The bump at the end of the railway bridge is a result of differential movement between the bridge deck and the approach embankment. The movement can have the form of a bump or a dip. Either defect in the track geometry can cause significant problems in track performance. The current state of practice was evaluated by conducting a literature review and an industry survey. According to the survey, approximately half of all railway bridges are affected by the bump/dip. The total annual cost for repairing these bridge transition problems is estimated at $26 million. This does not take into account the considerable cost resulting from speed reductions that railroads must place on trains at these locations. In addition to the increased maintenance costs, the bump/dip leads to higher impact loads, uncomfortable rides and possible safety hazards. The track response due to the bump at the end of the bridge was evaluated by creating a 4-D finite element model of the train, track structure and track substructure. The motion of the train model across a bridge/approach transition, with and without a bump/dip, was then simulated using LS-DYNA. It was found that a track modulus differential alone (no bump/dip) at a bridge/approach location leads to impact forces as well as increased ballast and subgrade pressures on the approach. This instigates the formation of a bump or dip in the track. The track response is increased when a bump/dip is present in the track profile. A parametric study looking at the influence of train direction, train speed, bump/dip size, approach embankment soil modulus, approach tie material, bridge tie material, bridge deck type, ballast thickness and approach tie length on the magnitude of impact forces, track deflection, ballast and subgrade pressures was also performed with the model. Finally, a design solution to minimize the bump at the end of the bridge is proposed. The solution involves installing varying length steel bars into a soft subgrade approach embankment. The solution addresses both the settlement and track modulus differential between the bridge and the embankment. A full-scale field test of this prototype solution is underway.

[pt] Predominantemente os tanques de armazenamento de combustíveis são construídos nas regiões costeiras, cujo subsolo é caracterizado por um perfil estratificado, formado por sedimentos recentes do período quaternário, com alternâncias de energia de deposição e sedimentação. Observa-se a existência de sedimentos de origem flúvio-lagunar (intercalações estratigráficas constituídas de areias finas, siltes e argilas moles) e de sedimentos marinhos (camadas espessas de areia), sendo o nível freático raso. A tensão aplicada no solo geralmente é de pequena magnitude, mas a ocorrência de recalques diferenciais devido ao adensamento é muito comum e às vezes não corretamente avaliada, comprometendo seriamente a interação do solo com os componentes principais do tanque e com as tubulações e conexões para o abastecimento. O principal desafio deste estudo foi avaliar corretamente o desempenho da placa de fundo de um tanque metálico vertical apoiado sobre um depósito de solo estratificado. O estudo considerou, na análise numérica por meio do método dos elementos finitos, a existência de camadas horizontais e levemente inclinadas. Como principais resultados, foram gerados gráficos tempo versus recalque para comparação. Os resultados indicaram que a consideração da variação de espessuras e inclinações naturais na estratificação das camadas do subsolo tem uma influência direta no recalque, especialmente nas camadas argilosas. O comportamento do sistema solo-estrutura (disposição das camadas, da fundação, recalque por adensamento, recalque diferencial) mostrou a importância e a influência dos diversos fatores que afetam o recalque da fundação e contribui na tomada de decisões mais adequadas sob pontos de vista técnico e econômico. / [en] Predominantly, fuel storage tanks are built in coastal regions, whose subsoil in characterized by a stratified profile, formed by recent sediments from the Quaternary period. It is possible to observe the existance of sediments of fluvial-lagoon origin (stratigraphic interchanges consisting of fine sands, slits and soft clays) and marine sediments (thick layers of sand), with a shallow water table. The stress applied to the soil is usually of small magnitude, but the occurrence of differential settlements due to densification is very common and sometimes not correctly evaluated, seriously compromising the interaction of the soil with the main components of the tank, pipes and other connections. The main objective of this study was to evaluate the performance of the bottom plate of a vertical metallic tank supported on a stratified soil deposit. This study considered, though numerical analysis by the finite element method, the existence of horizontal and slightly inclined layers. As main results, time versus settlement and loading versus settlement graphs were generated for comparison. The results show that the consideration of the variation of the variation of thickness and slopes of the subsoil layers has a direct influence on settlements, especially in the clayey layers. The behavior of the soil-structure system (layout of layers, foundation, settlement by consolidation, differential settlement) showed the importance and influence of the various factors that affect the settlement of the foundation and contribute to the making of more adequate decisions under technical and economic points of view.

A bridge approach is usually built to provide a smooth and safe transition for vehicles from the roadway pavement to the bridge structure. However, differential settlement between the roadway pavement resting on embankment fill and the bridge abutment built on more rigid foundation often creates a bump in the roadway. Previous work examined this issue at a microscopic level and presented new methods for eliminating or minimizing the effects at specific locations. This research studies the problem at a macroscopic level by determining methods to predict settlement severity to assist designers in developing remediation plans during project development to minimize the lifecycle costs of bridge bump repairs. The study is based on historic data from a wide range of Kentucky roads and bridges relating to bridge approach inspection and maintenance history. A macro method considering a combination of maintenance times, maintenance measures, and observed settlement was used to classify the differential settlement scale as minimal, moderate, and severe, corresponding to the approach performance status good, fair, and poor. A series of project characteristics influencing differential settlement were identified and used as parameters to develop a model to accurately predict settlement severity during preliminary design. Eighty-seven bridges with different settlement severities were collected as the first sample by conducting a survey of local bridge engineers in 12 transportation districts. Sample two was created by randomly selecting 600 bridges in the inspection history of bridges in Kentucky. Ordinal and/or multinomial logistic regression analyses were implemented to identify the relationships between the levels of differential settlement and the input variables. Two predictive models were developed. Prediction of bridge approach settlement can play an important role in selecting proper design, construction, and maintenance techniques and measures. The users can select one or two models to predict the approach settlement level for a new bridge or an existing bridge with different purposes. The significance of this study lies in its identification of parameters that had the most influence on the settlement severity at bridge ends, and how those parameters interacted in developing of a prediction model. The important parameters include geographic regions, approach age, average daily traffic (ADT), the use of approach slabs, and the foundation soil depth. The regression results indicate that the use of approach slabs can improve the performance of approaches on mitigating the problem caused by differential settlement. In addition, current practices regarding differential settlement prediction and mitigation were summarized by surveying the bridge engineers in 5 transportation districts.

O trabalho propõe avaliação das respostas de esforços e deslocamentos de edifícios 3D considerando a interação solo-fundação-estrutura usando o conceito de Confiabilidade Estrutural. Para isso, empregam-se os Métodos dos Elementos Finitos (MEF) para a análise de estruturas e os métodos de Monte Carlo Simples (MCS) e First Order Second Moment (FOSM) para calcular sua segurança perante a inserção de variabilidade em certos parâmetros significativos no projeto, como as incertezas dos dados de rigidez do solo e a velocidade de vento. A formulação do edifício é baseada no MEF com elementos de barra e de casca, sendo as vigas, pilares e estacas elementos de barra e as sapatas em elementos de casca. Essa formulação é elastostática, mas permitindo a analise não-linear geométrica para os pilares. O solo é representado pelo modelo discreto de Winkler, o qual substitui sua influência contínua por molas pontuais com rigidezes equivalentes, tanto para a fundação rasa (sapatas isoladas) como para profunda (estacas). Com os resultados obtidos pelos modelos gerados, são feitas discussões e comparações com os métodos tradicionais de avaliação do fenômeno de recalque diferencial confrontando limites de índices de confiabilidade apresentados no Joint Committee on Structural Safety (JCSS, 2001) e os valores absolutos propostos pela literatura com base na Associação Brasileira de Normas Técnicas, ABNT, NBR6122: Projeto e execução de fundações (2010). Realiza-se também a análise de Estado Limite Último de pilares submetidos a flexo-compressão oblíqua com não linearidade física, de modo a avaliar o dimensionamento com fatores de segurança parciais da NBR 8681: Ações e segurança nas estruturas - Procedimento (2004) e Métodos de Confiabilidade Estrutural. / This work proposes the evaluation for the effects of forces and displacements about 3D buildings considering the soil-foundation-structure interaction using the concept of Structural Reliability. To do so, it is applied the Finite Elements Method (FEM) for the structural analysis and Simple Monte Carlo Method (SMC) and the First Order Second Moment (FOSM) to calculate its safety towards the application of variability at certain significant parameters of the project, as the uncertainness about the data of soil stiffness and wind speed. The building\'s formulation is based on the FEM with framed bars and shell elements, being beams, columns and piles as beam elements and the footings as shell elements. That formulation is elastostatic, although permits a non-linear geometric analysis for the columns. The soil is represented by the discrete Winkler\'s model, in which substitutes its continuum influence by nodal springs with equivalent stiffness, such as for shallow foundations (isolated footings), as for deep foundations (piles). With the results obtained by the generated models, discussions are done and comparisons about traditional method to evaluate the phenomenon of the differential settlement confronting the limits of the reliability presents in the Joint Committee on Structural Safety (JCSS,2001) and the absolute values proposed by the literature based on the Brazilian Association of Technical Standards, ABNT, NBR6122: Project and execution of foundations (2010). An analysis about the Ultimate Limit State of columns submitted by flexo-compression with physical non-linearity it is also performed, so that to compare the design with partial safety factors of the NBR 8681: Action and safety on structures - Proceedings (2004) and structural reliability methods.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / The Kansas Department of Transportation’s (KDOT) Bridge 059-045 is a reinforced concrete box girder bridge constructed in 1965 to connect the rural Shawnee Drive across Interstate 135 near McPhearson, Kansas, in between Salina and Wichita. The bridge was observed, during an annual inspection in 1998, to have experienced some settlement, which was further found to be due to its proximity to a sinkhole. This settlement progressed to noticeable levels in 2012 necessitating a semi-annual elevation profile survey that was consistently conducted by KDOT. In April 2016, KDOT determined that the bridge required a detailed finite element analysis to determine the safety and suitability of the bridge to stay open to traffic. Accordingly, a two-level Finite Element Analysis was performed using RISA 3D and Abaqus to assess the level of distress in the bridge due to the continuous differential settlement as a result of the active sinkhole deep in the soil under the bridge. The force-moment results were taken from the RISA 3D model for further analysis of various structural components that make up the bridge, including the box girder, piers, and piles. The stress distribution results from the Abaqus model were investigated for the same components of the bridge. A strengthening design scheme using near surface mounted fiber reinforced polymer rebar was developed to extend the service life of the bridge.

[pt] O comportamento de radiers estaqueados submetidos a carregamento vertical é estudado nesse trabalho. O método de análise é baseado no método dos elementos finitos, através da utilização do programa ABAQUS. Estimativas de valores de recalque ao longo de três seções distintas e distribuição de forças nos topos das estacas são obtidas para diversas configurações de radiers estaqueados em meio homogêneo com diferentes quantidades e arranjos de estacas, para os quais são adotados diferentes comprimentos relativos das estacas L/d, coeficientes de Poisson do solo Vs e espessuras do radier. A maior parte do recalque ocorre imediatamente após a construção, sendo que os recalques por adensamento se apresentam maiores no centro do que na borda do radier. Uma considerável parcela da carga aplicada é transferida diretamente ao solo através do radier, especialmente sob condições não-drenadas. Para condições drenadas essa proporção é reduzida, mostrando que o efeito do coeficiente de Poisson do solo na distribuição de cargas é bastante significativo. A posição das estacas no radier afetam diretamente a proporção da carga transmitida diretamente do radier para o solo, sendo este efeito mais representativo à medida que aumentam o comprimento relativo das estacas e a rigidez do radier. Análises de capacidade de carga são realizadas em condições não-drenadas para todas as configurações avaliadas, mostrando que o aumento na rigidez do radier contribui significativamente para o aumento dos coeficientes de segurança das estacas. / [en] The behaviour of vertically loaded piled rafts is studied in this research. The main objective of this thesis is to analyse the behaviour of a piled raft foundation system acting on a homogeneous half-space subjected to vertical loading. The analysis is based on finite element method by using of the computational program ABAQUS. The evaluation of settlements along three main sections and the load distribution on pile top were obtained for several piled raft configurations in single layered soil profile with different pile number and position, considering different values of pile slenderness ratio, soil Poisson s ratio and also of raft thickness. It has been shown that the major component of the total settlement takes place immediately after the loading application and the component of the consolidation settlement are bigger close to the raft centre than values at the raft edge. A big part of the total applied load is directly transferred to the subsoil by the raft, which becomes more significant under undrained conditions. For drained conditions this ratio decreases, which have shown that the soil Poisson s ratio influence at the load distribution is significant. The pile position under the raft influences the percentage of the load transferred directly to the subsoil by the raft. This influence becomes more significant with the increase of the pile slenderness ratio and of the raft stiffness. The bearing capacity of the piled raft configurations for undrained conditions was evaluated, which have indicated that the increase of the raft stiffness contributes to the increase of the pile safety factors.

This thesis is focusing on general issues of floor concrete slabs, technology, implementation, subsoil models, calculation of internal forces and design approaches. Based on these data the thesis monitors the behaviour of floor slabs according to the various parameters. It also includes three versions of design of the real floor slab, made of steel fibre reinforced concrete, reinforced concrete and prestressed concrete. Economic comparison is also included. In addition it developes a design of the chalice base and reinforced concrete column of the supporting hall system, instead of the original usual base with steel column.