Loss Assessment of Non-Ductile RC Buildings Accounting for Bidirectional Ground Motion

Abstract

The ongoing seismic events in the world highlight the significant vulnerability of the existing building stock. In particular, in Italy, several structures have been designed without seismic criteria and showed significant damage after recent earthquakes, causing many casualties and great economic losses. Earthquake impact assessment has become one of the most investigated topics by several research groups and within national and international projects. In Italy, for example, the National Department of Civil Protection has allocated several economic funds within the ReLUIS project to define methodologies able to support the decision-making process for seismic prevention activities and risk reduction.This work aims to assess economic losses using the methodology proposed by FEMA-P58, according to the Performance-Based Earthquake Engineering method, evaluating the influence of bi-directional ground motion on loss estimates. The analyzed case study is a three-dimensional nonlinear frame characterized by one weak and one strong seismic directions and modeled using OpenSees software. The model considers the joint deformability and the flexural and shear damaging behavior of beams and columns. Thirty time-history analyses were performed considering bi-directional ground motions applied in the two main directions of the building and applying the higher spectral acceleration firstly in the weaker direction and then in the stronger one. Eight increasing hazard levels were selected for the nonlinear time-history analyses, and the corresponding structural analysis results, in terms of interstory drift ratio and peak floor acceleration, were implemented for the loss assessment. The results of the loss assessment are then discussed in terms of expected annual loss and loss hazard curve.