Structural Design of the Gerber Girder Cantilever System and Updates in CSA S16-19

Date: February 26, 2020

Presenter: Andy Metten, P.Eng., Struct.Eng., Partner at Bush, Bohlman & Partners LLP

The Gerber Girder cantilever system is a popular roof design system for steel buildings in Canada. The system generates material savings and reduces deflections and is popular for the design of roofs in many big-box retail stores. With cantilever girders, the system has stability issues that are not present in roof framing systems containing only simple span members. These stability issues have led to failures in the past, the most notable of which is the Station Square Save-On foods roof collapse of 1989. Following this failure there was a concerted effort on the part of the CISC and the steel industry to develop design procedures that would prevent similar failures in the future. Unfortunately, as the memory of the 1989 failure fades and engineers practicing at the time retire, there is a loss of the knowledge of how to design this popular system.

This talk presented simple ways of looking at and addressing the stability issues in design and how the important knowledge of this system design is now being passed on and how S16-19 will include provisions to cover Gerber framing system. Andy also reviewed some of the other notable updates contained in the recently-released CSA S16-19 steel standard.

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