Numerical Investigation of Fully Grouted Reinforced Concrete Masonry Walls under Bidirectional Loading: In-Plane Capacity Reduction due to Out-of-Plane Loading

The structural behavior of fully grouted reinforced concrete masonry (RM) walls subjected to either pure in-plane (IP) or pure out-of-plane (OOP) loading has been thoroughly examined in the literature. However, in certain circumstances (e.g., seismic loading), RM walls could be subjected to combined IP and OOP loads. This study conducts a comprehensive numerical investigation into the structural behaviors of RM walls under combined IP and OOP loading, focusing on the influence of geometric parameters (aspect ratio and height-to-thickness ratio) and precompression load. To capture the possible failure modes of RM walls under bidirectional loading scenarios, a simplified micromodeling approach is employed in this study. The numerical simulations were performed in the general-purpose finite element software package ABAQUS. The simulation results indicated that the presence of OOP loads can induce substantial IP capacity reductions, especially for flexural-governed walls characterized by a larger aspect ratio and a low level of precompression load. For flexural-governed walls, IP and OOP capacity interactions were found to be less sensitive to geometrical parameters and precompression load than shear-governed walls. The most interaction was observed for highly slender walls without precompression loads, indicating a reduction in IP capacity by 45% when OOP loading is at 80% of its corresponding capacity. A further comparison between the RM walls and their counterparts, unreinforced masonry (URM) walls, suggested that the IP capacity reduction of RM walls could be 11.6% less than that in URM walls, indicating the positive effects of reinforcements in mitigating the IP-OOP interaction effects.