Calibrated DEM models to simulate mechanical behavior of masonry structures under quasi-static lateral loads

Abstract

Numerical approaches based on the Discrete Element Method (DEM) have proven effective in reproducing complex cracking and failure mechanisms of masonry structures. However, when intending to use them for virtual testing, an important constraint is that their predictive capability strongly depends on the appropriate calibration of material and contact parameters. This study presents the calibration of three-dimensional DEM models developed in 3DEC to simulate in-plane response of full-scale masonry wall with opening, subjected to quasi-static monotonic lateral loading. The experimental results, including the lateral force–displacement relationship, crack patterns and damage mechanisms, are used as benchmark data for the numerical model with exact geometry, boundary condition and loading scenario. Two models were calibrated, composed of rigid blocks and elastic deformable blocks. In both cases the blocks were connected through contact interfaces governed by Mohr–Coulomb joint model. To capture results of the experimental test, a tailored joint-displacement-based softening model is introduced on subcontact scale, representing main novelty of the study. Calibration using the proposed joint model successfully captures the main features of experimental behavior, including initial elastic part, stiffness degradation, peak lateral load, and post-peak softening (including an abrupt decrease in lateral load bearing of the wall at proper displacement), together with experimentally found damage mechanisms. The results demonstrate the capability of DEM-based simulations to reproduce nonlinear in-plane behavior of masonry wall without need for fracture energy parameters and highlight the importance of accurate joint softening models for reliable structural assessment of masonry structures.