Novel enhanced slip-resistant inter-modular connections with cementitious non-shrink grout: Experimental and numerical studies

Efficient inter-modular connections are key components that affect the construction speed and structural performance of modular building structures. While uplift-unconstrained connections constructed with tolerances are convenient options to facilitate assembling gravity-force-resisting modules, they may not satisfy serviceability limit states because of their potential to slip. This study proposes two types of inter-modular connections in which the slip is mitigated/blocked by employing mechanisms with a cementitious non-shrink grout mixture: (1) grout is poured directly into the connection zone inside a hollow-core structural section column; (2) grout is poured into an exterior built-up shear key zone. The behaviors of the enhanced connections were investigated experimentally and numerically in material, connection, and building structure levels. The results showed that the proposed cementitious non-shrink grout mixture is fluid, resistant, and does not shrink. The connection test results confirmed that both types of enhanced connections show superior mechanical performance compared to their "basic"counterpart (without grout). Both types of grouted connections can be adopted in modular building structures based on the specific project's logistics and manufacturers' facilities. The nonlinear analyses performed on a 12-story prototype model of a modular building structure revealed that the serviceability issues caused by potential slips in inter-modular connection components are overcome by using the grouted inter-modular connections in specific stories.