Analysis On Mechanical Behaviour Of Masonry Infill Wall Under Out-of-plane Action

The frequent damage and collapse of infill wall under earthquake have given rise to great casualties and tremendous loss of wealth, which make the research of infill wall on agenda. The influence of infill wall on structure stiffness and the mechanical property of infill wall in plane has been more mature in the academic research, but its out-of-plane mechanics is not complete at home and abroad. In this paper, ANSYS analysis software was adopted. The masonry wall was simulated by SOLID65element, and the steel bar by BEAM4element, the problem of out-of-plane action on infill wall was converted to the issue of plane strain, then the finite element models were established. According to the out-of-plane action of wind and earthquake on infill wall, the wind load was simulated as the uniformly distributed load and the seismic action was simulated as horizontal displacement, numerically simulations and analysis were carried out in nonlinear way under different connection types.The main content of this paper includes:1. Of the infill walls with different connection types under uniformly distributed load, the cracking history and failure mode were analyzed in detail. The simplified three hinged arch model was put forward for the rigidly connected walls for carrying capacity at ultimate state, and the simplified model with hinge joint on the top and rigid joint on the bottom was suggested for the walls separated from top beam and connected by reinforcement (including two steel bars connection and one steel bar connection).2. Of the infill walls under horizontal storey displacement, the cracking history and failure mode were analyzed in detail, the simplified two hinged arch model was put forward for the rigidly connected walls for carrying capacity at ultimate state, and the simplified model with hinge joint on the top and rigid joint on the bottom would be suitable for the walls separated from top beam and connected by reinforcement (including two steel bars connection and one steel bar connection).3. Stress analysis of rigidly connected infill walls under uniformly distributed load and horizontal storey displacement were simulated and studied, the arching action was displayed on stress contour, which made the carrying capacity and deformation capacity of the infill walls increasing obviously. However, no arching action could be found at walls separated from top beam and connected by reinforcement, its carrying capacity and deformation capacity is lower than the former.4. Changing the material and dimension of the infill walls or the condition of connection, the simplified models above were universally applicable through analysis.5. The effects of arching action on rigidly connected walls were explored. The analysis results have indicated that the constitutive relation, the strength of masonry and the ratio of height to thickness influenced the arching action, and that the arching action was directly related to the carrying and deformation capacity of infill wall. When the material and the strength were fixed, the greater the ratio of height to thickness was, the smaller the carrying capacity and deformation capacity were. The simplified formulae of carrying capacity and deformation capacity were proposed.