Structural Response of Laterally Loaded Ridge Vent Light Frame Diaphragms

Abstract

Residential construction is a major segment of the built environment, and it accounts for substantial energy use in many regions—particularly in hot and cold climates. As efforts to address the impacts of climate change intensify, research on building envelopes, particularly in extreme climates, continues to evolve. Traditionally, a combination of eave, soffit, and roof vents has been used to passively cool attic spaces. Ridge vents have emerged as a highly effective passive cooling strategy. However, despite their benefits, the installation of ridge vents can disrupt diaphragm shear transfer at ridges, resulting in reduced strength and stiffness of the existing diaphragm. This paper presents the findings from a series of full-scale tests on 2.44×4.88 m (8×16 ft) wood and cold-formed steel light frame simply supported diaphragms sheathed with 9.5 mm (0.37 in.) wood structural panels. For each framing material, blocked, unblocked, and ridge-vented diaphragms were tested. The test results showed that compared to a blocked diaphragm, both the strength and stiffness of ridge-vented diaphragms were reduced. Specifically, the ridge-vented diaphragm peak strength was between 46% and 58% that of the blocked diaphragm, and between 62% and 70% of the unblocked diaphragm. Further, the ridge-vented diaphragm initial stiffness was between 41% and 50% that of the blocked diaphragm.