Behavior of Cold Formed Light Gauge Steel Framed Hollow and In-Filled Shear Walls With Fiber Cement Board Sheathing

Abstract

Being light in weight, cold-formed steel shear wall panels made with light gauge steel are extensively used in residential and office buildings (low to mid-rise), particularly in structures under seismic loadings. These shear wall panels use shear resistance to resist lateral loads. Shear walls in light gauge steel structure are made by bracing the walls, which is accomplished by attaching flat strap cross-bracing or by fixing a sheathing material on the wall panel using fasteners. Cold formed light gauge steel construction has become an emerging trend in Pakistan owing to 2005 Kashmir earthquake. Local design practices involve the use of fiber cement board (FCB) as sheathing material both for hollow and in-filled walls with foam concrete. In the absence of design guidelines based on cold-formed light gauge steel shear walls with FCB sheathing, the designers resolve to use the guideline available for gypsum wall board (GWB) and fiber board (FB) available in American Iron and Steel Institute Lateral Design (AISI 2007). There is lack of design guidelines and test data on cold-formed light gauge steel shear walls with FCB sheathing, that can help incorporate the design strength and behavior parameters of such shear walls. An experimental program was designed to study the behavior of cold-formed light gauge steel shear walls with FCB sheathing under lateral loading. Two types of shear walls namely hollow and shear walls in-filled with expanded polystyrene (EPS) foam concrete, were investigated under monotonic loading. The results were used to compare the response of hollow and in-filled shear walls and also to compare the response with state-of-the-art and existing design practices. The tests were performed according to ASTM E564 (2006) with minor modifications. Results show that the strength of FCB is far greater than GWB and FB, suggesting that the local design practices are highly conservative. The strength of hollow FCB is nearly equal to oriented strand board (OSB) with similar configurations, whereas, EPS foam concrete infilled shear wall exhibit significantly higher shear strength. This research will help designers use cold-formed light gauge steel shear walls with FCB sheathing both hollow and in-filled with EPS foam concrete more efficiently by choosing appropriate framing material, sheathing and infill based on desired lateral stiffness and load carrying capacity.