The Influence Of Openings On Mechanical Properties Of Masonry Walls

Masonry structure is economical, practical and historical, which is common in all kinds of buildings in our country. In the masonry structure, the wall is the most important load-bearing component. But the door and window openings in the wall weaken the mechanical properties of the wall. Currently wall with different openings is still a lack of sufficient experimental data in the mechanical parameters containing wall stiffness, ultimate bearing capacity, ductility and so on. This brings great difficulties to the earthquake damage mechanism analysis and seismic design of masonry structures. In order to research of the influence of the door and window openings on the mechanical properties of the wall, this paper selects three longitudinal walls of the bottom of Beichuan Bureau staff residential as the research object. We design and produce three groups scale walls model according to the object. The wall models are tested under low cyclic reversed load to study the relationship between the opening forms and mechanical parameters of masonry wall. The main results of this paper are as follows:(1) Summarize the laws and reasons for masonry buildings earthquake damage. Through the field investigation and theoretical analysis of seismic damage, we summarize the experiences and lessons from the collapsed masonry buildings, illustrate masonry failure law and characteristic. We generalize the reasons for masonry structure damage from the "scattered partial crisp single" four aspects;(2)Reveal the failure mechanism of the masonry wall with openings, under the action of the horizontal load, the radial shaped cracks occur firstly in the angle of holes for large principal tensile stress. These cracks continue to develop and the wall will be divided into several mutual separate parts. If the cyclic load continues, each part continues to separate, resulting in loss of vertical bearing capacity.(3) By analyzing the lateral stiffness and the maximum bearing capacity of the walls with openings, we determine the destruction order of three longitudinal walls of Beichuan Bureau staff residential bottom floor under the action of earthquake. It is: the internal longitudinal wall with wicket hole, the front longitudinal wall with door hole, the posterior longitudinal wall with window open. We explain why Beichuan Bureau staff residential don’t collapse.