Lateral Seismic Force Distribution Between Gravity-Force-Resisting Steel Modules and Reinforced Concrete Shear Walls

Volumetric modular building structures are becoming increasingly popular due to their significant advantages over traditional on-site construction in terms of speed, quality of workmanship, and environmental impacts. A common type of modular building structure consists of gravity-force-resisting steel modules laterally supported by precast or cast-in-situ reinforced concrete shear walls. This type of modular structural system is common in mid- and high-rise modular buildings. In this system, the shear walls are designed to resist 100% of the lateral loads, followed by designing the gravity-force-resisting modules to stay elastic or have the sufficient nonlinear capacity to support the gravity loads while undergoing earthquake-induced deformations. However, the steel modules inherently exhibit a certain amount of lateral rigidity intended to resist the handling and transportation loads, forming a hybrid system that inevitably attracts a fraction of the total lateral loads. This study examines the effects of three parameters on inter-story shear distribution between gravity-force-resisting modules and the reinforced concrete shear walls: (1) the partial rigidity of intra-module connections, (2) the rotational rigidity of the vertical component of the inter-module connection, and (3) the in-plane stiffness of discrete floor diaphragms. It was found that the proportion of inter-story shear in gravity-force-resisting modules can be minimized by adequately designing the three aforementioned components above.