DOI: 10.17603/ds2-encf-vj32
title: Wall Line Tests: Phase 2 -- Quasi-Static Tests
title: in CFS-NHERI: Seismic Resiliency of Repetitively Framed Mid-Rise Cold-Formed Steel Buildings

description: The need for low cost, multi-hazard resilient buildings constructed of sustainable, low-carbon footprint materials is urgent. Mid-rise buildings framed from thin-walled, cold-formed steel (CFS) have the ability to support this urgent need. The potential benefits of CFS-framed structures include low installation and maintenance costs, high durability and ductility, lightweight framing, and use of a non-combustible material. By using framing schemes with closely-spaced vertical members repetitively placed in the walls, CFS buildings develop lateral resistance through sheathing attached to these vertical members. The response of these building systems under earthquake loads and, in particular, the contribution of portions of the building system not specifically designated by design engineers (such as finished and/or gravity loaded components) to resist earthquake loads are not well understood. To this end, the seismic resistance of light, repetitively framed structures is unique and not well understood due to the large over strength and the significant contribution of non-designated systems in the lateral response. 

To address this limitation, in the present multi-University collaborative research program, mid-rise CFS-buildings are de-constructed into their essential components (fasteners, shear and gravity walls, and as a companion diaphragms) and investigated on multiple scales using experimental and numerical simulations. Physical experiments are conducted at each of the partner Universities, namely Johns Hopkins University (JHU), UC San Diego (UCSD), and UMass-Amherst (UMA), with the goal of advancing numerical tools being utilized in the project and more broadly in design practice. Shake table and quasi-static testing at UCSD examine the lateral load sharing between shear walls and gravity walls, the effect of location and size of opening on the lateral resistance of CFS-framed walls (shear/gravity) provided with or without an exterior finish. They also explore detailing issues such the behavior of Type I vs Type II shear walls, and hold-downs vs tension tie rod systems. Testing at JHU investigates the impact of strength, stiffness, and failure mode on multi-ply screw fastened connections, with particular emphasis on steel-steel sheet connections. Complementary efforts at UMA investigate model-scale CFS-diaphragms seismic performance using quasi-static tests. The project effort culminates with the shake table testing of a 10-story CFS-framed building system at the newly upgraded LHPOST6 equipment facility at UC San Diego.
description: Phase 2 of a series of tests to characterize the lateral performance of shear wall-gravity wall wall lines. Conducted at the UC San Diego Powell Labs, ten wall-line configurations were tested under cyclic quasi-static displacement controlled loading conditions. Walls were CFS-framed single story sheathed with steel sheathing and/or gypsum overlaying steel sheathing. The impacts of finishes, window opening, holdown tie-down system, asymmetry in the walls were also investigated during this phase of testing.