Abstract
This paper presents a seismic fragility assessment of medium-rise reinforced concrete (RC) wall buildings, focusing on fishbone-type buildings with high wall densities and other features such as the presence of thin unconfined walls subjected to high axial loads and significantly larger vertical irregularities. Such buildings are typical of residential buildings in Chile and other seismic countries. To do so, finite element models of three index buildings with different levels of axial load representing this class of buildings were developed using the software DIANA. Nonlinear time-history analyses were performed to estimate the engineering demand parameters (EDPs) for each building through a multiple stripe analysis. Finding that existing component damage fragility models did not well capture the damage in these buildings, global and local EDPs were examined, recommending new damage limit states better aligned with the expected and previously observed damage to this type of buildings, capturing their critical characteristics (i.e., thin unconfined walls, high axial loads, and flag-shaped walls). This study subsequently shows seismic fragility curves for the three index buildings using the proposed damage limit states. The fragility curves are similar for the same building, whether developed using local or global EDPs. On this basis, it can be concluded that the damage limit states proposed for either type of EDPs can be used to reliably obtain analytical fragility curves for medium-rise RC wall buildings with similar characteristics to those considered in this paper.