Load-Displacement Characteristics for Out-of-Plane of Unreinforced Masonry Walls

Abstract

Seismic damage shows that the out-of-plane collapse of unreinforced masonry walls is very common. Especially in the teaching buildings, the out-of-plane collapse of the longitudinal load-bearing walls leads to the disproportionate collapse of the building, which results in serious loss of life and property. It is assumed that the in-plane stiffness of the unreinforced masonry floor system is infinite, and the effect of the integral bending of building on the story drift is ignored. The load-displacement relationship for out-of-plane of unreinforced wall under vertical dead load and horizontal seismic load was deduced with the bilinear constitutive relationship of masonry under compression, the second-order effect of vertical load on deformation being considered. The influence of axial compression ratio and the height-thickness ratio of the wall on the failure model and the load-displacement characteristics in the elastic state, ultimate state and collapse state were also studied. A theoretical method for the collapse mechanism and the aseismic design of the unreinforced masonry structure based on displacement was provided. This study has significant implications for the seismic performance design, post earthquake structural reinforcement, and seismic grade evaluation of unreinforced masonry structures.

Keywords

• disproportionate collapse
• P-Δ curve
• out-of-plane
• second-order effect
• seismic design
• unreinforced masonry