Study On Mechanical Properties Of Bending And Shearing Of Brick Masonry Typical Unit Under Out-of-plane Loads

As a traditional form of structure, the brick masonry structure is widely used in the residential buildings, office buildings, schools and other multi-story buildings because of its low cost and rapidly speed of construction. Brick masonry structure is made of bricks and mortar, due to weak bonding force between them, both the bending strength and shearing strength are low, and the ductility is poor. The brick masonry structure is prone to in-plane shearing damage and the out-of-plane arch damage under seismic forces. The in-plane damage is generally not collapse, but out-of-plane arch damage often cause collapse of walls and cause progressive collapse, then bringing more casualties and property losses.Based on the repetitive characteristics of masonry, a typical unit consisting of four bricks in Flemish bond form is selected. The mechanical properties of bending and shearing of the typical unit under out-of-plane loads are studied in detail. The main contents of this paper are as follows:1. The experimental study of bending properties of typical unit under out-of-plane loads. Considering the impact of mortar strength, research the three-point bending test of two groups (n=3) of specimens. The results show that the out-of-plane bending damage of typical brick unit is unexpected, and the bending strength is significantly affected by the mortar strength.2. The experimental study of the shearing properties of typical unit under out-of-plane loads. Considering the impact of mortar strength and vertical pressure separately, research the shearing test of nine groups (n=3) of specimens. The results show that improving the mortar strength or increasing the vertical pressure can delay cracking, and increase ultimate load of typical unit.3. Applying acoustic emission (AE) detection technology to monitor continuously the shearing damage of experiment. Comparing and analyzing the signal strength of different sensors, then we can roughly locate the damage position and predict when structure is close to cracking load and failure load.4. Using separate finite elements models, applying the LS-DYNA software, selecting the nonlinear constitutive relation of brick and mortar, and setting frictional contact parameters between them, then research the numerical simulation analysis by establishing the nonlinear models. The simulation of the sliding process and the curve of load-displacement are in good agreement with experimental results.Through the above experimental study and theoretical analysis of bending and shearing mechanical properties of brick masonry typical unit under out-of-plane loads, providing the parameters of mechanical properties of bending and shearing when brick masonry structure withstands out-of-plane loads.