Seismic Behavior and Stability of Multi-Story Volumetric Modular Buildings: Comparison Between Concentrically Braced Frames and Reinforced Concrete Shear Walls
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Multi-story modular buildings, constructed from prefabricated steel modules, are gaining popularity due to their efficiency, cost-effectiveness, and reduced construction time. However, their seismic performance and stability remain key areas of research. While reinforced concrete shear walls are commonly used as seismic force-resisting systems (SFRS), this study investigates the feasibility of using concentrically braced frames (CBF) as an alternative. Although CBF effectively resist lateral loads, they are susceptible to soft-story collapse under seismic excitation. This paper examines the lateral behavior of two 12-story modular buildings, where steel modules serve as the gravity force-resisting system (GFRS), and either CBF or reinforced concrete shear walls act as the SFRS. Nonlinear finite element pushover analyses are conducted using OpenSees to evaluate key performance metrics, including global behavior, inter-story drift, and shear distribution between the GFRS and SFRS. The findings highlight the potential for efficiently using CBF in multi-story modular steel structures while providing deeper insights into the seismic force distribution between the GFRS and SFRS. Notably, results indicate that the GFRS can carry a significant portion of seismic forces, particularly in the upper stories.