Seismic performance assessment of a super high-rise twin-tower structure connected with rotational friction negative stiffness damper and lead rubber bearing

In this paper, a novel rotational friction negative stiffness damper (RFNSD) composed of negative stiffness device (NSD) and rotational friction dampers (RFDs) is proposed to develop flexible connection for improving the seismic performance of an asymmetrical super high-rise twin-tower connected structure. The prototype structure is rigidly connected by long-span steel truss, and shaking table test has shown that the rigid connection between the towers and the truss corridor generally cause buckling of steel truss members and structural damage on the connected floors. To mitigate seismic responses of the truss corridor and the towers, the rigid connection is replaced by flexible ones using the proposed RFNSD and lead rubber bearing (LRB). The working principle of RFNSD is introduced and the theoretical force-displacement model is derived. The numerical model for the proposed flexible connection is presented and detailed three-dimensional finite element models for the rigidly and flexibly connected structures are established. Then by nonlinear time history analysis, seismic responses of the models under three-directional excitations are analyzed, and the effect of flexible connection's design parameters is discussed. The results show that the developed flexible connection can obviously mitigate the dynamic responses and structural damages. As the stiffness of the pre-tensioned spring in NSD increase, the dynamic response of the steel truss connection corridor would be further decreased. The RFDs can effectively control the increased deformation of the flexible connection caused by the NSD, and promotes the energy dissipation capacity. The model with the flexible connections presents good seismic performance, indicating the effectiveness of the proposed RFNSD.