Computational modelling of low bond strength brickwork wall/beam panels with retro-fitted reinforcement

Retro-fitted stainless steel reinforcement is being used increasingly to strengthen the masonry cladding of low to medium rise buildings, particularly where cracking has occurred adjacent to a long-span window or similar opening. This paper describes the development of a computational model which was used to predict the behaviour of unreinforced and reinforced clay brick wall/beam panels subjected to vertical in-plane static loading. In practice, cracking in unreinforced walls of this type, particularly where low cement content mortar has been used, tends to occur along the brick/mortar interfaces and failure usually results from de-bonding of the bricks. As a result, software based on the Distinct Element Method (DEM) of analysis was used. The bricks were represented as an assemblage of stiff but deformable distinct blocks and the mortar joints were modelled as zero thickness interfaces. These interfaces could open or close depending on the magnitude and direction of the stresses applied to them. Reinforcement was modelled using spring connections attached to the masonry surface. The masonry material parameters were obtained from the results of experimental tests carried out in the laboratory on full-scale unreinforced wall/beam panels. The computational model was then used to predict the behaviour of wall/beam panels containing bed joint reinforcement. Good correlation was achieved with the results obtained from the testing of full-scale reinforced panels in the laboratory, in particular, the load to cause first visible cracking, the propagation of cracks with increasing applied load, the mode of failure and the magnitude of the collapse load