A possibilidade de redução ou até mesmo da eliminação do uso de formas e escoramento, diminuição do tempo e melhoria da qualidade da obra, são alguns aspectos que têm levado à adoção da pré-moldagem em superestruturas de pontes. Recentes estudos relatam que as chamadas pontes integrais - pontes sem juntas - estão tornando-se cada vez mais utilizadas nos Estados Unidos e Canadá, pois minimizam os custos com manutenção e prolongam a vida útil da obra. Procurando associar os benefícios conseguidos com a utilização dos elementos pré-moldados aos da ausência de juntas, apresenta-se neste trabalho um tipo construtivo para pontes de pequenos vãos em pórtico, com utilização de elementos pré-moldados na superestrutura ligados rigidamente à infraestrutura. Um processo aproximado de cálculo é apresentado e, a partir de um exemplo desenvolvido, compara-se esta alternativa com uma construção similar em viga, verificando-se que os custos diretos são basicamente iguais. Através da avaliação dos esforços provenientes do carregamento móvel com a técnica dos elementos finitos, chega-se a momentos fletores até 50% menores que os obtidos pelo método aproximado, resultando assim numa considerável redução dos custos diretos quando se utiliza o sistema estrutural em pórtico. / The possibility of reduction or even the elimination of the use of forms and bearings, reducing the time and improving the qualitity of the work, are some aspects which have led to the use of precasting in bridges superstructure. Recent studies report that the so-called integral bridges, jointless bridges, are becoming more used in the United States of America and in Canada because they reduce the costs of maintenance and prolonge the useful life of the constructions. Trying to associate the benefits which have resulted from the utilization of precast elements to the ones from the absence of joints, it is present in this work a constructive proposal to small span frame bridges using the precast elements in the superstructure strictly connected to the infrastructure. A design process for bending moments is presented. The comparation between the construtive proposal and similar with joint between the superestructure and infrastructure, by using this design process, shows that the direct cost is basically the same. Through the evaluation of the efforts that come from the mobile carrying with the technique of finite elements, it can reach bending moments that are even 50% lower than those gotten from the presented method. In this case, a significative direct cost reduction can gotten with frame structure system.

The goal of the thesis is to improve the existing Editor and Simulator applications that have been created by the autor as his Bachelor Thesis. Document speaks about the main aspects of bridge; about the auction and the bridge play. The whole document is based on the author's Bachelor Thesis which is frequently referenced in the document. Nevertheless, the document should be readable without any previous knowledge of author's former work. The author is discussing his effort to create logic expressions to describe bridge hands and truths in the bridge world. These expressions are then used to construct auction conventions and whole auction systems. The author is discussing the bridge problems and presenting the improved algorithm to solve double-dummy problems. The work also describes the software from the engineering point of view and speaks about the graphic user interface of both programmes.

A closed, orientable, splitting surface in an oriented 3-manifold is a topologically minimal surface of index n if its associated disk complex is (n-2)-connected but not (n-1)-connected. A critical surface is a topologically minimal surface of index 2. In this thesis, we use an equivalent combinatorial definition of critical surfaces to construct the first known critical bridge spheres for nontrivial links.

In April of 2008, the Federal Highway Administration (FHWA) launched the Long Term Bridge Performance (LTBP) program. The program was established to collect scientific quality data from a number of bridges across the nation over a period of 20 years. The data will be used to provide a better picture of bridge health and structural performance. Utah Department of Transportation (UDOT) structure number 1F 205, located 2.4 km (1.5 mi) west of Perry, Utah, was selected as one of the LTBP pilot bridges (this bridge will also be referred to as the Cannery Street Overpass). UDOT performs regular maintenance on this bridge and in April of 2011 they began a rehabilitation project over a 13-km (8-mi) section of I-15 that included the Cannery Street Overpass. The main purpose of this rehabilitation was to improve pavement conditions. As part of this work, in the fall of 2011 UDOT removed all of the asphalt from the bridge deck, performed deck repairs, and placed a new asphalt layer. A unique opportunity presented itself to better understand the relationship between the mass and resonant vibration frequencies of the structure. This relationship is understood by (omega_n)^2=k/m, where omega_n=resonant frequency; k=stiffness; and m=mass. A decrease in mass should yield an increase in resonant frequency. Dynamic testing was done on the bridge to obtain its resonant frequencies. This testing included measuring the velocity response of the structure at different points on the bridge due to ambient vibrations (mainly from traffic). Three tests were performed before, during, and after UDOT's scheduled maintenance. These testing states include: State 1. Original asphalt on bridge deck State 2. No asphalt on bridge deck State 3. New asphalt on bridge deck These three states represent three different mass states of the bridge. The original asphalt layer was substantially heavier than the new asphalt layer. The data obtained from all three tests was processed in order to extract modal properties of the bridge. The changes in modal properties were analyzed and the results of the testing proved to be insightful at defining the relationship between mass and resonant frequency.

Bridge scour is the leading cause of bridge damage nationwide. Successfully mitigating bridge scour problems depends on our ability to reliably estimate scour potential, design safe and economical foundation elements that account for scour potential, identify vulnerabilities related to extreme events, and recognize changes to the environmental setting that increase risk at existing bridges. This study leverages available information, gathered from several statewide resources, and adds watershed metrics to create a comprehensive, georeferenced dataset to identify parameters that correlate to bridges damaged in an extreme flood event. Understanding the underlying relationships between existing bridge condition, fluvial stresses, and geomorphological changes is key to identifying vulnerabilities in both existing and future bridge infrastructure. In creating this comprehensive database of bridge inspection records and associated damage characterization, features were identified that correlate to and discriminate between levels of bridge damage. Stream geomorphic assessment features were spatially joined to every bridge, marking the first time that geomorphic assessments have been broadly used for estimating bridge vulnerability. Stream power assessments and watershed delineations for every bridge and stream reach were generated to supplement the comprehensive database. Individual features were tested for their significance to discriminate bridge damage, and then used to create empirical fragility curves and probabilistic predictions maps to aid in future bridge vulnerability detection. Damage to over 300 Vermont bridges from a single extreme flood event, the August 28, 2011 Tropical Storm Irene, was used as the basis for this study. Damage to historic bridges was also summarized and tabulated. In some areas of Vermont, the storm rainfall recurrence interval exceeded 500 years, causing widespread flooding and damaging over 300 bridges. With a dataset of over 330 features for more than 2,000 observations to bridges that were damaged as well as not damaged in the storm, an advanced evolutionary algorithm performed multivariate feature selection to overcome the shortfalls of traditional logistic regression analysis. The analysis identified distinct combinations of variables that correlate to the observed bridge damage under extreme food events.

Returning to work after retiring, called bridge employment, is rapidly becoming a common phenomenon in the work world. Despite its increasing prevalence, relatively little is known about the outcomes and processes. One proposed explanation of the relationship between bridge employment and outcomes such as health and life satisfaction is the role of identity-related changes. There are many identity related losses (e.g., loss of status) and transitions (e.g., no longer a full-time employee, no longer a supervisor) inherent in bridge employment. However, no studies have directly considered how identities are constructed to respond to these changes. Using a qualitative, grounded theory approach in which 46 individuals participated in semi-structured interviews, this dissertation seeks to answer the question of “How do individuals come to define who they are during the identity-related losses and liminality experienced during bridge employment?” These results expand existing theory to explain how bridge employment identities are constructed through an iterative process of reconciling preretirement career identities, retirement identities, and bridge employment identities. Specifically, identity threats, often spurred by losses of work roles, relationships, and health related to retiring, were successfully eliminated through substituting the motive for an alternative motive or redefining the motive. Bridge employment was also a time for motives such as self-actualization, reinvention, and generativity. Successful satisfaction of identity motives drove participants to internalize the bridge employment identities. Moreover non-work identities, such as being a volunteer or grandparent, became more important and fulfilled identity motives, even though they were generally in conflict with bridge employment identities and took time away from it. Moreover, participants reported that non-work activities were able to fulfill identity motives. In proving important to one’s identity, non-work identities became more central to one’s identity. Finally, the preretirement career identity enhanced the bridge employment identity and was sometimes changed itself through the iterative nature of the identity construction process. This research enriches our understanding of identity construction during bridge employment as well as suggests practical ways to improve the experience of working after retirement.

A database of United States bridge failures was used to ascertain the failure rate of bridge collapses for a sample population with associated rates by causes. By using the National Bridge Inventory bridge counts, the bridge population, from which the collapsed bridge came from, was determined. The average number of bridge collapses based on the sample population was approximately 1/4,700 annually. The geometric distribution was determined to be a valid model for the number of bridge failures per annum through multiple methods. Based on the data extrapolation and 95% confidence interval, the estimated average annual bridge collapse rate in the United States is between 87 and 222 with an expected value of 128. The database showed hazards that have caused bridges to collapse historically, throughout the United States. Conditional probabilities of collapse rate with consideration for the features under the structures were constructed. The most likely cause of collapse was determined to be hydraulic in nature when adjusting for the features under the structure. The collapse rate of hydraulic causes was unknown from past investigations; however, the value was determined to be an annual rate of 1.52E-4. Collapse rates were also quantifiably established for other causes. The consequences coupled with the rate of failure by cause were quantitatively evaluated. A benchmark, set by the United States Army Corps of Engineers interim guideline for dam safety, was used to show that bridge collapses within the United States are within a tolerable range comparing collapses to life loss. To enhance risk-based and data-driven approaches to bridge management systems in compliance with Moving Ahead for Progress in the 21st Century Act, efficacious bridge collapse data collection is examined for this investigation. Trends obtained from statistical analysis of existing data show 53% of collapsed bridges were structurally deficient prior to collapse, and a failure rate of structurally deficient bridges to be 1/1,100 annually. Age and structural deficiency are related, structural deficiency and collapse are related, and age at collapse is contingent on collapse cause. It was determined that deterioration-caused and overload-caused bridge collapses are age related, but hydraulic-caused and collision-caused bridge collapses are not. Based on the desired results, trends seen in existing collapse data, improved collection efforts and data fields of interest are assessed with recommendations for analytical methods and consequence assessment while maintaining concise data. A national repository of bridge collapses at the federal level is paramount for effective bridge collapse risk analysis. Currently, bridge failure data is incomplete and insufficient to enable in-depth lifetime data analysis for improved bridge preservation. However, the frequency of collapses is often enough for large amounts of data to be collected in relatively few years.

Precast concrete bridge deck panels have been used for decades to accelerate bridge construction. Cracking of the transverse connection between panels is a common problem that can damage deck overlays and cause connection leaking leading to corrosion of lower bridge elements. To better understand the behavior of bridge deck transverse female-to-female connections, shear and moment lab testing were performed at Utah State University for the Utah Department of Transportation. Two existing UDOT connections were tested, a welded stud connection and a post tensioned connection. A variation of the welded connection using rebar was also tested. In addition, two new curved bolt connections were tested as a new method of post tensioning a connection. The manner of connection cracking and associated cracking loads were recorded along with the ultimate connection capacities. The connections were also tested in a low cycle, high amplitude cyclical shear test. Lab testing showed that the welded stud connection had the lowest moment capacity. It also showed that the welded rebar connection had significantly higher strength than the welded stud connection with higher cracking and ultimate loads. Curved bolts were also shown to be a good way to post tension a connection with similar moment capacities as the post tensioned connection. Longer curved bolts were found to perform better than shorter curved bolts.

Seismic considerations greatly influence the lateral and vertical design of a structure, often necessitating larger elements than would otherwise be required. Seismic isolation greatly reduces the demands on a structure due to earthquake loading, allowing the use of smaller, more efficient members and foundations. This case study illustrates the theory and procedure of evaluating the response of a recently built multi-span highway bridge using the most recent (2009) AASHTO code. Based on this response, an equivalent structure was designed to incorporate a seismic isolation system, and the substructure of the isolated bridge redesigned to meet the reduced demands more economically. The reduction in demands was quantified, and the member demands and overall responses of the two designs were compared. An overview of isolator design for the common isolator types available in the United States, with examples specific to the isolated structure that was designed, is also included as an addendum.

In this research the environmental effects related to the position of a redox moiety with the electrochemical double layer were studied. This project was made possible with the synthesis of a series of lengths of ferrocene derived alkanethiols, a series of lengths of ferrocene derived norbornylogous bridges and a series of lengths of anthraquinone derived norbornylogous bridges. The series of ferrocene derived alkanethiols were used to study the effect of gradually varying the polarity of the self-assembled monolayers (SAMs) surface on the standard electron transfer rate constant and formal potential. This was achieved by varying the portion of hydroxyl to methyl terminated alkanethiol diluent in the SAM preparation step. It was found that the formal potential increased with a decreasing proportion of hydroxyl terminated diluent and increasing length of the diluent. For pure hydroxyl terminated diluent the formal potential was relatively independent of length. It was found that the rate constant increased for short alkane chain lengths with decreasing proportion of hydroxyl terminated diluent. However, it decreased in magnitude with long alkane chain lengths for low proportions of hydroxyl terminated diluent. The norbornylogous bridges were shown to stand proud above the diluent with a similar tilt angle as the alkanethiol diluent. The ferrocene derived norbornylogous bridges showed hydroxyl terminated monolayers had a slower rate constant then methyl terminated diluents independent of length and that it is highly probable that an alkane bridged redox moiety is located very close to the surface of the monolayer. SAMs were created with the ferrocene of the ferrocene derived norbornylogous bridges located at various heights above the monolayers surface. This was done by using various lengths of hydroxyl terminated diluent. It was found that the rate constant and the formal potential decreased with height above the surface. Interfacial potential distribution was used to account for this and to estimate a ??true?? formal potential. The anthraquinone derived norbornylogous bridges were tested at various pH values and heights above the surface. It was found that an accurate estimate for the electron transfer mechanism can not be made for surface bound species due to the effects of interfacial potential distribution. They demonstrated a novel technique for estimating the point of zero charge of the electrode.