Pushover analysis of large scale unreinforced masonry structures by means of a fully 2D non-linear model

A simple 2D model for the evaluation of the seismic performance of large scale unreinforced masonry structures in-plane loaded is presented. The approach is fully two dimensional and allows performing pushover analyses on large scale structures without the reduction of the walls to an equivalent frame, competing with 1D codes. In the model, a macroscopic approach is used, where the so called disturbed state concept (DSC) with modified hierarchical single yield surface (HISS) plasticity are used to characterize the constitutive behavior of masonry in both compression and tension. Two HISS yield surfaces for compressive and tensile behavior are utilized. The DSC model allows for the characterization of non-associative behavior through the use of disturbance, and it computes micro-cracking during deformation, which eventually leads to fracture and failure. The DSC model is validated at both (1) specimen and (2) structural level. At a structural level, three large scale masonry walls subjected to incremental horizontal loads are analyzed and pushover curves obtained with the model proposed are compared to those obtained by means of standard equivalent frames and existing literature models.