Shake table testing and computational investigation of the seismic performance of modularized suspended building systems

Abstract

Suspended building structures have inherent architectural aesthetics and are able to achieve low seismic-induced displacements of the primary structure and accelerations of the suspended segments. A recently proposed subtype of suspended building structures harnesses discrete prefabricated modules to overcome the fragility originating from inter-story drift within the suspended segment and to enhance the overall attenuation. This paper presents the first shake table experimental study of this subtype to directly evaluate its aseismic performance and develop a physics-based modeling strategy that is validated and therefore is reliable. For this purpose, 1:15 scaled shake table experiments of modularized suspended structures were conducted with three fundamental configurations. Each model in each configuration was subjected to at least five ground motions. Results indicate that displacements at the top of the primary structure are reduced by around 50%; in the structure with discrete modules and inter-story dampers, quicker decay was shown, accompanied by lower accelerations of the modules. The inter-story drift ratio of the suspended segment reached 3.75% under 0.12 g PGA excitation, indicating the potential of drift-induced fragility if a regular structure is adopted and proving the benefit of modularization. Numerical models of the tested structural systems have been developed in OpenSees platform. Simulated responses show satisfactory agreement with the measured ones. Subsequent parametric analyses reveal that the performance is sensitive to both the stiffness and damping values especially when the damper is of viscous type. Optimal stiffness facilitates tuning between the primary and secondary structures while optimal damping enhances dissipation notably. Moreover, it is observed that the inherent friction handicaps dissipation instead of facilitating it.