Shear capacity of single- and double-layered gypsum board to steel stud screw connections in non-structural partitions

Gypsum steel-stud partition walls are composed of light-gauge, cold-formed steel studs and gypsum boards attached with self-drilling screws. These non-structural elements are commonly used in volumetric modular building structures serving as partitions or exterior walls. Volumetric modular building structures are prefabricated, prefinished constructions where three-dimensional units, known as modules, are built in a factory and then transported to the construction site where they are placed and interconnected. The volumetric modules experience different loading scenarios during handling and transportation. While the modules may be designed to resist transportation and handling loads structurally, damage to nonstructural elements, such as gypsum board to stud connections, can still occur even under lower amplitude excitations. These non-structural damages, if not avoided, will require additional on-site repairs, leading to an increase in the overall costs of modular projects. This study investigates the shear capacity and damage mechanisms of gypsum board to steel stud screw connections. A series of experimental tests are performed to determine the capacity of these connections varying with the number of gypsum board layers (one- or two-layer), fastener edge distance and direction of loading (parallel or perpendicular to the edge). Finally, an analytical formulation was proposed to estimate the shear capacity of these connections. Results indicate that the distance of fasteners to the gypsum board edges dramatically affects the behavior of these connections. The connection capacity at the damage state and the failure modes can fairly be predicted through the proposed analytical approach, showing a reasonable match with experimental results.