Seismic Retrofit of an Existing Building Using Energy-Dissipation Devices

摘要

This paper presents the seismic analysis performed and the development and implementation of an innovative seismic retrofit scheme for two non-ductile buildings. The buildings, designed and constructed in 1960's, have somewhat unique structural system and lack a well-defined seismic bracing system in one of the directions. Given that it was located within few miles of the San Andreas fault, there was significant concern that the existing buildings may sustain extensive damage that would represent high life hazards during a strong seismic disturbance at the site. The objective of the proposed seismic strengthening was two-fold - (a) to mitigate the principal seismic deficiencies in the existing building configuration and (b) to meet the general intent of the current code, i.e. "the retrofitted building, in general, should be able to resist a major earthquake ground motion without collapse, but possibly with some structural and nonstructural damage". The strengthening schemes were developed using a Performance-Based approach. The design was not intended to meet all the prescriptive requirements of the current building codes, which are intended for new buildings. At the conceptual design phase, both conventional (concrete shear-walls and steel braced frame systems) and non-conventional (energy dissipation systems) retrofit schemes were investigated. The non-conventional seismic strengthening scheme, which involved using fluid-viscous dampers, proved not only to be more economical but also significantly reduced the disruption (to the existing tenants) during construction.