Numerical modelling of renforced masonry to enhance seismic resistance

This paper describes how numerical modelling based on a discrete element formulation has been employed to simulate the response of masonry to seismic loading. Using dynamic non-linear numerical analysis the performance of shear walls with and without retrofitted strengthening has been compared. Models representative of ashlar masonry laid with a weak lime-based mortar have been investigated. In general, wall arrangements are typical of those forming the end elevations of conventionally constructed lowrise buildings loaded horizontally. Walls including idealised openings have also been investigated. The benefits of strengthening by the introduction of passively stressed reinforcement are predicted for various arrangements when subjected to seismic loading. The reinforcement is represented explicitly in the analysis allowing direct assessment of damage and potential failure mechanisms. It is concluded that, although more work is required to verify simulations against tests and field experiences, the discrete element technique is ideally suited to dynamic masonry simulation and overcomes many difficulties experienced with traditional finite element analysis. The overall performance of masonry acting compositely with retrofitted reinforcement has been predicted and comparisons made between different reinforcement dispositions. It has also been shown that unless carefully placed reinforcement may actually reduce seismic resistivity.