SEISMIC ANALYSES OF A SOFT-FIRST-STORY RC BUILDING RETROFITTED BY THICK HYBRID WALL TECHNIQUE DURING STRONG EARTHQUAKE EXCITATIONS

Abstract

Experimental investigations on retrofitting soft-first-story RC frames by thick hybrid wall technique as a strengthening-ductile method are briefly explained. The mathematical models and hysteretic behaviors of the members retrofitted by thick hybrid wall technique were assessed and calibrated through the experimentally observed mechanisms. An existing soft-first-story RC building was selected to evaluate the efficiency of thick hybrid wall method on improving seismic performance of the building during strong earthquake excitations. The building was assumed to be retrofitted by two types of retrofitting methods including installation of shear wall (strengthening type) and application of thick hybrid wall (strengthening-ductile type). The evaluations were implemented approximately by seismic vulnerability assessment based on the guidelines by Japan Building Disaster Prevention Association and exactly by nonlinear dynamic response analysis. The analytical results showed the retrofitted building obtained reasonable performance for design basis earthquake at life safety limit state. Moreover, as a case study, the collapse prevention performance of the building retrofitted by thick hybrid wall was checked under an upper-bound of earthquake excitations based on recorded strong earthquakes (which herein are called maximum capable earthquake), and the obtained results demonstrated an acceptable performance.