Experimental Testing of a Rotational Friction Connection for Use with Precast Concrete Cladding Panels in Metal Building Systems

Abstract

Lightweight clad metal building systems have been shown to exhibit excellent performance in seismic events; however, metal building systems clad in masonry or precast concrete panels (hard walls) have been shown through analytical studies, shake table tests, and post-earthquake reconnaissance to be susceptible to significant damage and potential panel collapse. There exists a stiffness incompatibility between the stiff wall cladding and the flexible steel frame. Improper connection design between the hard walls and steel frame have resulted in premature failure of the connections, leading to a loss of a critical load path and the wall system falling away from the structure. To improve the seismic performance of metal building systems, clad with hard walls, it is necessary to develop a new seismic force resisting system in the longitudinal direction (parallel to the ridgeline). A new rotational friction connection (RFC) between the hard wall and steel frame has been developed to act as the ductile fuse element in the new system. Emphasis was placed on the connection being economic, easy to construct, minimize the need for repairs after seismic events, and have a high energy dissipating capacity. Energy dissipation is geared in the in-plane horizontal direction while maintaining out-of-plane capacity. This thesis reports the experimental component testing of the new rotational friction connection for various bolt sizes. The testing included a monotonic pushover test, unidirectional cyclic testing in the in-plane horizontal direction, a biaxial test, pullout test, and extended uniaxial test. Hysteretic behavior of the connection is discussed. The results of the testing show that the connection can withstand large displacements as well as dissipate energy in a stable manner without damaging the surrounding components. The rotational friction connection is suitable for use as the ductile fuse component in metal building systems with hard walls.