Research On Macro Model Of SRC Frame Joints

As a new structural system, Steel reinforced concrete (SRC) structure, whichcontains advantages of both steel structures and reinforced concrete structures andpossesses high bearing capacity, stiffness, good endurance, makes a rapiddevelopment in recent years. Joints are the key parts to transfer load in the seismicresisting structural systems, and the softy of them is the premise of structure’s normalworking. In addition, a series of frame joints tests and earthquake damage studies madeat home and abroad show that the damage of the joints is one of the main reasons thatlead to the failure of the entire frame structure. Therefore, the response of the jointsshould be considered in the analysis of the frame structures. Because of thecomplicated mechanical property and construction of the joints, a simple and effectivemacro model is necessary to make a numerical simulation of the SRC frame structure.However, the studies of the macro model mostly concentrated in reinforced concretejoints while rarely concentrated in SRC joints presently.Firstly, the existed reinforced concrete joint element is investigated. Based on theresponse characteristics of SRC frame joints under cyclic loading, a new elementmodel for SRC frame joints is presented. The proposed model includes one shear-panelcomponent that is intended to simulate the response of the joint core and twelve springcomponents that are intended to simulate the response of the end of columns andbeams. Then, According to the experimental investigation of the joints, theload-deformation relationships of the spring components are derived, and the loadtransfer mechanism of the joints is analyzed. Based on the load transfer mechanismand deformation characteristics of the joints, the equilibrium and deformationcompatibility equations are established. On basis of that, the stress-strain relationshipof the shear-panel component under monotonic loading is derived, and the computation program is completed. Finally, the new element is introduced into the OpenSEES, andthe joint tests are simulated. Comparison of the simulation results and the tests resultsindicates that the joint model proposed can accurately describe the responsecharacteristics of SRC frame joints under cyclic loading.