Experimental evaluation on seismic performance of a novel plug-in modular steel structure connection system

Abstract

A novel plug-in modular steel structure (MSS) connection with cover plates for assembly efficiency, flexible serviceability, and stable workability is presented in this study. A seismic retrofit solution with self-centering (SC) haunch braces is then utilized for the MSS connection, aiming at damage mitigation and post-earthquake functional recoverability. In order to confirm the structural characteristics and evaluate the seismic behaviors of the MSS and self-centering MSS (SC-MSS) connections. Three corner connections were designed, manufactured, and tested under cyclic reversed loadings, including two MSS connection specimens with different design parameters and one SC-MSS connection specimen. Test results indicate that the two MSS connection specimens havetheabilityto make full development of the plastic strength of the modular beams and fail in the weld tearing, steel fracture, and local buckling of the beam flanges. The higher tenons of the plug-in connector enhance the local strength of the columns, guaranteeing more concentrated plasticity in the beams for better ductility. In comparison to the MSS connection specimens, the SC-MSS connection specimen has greatly improved stiffness, strength and displays the expected flag-shaped hysteretic responses with a satisfactory self-centering capability. The SC haunch braces effectively control the damage development in the connection core region and the surrounding components, mitigate the deterioration of global strength, significantly reduce the residual deformation, and thus achieve functional recoverability of the connection system. Furthermore, due to the prominent contribution of the haunch braces to the stiffness and strength, the SC-MSS connection shows great potential for sustainable and stable energy dissipation. This experimental study offers a reference for the practical design and application promotion of modular steel structures.