Vulnerability of Low-Rise Buildings Based on Deck Type

This study investigates the influence of diaphragm stiffness on the seismic vulnerability of low-rise masonry buildings using nonlinear static pushover analysis. Two limiting structural idealisations are considered: a rigid-diaphragm model and a conservative model with no effective in-plane diaphragm action. The models are applied to buildings with quasi-rectangular and U-shaped floor plans, and their responses are compared using capacity curves, vulnerability functions, and EMS-98 damage grades. The results show that rigid diaphragms improve the redistribution of seismic forces among load-bearing walls, increase global lateral capacity, reduce displacement demand, and produce a more uniform structural response. In contrast, the absence of effective diaphragm action leads to non-uniform force transfer, increased differential displacements, amplified torsional effects, and substantial reductions in lateral capacity, particularly in the U-shaped building. These effects become more pronounced under higher seismic demand. The results demonstrate that both diaphragm action and floor-plan regularity should be considered explicitly in the seismic assessment of low-rise masonry buildings.