A aplicação de Ensaios Não Destrutivos (END) é considerada uma alternativa para monitorar o estado das estruturas de concreto armado, principalmente quando ocorrem falhas de projeto, erros de dosagem, problemas na mistura, transporte ou lançamento do concreto. A medida da Velocidade de Pulso Ultrassônico (VPU) é um END que vem sendo usado comumente em diversas áreas da engenharia civil, devido à facilidade da operação, ao seu baixo custo, à rapidez na execução dos testes e à ausência de danos ao material analisado. O objetivo deste trabalho consiste em apresentar o resultado de uma pesquisa experimental, que visou estudar a influência que determinadas variáveis operacionais exercem sobre os resultados obtidos nos ensaios de VPU e qual a real capacidade de penetração e detecção de defeitos de diversas magnitudes. As medições foram realizadas utilizando o ultrassom pelo modo de transmissão indireta, pois esta é a alternativa que mais se adapta às condições verificadas no exame de estruturas reais de concreto armado. Primeiramente, foram moldados em laboratório dois blocos de concreto, com dimensões próximas às encontradas em estruturas reais de grande porte: um com armadura nas duas faces e outro sem armadura. Em ambos os elementos foram introduzidos objetos para simular possíveis falhas de concretagem. Em uma segunda etapa, foram realizadas perfurações visando identificar a capacidade de detecção de vazios da técnica de VPU para diferentes profundidades. Os resultados são apresentados na forma de imagens geradas através de software e por meio de analises estatísticas. Este estudo verificou que a escolha dos parâmetros de ensaio é um fator determinante para permitir a interpretação correta dos resultados, salientando-se que a experiência do operador e as dimensões de grid são os parâmetros que mais interferem na interpretação dos dados. / The use of Non-destructive Testing (NDT) methods is considered an alternative to monitor the behaviour of reinforced concrete structures, especially when there are design problems or errors related to concrete mixing, transport, placement and casting errors. The Ultrasonic Pulse Velocity (UPV) method is a Non-Destructive Test that is gaining acceptance. The test has been commonly used in various civil engineering areas due to the fact that it is easy to operate and rapid to perform, and to the low cost and lack of damage to the tested material. The objective of this work is to present the results of an experimental research that aimed to study the influence of certain technological variables on the measurements obtained from UPV tests. The work also aims to gather data to assess the penetration capacity of the US waves and their ability to detect defects of various dimensions. The measurements were performed using the indirect transmission mode, to simulate real work conditions on large structures. Firstly, two massive concrete blocks were cast in the laboratory, with dimensions close to real life structures: one with steel reinforcement on both sides and the other without reinforcement. Objects were introduced in both elements to simulate possible defects due to casting. In a second stage, perforations were conducted in the concrete elements to identify the void detection capability of the UPV technique for different depths. The results are presented by images generated by specific software and by using statistical analysis. This study found that the test parameters influence significantly the correct interpretation of the results. The operator experience and the grid dimensions are the parameters that most influence UPV data analysis.

O risco de incêndio e seus prejuízos às vidas humanas e ao patrimônio tornaram-se cada vez maiores com o desenvolvimento urbano e a evolução da construção civil. Assim, os meios de proteção contra o incêndio tornam-se cada vez mais necessários, tanto os meios ativos (sprinklers, brigada de incêndio, etc), quanto os meios passivos (proteção térmica de estruturas, etc). Em situação de incêndio, a proteção à vida e ao patrimônio deve ser garantida pelos meios de proteção das edificações evitando-se o colapso de parte ou toda estrutura. A eventualidade do sinistro não deve ser desprezada sendo que, melhorar o desempenho das estruturas visando a iminência de um incêndio é sinônimo de economia em um aspecto abrangente: proteção à vida, ao patrimônio e à atividade econômica desenvolvida no estabelecimento. Neste trabalho, realiza-se uma apresentação do tema comportamento das estruturas de concreto em situação de incêndio, abordando aspectos de análise de risco incêndio, seguro contra incêndio, o fenômeno incêndio e suas variáveis, meios de proteção térmica das estruturas e aspectos arquitetônicos e estruturais que influenciam na probabilidade de ocorrência de um incêndio. No plano experimental, analisa-se a susceptibilidade ao fogo do concreto, através da aferição da perda de resistência mecânica de alguns traços submetidos a curvas de temperatura. Realiza-se também a análise de um caso real de incêndio sob o ponto de vista da descrição do incêndio, seus danos às estruturas de concreto e metodologia de recuperação das estruturas afetadas. / The fire risk and its damage to the human being lifes and to the assets had become each time greater with the urban development and the evolution of civil construction. Thus, the ways of fire protection become each time more necessary, as much the direct assets (fire sprinklers, brigade, etc), as the indirect assets (structural thermal insullation, etc). In fire situation, the protection to the life and the assets must be guaranteed by the ways of protection inside buildings, preventing high costs of structural recovery and, mainly, the immediate collapse of all or part of the structure. The ocurrence of a fire accident does not have to be rejected and improving the performance of the structures aiming at the imminence of a fire is synonymous of economy in an including aspect: protection to the life, protection to the assets and to the activities in the building. In this work, a general overview of the behavior of concrete structures in fire situation is presented, approaching aspects of fire risk analysis, fire insurance, the fire phenomenon and its interferences, methods for thermal insullation and structural and architectural aspects that have influence in the probability of a fire occurrence. In the experimental plan, the susceptibility of hardened concrete to the fire is analysed, through the measurement of its mechanical resistance loss submitted to the high temperatures. The analysis of a real fire case in a building is also presented, highlighting the description of the fire, its damages to the hardened concrete structures and the development of a methodology of recovering the affected structures.

Este trabalho trata de detalhes de modelagem de estruturas de contraventamento de edifícios de concreto armado. Inicialmente são discutidos esquemas de modelagem para núcleos de rigidez. São comparados resultados obtidos através de três procedimentos distintos, com diferentes graus de simplicidade e eficiência. É também avaliada a contribuição de vigas secundárias, vigas que não estão conectadas diretamente em pilares, na estrutura de contraventamento. Para tanto são apresentados alguns arranjos onde a consideração das referidas vigas muda significativamente os resultados obtidos e a modelagem de uma estrutura completa de edifício com e sem as referidas vigas secundárias. Por fim, são apresentados um gerador de estruturas de contraventamento e um pós-processador gráfico para visualização da estrutura gerada e dos resultados obtidos, sejam esforços ou deslocamentos. / This work deals with some modelling details of bracing structures for reinforced concrete buildings. lnitially, modelling schemes of structural cores are discussed. Results obtained by three different procedures, with distinct levels of simplicity and efficacy, are compared. The work also shows the contribution of secondary beams, ones that are not directly connected to columns, to the stiffness of bracing structures. Some schemes, in which the consideration of those beams changes expressively the obtained results, and the complete modelling of a building structure, with and without secondary beams, are presented. Finally, the work also introduces a generator of bracing structures and a pos-processor, that permit the visualisation of the obtained results: internal efforts and displacements.

Em estruturas de concreto pré-moldado, as ligações usualmente apresentam comportamento semi-rígido, apesar desse tipo de vinculação não ser sempre considerado no projeto e análise das estruturas. Ensaios dinâmicos para a determinação da rigidez da ligação apresentam a vantagem de serem não-destrutivos e a possibilidade de serem utilizados na verificação das condições reais de vínculo ou para a avaliação da necessidade de um eventual reforço estrutural. Este trabalho apresenta o desenvolvimento de um método para a análise da deformabilidade de estruturas de concreto baseado em ensaios dinâmicos, focalizando a semi-rigidez das ligações de elementos pré-moldados. Os objetos de estudo específicos são as ligações viga-pilar com capacidade de transmissão de forças e momentos. Em uma etapa preliminar desta pesquisa, realizaram-se ensaios-piloto em diferentes modelos de estruturas de concreto e de aço, em tamanho real e reduzido, com diferentes condições de contorno, para avaliar os instrumentos, equipamentos e sensores disponíveis. A partir da verificação da metodologia experimental proposta, realizou-se um estudo comparativo dos resultados obtidos com ensaios estáticos e dinâmicos em um modelo reduzido de pórtico de concreto pré-moldado, utilizando métodos diretos na obtenção da rigidez da ligação entre os elementos. Na confecção das ligações viga-pilar, foram empregados dispositivos usuais, tais como: dente e consolo, chumbador, almofada de apoio e preenchimento com graute e, posteriormente, aplicados reforços por inserção de laminado de PRFC inseridos no concreto de cobrimento, que permitiu o incremento da resistência e da rigidez à flexão das ligações. A metodologia experimental para determinar a rigidez da ligação viga-pilar envolveu procedimentos diretos, com ensaios dinâmicos de vibração forçada e sinais medidos por acelerômetros, e ensaios estáticos usuais em que se utilizam transdutores de deslocamento e clinômetros. Os resultados dos ensaios com os modelos de concreto, corroborados pelos resultados dos modelos metálicos, demonstram a validade da utilização da metodologia experimental dinâmica para determinação direta da rigidez de ligações. As conclusões obtidas aplicam-se diretamente ao projeto das estruturas e à prática da investigação estrutural, dentro do ambiente acadêmico e da indústria. / Usually precast concrete connections are considered as perfect joints (pinned or rigid), however the real behavior can be intermediate what is called semi-rigid. The use of dynamic tests is an advantage to obtain stiffness values without damaging the structure and can be used to assess the real boundary conditions or verify the need for structural strengthening. This research aims to develop a dynamic experimental procedure to determine the beam-to-column connection stiffness of precast concrete structures directly from accelerometer measured data. The preliminary tests were carried on specimens of real size or reduced scale, as well as concrete or steel connection specimens with different boundary conditions. The experimental tests were conducted in a reduced scale concrete frame composed of precast columns and beam. The frame was tested through dynamic and static methods in order to obtain the beam-to-column stiffness value directly. The beam was connected to the columns by pinned connections, formed by support cushions and dowels. In addition, the connections were strengthened by embedding CFRP strips in the lateral concrete cover, according to NSM technique (Near-Surface Mounted). Experimental static and dynamic tests were done at different loading steps. The results obtained with concrete and steel models show good agreement between static and dynamic tests.

The diploma thesis deals with a new building of a single-storey production object, which is made as a precast concrete frame with a lightweight cladding. Part of the new building is also facilities for employees and its administrative staff, which is also based on precast concrete frame divided into two floors. Cladding is made as masonry with ventilated facade. The internal division of buildings is made by plasterboard partitions. The project is located in the industrial zone Košíkov near Velká Bíteš.

Concrete is essential for the construction industry with characteristic properties that make it irreplaceable in some aspects. However, due to the large volumes consumed and the energy intense cement clinker production it also has a notable climate impact. In order to reach the international and national sustainability goals it is therefore important to reduce the climate impact of concrete structures. There are many ways to influence the environmental impact of concrete and a detailed analysis is one of the actions that could push the industry and the society towards a sustainable development. The purpose of this research is to evaluate the environmental impact of concrete structures and the built environment and to highlight the possibilities to reduce that impact with choice of concrete mix and innovative design solutions. A life cycle assessment (LCA) was carried out to analyze the environmental impact of two thin façade solutions with innovative materials and to evaluate influences of different greenhouse gas reducing measures on concrete bridges. The influence of supplementary cementitious materials (SCM) in terms of climate impact and durability was also analyzed. The results indicate that SCMs have a twofold effect on the climate impact of reinforced concrete structures. Not only do they reduce the greenhouse gases through cement clinker replacement but also by an improvement of durability regarding chloride ingress. Currently, this is not considered in the regulations, which makes it difficult to foresee in LCA at early design stages. The results also show great possibilities to reduce the climate impact through different measures and design alternatives and the need for further development of products and solutions. / <p>QC 20171002</p>

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.

[pt] Essa tese apresenta as questões experimentais relativas à avaliação da saúde de estruturas de concreto com o objetivo de propor uma alternativa à avaliação subjetiva tradicional de estruturas civis, complementando-a com uma avaliação mais objetiva utilizando o GPR. A ênfase foi na validação de um procedimento sólido de avaliação da saúde de edifícios, de estações de tratamento de águas residuais e de túneis. O GPR foi escolhido por ser considerado um dos métodos de ensaios não destrutivos mais adotados para investigação de estruturas de concreto devido à sua relativa insensibilidade às condições ambientais, ter alta resolução, eficácia e disponibilidade de resultados preliminares em tempo real. A pesquisa desenvolvida nessa tese teve ênfase na verificação de as-built da construção, detecção de danos, locação e quantificação de armadura que são de grande interesse no contexto do controle estrutural. Os resultados apresentados nessa tese demonstram que o Ground Penetrating Radar (GPR) pode ser uma ferramenta muito útil para produzir projetos de detalhamento estrutural já que ele pode estimar espessura de recobrimento de concreto e profundidade e locação do reforço. Os resultados também mostram que a deterioração do concreto, bem como a corrosão das barras podem ser verificados após a análise de atributos fornecidos pela verificação feita com o GPR. Danos são detectados por meio da redução da profundidade do refletor, aumentando a amplitude das ondas eletromagnéticas e aumentando a atenuação expressa pelo gráfico de dB decay. Além disso, também verificou-se que a condição da barra de aço pode ser avaliada através de fatias em diferentes tempos/profundidade, obtidas na prospecção tridimensional. Adicionalmente, o programa experimentado também avaliou a viabilidade de empregar o GPR na avaliação da distribuição de fibras de aço em revestimento de túnel de concreto projetado, considerando-se o GPR como uma ferramenta útil para monitoramento e mapeamento in situ durante a o método de construção NATM de túneis. Os resultados dos ensaios realizados em prismas de concreto auto adensável reforçado com fibra de aço demonstraram que a distribuição das fibras não é uniforme. O processamento digital de imagem mostrou que as fibras não são distribuídas uniformemente e há variação do número de fibras em diferentes seções do prisma. A análise estatística realizada nos resultados também identificou que a distância entre as fibras também varia. Quando compara-se os resultados obtidos com o GPR e os resultados obtidos das análises digitais de imagens percebe-se uma boa relação entre ambos. Também foi observado que a amplitude do sinal do GPR não apenas fornece informações sobre a distribuição das fibras, mas também sobre regiões com ausência delas. Com base nos resultados do programa experimental, acredita-se que o GPR possa fornecer um feedback imediato das informações e pode ser usado como uma ferramenta de ajuste dinâmico no projeto NATM. / [en] This thesis presented the experimental issues concerning the health assessment of concrete structures with the desire to replace the traditional subjective assessment of civil structures with a more objective assessment using the GPR. The emphasis here was on validating a sound procedure of health assessment for buildings, wastewater treatment stations and concrete test specimens. GPR was chosen since it is considered one of the most popular non-destructive testing methods adopted for concrete structure imaging because of its relative insensitivity to ambient conditions, high resolution, effectiveness, and availability of real-time images The research carried out in this thesis emphasized on as-built designing, damage detection, location, and quantification, which is of interest in the context of structural control. The results presented in this thesis demonstrated that the groundpenetrating radar (GPR) could be used as a useful tool in producing structural detailing drawings since it can provide the thickness of covering concrete and the depth and location of reinforcement. The results also show that deterioration of concrete mass and corrosion of its rebars could be also be assessed by the attributes provided by a GPR scan. Damages are detected by reducing the depth of the reflector, increasing the amplitude of EM waves and increasing attenuation expressed by the dB decay. Further to these, it was also indicated that the rebar condition can be assessed through slices at different times/depths obtained from a 3-D survey. In addition to that, the program also assessed the feasibility of GPR in evaluating steel fiber distribution within short beam test specimens used in several standard test methods for determining mechanical properties. Results revealed that the distribution of steel fibers within a beam is not uniform. Digital and processed images showed that fibers are not evenly distributed and there is a disparity between the numbers of fibers in different sections of the short beam. A statistical analysis performed on the results also found that the distance between fibers also varies within the short beam. When sketches of the emitted and recorded GPR signal in a single radar trace mode are compared to the digital and processed images it was perceived a good relationship between the GPR signal and the distribution of steel fibers within the short beam. It was additionally noticed that GPR signal amplitude not only supplies information on how the fibers are close to each other but also reflects regions with the absence of fibers. Results have also shown that a GPR system using a high-frequency antenna could assess weaker zones of steel fiber reinforcement within self-consolidating concrete short beams.

Despite being the world’s second most important low-carbon source of electricity, the development of nuclear capacities is limited and does not comply with the International Energy Agency’s Sustainable Development Scenario. One of the main reasons for this lack of development is high and increasing costs of new nuclear capacities. In fact, capital costs can account for more than 80% of the Levelized Cost of Energy of a new nuclear power plant. Design accounts for about 10% and construction accounts for about 20% of the total capital cost. The importance of design and construction in nuclear power plants’ costs is partly due to limitations of traditional construction methods regarding both technical possibilities and realization schedules. Modular construction methods are proposed to reduce new nuclear power plants’ construction costs, and in particular steel-plate composite structures modular construction. Steel-plate composite structures consist of a structural interaction between thin steel plates and precast concrete. The aim of this thesis was to evaluate the capacity of modular construction, using steel-plate composite panels, to fulfil nuclear safety and functional requirements; as well as to identify potential related gains and opportunities. Advantages and constraints of steel-plate composite modules were identified in scientific literature and intergovernmental opportunity studies, and were related to the specificities of nuclear structures’ design and construction. Steel-plate composite structures modular construction is based on the manufacturing of steel concrete composite modules outside of the civil works site. The higher productivity of workshops and the possible task parallelization may lead to significant construction schedules shortening and capital costs reduction. In addition, steel-plate composite modules offer new technical possibilities which may help solving some constructability issues. However, steel-plate composite structures modular construction requires a reconsideration of the traditional design and construction methods, as they imply new challenges and constraints. In particular, the modularization issue should be addressed as soon as possible in the design, and the module manufacturing capacities should be quickly identified or created in order to deliver properly manufactured modules on-time. Considering the advantages and constraints of steel-plate composite structures modular construction, it appears that steel-plate composite modules may fit advantageously most of the nuclear design requirements. However, due to the lack of feedback, it is proposed that the usage of steel-plate composite modules be limited to critical concrete structures of the containment building. In particular, it appears that the containment dome and the reactor pit construction may benefit from steel-plate composite structures construction methods. / Trots att kärnkraften är världens näst viktigaste koldioxidsnåla elkälla är utvecklingen av kärnkraftskapaciteten begränsad och överensstämmer inte med Internationella energiorganets scenario för hållbar utveckling. En av de viktigaste orsakerna till denna långsamma utveckling är de höga och ökande kostnaderna för ny kärnkraftskapacitet. Kapitalkostnaderna kan faktiskt utgöra mer än 80 % av den energikostnaden för ett nytt kärnkraftverk. Konstruktionen står för cirka 10 % och byggandet för cirka 20 % av den totala kapitalkostnaden. Att projektering och byggande har så stor betydelse för kärnkraftverkens kostnader beror delvis på begränsningar i de traditionella byggmetoderna när det gäller både tekniska möjligheter och tidsplaner för genomförandet. För att minska byggkostnaderna för nya kärnkraftverk föreslås byggmetoder som bygger på moduler, ”modulära byggmetoder”, särskilt sådana byggmetoder för stålplåtskompositkonstruktioner. Stålplåtskompositkonstruktionen består av en tunn plåt som samverkar med förtillverkad betong. Syftet med denna avhandling var att utvärdera möjligheterna för modulära konstruktioner med stålplåtskompositpaneler att uppfylla kraven på kärnkraftssäkerhet och funktionalitet samt att identifiera potentiella vinster och förbättringar i samband med detta. Fördelar och begränsningar med stålplåtskompositmoduler identifierades i vetenskaplig litteratur och i mellanstatliga studier om möjligheter och relaterades till de särskilda egenskaperna hos kärnkraftstekniska konstruktioners utformning och konstruktion. Modulär konstruktion av stålplåtskompositkonstruktioner bygger på tillverkning av stålbetongkompositmoduler utanför byggarbetsplatsen. Den högre produktiviteten i verkstäderna och den möjliga parallelliseringen av arbetsuppgifter kan leda till en betydande förkortning av produktionstiderna och en minskning av kapitalkostnaderna. Dessutom erbjuder stålplåtskompositmoduler nya tekniska möjligheter som kan bidra till att lösa vissa byggbarhetsproblem. Modulbyggandet av stålplåtskompositkonstruktioner kräver dock en omprövning av de traditionella konstruktions- och byggmetoderna, eftersom de innebär nya utmaningar och begränsningar. I synnerhet bör modulariseringsfrågan tas upp så snart som möjligt i byggprocessen, och modultillverkningskapaciteten bör snabbt identifieras eller skapas för att kunna leverera korrekt tillverkade moduler i tid. Med tanke på fördelarna och begränsningarna med modulbyggandet av stålplåtskompositkonstruktioner verkar det som om stålplåtskompositmoduler med fördel kan uppfylla de flesta av kraven för kärnkraftsteknisk konstruktion. På grund av bristen på feedback föreslås dock att användningen av stålplåtskompositmoduler begränsas till kritiska betongkonstruktioner i inneslutningsbyggnaden. I synnerhet verkar det som om konstruktionen av inneslutningskupolen och reaktorstödstrukturen kan dra nytta av konstruktionsmetoderna för stålplåtskompositkonstruktioner

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.