Lateral stiffness evaluation on corner-supported thin walled modular steel structures

Corner-supported modular steel buildings (CMSBs) are mainly composed of repetitive room-sized modules and inter-module connections. However, there is a lack of relevant understanding on the structural performance of CMSBs such as lateral stiffness. This study therefore investigated the lateral stiffness of the two-storey planar modular structure taken from CMSBs with the vertical rotary inter-module connections. Three full-scale monotonic experiments representing container-type modules, framed modules and their combination, were carried out to evaluate their lateral performance. The results indicated that all the three structures showed the satisfactory ductile behavior but the container-type modular structure could possess much higher initial stiffness when subjected to lateral load. Two lateral-force resistance mechanisms with different structural configurations were clarified including the framed moment resisting mechanism and the membrane tension action mechanism. The load transferring mechanism of inter-module connections was analyzed where modules stiffness as well as inter-module connections rotational stiffness were considered. In this way, theoretical modellings were developed to estimate the initial lateral stiffness of such two-storey modular structures and verified by the experimental results. Furthermore, the bending moment transferred by inter-module connections was obtained from the theoretical derivation and used to demonstrate the above load transferring of inter-module connections.