Stability Response and Design of Steel Cantilevered Systems

In the design of roof structures for large single-storey buildings in North America, it is common practice to extend the primary girders of alternate bays beyond the columns to support the girders in the other bays. This structural system, typically with overhanging girders constituting the main components, is commonly known as Gerber construction. The beauty of this system is that it enjoys more balanced moment distributions than its conventional counterpart with simply-supported girders. In addition, simpler connections and ease of erection are among the comparative merits of such a structural system. Nevertheless, contemporary steel design standards remain mostly silent on how to take into account the interaction between the back span and the cantilever in the stability design of overhanging girders. Moreover, collapses of Gerber roofs in Canada and the United States have heightened the above-mentioned concern. In response to this need of industry, my colleagues and I in the Steel Centre—in active collaboration with our industry partners—have planned a comprehensive research program so as to provide new insights to the structural behavior of Gerber systems, and—ultimately—propose a comprehensive design guideline for overhanging steel girders to be implemented in S16-24.