New Constitutive Model for Interface Elements in Finite-Element Modeling of Masonry

Abstract

A new interface element constitutive model is proposed in this study for analyzing masonry using the simplified micromodeling (SMM) approach, in which mortar and two unit–mortar interfaces are lumped into a zero-thickness joint (modeled using an interface element) between expanded masonry units. The new model is capable of simulating tension cracking, shear slipping, and compression failure, and is defined by a convex composite failure surface consisting of a tension-shear and a compression cap failure criterion. It removes the singularity in the tension-shear region but not in the compression-shear region. In addition, the proposed model is based on the hypothesis of strain hardening. The robustness and computational cost of the proposed model were compared with different constitutive models (which are based on three, two, and one failure criteria) that have been widely used in the literature to describe masonry behavior through a series of one-element tests and through the comparison of finite-element (FE) response simulation of an unreinforced masonry shear wall. The FE response results indicate that the proposed constitutive model is more efficient than and at least as accurate as the other constitutive models for analyzing masonry using the SMM approach.