The feasibility of using superelastic shape memory alloys in the retrofit of multiple frame bridges is investigated. First, three shape memory alloy constitutive models with various levels of complexity are compared in order to determine the significance of including subloops and cyclic loading effects on the structural response. The results show that the structural response is more sensitive to the shape memory alloys strength degradation and residual deformation than the sublooping behavior. Next, two parametric studies are conducted to explore the sensitivity of hinge opening to the mechanical behavior of the superelastic shape memory alloys. The first study is focused on the hysteretic properties of the alloy that could vary depending on the chemical composition or the manufacturing process of the alloy, while the second study targets the changes in the mechanical behavior of shape memory alloys resulting from the variability in the ambient temperature. The results show that the hysteretic behavior of shape memory alloys has only a slight effect on the bridge hinge opening as long as the recentering property is maintained. A detailed study on the effect of temperature shows that a reduction in the ambient temperature tends to negatively affect the hinge opening while an increase in temperature results in a slight improvement. Next, a parametric study is conducted to examine the effectiveness of shape memory alloy retrofit devices in limiting hinge openings in bridges with various properties. In addition, a comparison is made with other devices such as conventional steel restrainers, metallic dampers, and viscoelastic solid dampers. The results illustrate that superelastic shape memory alloys are superior in their effectiveness compared to other devices in the case of bridges with moderate period ratios and high level of ductility, especially when subjected to strong earthquakes.

This thesis investigates the performance of composite frame structures with smart partially-restrained (PR) concrete filled tube (CFT) column connections through simplified 2D and advanced 3D computational simulations. It also provides a design methodology for new types of innovative connections based on achieving a beam hinging mechanism. These types of connections intend to utilize the recentering properties of super-elastic SMA tension bars, the energy dissipation capacity of low-carbon steel bars, and the robustness of CFT columns. In the first part of this study, three different PR-CFT connection prototypes were designed based on a hierarchy of strength models for each connection component. Numerical simulations with refined three dimensional (3D) solid elements were conducted on full scale PR-CFT connection models in order to verify the strength models and evaluate the system performance under static loading. Based on system information obtained from these analyses, simplified connection models were formulated by replacing the individual connection components with spring elements and condensing their contributions. Connection behavior under cyclic loads was extrapolated and then compared with the monotonic behavior. In the second part of this study, the application of these connections to low-rise composite frames was illustrated by designing both 2D and 3D, 4 and 6 story buildings for the Los Angeles region. A total of 36 frames were studied. Pushover curves plotted as the normalized shear force versus inter story drift ratio (ISDR) showed significant transition points: elastic range or proportional limit, full yielding of the cross-section, strength hardening, ultimate strength, and strength degradation or stability limit. Based on the transition points in the monotonic pushover curves, three performance levels were defined: Design Point, Yield Point, and Ultimate Point. All frames were stable up to the yield point level. For all fames, after reaching the ultimate point, plastic rotation increased significantly and concentrated on the lower levels. These observations were quantified through the use of elastic strength ratios and inelastic curvature ductility ratios. The composite frames showed superior performance over traditional welded ones in terms of ductility and stability, and validated the premises of this research.

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La escasez de registros sísmicos de gran magnitud considerados significativos, limita la determinación de la respuesta sísmica de una edificación de concreto armado. En este sentido, los acelerogramas artificiales representan una alternativa para definir el evento sísmico porque consideran condiciones específicas del sitio en estudio. Esta investigación analiza la respuesta sísmica de las estructuras para diversos registros sísmicos artificiales generados de espectros de diseño para distintas condiciones geotécnicas. El procedimiento de análisis empleado será el dinámico tiempo historia no lineal para obtener una mayor precisión en la respuesta sísmica. Los resultados obtenidos muestran que las derivas de entrepiso de las señales artificiales creadas con la función de intensidad de Liu se ajustan mejor a las derivas obtenidas del sismo real escalado. / The lack of large seismic records in some world regions limits the determination of the seismic response of a building. For that reason, artificial accelerograms represent an alternative to define the seismic event because they consider specific conditions of study site. This research analyses the structures seismic response for various artificial seismic records generated from design spectra and different geotechnical conditions. Dynamic nonlinear time history analysing was used to obtain greater precision in the seismic response. The results obtained show that the mezzanine drifts of the artificial signals created with the Liu intensity function better fit the drifts obtained from the scaled real earthquake. / Tesis

El presente estudio de investigación evalúa la respuesta sísmica de una clínica con aislamiento símico en Lima bajo la Norma Peruana de Aislamiento Sísmico E.031. Esta será comparada con la norma la Norma Chilena de Diseño Sísmico de Edificios NCh2745 y la Norma Americana ASCE/SEI 7, dichas normas internacionales han sido diseñadas para soportar eventos sísmicos severos, presentando parámetros rigurosos, con los cuales se podrá destacar las fortalezas y debilidades frente a la nueva Norma Peruana. En los capítulos siguientes se da entendimiento a la información que se debe poseer para analizar las tres normas, conceptos básicos de sismología y dinámica estructural, dentro de cada norma se verán los alcances, factores y parámetros que intervienen en la determinación del espectro de diseño, así como el análisis sísmico dinámico que las normas proponen y el modelamiento de la estructura de la clínica en el software ETABS. Luego se comparan los resultados de la respuesta sísmica, desplazamientos laterales, derivas y fuerzas cortantes, en las que se verán las exigencias que cada norma, llegando a saber si nuestra Norma Peruana en su modificación y mejora de su contenido se proyecta a ser una de las mejores normas de diseño sismorresistente, obteniendo así una perspectiva de nuestra Norma Peruana frente a una norma internacional ya consolidada y avalada por los años frente a sismos severos. / This research study evaluates the seismic response of a clinic with simian isolation in Lima under the draft Peruvian Seismic Isolation Standard E.031. This will be compared with the North American standard ASCE SEI 7-16 and the Chilean Seismic Design Standard for Buildings 2745, these international standards have been designed to withstand severe seismic events, presenting rigorous parameters, with which we can highlight the strengths and weaknesses against the new Peruvian Standard. In the following chapters, understanding is given to the information that must be possessed to analyze the three norms, basic concepts of seismology and structural dynamics, within each norm the scope, factors and parameters that are involved in the determination of the design spectrum will be seen, as well as the dynamic seismic analysis that the standards propose and the modeling of the clinical structure in the ETABS software. Then the results of the seismic response, lateral displacements, drifts and shear forces are compared, in which the requirements of each norm will be seen, getting to know if our Peruvian Standard in its modification and improvement of its content is projected to be one of the best seismic resistant design standards, thus obtaining a perspective of our Peruvian Standard against an international standard already consolidated and endorsed by the years against severe earthquakes. / Tesis