However, a nonlinear foundation–soil interaction analysis is required to perform a reliable evaluation of capacity and displacement demands for seismic design. A detailed nonlinear analysis using advanced numerical techniques, such as the finite element method to model the soil response and soil–foundation interactions during a seismic event, can be complex and time-consuming. The complexity is significantly greater when the foundation supports high and multidirectional dynamic loads induced during seismic events, especially when the foundation soil is soft or predicted to liquefy. Because of time and resource constraints—and for the case of liquefied soils, considering the difficulties and uncertainties associated with developing constitutive models—such an analysis is often neither feasible nor desirable for small to medium-size projects. It is, therefore, necessary to develop simplified and practical analysis methods, with clearly defined applicability and limitations, and with appropriate built-in conservatism, for the seismic analysis and design of such foundations. This paper summarizes the results of a recent study on the subject. Applications of simplified two-dimensional and three-dimensional analysis methods are demonstrated. Effects of the footing rigidity and direction of the applied seismic shear and moment on the response are also presented.
Probabilistic Vulnerability Scenarios for Horizontally Curved Steel I-Girder Bridges under Earthquake Loads
Authors: Seo Junwon , Linzell Daniel G.
Published: December 2010

Horizontally curved steel I-girder bridges are located in all seismic zones in the United States. Research has shown that damage can occur to steel bridge components under earthquake loads. Probabilistic-based techniques are one tool that can be used to assess more accurately the seismic vulnerability of curved bridges for various damage states and at various seismic hazard levels. To examine probabilistic-based vulnerability criteria efficiently, the study used response surface metamodels (RSMs) in conjunction with Monte Carlo simulations to generate horizontally curved steel I-girder bridge fragility curves. The generated curves were then used to evaluate bridge damage in terms of previously published structure damage states. The use of RSMs reduces the required number of computer simulations needed to generate the fragility curves. The paper summarizes the fragility curve generation procedure for a group of horizontally curved steel I-girder bridges using RSMs in association with Monte Carlo simulation. Probabilistic vulnerability scenarios are presented via application to existing horizontally curved steel bridges located in Pennsylvania, New York, and Maryland to estimate seismic demands for those bridges and to generate fragility curves.