As America's infrastructure ages, many of the nation's bridges approach the end of their service life. In order to develop a method for handling the rising number of deficient and functionally obsolete bridges, nondestructive tests and evaluations must be undertaken. Valuable information from these tests regarding the strength and condition of bridges will help in making decisions about their rehabilitation and replacement. Two adjoining open spandrel reinforced concrete arch bridges in downtown Appalachia, Virginia were selected for live load testing by Virginia Department of Transportation (VDOT). Both bridges have supported an increasing amount of extreme coal truck traffic throughout their service life and are essential to the efficient transport of coal in the region. Because of their age, having been built in 1929, and the amount of visible damage and repairs, VDOT was concerned about their remaining capacity and safe operation. The live load tests focused on global behavior characteristics such as service strain and deflection as well as local behavior of the arches surrounding significant repairs. It was found that the strain and deflection data collected during load testing displayed linear elastic behavior, indicating excess capacity beyond the test loads. Also, given the loading applied, the measured strains and deflections were small in magnitude, showing that the bridges are still acting as stiff structures and are in good condition. Data collected during these tests was compared to results from a finite element model of the bridges to determine the coal truck size which is represented by the live load test loading configurations. The model comparisons determined the test loads produced comparable deflections to those produced by the target coal truck load. Through this approach, a recommendation was given to VDOT regarding the satisfactory condition of the aging bridges to aid in the process of load rating and maintenance scheduling for the two bridges. / Master of Science

The Long Term Bridge Performance (LTBP) program is an organization within the Federal Highway Administration that inspects, tests, analyzes, and observes, for an extended period of time, a variety of bridge types throughout the United States. Part of the program includes periodic testing of select bridges of a span of 20 years. The Kettle River Bridge located outside of Sandstone, Minnesota was selected for study due to its unique design. The Kettle River Bridge is a historical steel cantilevered deck arched Pratt truss bridge. The bridge was instrumented with 151 strain gauges on various floor and truss members along with eight displacement gauges strategically placed along the truss. All gauges were read simultaneously as the bridge underwent non-destructive live loading. The recorded gauge readings were analyzed to determine bridge behavior and then used in the assistance of calibrating a working finite-element model. After a working model was verified the distribution factors for the interior and exterior floor stringers were determined. By using the controlling distribution factor, a load rating for the bridge was determined for both inventory and operating. The distribution factors and load ratings determined using the working finite-element model were then compared to the AAHSTO LRFD specifications.

Nowadays, many different efficient solutions are being studied to solve engineering problems. Inside this group of solutions we can find the Soil Steel Composite Bridges (SSCB) as an alternative to traditional bridges. SSCB are being used more often every day and they are showing themselves as competitive structures in terms of feasibility and constructability. This project was started to achieve two different goals. The first one was to create a general database of SSCB including few selected tests all around the world and the second one was to compare and discuss full scale tests using the Pettersson-Sundquist design method. To create the database and the following comparisons, twenty-five different full scale tests were used. From this tests all the necessary information was extracted and used to create the database. After creating the database, the project continued with the discussion and comparison of the full scale tests. Specifically those discussions and comparisons were related to the resistance of the soil (the soil modulus) used in the construction of the SSCB. All the values of the different soil modulus of each full scale test used in the comparisons were calculated using the Swedish Design Manual (SDM). Two different types of soil modulus were calculated in this project using SDM, ones are the soil modulus back calculated using the values reported from the live load tests performed on the culverts and the others are theoretical soil modulus calculated using the detailed information of the soil. The report continues with the explanation of the different conclusions ended up with during this project. It can be highlighted within this group of conclusions, the one related to the importance of reporting all the necessary information from the full scale tests including the soil parameters, the measures of the culvert, the cross sectional parameters and the vehicle dimensions among others. Another important conclusions are the effect of using the slabs over the top of the culvert and how it would effect to the sectional forces over the culvert and also the limitations using method B of the SDM regarding the type of soil used as backfilling Finally, the project finishes explaining some proposals for future research about other fields of the study of SSCB.

The inverted T-beam bridge system provides an accelerated bridge construction alternative for short-to-medium-span bridges. The system consists of adjacent precast inverted T-beams finished with a cast-in-place concrete topping. The system offers enhanced performance against reflective cracking, and reduces the likelihood of cracking due to time dependent effects. The effects of transverse bending due to concentrated wheel loads are investigated with respect to reflective cracking. Transverse bending moment are quantified and compared to transverse moment capacities provided by a combination of various cross-sectional shapes and transverse connections. A design methodology for transverse bending is suggested. Tensile stresses created due to time dependent and temperature effects are quantified at the cross-sectional and structure level and strategies for how to alleviate these tensile stresses are proposed. Because differential shrinkage is believed to be one of the causes of deck cracking in composite bridges, a study on shrinkage and creep properties of seven deck mixes is presented with the goal of identifying a mix whose long terms properties reduce the likelihood of deck cracking. The effects of differential shrinkage at a cross-sectional level are numerically demonstrated for a variety of composite bridge systems and the resistance of the inverted T-beam system against time dependent effects is highlighted. End stresses in the end zones of such a uniquely shaped precast element are investigated analytically in the vertical and horizontal planes. Existing design methods are evaluated and strut-and-tie models, calibrated to match the results of 3-D finite element analyses, are proposed as alternatives to existing methods to aid designers in sizing reinforcing in the end zones. Composite action between the precast beam and the cast-in-place topping is examined via a full scale test and the necessity of extended stirrups is explored. It is concluded that because of the large contact surface between the precast and cast-in-place elements, cohesion alone appears to provide the necessary horizontal shear strength to ensure full composite action. Live load distribution factors are quantified analytically and by performing four live loads tests. It is concluded that AASHTO's method for cast-in-place slab span bridges can be conservatively used in design. / Ph. D.

O objetivo desta pesquisa foi desenvolver um método para estabelecer o efeito das características e da operação dos veículos pesados sobre a infra-estrutura rodoviária através do uso de resultados de simulação microscópica de tráfego. Para tanto, foram definidos dois objetivos secundários. O primeiro deles envolveu a obtenção de um banco de dados detalhado sobre as características de 6.253 veículos pesados. Esses dados foram coletados em sete balanças localizadas em rodovias de pista dupla do estado de São Paulo. O segundo objetivo secundário consistiu na calibração e validação do simulador de tráfego CORSIM com o auxílio de um algoritmo genético, que adaptou simultaneamente 19 parâmetros do simulador para que ele reproduzisse adequadamente as características e o comportamento do tráfego observado em um trecho de rodovia de pista dupla paulista. A metodologia desenvolvida é demonstrada através da realização de um estudo de caso em que foram simulados dois cenários de tráfego e em que foi considerada uma ponte hipotética com 100 m de extensão. Nele, foram determinadas as probabilidades de ocorrências simultâneas dos veículos pesados sobre a ponte. As conclusões da pesquisa indicam que o método de calibração de simuladores de tráfego com uso de um algoritmo genético mostrou-se eficaz, reduzindo o erro médio de 9,11% para 6,32%. Além disso, as conclusões revelam que a obtenção de um carregamento móvel a partir de dados extraídos de um simulador de tráfego é possível e que a associação dos dados simulados a um banco de dados detalhado permite o cálculo do efeito do tráfego dos veículos pesados sobre a infra-estrutura rodoviária. Do estudo de caso, pode-se concluir que: (1) a probabilidade de ocorrência simultânea de veículos pesados sobre a ponte é muito freqüente e está diretamente relacionada às características do fluxo de tráfego e; (2) a distribuição das cargas e seus respectivos valores são fatores determinantes para o cálculo dos esforços. Os resultados do estudo de caso demonstram a viabilidade do procedimento proposto. / The objective of this research was to develop a method for establishing the effect of heavy vehicles characteristics and operation on highway infra-structure by using the results of a microscopic traffic simulation model. Therefore, two secondary objectives were defined. The first of them involved the attainment of a detailed database containing the characteristics of 6,253 heavy vehicles. This data was collected at seven weight stations located on the state of São Paulo multilane highways. The other secondary objective was to calibrate and validate CORSIM by using a genetic algorithm, which simultaneously adapted 19 model parameters in order to appropriately reproduce the characteristics and the behavior of the observed traffic flow. The developed methodology is demonstrated through a case study in which two traffic scenarios were simulated and in which a hypothetic 100 m bridge was considered. In the case study, the probabilities of simultaneous presence of heavy vehicles on the bridge were determined. The conclusions of this research indicate that the method of calibrating a traffic simulation model utilizing a genetic algorithm was efficient, reducing the mean error from 9.11% to 6.32%. Additionally, the conclusions reveal that the attainment of a live load from extracted data through a traffic simulation model is possible and that the association of simulated data with a detailed database allows the estimation of heavy vehicle traffic effect on highway infra-structure. From the case study, it can be concluded that: (1) the probability of simultaneous presence of heavy vehicles on the bridge is very frequent and; (2) the loads distribution and its respective values are determinant in calculating efforts. The case study results demonstrate the proposed procedure viability.

O objetivo desta pesquisa foi desenvolver um método para estabelecer o efeito das características e da operação dos veículos pesados sobre a infra-estrutura rodoviária através do uso de resultados de simulação microscópica de tráfego. Para tanto, foram definidos dois objetivos secundários. O primeiro deles envolveu a obtenção de um banco de dados detalhado sobre as características de 6.253 veículos pesados. Esses dados foram coletados em sete balanças localizadas em rodovias de pista dupla do estado de São Paulo. O segundo objetivo secundário consistiu na calibração e validação do simulador de tráfego CORSIM com o auxílio de um algoritmo genético, que adaptou simultaneamente 19 parâmetros do simulador para que ele reproduzisse adequadamente as características e o comportamento do tráfego observado em um trecho de rodovia de pista dupla paulista. A metodologia desenvolvida é demonstrada através da realização de um estudo de caso em que foram simulados dois cenários de tráfego e em que foi considerada uma ponte hipotética com 100 m de extensão. Nele, foram determinadas as probabilidades de ocorrências simultâneas dos veículos pesados sobre a ponte. As conclusões da pesquisa indicam que o método de calibração de simuladores de tráfego com uso de um algoritmo genético mostrou-se eficaz, reduzindo o erro médio de 9,11% para 6,32%. Além disso, as conclusões revelam que a obtenção de um carregamento móvel a partir de dados extraídos de um simulador de tráfego é possível e que a associação dos dados simulados a um banco de dados detalhado permite o cálculo do efeito do tráfego dos veículos pesados sobre a infra-estrutura rodoviária. Do estudo de caso, pode-se concluir que: (1) a probabilidade de ocorrência simultânea de veículos pesados sobre a ponte é muito freqüente e está diretamente relacionada às características do fluxo de tráfego e; (2) a distribuição das cargas e seus respectivos valores são fatores determinantes para o cálculo dos esforços. Os resultados do estudo de caso demonstram a viabilidade do procedimento proposto. / The objective of this research was to develop a method for establishing the effect of heavy vehicles characteristics and operation on highway infra-structure by using the results of a microscopic traffic simulation model. Therefore, two secondary objectives were defined. The first of them involved the attainment of a detailed database containing the characteristics of 6,253 heavy vehicles. This data was collected at seven weight stations located on the state of São Paulo multilane highways. The other secondary objective was to calibrate and validate CORSIM by using a genetic algorithm, which simultaneously adapted 19 model parameters in order to appropriately reproduce the characteristics and the behavior of the observed traffic flow. The developed methodology is demonstrated through a case study in which two traffic scenarios were simulated and in which a hypothetic 100 m bridge was considered. In the case study, the probabilities of simultaneous presence of heavy vehicles on the bridge were determined. The conclusions of this research indicate that the method of calibrating a traffic simulation model utilizing a genetic algorithm was efficient, reducing the mean error from 9.11% to 6.32%. Additionally, the conclusions reveal that the attainment of a live load from extracted data through a traffic simulation model is possible and that the association of simulated data with a detailed database allows the estimation of heavy vehicle traffic effect on highway infra-structure. From the case study, it can be concluded that: (1) the probability of simultaneous presence of heavy vehicles on the bridge is very frequent and; (2) the loads distribution and its respective values are determinant in calculating efforts. The case study results demonstrate the proposed procedure viability.

The highway bridge infrastructure system within the United States is rapidly deteriorating and a significant percentage of these bridges are approaching the end of their useful service life. Deterioration mechanisms affect the load resisting capacity of critical structural components and render aging highway bridges more vulnerable to earthquakes compared to pristine structures. While past literature has traditionally neglected the simultaneous consideration of seismic and aging threats to highway bridges, a joint fragility assessment framework is needed to evaluate the impact of deterioration mechanisms on bridge vulnerability during earthquakes. This research aims to offer an efficient methodology for accurate estimation of the seismic fragility of aging highway bridges. In addition to aging, which is a predominant threat that affects lifetime seismic reliability, other stressors such as repeated seismic events or simultaneous presence of truck traffic are also incorporated in the seismic fragility analysis. The impact of deterioration mechanisms on bridge component responses are assessed for a range of exposure conditions following the nonlinear dynamic analysis of three-dimensional high-fidelity finite element aging bridge models. Subsequently, time-dependent fragility curves are developed at the bridge component and system level to assess the probability of structural damage given the earthquake intensity. In addition to highlighting the importance of accounting for deterioration mechanisms, these time-evolving fragility curves are used within an improved seismic loss estimation methodology to aid in efficient channeling of monetary resources for structural retrofit or seismic upgrade. Further, statistical learning methods are employed to derive flexible parameterized fragility models conditioned on earthquake hazard intensity, bridge design parameters, and deterioration affected structural parameters to provide significant improvements over traditional fragility models and aid in efficient estimation of aging bridge vulnerabilities. In order to facilitate bridge management decision making, a methodology is presented to demonstrate the applicability of the proposed multi-dimensional fragility models to estimate the in-situ aging bridge reliabilities with field-measurement data across a transportation network. Finally, this research proposes frameworks to offer guidance to risk analysts regarding the importance of accounting for supplementary threats stemming from multiple seismic shocks along the service life of the bridge structures and the presence of truck traffic atop the bridge deck during earthquake events.

The main aim of the present study is to evaluate the safety level of Turkish type precast prestressed concrete bridge girders designed according to American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) based on reliability theory. Span lengths varying from 25 m to 40 m are considered. Two types of design truck loading models are taken into account: H30S24-current design live load of Turkey and HL93-design live load model of AASHTO LRFD. The statistical parameters of both load and resistance components are estimated from local data and published data in the literature. The bias factors and coefficient of variation of live load are estimated by extrapolation of cumulative distribution functions of maximum span moments of truck survey data (Axle Weight Studies) that is gathered from the Division of Transportation and Cost Studies of the General Directorate of Highways of Turkey. The uncertainties associated with C40 class concrete and prestressing strands are evaluated by the test data of local manufacturers. The girders are designed according to the requirements of both Service III and Strength I limit states. The required number of strands is calculated and compared. Increasing research in the field of bridge evaluation based on structural reliability justifies the consideration of reliability index as the primary measure of safety of bridges. The reliability indexes are calculated by different methods for both Strength I and Service III limit states. The reliability level of typical girders of Turkey is compared with those of others countries. Different load and resistance factors are intended to achieve the selected target reliability levels. For the studied cases, a set of load factors corresponding to different levels of reliability index is suggested for the two models of truck design loads. Analysis with Turkish type truck models results in higher reliability index compared to the USA type truck model for the investigated span lengths

The construction of curved I-girder bridges generally requires detailed attention to the steel erection plan as well as the deck placement sequence. There is limited quantitative information available on the performance of large curved bridges under construction. This study seeks to address this limitation through the study of a curved ramp I-girder bridge. The bridge under study is the last of several bridges needed to complete the interchange between I-40 and Briley Parkway (TN SR155) in western Nashville, TN. The study consists of three parts. First, the bridge was instrumented and its behavior during construction was monitored using vibrating wire strain gages, clinometers, and a robotic total station. Through these technologies it was possible to monitor changes in strain/stress, angle of rotation, and deflections throughout the girder erection, installation of concrete formwork, and concrete placement. Second, a static load test of the completed bridge was conducted using ten trucks loaded to a total weight of 72 kips each, during which measurements of the stress/strain and deflections were acquired. Finally, the collected data was compared to analytical results obtained from a 3D finite element analysis (FEA) model to assess the correlation between measurements and refined analytical predictions. The refined 3D FEA predictions are used as a baseline for evaluation of various simplified analysis methods in a parallel National Cooperative Highway Research Program project, NCHRP 12-79, Guidelines for Analytical Methods and Construction Engineering of Curved and Skewed Steel Girder Bridges. Overall, the comparisons show that the 3D FEA model provides a reasonable approximation of the bridge's behavior in terms of both stresses and deflections.

Accelerated Bridge Construction (ABC) has gained substantial popularity in new bridge construction and bridge deck replacement because it offers innovative construction techniques that result in time and cost savings when compared to traditional bridge construction practice. One technology commonly implemented in ABC to effectively execute its projects is the use of prefabricated bridge components (precast/prestressed bridge components). Precast/prestressed bridge components are fabricated offsite or near the site and then connected on-site using small volume closure pour connections. Diaphragms are also commonly used to strengthen the connection between certain prefabricated components used in ABC, such as beam elements. Bridges containing closure pour connections and diaphragms can be designed using AASHTO LRFD live-load distribution factor formulas under the condition that the bridge must be sufficiently connected. However, these formulas were developed using analytical models that did not account for the effects of closure pours and diaphragms on live-load distribution. This research study investigates live-load distribution characteristics of precast/prestressed concrete bridges with closure pour connections and diaphragms. The investigation was conducted using finite element bridge models with closure pour joints that were calibrated using experimental data and different configuration of diaphragms. The concrete material used for the closure pour connections was developed as part of a larger project intended to develop high early-strength concrete mixtures that specifically reach strength in only 12 hours, a critical requirement for ABC projects.