An innovative displacement-based seismic design procedure for regular planar framed structures considering sidesway collapse prevention is presented. The method proposed, based on the characterization of a multiple degree of freedom system by means of a single degree of freedom system, allows the design of structures with a P-Delta induced negative stiffness to satisfy an interstorey drift threshold and/or prevent dynamic instability. The design procedure relies on the use of elastic analysis of simplified models and collapse or constant ductility spectra, hence, non-linear dynamic analyses are not required. To illustrate the potential of the method proposed, example applications and validation of the results obtained via incremental dynamic analysis are shown.
Se presenta un método novedoso de diseño sísmico basado en desplazamientos para marcos de concreto reforzado. Su formulación se sustenta en el concepto de sistema de referencia, el cual radica en la caracterización de la respuesta estructural mediante las propiedades elásticas e inelásticas del modo fundamental. El método propuesto consiste en la construcción de una curva bilineal de seudoaceleracion vs desplazamientos espectrales, denominada curva de comportamiento; el desplazamiento de fluencia se define acorde con la geometría y propiedades de la estructura, y el desplazamiento último se limita con base en una distorsión objetivo asociada al estado límite considerado. Los elementos estructurales se diseñan con las fuerzas obtenidas de un análisis elástico simplificado para las demandas definidas en dicha curva. Este método permite garantizar un estado límite mediante un procedimiento de diseño transparente y directo por lo que se puede considerar como una alternativa viable en la práctica de la ingeniería sísmica.
Summary
This paper presents a new methodology based on structural performance to determine uniform fragility design spectra, i.e., spectra with the same probability of exceedance of a performance level for a given seismic intensity. The design spectra calculated with this methodology provide directly the lateral strength, in terms of yield‐ pseudo‐accelerations, associated with the rate of exceedance of a specific ductility characterizing the performance level for which the structures will be designed. This procedure involves the assessment of the seismic hazard using a large enough number of seismic records of several magnitudes; these records are simulated with an improved empirical Green function method. The statistics of the performance of a single degree of freedom system are obtained using Monte Carlo simulation considering the seismic demand, the fundamental period, and the strength of the structure as uncertain variables. With these results, the conditional probability that a structure exceeds a specific performance level is obtained. The authors consider that the proposed procedure is a significant improvement to others considered in the literature and a useful research tool for the further development of uniform fragility spectra that can be used for the performance‐based seismic design and retrofit of structures.
This study utilized focus groups with Latinx students at a private, Midwestern university to explore the complexities inherent in the process of becoming a Hispanic-Serving Institution (HSI). The purpose of the study was: (a) to better understand Latinx students’ experiences at an “emerging” HSI, and (b) to understand how students understand an institutional journey toward the HSI designation. Findings point toward the value in exploring the Latinx student experience and perspective on HSI initiatives.
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