Initial lateral stiffness of plate-type modular steel frame structure with semi-rigid corner connections

The plate-type modular steel frame buildings with semi-rigid corner connections are assembled structures, whose prefabricated plate-type modules are constructed in the factory and assembled on site. Owing to the assembly of different plate-type modules, this self-bearing building forms a double-beam and multi-column structure. To calculate the initial lateral stiffness of the plate-type modular steel frame structure with semi-rigid corner connections, based on the modified displacement method, the lateral amplification effect caused by semi-rigid connections between upper and lower modules was transferred to the lower beam of the upper module; according to the concept of superposed beam, the structure can be simplified into the form of single beam and multiple columns; in addition, by using the combination method of multiple columns with different corner connections, the theoretical formulas of the initial lateral stiffness of the semi-rigid connected plate-type modular frame structure were derived. Compared with the plate-type modular frame with rigid connections, the lateral amplification coefficients of regular plate-type modular frames with semi-rigid connections were derived and the influence of the number of spans and stories on the lateral amplification coefficient were investigated. The theoretical values of the initial lateral stiffness of the plate-type modular steel frame with semi-rigid connections were in good agreement with the experimental values and FEM evaluations.