NUMERICAL MODELLING OF BONDED BRICKWORK UNDER CYCLIC COMPRESSION LOADING

Abstract

Bonded brickwork as loadbearing walls is widely found in the heritage structures worldwide. The bonded brickwork consists of two or more bricks in the thickness direction which causes them to behave differently to single leaf walls which are the basis of masonry design guide-lines. The evaluation of bonded masonry structures under dynamic seismic actions therefore requires appropriate numerical modelling techniques accounting for the cyclic loading. Sub-sequently, a simplified 3D mesoscale numerical model has been developed in this paper to analysis different thicknesses of bonded brickwork under cyclic compression. Each masonry brick was defined using 3D solid elements with 8 nodes and 24 degree of freedom (DOF) representing an enlarged brick consists of a full-scale brick enveloped by half thickness of the mortar bedding layer all around. These masonry bricks were arranged in multiple layers using zero thickness cohesive interface elements to simulate the bond behaviour under shear, tension, and compression actions. A plasticity-based damage constitutive model to represent the damage in the masonry bricks under cyclic compression loading was employed. A thresh-old strain level was used to enact the element deletion technique for initiating the brittle crack opening in the masonry units. Whereas the joint interface failure between the masonry units was defined using a cohesive model represented by a simple bi-linear traction-separation constitutive law exhibiting an initial linear elastic behaviour at the interface fol-lowed by the initiation of the damage and evolution until the surface bonding degradation. The robustness of the developed model under cyclic compression loading has been proven by validating the test data presented for the clay brick selected to construct 9 masonry wallettes of single, double and triple brick thicknesses. The failure modes, cyclic stress-strain curves and stiffness degradation have been studied.