A Simplified Mechanical Approach for a Large-Scale Seismic Vulnerability Assessment of the Algerian Masonry Buildings

Abstract

ABSTRACT Hitherto, considerable research has been developed on the city scale to estimate the seismic hazard in terms of peak ground acceleration (PGA), which could be a valuable tool for the assessment of the building vulnerability using mechanical approaches. However, as material properties and dynamic characteristics are commonly unavailable to define detailed models for large-scale analysis, mechanical methods cannot be applied building-by-building. The only way to perform this task is by correlating the mechanical method with a macroseismic approach, which can be highly useful when only structural and geometrical surveys are available. In this context, this research aims to develop a simplified mechanical approach to assess the seismic vulnerability and the probability of damage of the Algerian masonry buildings at a large scale using a general structural data survey and in the presence of the seismic hazard in terms of PGA or spectral values. Accordingly, an existing macroseismic method derived from the GNDT II approach was correlated with the mechanical N2 method, which is herein adapted and applied to fit the features of the Algerian masonry buildings. This nonlinear method identifies the performance of buildings by means of “performance point,” referred to as the intersection between the earthquake demand curve, built here according to the Algerian seismic code (RPA 99/version 2003), and the capacity curve of an equivalent nonlinear S.D.O.F. system. For the implementation of the proposed approach, a total of 380 masonry buildings located in Annaba City (North-east in Algeria) were assessed. The fragility and the probability of damage results of the building stock were obtained through a comparison between the application of the vulnerability index method and the simplified mechanical approach for different seismic scenarios.