Abstract:In this study, we explore the mechanism of wall instability in a building under dynamic load. Based on the theory of elastic mechanics, we analyze the stress field distribution of an unreinforced masonry wall with a rigidly fixed end under the disturbance of vertical seismic waves and obtain the analytical expression of the stress. The results show that the stress characteristics are determined by several factors, i.e., the particle velocity, dead load, density, and geometric size of the wall. We found that the horizontal stress values are 5 and 25 orders of magnitude greater than the shear and vertical stress values, respectively. As such, the horizontal stress is the control stress, and the stress concentration area is located at the top and bottom angles of the wall at the rigidly fixed end. The stress change gradient is 180 MPa/m, and the stress field is further concentrated on the rigid fixed side of the wall with increases in the earthquake intensity. Based on the principle that the principal stress leads to wall cracks, we predict the distribution positions, lengths, and angles of open wall fractures, and identify the most vulnerable parts of the wall. The results of this study can provide a reference for further investigation of the mechanical behavior of walls under dynamic load.
