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Reinforced concrete (RC) moment frames comprise a significant portion of the built environment in areas with seismic hazards. The beam-to-column joints of these frames are key components that have a significant impact on the structure's behavior. Modern detailing provides sufficient strength within these joints to transfer the forces between the beams and the columns during a seismic event, but existing structures built with poor detailing are still quite prevalent. Identifying the need and extent of retrofits to ensure public safety through nondestructive means is of primary importance. Existing models used to analyze the performance of RC beam-to-column joints have either been developed for modern, well-detailed joints or are simplified so that they do not capture a broad range of phenomena. The present study is aimed to extend a modeling technique based on the nonlinear truss analogy to the analysis of RC beam-to-column joints under cyclic loads. Steel and concrete elements were arranged into a lattice truss structure with zero-length bond-slip springs connecting them. A new steel model was implemented to more accurately capture the constitutive behavior of reinforcing bars. The joint modeling approach captured well the shear response of the joint. It also provided a good indication of the distribution of forces within the joint. The model was validated against three recently tested beam-column subassemblies. These tests represented the detailing practice of poorly-detailed RC moment frames. The analytical results were in good agreement with the experimental data in terms of initial stiffness, strength and damage pattern through the joint. / Master of Science

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The purpose of this study is to analyze the foundation beam linked between two shear walls in the presence of lateral loads. Mat foundation with shear walls is one of the most commonly used reinforced concrete structural systems to resist the lateral load. When two independent walls are connected with a link beam, also known as the coupling beam, the overturning resistance of the building is largely increased. However, the coupling beams are relatively weaker structures and can develop larger stresses. When there is a mat foundation, or pile cap in case of pile foundation, the part of the foundation which is right below the coupling beam where no shear wall is present, will also get large stresses due to the highly rigid nature of adjacent shear walls. Most of the lateral deformations are imposed only on the coupling beams and foundation beam. There is not much literature or design procedure found in books and codes to mitigate the high risks associated with the foundation beam between shear walls on its design vulnerability. This thesis is focused on the risks associated with exceptionally high forces on the foundation beam due to earthquake forces.

Siempre ha sido una constante preocupación para los ingenieros representar la edificación lo más fielmente posible a lo real y del lado de la seguridad. A partir de este concepto, la presente investigación inicia con la disyuntiva de considerar a los elementos no estructurales dentro del análisis sísmico, cabiendo la posibilidad de generar efectos de torsión por una distribución asimétrica de tabiquería. El documento se divide en 4 capítulos, en el primero, se exponen los antecedentes, la problemática y los objetivos del documento, además de que se presenta el caso en estudio. En el segundo capítulo, se desarrolla el marco teórico del documento, el cual empieza por describir algunos conceptos básicos con los cuales se podrá entender mejor el resto del documento, luego se muestra el modelo para modelar los tabiques adheridos: puntales diagonales, y se analiza los diferentes modelos usados para la normativa nacional y algunas internacionales. Asimismo, se presentan flujogramas sobre los tipos de análisis sísmicos: dinámico y tiempo-historia. En el tercer capítulo, se plantea la metodología de trabajo y se proponen 4 casos de estudios. En el cuarto capítulo, se expondrán los modelos realizados con una comparación estratégica y gráfica de los resultados. A partir de ello, llegar a conclusiones y recomendaciones, los tabiques fallan por resistencia luego de un lapso por lo que se propone un modelo sísmico alterno al usualmente realizado con tabiques aislados. / It has always been a constant concern for engineers to represent the building as faithfully as the real case and safe as possible. From this concept, the present investigation began with the dilemma of considering the non-structural elements within the seismic analysis, the possibility of generating torsion effects due to asimetric distribution of infilled walls. The document is divided into four chapters, the first maps out the background, the problem and the objectives of the document, as well as the presentation of the case study. The second chapter develops the theoretical framework of the document, which be started with basic concepts with which the rest of the document can be understood, then the model for modeling the joined partitions is shown: diagonal struts, and is analyzed the different models used for national standards and some international ones. Likewise, a flow diagram is presented on the types of seismic analysis: dynamic and linear historical time. In the third chapter, the work methodology is presented and four cases of studies are proposed. In the fourth chapter, the models will be presented with a strategic comparison and the graph of the results. Based on this, reach conclusions and recommendations, partitions fail due to resistance after a period of time, so an alternative seismic model is proposed to the one generally carried out with isolated partitions. / Tesis

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This thesis presents a numerical study of the influence of varying story strength on the seismic performance of multi-story wood-frame shear wall buildings. In the prior FEMA P695 studies of these buildings, the non-simulated collapse limit-state was exceeded primarily in the first story. This observation raised interest in quantifying the influence of varying strength from story to story on seismic response. In this study, four distributions of strength are used as bounding cases. The Parabolic strength distribution (1) results from the ELF vertical force distribution method in ASCE 7 that assigns forces to each level based on weight and story height. The Triangular strength distribution (2) results from an assumed vertical force distribution that assigns lateral forces based on the seismic weight at each level. The Constant strength distribution (3) results from an assumed vertical force distribution that assigns a concentrated lateral force at the uppermost level based on the total seismic weight of all levels. The Baseline distribution (4) reflects a realistic vertical strength distribution resulting from the ELF vertical force distribution method. The FEMA P695 methodology, which quantifies seismic performance via adjusted collapse margin ratios, is employed in this study. The analytical models include P-Delta effects and utilize the 10-parameter hysteresis CASHEW model. It is observed that the Parabolic strength distribution allows for dissipation of energy over the height of the building, has less collapse risk than other strength distributions studied, and reduces occurrence of concentrated deformations in a single story from the onset of applied lateral force. / MS

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