The inland waterway system in the United States is fundamental to the transportation system as a whole and the success of the nation’s economy. Barge transportation in these waterways levitates congestion on the highway system and is beneficial when comparing barge transportation to other modes of freight transportation in measures of capacity, congestion, emissions, and safety. Unavoidably, the highway system intersects with the waterways, resulting in the risk of vessels collision into bridge structures. Particularly for barge impact, the literature is questioning the accuracy and oversimplification of the current design specifications. The impact problem was investigated in this research using three-dimensional finite-element analyses. To investigate the collision of a barge into a bridge pier, a range of material models are first investigated through simulating a drop-hammer impact onto a reinforced concrete beam. A detailed model of a jumbo hopper barge is then developed, with particular detail in the bow. The barge model is examined for its response to impact into rigid piers of different size and shape. RC piers, having different shape and boundary conditions, are impacted by the barge model and assessed using selected metrics. The final part of the research examines the response of an existing bridge pier subject to an impact by a chemical transporter barge that frequently travels in the waterway.

There has always been a challenge for designing structures against extreme dynamic loads. Blast loading falls under these loads category and blast resistant design has been gaining more interest during the past decade. Among different types of structures, Reinforced Concrete (RC) structures are usually recommended to be used for blast resistant design. However, the nonlinearities associated with these structures make their accurate analysis complicated. Therefore, simplified techniques have been introduced for nonlinear dynamic analysis of these structures. This study focuses on developing simplified computational strategies for the dynamic analysis of blast loaded RC elements including beams, panels/slabs and columns. For RC beams, the basis for commonly used Single-Degree-of-Freedom (SDOF) models has been outlined. A Multi-Degrees-of-Freedom (MDOF) model which takes into account the concrete nonlinear properties has been developed and the effect of varying the number of degrees-of-freedom (DOF) on response has been studied. Results showed that increasing the number of DOF affects the pressure-impulse (P-I) diagrams, especially in the impulsive regime, as the extent of damage increased. In addition, the model was compared with the experimental data and showed good agreement. For RC panels, a SDOF technique, based on the US Army Technical Manual TMS-1300 instructions, was constructed and results were compared with the ones obtained from explicit Finite Element (FE) analysis. Compared to the FE results, SDOF model yielded conservative predictions for deflection but it usually underestimated the dynamic reactions. A modification for reaction calculation was proposed which resulted in significantly better prediction of the reaction for the impulsive range of loading. Finally, considering the important role of columns in providing the overall stability of the structure, a MDOF model was developed for RC columns and the load carrying capacity of the columns was investigated for different levels of axial load, strain rate and damage. Increasing the strain rate enhanced the column's cross section properties whereas increasing the levels of axial load reduced the cross section curvature and the column deflection capacities. Results also showed that good detailing at the supports can significantly improve the load carrying capacity of RC columns. / Thesis / Master of Applied Science (MASc)

Reinforced concrete (RC) moment frame structures make up a notable proportion of buildings in earthquake-prone regions in the United States and throughout the world. The beam-column (BC) joints are the most crucial regions in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Thus, accurate simulations of the joint behavior are important for assessment of the local and global performance of both one-way and two-way interior BC joints. Such simulations can be used to study the flexural-shear-bond interaction, the failure modes, and sensitivity of various parameters of structural elements. Most of the existing analytical approaches for interior BC joints have either failed to account for the cyclic bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibrations on parameters as to render them impractical. The core motivation for this study is the need to develop robust models to test current design recommendations for 3D beam-column-slab subassemblies subjected to large drifts. The present study aims to first evaluate the flexural-shear-bond interactive behavior of two-way beam-column-slab interior connections by both finite element and nonlinear truss methodologies. The local performance such as bond-slip and strain history of reinforcing steel are compared with the experimental results for the first time. The reliability of applied finite element approach is evaluated against a series of one-way interior BC joints and a two-way interior beam-column-slab joint. The accuracy and efficiency of the nonlinear truss methodology is also evaluated by the same series of joints. Results show good agreement for finite element method against both global and local response, including hysteretic curve, local bond-slip development and beam longitudinal bar stress/strain distributions. The nonlinear truss model is also capable in obtaining satisfactory global response, especially in capturing large shear cracks. A parametric study is exhibited for a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, to quantify several non-consensus topics in the design of interior BC connections, such as the joint shear force subjected to bidirectional cyclic loading, the development of bond-slip behavior, and the failure modes of two-way interior joints with slab. Results from connections with different levels of joint shear force subjected to unidirectional loading show that meeting the requirements from ACI 352 is essential to maintain the force transfer mechanism and the integrity of the joint. The connections achieved satisfactory performance under unidirectional loading, while the bidirectional monotonic loading decreases the joint shear force calculated by ACI 352 by 10%~26% based on current results. Poorer performance is obtained for wider beams and connections fail by shear in the joint rather than bond-slip behavior when subjected to bidirectional cyclic loading. In general, the study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to 2D joints (planar) under monotonic and cyclic loads. Less satisfactory performance was found for cases of 3D joints with slabs. / Doctor of Philosophy / Reinforced concrete (RC) moment frames are one of the most popular structure types because of their economical construction and adaptable spaces. Moment frames consist of grid-like assemblages of vertical columns and horizontal beams joined by cruciform connections commonly labelled as beam-column joints. Because of the regularity of the grid and the ability to have long column spacing, moment frames are easy to form and cast and result in wide open bays that can be adapted and readapted to many uses. In RC structures, steel bars embedded in the concrete are used to take tensile forces, as concrete is relatively weak when loaded in tension. Forces are transferred between the steel and concrete components by so-called “bond” forces at the perimeter of the bars. The proper modeling of the behavior of bond forces inside the beam-column joints of reinforced concrete moment frames is the primary objective of this dissertation. Reinforced concrete moment frames constitute a notable proportion of the existing buildings in earthquake-prone regions in the United States and throughout the world. The beam-column joints are the most crucial elements in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Physical experimentation is the most reliable means of studying the performance of beam-column joints. However, experimental tests are expensive and time-consuming. This is why computational simulation must always be used as a supplemental tool. Accurate simulations of the behavior of beam-column joints is important for assessment of the local and global behavior of beam-column joints. However, most of the existing analytical approaches for interior beam-column joints have either failed to account for the bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibration parameters as to render them impractical. The present study aims to provide reliable numerical methods for evaluating the behavior of two-way beam-column-slab interior joints. Two methods are developed. The v first method is a complex finite element model in which the beam-column joint is subdivided into many small 3D parts with the geometrical and material characteristics of each part carefully defined. Since the number of parts may be in the hundreds of thousands and the geometry and material behavior highly non-linear, setting up the problem and its solution of this problem requires large effort on the part of the structural engineer and long computation times in supercomputers. Finite element models of this type are generally accurate and are used to calibrate simpler models. The second method developed herein is a nonlinear truss analogy model. In this case the structure is modelled as nonlinear truss elements, or elements carrying only axial forces. When properly calibrated, this method can produce excellent results especially in capturing large shear cracks. To evaluate the accuracy and to quantify the current seismic design procedure for beam-column joints, a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, the current design guide used for these elements in the USA, is analytically studied by the finite element methodology. The study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to one-way (planar) joints under monotonic and cyclic loads. Less satisfactory performance was found for cases of three-dimensional (3D) joints with slabs.

Este trabalho é iniciado apresentando os conceitos teóricos necessários para o bom entendimento do tema tratado, incluindo corrosão de armaduras, passivação, despassivação, vida útil e também conceitos de análise de riscos e teoria da confiabilidade. No terceiro capítulo é feita a revisão bibliográfica das variáveis que influem na carbonatação do concreto, apresentando um panorama do conhecimento atual sobre o tema, tanto no Brasil como no exterior. No quarto capítulo são apresentados e discutidos os modelos de previsão da carbonatação sendo também feitas comparações entre os resultados obtidos pelos modelos principais. No capítulo cinco é apresentado o trabalho experimental que objetiva contribuir com o conhecimento sobre a variabilidade da carbonatação e dos cobrimentos por meio de um estudo de caso real. A estrutura estudada foi o subsolo de um edifício residencial na zona central da cidade de São Paulo, no qual foram feitas diversas medidas de profundidade de carbonatação, cobrimentos de armaduras, concentração de CO2 ambiente e umidade relativa do ar. Os resultados foram tratados por meio de análise de variância e os valores de profundidade de carbonatação foram comparados com os valores previstos empregando modelos de previsão. Foi realizado o cálculo teórico da probabilidade de despassivação que foi comparada com a incidência real de despassivação observada. Os coeficientes de variação encontrados também foram comparados com os resultados de outras pesquisas atuais. É apresentado o desenvolvimento de um programa computacional para previsão do período de iniciação por métodos deterministas e probabilistas. / This work starts presenting the theoretical concepts needed for a good understanding of it’s contents, including corrosion of steel in concrete, passivation, despassivation, service life and concepts of risk analysis and reliability theory. In chapter three it’s discussed the several variables that have influence in concrete carbonation, presenting a general view of the knowledge concerning the topic in Brasil and other countries. Chapter four presents and discuss the prediction models of carbonation and comparisons are made between the results of the main models. In chapter five it is presented the experimental work that intends to contribute with the knowledge about the carbonation and concrete covers variability by means of a case study. The studied structure was the parking garage of a 30 years residential building, located in the central zone of São Paulo city in Brasil, in witch were made a several number of measurements of carbonation depth, concrete cover, CO2 concentration and air relative humidity. The collected data was analyzed using variance analysis and the values of carbonation depth were compared with that estimated using prediction models. The theoretical calculation of the despassivation probability was compared with the real despassivation incidence. The variation coefficients obtained were almost compared with the results of other recent investigations. It is still presented the development of a computer program for predicting the initiation period using deterministic and probabilistic methods.

Neste trabalho foram discutidos os aspectos de dimensionamento e verificação da segurança de elementos estruturais de concreto armado considerando a não-linearidade dos materiais. O estudo abordou uma nova proposta para a verificação simultânea dos estados limites últimos (ELU) e dos estados limites de serviço (ELS) para elementos de concreto armado submetidos à flexão, voltada especialmente para aplicações considerando a não-linearidade física utilizando o método dos elementos finitos. As propostas alternativas apresentadas na consideração de coeficientes minoradores das resistências dos materiais, trataram da utilização de valores médios para as relações tensão-deformação e para as resistências dos materiais; valores de referência que permitiram a composição de coeficientes globais de segurança, que independem da ruptura ser causada por esgotamento da capacidade resistente do concreto ou do aço e, finalmente, valores médios para as relações tensão-deformação no aço e no concreto, com limitação das resistências em seus valores de projeto. Foram analisadas seções transversais retangulares e do tipo T submetidas à flexão pura, com o uso das propostas alternativas. Foram, também, estudadas vigas isostáticas e hiperestáticas incluindo a verificação das reservas da capacidade resistente da estrutura, sendo que foi considerada a redistribuição dos esforços internos no caso hiperestático. As análises realizadas serviram de base para assumir-se que a terceira proposta anteriormente citada, é a mais adequada e a que atendeu, simultaneamente, às verificações dos ELU e ELS; o que a torna viável para aplicações práticas / The present work deals with dimensioning and verification of the safety conditions of reinforced concrete structural elements, taking into account the material non-linearity. It includes a new proposal for the simultaneous verification of the ultimate limit states (ULS) and the serviceability limit states (SLS) for reinforced concrete bending elements, enhancing finite element applications with physical non-linearities. The alternative proposals for the material safety factors include the use of mean values for the stress-strain relationships and the strength of materials; reference values that allow the composition of global safety coefficients that do not dependent on the type of failure, brittle in the concrete or ductile in the steel and, finally, means values for the concrete and steel stress-strain relationships, keeping the stresses always lower than the design strength values. Rectangular and T-type cross-sectional areas in pure bending were analyzed, using the alternative proposals. Statically determinate and hyperstatic beams were also studied to verify the safety conditions, including the redistribution of the internal forces in the hyperstatic cases. According to the analyses performed it is apparent that the third proposal is the most adequate and satisfies simultaneously the ULS and SLS verifications, being viable for practical applications

A evolução das pontes estaiadas modernas mostra a procura da engenharia de pontes por sistemas estruturais cada vez mais leves e esbeltos. No intuito de dar contexto ao problema de análise de estruturas esbeltas, de maneira geral e desde a perspectiva da concepção, se discutem os vários arranjos estruturais que podem se obter ao combinar o pilão, o sistema de suspensão por estais e o tabuleiro, elementos que compõem qualquer sistema estrutural de ponte estaiada. Este trabalho apresenta um método de análise estrutural estático não linear que considera os efeitos decorrentes da mudança da geometria da estrutura sob carregamentos (não linearidade geométrica) e os efeitos da resposta não linear da seção de concreto estrutural quando solicitada por flexão oblíqua composta (comportamento não linear do material). O programa ANLST foi elaborado para obter as relações momento-normal-curvatura e as rigidezes secantes na flexão oblíqua composta para uma seção de concreto de geometria arbitraria, esses resultados são integrados com uma análise elástica de segunda ordem, que é executada no programa SAP2000 para análise estrutural por elementos finitos. Mostra-se a formulação do método de análise elástica de segunda ordem pelo princípio dos deslocamentos virtuais, que leva em consideração os efeitos dos deslocamentos finitos dos nós do modelo para a resposta da estrutura, por meio da matriz de rigidez geométrica do elemento barra no espaço. Finalmente são apresentados dois exemplos de estruturas planas para validar o método e um exemplo de uma estrutura espacial para a aplicação do método. Todos esses exemplos mostram que os esforços e deslocamentos de segunda ordem, em este tipo de estruturas, não podem ser desprezados. / Modern cable stayed bridges evolution shows the bridge engineering searching for lightweight and slender structural systems. Trying to give context for the problem of analysis of slender structures, of a general mode and from the conception perspective, is discussed the several structural layouts that can be obtained from the combination of pylon, cable stayed suspension system and girder, elements that compose any structural system of cable stayed bridges. This work presents a method of non-linear static structural analysis that consider the resulting effects of geometry change under loading (geometric non linearity), and the effects of nonlinear response of the structural concrete section when it is loading for biaxial bending and axial force interaction (material non linearity). The ANLST program was developed to obtain the moment-axial-curvature relationships and the secant stiffness for biaxial bending and axial force interaction for a concrete section of arbitrary geometry. These results are integrated with the second order elastic static analysis, which is executed in the finite element program SAP2000 for structural analysis. A formulation of method for second order elastic analysis is shown by the virtual displacement principle, which leads in consideration the effects of finite displacement of the model\'s nodes for the structural behavior, by means of geometric stiffness matrix for space frame element. Finally are shown two examples of plane structures for the validation of the method and one example of space structure for the application of the method. All of these examples showed that second order forces and displacements can\'t be despised in this type of structures.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-10-16T13:23:47Z No. of bitstreams: 1 Andréia Grasiela Führ_.pdf: 1188946 bytes, checksum: 1e639f31e0753bea5b50ab2319cc96a4 (MD5) / Made available in DSpace on 2017-10-16T13:23:47Z (GMT). No. of bitstreams: 1 Andréia Grasiela Führ_.pdf: 1188946 bytes, checksum: 1e639f31e0753bea5b50ab2319cc96a4 (MD5) Previous issue date: 2017-07-19 / Nenhuma / É crescente a preocupação com o desempenho das edificações concomitantemente com os danos causados ao meio ambiente durante a execução de uma obra. No âmbito do conceito do tripé da sustentabilidade é de extrema importância analisar os materiais que compõem uma edificação, pois estes influenciam os fatores que podem reduzir custos, melhorar o desempenho da edificação e minimizar os impactos ambientais. Com o intuito de melhorar o desempenho térmico, reduzir o peso próprio e reduzir custos com a estrutura, podem ser utilizados painéis monolíticos com núcleo de poliestireno expandido (EPS) como vedações verticais. Os painéis monolíticos são compostos por um núcleo de EPS, envolto por malha metálica e camadas interna e externa de revestimento argamassado, composto por fibras de polipropileno. Foi analisada a influência no dimensionamento da estrutura e nos custos da obra com painéis monolíticos em EPS e paredes convencionais de alvenaria de blocos cerâmicos. Esta análise foi realizada a fim de verificar a redução do volume de concreto, do peso de aço e no custo total da obra, ao utilizar este sistema. Para tal finalidade, foi utilizado um projeto de uma edificação multiresidencial de 4 pavimentos com área total de 1432,00m² e outro projeto de um condomínio horizontal com área total de 600,43m², avaliando duas tipologias. A partir destes projetos foi dimensionada cada edificação com as vedações verticais em blocos cerâmicos e painéis monolíticos em EPS. Os modelos de cálculo foram analisados, para quantificar o total de concreto e aço em cada opção. Através da análise do quantitativo de concreto observou-se uma redução de 10,69% na edificação de 4 pavimentos e 7,23% no condomínio horizontal com os painéis monolíticos de EPS. Já no quantitativo de aço, a diferença foi um pouco menor, de 6,02% na edificação de 4 pavimentos e 1,69% no condomínio horizontal. Os painéis monolíticos em EPS também apresentaram vantagens em relação ao orçamento total da estrutura e vedações e em relação ao tempo de execução da obra. O orçamento da edificação de 4 pavimentos com vedações verticais em EPS ficou 4,92% mais barata, o que representa uma economia de R$ 30.698,08. E o tempo de execução foi reduzido em 19 dias, adotando este sistema. Já no orçamento do condomínio horizontal, a diferença foi semelhante, de 4,90%, o que representa uma economia de R$ 12.227,74. E o tempo de execução desta edificação seria reduzido em 18 dias. / There is growing the concern about the performance of buildings concorcomitantly with the damage caused to the environment during the execution of a work. Under the concept of the triple bottom line, it is extremely important to analyse the materials that make up a building, as they influence the factors that can reduce costs, improve performance of the building and minimize environmental impacts. In order to improve thermal performance, reduce your weight and reduce costs with the structure can be used monolithic panels in EPS and vertical seals. Monolithic EPS panels comprise a core of expanded polystyrene (EPS), surrounded by metal mesh and a coating layer. It will be consideration to influence of the structure and cost of the work is the masonry walls were replaced by monolithic panels in EPS. For this purpose, it will be used a design of a building of 4 floors with área of 1342,00 m² and another project of a horizontal condominium with a total area of 600,43m², evaluating two typologies. From this projects was dimensioned the structure with walls in ceramic blocks and monolithic panels in EPS. The calculation models were analyzed to quantify the total concrete and steel in each option. The concrete quantitative analysis showed a reduction of 10,69% in the building of 4 floors ans 7,23% in the condominium with the monolithic panels of EPS. In the quantity of steel, the difference was slightly lower, of 6,02% in the building of 4 floors and 1,69% in the horizontal condominium. EPS monolithic panels also had advantages over the total budget of the structure and fences and in relation to the execution time of the work. The budget os the building with 4 floors was 4,92% cheaper, wich represents a saving of R$ 30.698,08. And the execution time was reduced by 19 days, adopting this system. In the horizontal condominium budget, the difference was similar, of 4,90%, wich represents a saving of R$ 12.227,74. And the execution time of this building would be reduced in 18 days.

A fim de prever mecanismos para o controle dos danos impostos pela corrosão faz-se necessário deter ferramentas e conhecimento suficientes para entender os efeitos desta manifestação patológica sobre o comportamento mecânico do concreto armado. Nos últimos anos tornou-se crescente a utilização da modelagem numérica na simulação da degradação causados pela corrosão, graças ao baixo custo necessário à sua fomentação. Sabendo disso, nesta pesquisa foi desenvolvido um modelo numérico para a simulação em nível mesoscópico da expansão do concreto armado devido à formação de produtos de corrosão. O modelo desenvolvido é baseado no Método dos Elementos Finitos Posicional (MEFP) sob formulação Lagrangiana total, considerando material elástico isotrópico, com lei constitutiva de Saint-Venant-Kirchhoff e comportamento não linear geométrico. Para a representação das armaduras e dos produtos de corrosão, os quais estão inseridos na matriz de concreto, empregam-se elementos finitos lineares (fibras) ou planos (partículas) acoplados à malha de concreto por meio da técnica de embutimento. O comportamento dos produtos de corrosão é descrito por meio de formulações existentes na literatura, utilizando modelos analíticos relacionados a parâmetros intrínsecos ao fenômeno da corrosão e ao tempo de propagação. Os resultados encontrados neste trabalho apontam a eficiência do modelo desenvolvido e a sua aplicabilidade frente à simulação do comportamento mecânico de estruturas de concreto armado sujeitas à corrosão uniforme. / In order to provide the mechanisms for corrosion damage control, it is necessary to own sufficient software tools and knowledge for understanding the effects of this pathologic manifestation on the mechanic behavior of the reinforced concrete. In recent years it has become expanding the utilization of numeric modeling in the simulation of degradation arising from corrosion, thanks to low-cost of its fomentation. Knowing that in this research was designed a numeric model for a simulation at the mesoscopic level of the reinforced concrete because of the corrosion products. The designed model is based on the Finite Element Method (FEM) using the total Lagrange formulation, considering an elastic isotropic material, with a constitutive law of Saint-Venant-Kirchhoff and a behavior nongeometric linear. For a representation of the reinforcements and of the corrosion products (rust), which are inserted in the concrete matrix, it is used finite linear elements (fibers) or planes (particles) attached to the matrix of concrete through the technic embodiment. The products corrosion behavior is described by the formulations found in the literature, using analytical models related to parameters intrinsic to the corrosion phenomenon and to propagation time. The observed results in this work point out to the efficiency of this developed model and its applicability in view of the mechanical behavior of reinforced concrete structures liable to uniform corrosion.

The corrosion of steel reinforcement in reinforced concrete structures constitutes an alarming problem. To combat this problem, researchers at the University of Texas at Austin developed two, low-cost, passive, wireless sensors: a threshold, corrosion sensor and an analog conductivity sensor. Today, the basic circuit designs for both sensors are finished and their reliabilities are confirmed. However, multiple problems regarding the durability of the sensors remain. This research project: (a) identifies these problems, (b) proposes enhancements for each type of passive, wireless sensor, (c) tests and evaluates the proposed modifications to the sensors, and (d) proposes potential improvements and areas of research regarding the future development of these two sensors. / text

The amount of total and relative sway of a framed or a composite (frame-shear wall) building is of utmost importance in assessing the seismic resistance of the building. Therefore, the design engineer must calculate the sway profile of the building several times during the design process. However, it is not a simple task to calculate the sway of a three-dimensional structure. Of course, computer programs can do the job, but developing the three-dimensional model becomes necessary, which is obviously tedious and time consuming. An easy to apply analytical method is developed, which enables the determination of sway profiles of framed and composite buildings subject to seismic loading. Various framed and composite three-dimensional buildings subject to lateral seismic loads are solved by SAP2000 and the proposed analytical method. The sway profiles are compared and found to be in very good agreement. In most cases, the amount of error involved is less than 5 %. The analytical method is applied to determine sway magnitudes at any desired elevation of the building, the relative sway between two consecutive floors, the slope at any desired point along the height and the curvature distribution of the building from foundation to roof level. After sway and sway-related properties are known, the requirements of the Turkish Earthquake Code can be evaluated and / or checked. By using the analytical method, the amount of shear walls necessary to satisfy Turkish Earthquake Code requirements are determined. Thus, a vital design question has been answered, which up till present time, could only be met by rough empirical guidelines. A mathematical derivation is presented to satisfy the strength requirement of a three-dimensional composite building subject to seismic loading. Thus, the occurrence of shear failure before moment failure in the building is securely avoided. A design procedure is developed to satisfy the stiffness requirement of composite buildings subject to lateral seismic loading. Some useful tools, such as executable user-friendly programs written by using &ldquo / Borland Delphi&rdquo / , have been developed to make the analysis and design easy for the engineer. A method is also developed to satisfy the ductility requirement of composite buildings subject to lateral seismic loading based on a plastic analysis. The commonly accepted sway ductility of &amp / #956 / &amp / #916 / =5 has been used and successful seismic energy dissipation is thus obtained.