Evaluación de Simultaneidad de acciones sísmicas para diseño de estructuras con aislación sísmica en zonas de subducción

Abstract

This research evaluates the impact of the simultaneity of seismic components (X, Y, Z) on the design of structures with seismic isolation in subduction zones. The main objective is to quantify the underestimation of design demands produced by simplified methods (100/30, SRSS) compared to a realistic three-dimensional analysis. This study is justified by the need to guarantee the stability of critical infrastructure against uplift phenomena and excessive displacements. For the development, a sample of 53 acceleration records from subduction events was selected from the PEER NGA database. Nonlinear time history analyses (NLTHA) were performed using a Bouc-Wen constitutive model to represent the behavior of the isolator. The algorithms were numerically integrated using the Newmark-beta method, considering standards such as ASCE/SEI 7-22. The results indicated that the average horizontal simultaneity is 41%, a value that rises to 50% at the 84th percentile, exceeding the 30% prescribed by conventional practice. Furthermore, it was verified that the vertical component significantly alters axial forces, increasing the risk of tension and reaching participation levels in the 11% to 28% range. It is concluded that simplified methods systematically underestimate critical design demands. Therefore, the use of simultaneous three-dimensional analyses is recommended to ensure the resilience and operability of isolated structures in subduction scenarios. Keywords: Seismic Isolation, Simultaneity, Subduction, NLTHA.