Optimal load factors for earthquake-resistant design of buildings located at different types of soils

Abstract

This paper addresses the influence of the local soil type (firm or soft) on the reliability-based optimal load combination factors for seismic design of buildings. The approach aims to minimize the total expected life-cycle cost (LCC) of a structure. As a constraint, it is established that the mean annual rate of structural failure should be less than or equal to a certain prescribed value. The LCC of the structure includes 1) initial cost, 2) cost due to damages, and 3) social costs. The methodology is applied for two sets of reinforced concrete buildings; the first set is located on firm ground and the second on soft soil. The reinforced concrete buildings are designed using different load combination factors, and the total expected cost is estimated for each set of buildings. It is concluded that the optimal load combination factors for the buildings on soft soil are different from that obtained on firm ground. Finally, some recommendations are provided to estimate the seismic load factors for structures located at firm and soft soils.