Abstract
While wood and cold-formed steel light-frame structures generally provide adequate seismic life safety, damage and monetary loss due to moderate and severe earthquakes can be considerable. Furthermore, this damage can lead to displaced residents which can cause disruption to families, communities, and industry. In an effort to reduce this damage, two novel design approaches for new construction have been developed. In the first approach, architectural components such as partition walls and cladding are united with structural components to provide significantly enhanced lateral strength and stiffness, reducing structural period. This leads to sizeable reductions in lateral deformations and decreased reliance on inelastic building strength. These components are strengthened and stiffened by using construction adhesives and improved fasteners and boundary connections. The second design approach includes the implementation of a sliding base isolation system composed of inexpensive components. The combined use of both approaches is particularly beneficial for building sites located near faults or for other locations where predicted earthquake ground motion intensities are especially large. This paper describes the development of high-fidelity finite element models created to replicate the behavior of light-frame sheathed walls, with and without strengthened and stiffened connections. Enhanced details including stucco-to-framing connections, gypsum-to-framing adhesive connections, improved mechanical gypsum-to-framing connections, and gypsum panel edge connections were tested under reversed cyclic loading to determine hysteretic behavior. Small-scale and full-scale light frame walls utilizing these enhanced details were also tested using pseudo-static cyclic loading protocols. The test specimens consisted of walls with different sheathing materials, framing connectors, wall dimensions, wall perforation layouts, holdown and anchorage configurations, and end return arrangements. Three-dimensional models were developed using the software ABAQUS. Individual framing members, sheathing panels, and connectors were modeled explicitly. The creation of user-defined subroutines to model the effect of mechanical and adhesive framing-to-sheathing connections and other connection details is discussed. The performance of wall details from physical testing is compared to fitted model component analysis behavior. Global wall behavior from experimental testing is compared to analytical finite element behavior. The effect of wall perforations, end returns, and anchorage configuration on wall racking behavior is investigated. The benefits and drawbacks to using high-fidelity finite element modeling of light-frame wood and cold-formed structures and substructures are discussed. Ongoing and future testing of enhanced light-frame building components is described, including the design and analysis of a full-scale two-story house that will be tested at the NEES shaking table facility at the University of California, San Diego in 2014.