A 3D pilot simulation of masonry walls retrofitted with steel strips using a novel meso-scale damage-plasticity interface model

A novel interface model is introduced to faithfully and effectively simulate masonry walls retrofitted with steel strips (MWSS) under monotonic/cyclic lateral loads at the meso-scale level, where bricks and mortar joints are explicitly represented by 3D continuum elements and interface elements, respectively. The interface model’s formulation, rooted in a damage-plasticity framework, is presented herein, which allows for an accurate depiction of the complex nonlinear behaviors of masonry joints under tension, shear and compression. Subsequently, the model is calibrated and verified against existing experimental data from large-scale masonry specimens subjected to monotonic/cyclic lateral loading. The resulting push-over/hysteretic curves, along with the failure modes of the specimens, show relatively good agreement with their experimental counterparts. Leveraging this validated modelling approach, an extensive parametric study is undertaken to assess the impact of various factors on the in-plane behavior of MWSS. It turns out that the boundary conditions dictate the overall response of MWSS, whereas the material properties of the masonry have relatively minor effects. Given these insights, an improved truss-based analytical model is suggested to predict the lateral strength of MWSS, addressing the limitations of existing design procedures, particularly in scenarios where MWSS’s top edge is confined by high pre-compression.