Study on the seismic behaviour of upper masonry floor with variable stiffness for multi-story brick structures with bottom-frame based on finite element simulation

The upper masonry layers of multi-story brick structures with bottom-frame were usually severely destroyed in an actual earthquake. But, it is not clear that whether the design method of equal rigidity in vertical direction of upper masonry layer is reasonable. In this paper, four contrastive models of bottom frame structures were established though ABAQUS, and the different design methods of variable vertical stiffness were used for the upper masonry layers. The seismic response results show that the upper masonry layers especially the transitional layer is severely damaged when the design method of equal rigidity in vertical direction is used. According to the principle that the stiffness of the floor in proportion to its seismic force, which can lead to uniform failure of each layer, when the upper masonry layer uses the design method of variable stiffness along vertical direction, the seismic performance of the whole structure is greatly improved.