Seismic Performance of Joints between Steel K-Style Outrigger Trusses and Concrete Cores in Tall Buildings

Abstract

This paper presents finite-element analysis (FEA) and experimental study on the seismic behavior of joints between steel K-style outrigger truss and concrete core in tall buildings. Two new joint types with different details, including the joints with outside steel plates and encased steel plates, were conceived and intensively compared. Elaborate FEA models of the joints were developed, and a preliminary finite-element study was first conducted to evaluate the failure modes and hysteretic behavior of the joints to support the preparation of the laboratory test program. Then two specimens with different joint details were tested under cyclic loads. Several indexes that could reflect the seismic performance of the joints, such as the strength degradation, the rigidity degradation, the ductility, and the energy dissipation capacity, were analyzed. The mechanism of the joints was also revealed based on the stress distributions obtained by further FEA and test results, and a simplified FEA model was finally proposed for a more general purpose in routine design practice, and could provide a powerful tool for future research in design methods of the joints. The FEA and experimental results indicated that the joints exhibited favorable seismic performance which could transfer the loads reliably, and the joint with outside steel plates was better than that with encased steel plates, with more construction convenience, higher buckling load, and less concrete cracks.