Seismic behaviour of structural systems with separated gravity and lateral resisting systems

Abstract

An innovative composite structural system with separated gravity and lateral resisting systems (SGLR system) was proposed to overcome the shortcomings of existing prefabricated structural systems. Two representative frame specimens with a scale ratio of 0.5 were tested under vertical floor loads and lateral cyclic loads to investigate the mechanical behaviour of the SGLR system. The slab crack patterns, failure modes, load–displacement curves, strength and stiffness degradations, energy dissipation capacity, deformation characteristics and strain development were analysed. The experimental results showed that the bent frame specimen (SGLR-1) exhibited good and stable seismic performance and the shear wall–bent frame (SGLR-2) with higher stiffness and capacity demonstrated obvious degradation due to buckling and fracture of steel plates at the bottom of shear walls. From test observations, flexural deformation was the dominated deformation pattern of the SGLR system under lateral loads. On the basis of test data, seismic performance assessment indicated that the SGLR system had larger safety margin than the conventional composite rigid frame (RF) system with the same design criteria of inter-storey drift ratios. The internal force analysis of the SGLR system showed that the base shear distribution in shear walls and columns varied with the increase of overall drift ratio. Moreover, it was revealed from the experimental analysis that the semi-rigidity of connections was significant and had conspicuous influence on both gravity and lateral force transfer mechanisms of the SGLR system.