Development of stability design guidelines for modern I-shaped welded steel girders in Canada

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Many building structures and bridges in North America are built with welded steel girders to resist gravity**loads. The design of such girders is typically governed by their stability; however, various parameters can**affect their stability response, including cross-sectional properties, end and loading conditions, built-in stresses**and initial geometric imperfections. Current Canadian design standards are supported by studies that do not**necessarily represent the design and fabrication practice of modern girders. The validity of past experimental**studies and corresponding numerical simulations is questionable because of their reliance on small-scale test**specimens and fabrication processes that are no longer practiced. Additionally, few studies include detailed**quantification of the influential parameters. To better understand stability of modern welded steel girders,**designers need improved guidelines based on data that reflect the actual behaviour of the member under design**loads. Our research project focuses on four key objectives: 1) to thoroughly measure the amplitude and pattern**of residual stresses that develop in the course of contemporary manufacturing and welding processes; 2) to**evaluate the stability requirements for welded girders in steel bridges and buildings in light of the effect of**residual stresses; 3) to evaluate current Canadian stability design requirements for I-shaped welded steel**girders; and 4) to generate design recommendations for changes to Canadian standards for stability**requirements in steel construction and bridge design. To achieve these aims, the research team will perform**full-scale lab experiments and employ numerical modelling. We will also provide improved design tools to**structural engineers for their daily work, resulting in safer structures and reduced construction costs.