Substructural shake table tests examining the seismic performance of point-supported glass facades

This paper aims to investigate the seismic performance of the coupled system comprising a large-span spatial structure and point-supported glass facades (PSGFs) through substructural shake table tests. A two-story substructure testbed is proposed to replicate the target responses at the interface nodes between the primary structure and PSGFs, thereby simulating the realistic boundary conditions that PSGFs experience under seismic conditions. Ordinary, near-fault pulse-like, and far-field long-period ground motions are applied to the numerical model of the primary structure to obtain the target responses, and the corresponding shake table excitations are then derived using an inverse frequency-response function method. The seismic behavior of PSGFs, including failure mechanism, acceleration and displacement responses, is discussed. The results show that the designed substructure testbed accurately reproduces the seismic responses of the primary structure. Under unidirectional loading conditions, glass-panel failure is dominated by detachment from the metallic connecting pieces, whereas under bidirectional loading it is primarily induced by stress concentrations. Compared to unidirectional loading, bidirectional loading amplifies the nodal peak accelerations at the supporting-truss nodes to 1.18–1.69 times in the x -direction and 2.35–3.69 times in the y -direction. A significant dynamic amplification effect is observed in the PSGF compared to the bottom of the testbed, characterized by a mean amplification ratio of 2.55 in the in-plane direction and 2.42 in the out-of-plane direction. Moreover, bidirectional excitation significantly increases the IDRs, with an increase rate ranging from 5.06% to 59.81% relative to unidirectional excitation.