Assessment of out-of-plane behavior of non-structural masonry walls using FE simulations

Abstract

Having orthotropic two-way bending, out-of-plane (OOP) behavior of non-structural masonry walls is one of the most challenging topics among professional engineers and researchers. This study is devoted to investigate OOP behavior of non-structural masonry walls with in-plane isolated joints to accommodate inter-story drifts. This is done using pre-validated finite element (FE) models of 99 walls with different boundary conditions (BCs), different amount of bed joint reinforcements (BJRs) and different opening details under uniform monotonic OOP pressure. Effect of vertical seismic acceleration is also investigated. Obtained results indicated that BJRs almost always increased ultimate OOP strength of the walls regardless of their BC, opening details, and level of vertical seismic acceleration. However, BJRs did not necessarily increase response modification factor of the walls. Comparing ultimate strengths from FE results with those from yielding line theory (YLT), which is adopted by some codes and guidelines, revealed that YLT is a reliable simplified technique in order to estimate OOP strength of reinforced and unreinforced non-structural masonry walls with or without openings. Both ultimate OOP strength and deformation capacities and response modification factor of the walls are decreased by increasing downward vertical seismic acceleration. This is due to the fact that downward seismic acceleration tends to reduce self-weight axial compression of the walls. From OOP pressure-deformation curves, overstrength and response modification factors of the walls are evaluated and compared with those suggested by ASCE 7. It is seen that walls with openings have significantly higher response modification factors compared with solid walls.