Innovative analysis and design of steel structures for lateral torsional buckling

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Structural steel offers several advantages as a construction material: speed of construction, high strength-to-weight ratio, connection simplicity, amenability to structural modifications, and ability to bridge relatively long spans. As such, structural steel is widely used in Canada in various applications including industrial structures, oil refineries, power plants, petrochemical plants, pipe racks, high rise buildings, commercial structures, stadiums and arenas. In such applications, long span laterally unsupported beams are known to be governed by their lateral torsional buckling mode of failure. Given the complexity of lateral torsional buckling theory, current design standards provide simple solutions only for basic design situations. The application of such simplified design procedures to realistic complex problems lead either to (a) overly conservative designs resulting in costlier structures than needed or (b) inconsistent margins of safety. Within this context, the proposed research program aims at advancing methods of analysis and design of steel members for lateral torsional buckling. The proposed research will examine various effects not considered in present Canadian design standards on the lateral torsional buckling strength of steel members, including; (a) member initial out-of-straightness, (b) pre-buckling deformation, (c) cross-sectional distortion, and (d) presence of plates of modern strengthening materials such as Glass Fiber Reinforced Polymer (GFRP). The study will also examine the interaction of such effects by developing generalized theories which account for multiple effects. A spectrum of analysis and design methodologies will be developed; ranging from the simplified /conservative to the sophisticated/accurate. Such methods will involve (a) formulating and implementing reliable advanced beam buckling theories and finite elements, (b) Developing 3D FEA models based on shell and 3D FEA models for assessment and validation, (c) developing a comprehensive database of analysis results for common design problems, and (d) formulating simplified equations suitable for design. The research program is expected to provide structural engineers a basis to strike an informed balance between structural safety and economy. Over the long term, the adoption of advanced analysis/design methods stemming from the proposed research are expected to realize significant economic benefits to the design of steel structures in Canada.