Structural Performance Assessment of PACE Modular Precast Slab Structure Systems

Abstract

PACE building technology is an accelerated construction system involving prefabricated modular reinforced concrete elements of regular size, shape, and geometry, which are fabricated off-site and adjoined on-site using post-tensioned tendons. Due to the modularity and prefabrication of the building components, reductions in terms of project costs, construction times, and material requirements are achievable. Field experiences involving similar systems have demonstrated outstanding structural performance, making them a viable off-site construction alternative to cast-in-place slab systems employed in North America. However, the detailing of these modular connections is atypical to common building practice in that they rely on friction for transferring forces at connection interfaces. This paper presents numerical results from a series of nonlinear finite element analyses done to characterize modular connection gravity load resisting performance, lateral load/deformation resistance, and influences associated with connection detailing parameters. It was found that the friction-based connections do not control the gravity load resisting performance of the modular slab system. Under lateral loading scenarios that would arise from ground motions, the connections comprising the PACE system were estimated to provide sustained gravity load resistances that meet existing codified requirements. The system was also analyzed under extreme tendon loss (i.e., fault) conditions and comparatively assessed with more conventional reinforced concrete flat plate construction. It was shown that the connections provide redundancy to accommodate fault scenarios and are also highly efficient in terms of their load carrying capabilities. In comparison to conventional flat plates, the modular system was estimated to provide greater gravity load resistance, while utilizing significantly less concrete.