Influences of earthquake input models on nonlinear seismic performances of minaret-foundation-soil interaction systems

Abstract

Minarets, which are tall and slender structures, are important elements of mosques. Seismic performances of minarets can be strongly affected by the nonlinear dynamic soil-structure interaction and earthquake input mechanism models. The present paper investigates the influences of different earthquake input mechanism models on the nonlinear seismic performances of tall and slender minarets considering nonlinearity of both soil and structure behaviors. Three different minaret types constructed with concrete, masonry brick and stone materials are selected for the applications. Direct soil-structure interaction (SSI) approach is taken into account in the 3D finite element models of the minaret-foundation-soil interaction systems. Tie contact between the soil and foundation interfaces and infinite elements on the far sides of the soil domain are utilized in the 3D models. Nonlinear behaviors of masonry and concrete units, and homogenous soil domain are modeled using Concrete Damage Plasticity (CDP) and Mohr-Coulomb failure criteria. The standard rigid-base free, massless-foundation free, massed-foundation free and massed-foundation deconvolved earthquake input models are considered in the nonlinear seismic analyses. Three different earthquake records are selected for the nonlinear analyses and they are matched to the target response spectrum with return period of 475 years. The deconvolved ground motions at the rigid half-space bedrock are calculated from the matched records using the equivalent linear frequency domain analyses. Frequency and mode shapes, displacements, drift ratios, tensile strain and stress propagation patterns and damage ratios of brick, stone and concrete minaret models subjected to combined horizontal and vertical ground motions are determined for four earthquake input mechanism models and compared with each other.