Finite element modelling of unreinforced masonry shear wallettes strengthened using twisted steel bars

A numerical study was conducted to investigate the in-plane shear behaviour of unreinforced masonry wallettes strengthened with twisted stainless steel reinforcing bars. A two-dimensional finite element model was used to simulate the behaviour of strengthened wallettes tested in diagonal tension in a recent experimental programme. The test wallettes included single leaf modern masonry construction and double leaf historical masonry construction. The main aims of the current study were to evaluate the capabilities of the model and to study the behaviour of the wallettes in greater depth. The model was capable of simulating the behaviours of the strengthened wallettes with good accuracy. The model provided insights on the reinforcement mechanism: the reinforcement acts in tension to restrain crack opening, with vertical reinforcement restraining shear-induced crack opening (dilation) to increase the friction along a sliding crack (shear-friction mechanism). The analysis shows that the shear-friction mechanism is significant and requires further investigation. Another finding was that care should be taken when selecting an elastic stiffness for the interface between bar and masonry.