Nonlinear Analysis Of Cracks Under Seismic Load In Masonry Structures

The masonry structure is one of the primary structure forms of the residential buildings in our country. However, the cracks under seismic load is a problem which is common and urgently to be solved.This article classifies the cracks in masonry structures suffering earthquake, analyses the reason which produces cracks. By analysing present achievements of dynamic experimental studies in brick masonry structures, constitutive relation, failure criterion and crack model are analysed and compared.Based on the finite element theory, nonlinear finite element time-history analysis is used to the masonry structures which suffer earthquake. The six layers brick wall is established. Self-oscillation characteristic of the wall is analysed, self-vibration frequency is calculated and vibration type of the wall is observed. The entire developing process of cracks under seismic load in masonry structures is studied. Some results by FEM for example stress, strain and displacement are analysed.Through the analysis, we can draw some conclusions. Firstly, the cracks under seismic load in brick masonry structures are mainly due to the shear failure of principal stress. The most common pattern is diagonal crack. Secondly, stress concentration effect is occured at the door and window openings of the brick wall suffering earthquake,and the cracks are firstly appeared here, and then these cracks expand obliquely forming diagonal crack or crossing crack. Thirdly, when the building is under the action of earthquake, the concrete circle beams and construction columns in the masonry structures can undertake the horizontal shear effectively, and enhance the crack resistance of the brick wall to a great extent.