Fire performance of a novel concealed mass timber moment-resisting connection utilizing mechanically-fastened steel rods

Abstract

A major hindrance to more application of engineered-wood products in the Canadian building construction market is the lack of technical documentations and guidelines for the design of timber beam-to-column connections, especially those with moment-resisting capacities. In terms of designing for elevated temperatures, there is very limited research done for determining the fire resistance of moment-resisting timber connections. A comprehensive experimental testing program that consisted of thirty-seven full-size tension assemblies and eight novel full-size beamto-column connection test specimens were subjected to static loading at ambient temperature. In addition, eight beam-to-column connection test specimens identical to those tested at ambient temperature were examined at elevated temperatures of standard fire. Test variables investigated in this study included rod embedment length and washer size. The effects of these variables on the structural behaviour of the novel concealed glulam beam-tocolumn moment-resisting connection at both ambient and elevated temperatures were studied. The results of the nine different configurations from the tension tests were used to find the four most ductile and predictable configurations to be used for the newly designed beam-to-column connection configuration. For the tension connections, an embedment length to washer size ratio of about 4:1 provides a more predictable failure of rod pull-out. Accordingly, attention should be taken to ensure that the rod embedment length is to be slightly longer when compared to the washer size to maintain a ratio greater than 4 to 1 to promote for wood crushing failure.