Novel lateral torsional buckling solutions for new structures and strengthening applications

在加拿大的基础设施中，工字形截面的钢构件是常用的。由于它们具有强度重量比高、连接简单、结构易于修改、能够跨越较大跨度等优点，因此被广泛应用于工商业结构、炼油厂、电力石化厂、管架、高层建筑、体育场馆和桥梁。当无侧向支承的构件在荷载作用下受弯时，它们往往会失去稳定性，最终容易发生侧向扭转屈曲。目前加拿大的设计标准承认侧向扭转屈曲是控制大跨度和中跨度构件能力的一种破坏模式。标准中规定的设计程序具有以下限制：(A)导致对构件强度的不准确估计，或(B)使其不适用于某些实际设计情况。该研究计划的长期目标是(1)改进加拿大标准中关于钢梁弹性/非弹性横向扭转屈曲的现有设计规则，以及(2)为加强梁的弹性/非弹性横向扭转屈曲开发新的设计方案。短期目标是：(1)量化初始出直度和残余应力对钢梁弹性/非弹性横向扭转屈曲的影响；(2)确定盖板或翘曲加劲肋加固钢梁的弹性/非弹性横向扭转屈曲强度。HQP培训：该研究项目将对9名HQP(3PhD、3MSc和3BSC)进行钢结构分析/设计方面的培训，使他们具备扎实的力学/有限元分析基础，提高他们的沟通能力，并使他们能够将知识转移到结构咨询公司和研究机构。预期影响：(1)开发的分析/设计方法将使加拿大工程师能够获得具有成本效益和准确的方法来设计/修复结构，同时达到预期的安全水平。(2)制定加固构件的设计建议将使设计者能够避免过早拆除/重建现有结构，从而以重建费用的一小部分延长其预期寿命。(3)研究结果的计算机实现将免费提供。将努力将开发给加拿大结构分析软件公司的数值解决方案转移/修改/推进，以便在商业上实施。(4)从研究计划中获得的专业知识适用于/可修改其他建筑材料的梁(例如，胶合板梁、Wood I托梁、拉挤FRP梁和组合梁)。

Steel members with I cross-sections are commonly used in Canadian infrastructure. Owing to their advantages related to high strength-to-weight ratio, connection simplicity, amenability to structural modifications, and ability to bridge relatively long spans, they are widely used in industrial & commercial structures, oil refineries, power & petrochemical plants, pipe racks, high rise buildings, stadiums, arenas, and bridges. When laterally unsupported members undergo bending under loads, they tend to lose their stability and eventually become prone to lateral torsional buckling. Current Canadian design standards recognize lateral torsional buckling as a failure mode governing the capacity of long- and medium-span members. Design procedures provided in standards have limitations that either (a) lead to inaccurate estimates of the member strength, or (b) make them inapplicable in some practical design situations. The long-term goal of the research program is (1) improve present design rules in Canadian Standards for elastic/inelastic lateral torsional buckling for steel beams and (2) develop novel design solutions for the elastic/inelastic lateral torsional buckling for strengthened beams. The short-term objectives  (1) quantify the the effects of initial-out-straightness and residual stresses on the elastic/inelastic lateral torsional buckling resistance of steel beams and (2) determine the elastic/inelastic lateral torsional buckling strength of steel beams strengthened with cover plates, or with warping stiffeners. HQP Training: The research program will lead to the training of 9 HQP (3PhD, 3MSc & 3BSc) in the analysis/design of steel structures, equip them with a strong foundation in mechanics/FEA, sharpen their communication skills, and enable them to transfer their knowledge to structural consulting firms and research institutes. Expected Impact: (1) The analysis/design methods developed will enable Canadian engineers to access cost effective and accurate methodologies to design/rehabilitate structures while achieving the expected safety level. (2) The development of design recommendations for strengthening members will enable designers to avoid premature demolishing/reconstructing of existing structures and thus prolong their expected lifespan at a fraction of the reconstruction cost. (3) Computer implementations resulting from the research will be made freely available. Efforts will be made to transfer/modify/advance the numerical solutions developed to Canadian structural analysis software firms to implement them commercially. (4) The expertise gained, and knowledge acquired from the research program is applicable/modifiable to beams of other construction materials (e.g., Glulam beams, Wood I joist, pultruded FRP beams, and composite beams).