Grant: Collaborative Research and Development Grants

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.