Influence of slab composite effect on the seismic performance of a six-story timber-concrete composite moment-resisting frame

This study investigated the influence of slab composite effect on the seismic performance of a sixstory timber moment-resisting frame (TMF) with concrete slabs through nonlinear time history analysis in OpenSees. The seismic performance of the timber-concrete composite momentresisting frame (TCCMF) was compared to that of a bare TMF in terms of the natural vibration characteristics, displacement response, acceleration response, and failure modes. To obtain the hysteretic behavior of the beam-to-column joints in the frames, reversed cyclic loading tests and finite element (FE) analysis were conducted on the joints. The simulation method for the joints was validated and subsequently applied to the FE models of the frames. The time history analytical results demonstrated that the natural vibration periods and displacement responses of the TCCMF were at least 33.4 % and 40 % lower than those of the bare TMF, respectively, owing to the enhancement in lateral stiffness provided by the slab composite effect. Moreover, the slab composite effect considerably lowered the stress of the timber members and rotational deformation of the beam-to-column connections, which improved the seismic performance of the TMF and reduced the risk of structural collapse. However, the adoption of concrete slab enhanced the diaphragm action, leading to an increased proportion of inter-story shear deformation in the overall deformation and a downward movement of the weak floor in the structure. Lastly, the seismic design method was proposed for the bolted timber beam-to-column joints with concrete slabs.