Efecto de uso de factores de seguridad para el diseño de sistemas de aislación sísmica elastomérica en el desempeño sísmico de infraestructura crítica

Abstract

Hospital infrastructure represents a critical system whose post-seismic functionality is essential for emergency response. Elastomeric seismic isolation systems constitute the most effective technology to ensure this operational continuity; however, the disparity in safety factors among international standards generates uncertainty regarding their actual effect on seismic performance. This study evaluates the effect of normative safety factors on the seismic performance of elastomeric isolators for a ten-story hospital, through incremental dynamic analysis and analytical fragility curves, with the objective of providing quantitative evidence for the selection of appropriate normative criteria in the Ecuadorian context. Four elastomeric isolation systems were designed applying the requirements of Eurocode 8, NCh 2745, NTE E.031, and GB 50011, resulting in 163 devices distributed in four types according to vertical load level. The designed systems were implemented in a nonlinear structural model and subjected to incremental dynamic analysis using 22 pairs of seismic records with moment magnitude Mw ≥ 7.5 and high energy content in the period range of 3 to 5 seconds. The resulting fragility curves revealed that Eurocode 8, NCh 2745, and NTE E.031 produce median limit-state values for the critical isolators between 0.65g and 0.67g, statistically equivalent levels exceeding the site design PGA. The GB 50011 standard generated the greatest seismic vulnerability with a median of 0.50g, despite producing the dimensionally most robust system with 164.5 m³. The selection of the normative framework significantly determines both the dimensions and the seismic performance of the isolation system, with Eurocode 8 being the most efficient alternative in the performance-to-material ratio for the analyzed conditions. Volumetric conservatism does not guarantee greater seismic safety; the adequate distribution of hysteretic mechanisms constitutes the determining factor of system performance. Keywords: Seismic isolation, normative sa