Internal force analysis of the resistance unit of frame-truss composite wall

Abstract The frame-truss composite wall is a wall assembled by a certain number of resistance unit composed of outer frame and internal diagonal struts. As the primary energy dissipation unit of the system, the resistance unit should be studied in the perspective of internal force analysis. When the internal force of resistance unit is analyzed, the outer frame and the internal diagonal struts are regarded as composite members of reinforced concrete. According to the characteristics of resistance unit, the outer frame is regarded as a rigid frame and the internal diagonal struts are treated as struts hinging with the rigid frame and mainly subjected to axial force. So the simplified model is formed and it can be regarded as seven-degree statically indeterminate structure in mechanics. The internal forces of outer frame and internal diagonal struts corresponding to the constraint forces of simplified model can be calculated by solving the statically indeterminate problem. The ABAQUS model of resistance unit is established to simulated the performance so that the internal force can also be obtained in another way. The constrain force of simplified model and the internal force of ABAQUS model are comparatively analyzed and the results show a feasibility of simplified model. The phenomenon of cracks on diagonal struts and ultimate failure state of resistance unit are compared with the stress cloud of ABAQUS model to explains the reasonability of simplified model. The applicability of ABAQUS model is further stated by comparing the stress of longitudinal rebar on the most dangerous section between the simplified model and ABAQUS model for the resistance unit. This simplified model can provide a method to analyze the internal force of the resistance unit under external load, which also lays a foundation for the subsequent researches.