Material, Component, and System Level Experimental Efforts within CFS NHERI

Buildings with cold-formed steel (CFS) framing have shown great potential as a modern building system offering several benefits such as low installation and maintenance costs, high durability and ductility, lightweight framing, and use of a non-combustible material. However, understanding regarding their structural behavior, and particularly the contribution from non-designated systems and architectural finishes during seismic events is limited. As part of a multi-University collaborative effort, short named ‘CFS-NHERI’, an effort to gain a comprehensive understanding and expand the possibilities for effective CFS systems for taller mid-rise buildings under high lateral demands is underway. Essential to this effort is the generation of experimental data spanning the material to system level; this includes material testing at fastener scale, component level testing of diaphragm and wall specimens, and full-scale building shake table tests at NHERI Large High-Performance Outdoor Shake Table. This experimental program is complemented with high fidelity numerical models across the same scales, validated with experimental results, for advancing design standards and promoting improved building designs. This presentation presents results from ongoing experiments within CFS-NHERI, namely, stud to sheathing fastener tests conducted at UMass and full-scale wall-line tests, comprising shear walls in-line with gravity walls, tested at NHERI shake table at UCSD. In the later program, specimens were first tested under a sequence of increasing amplitude earthquake motions, and subsequently, for select specimens, under slow monotonic pull conditions to failure. Variations within the wall specimens focused on investigation of response of compression chord stud packs with steel tension tie-rods assembly versus hold-down systems, systems with and without architectural finish, and symmetric versus asymmetric configurations. Design details selected for the experimental program, developed in context of archetype CFS buildings, will also be described. The complementary numerical modeling efforts of CFS-NHERI will be presented in a follow-on presentation by Zhang and Derveni et al.

2020 National Earthquake Conference, San Diego, CA.