Hysteretic Behavior And Design Method On Two Types Of Wall Panel Encasing Unbonded Steel Plate Brace

Unbonded steel plate brace encased in wall panel(panel BRB) is a type of buckling-restrained brace(BRB) which uses the wall panel as a constraint member to restrict inner steel plate brace and can be applied as central brace in braced steel frame structure. Due to unbonded material or clearance between wall panel and inner brace, inner brace is used to resist the storey shear force. Wall panel is mainly used to provide lateral restraint for inner brace, which belongs to flexural member and acts as partition wall. Due to the constraints of outer panel, inner steel plate brace can avoid buckling in axial compression. Unde large displacement, inner steel plate brace can yield in both axial tension and axial compression and keep good energy dissipation. The conventional wall panel used for unbonded steel plate brace is reinforced concrete panel, which is prone to cracking and punching failure and inconvenient in the process of manufacturing and installation.The light-weight steel assembled panel and the closed profiled steel sheet-concrete composite panel are two types of new wall panels. The light-weight steel assembled panel does not need concrete and is assembled by high-strength bolts. The weight of light-weight steel assembled panel is obviously less than that of the reinforced concrete panel. The profiled steel sheets in the closed profiled steel sheet-concrete composite panel can be used as both concrete formworks and steel bars, so the concrete panel doesn’t have to use reinforcement and the concrete pouring quality is more easily guaranteed. In conclusion, these two types of new wall panels have more advantages over conventional reinforced concrete panel, but there are few papers dealing with these two types of new wall panels encasing unbonded steel plate brace. In order to promote the use of these two types of new wall panels encasing unbonded steel plate brace in engineering, a study has been carried out to investigate constructional details, the hysteretic behavior and other relevant problems by test researches and numerical simulations in this paper. The main research contents are as follows:(1) Quasi-static tests for four light-weight steel assembled panels encasing unbonded steel plate brace were conducted, the test results verify the validity of the construction details and indicate the good hysteretic performance of this unbonded steel plate brace encased in light-weight steel assembly panel. Before the fracture of steel plate brace, the wall panels are kept intact. Therefore, the wall panels can be reused.(2) Finite element models of two types of new wall panels encasing brace which are the same as the test specimens were built up by the ABAQUS program, in which the geometrical, material and contact nonlinearity are simulated. That the simulation results are in good agreement with the test results provides numerical model that can be used for parameter analysis of the wall panel encasing brace. Finite element analysis was used for the purpose of examing the effects of wall panel constraint width, gaps between wall panel and encased brace, thickness of the plate brace, initial flexural deformation and other factors on the working behavior of the brace encased in wall panel.(3) Two types of new wall panels encasing brace in full scale model were built up to study the influence of constructional details on the performance of wall panel encasing brace. Based on the analysis results, the design formula on the overall stiffening requirement of these two types of new wall panels was put forward by considering the actual effective length of wall panel encasing brace, overstrength of encased brace, the gaps between wall panel and encased brace and other factors.