Novel lateral torsional buckling solutions for new structures and strengthening applications

在加拿大的基础设施中通常使用I形截面的钢构件。由于其具有强度重量比高、连接简单、易于结构修改以及能够桥接相对较长的跨度等优点，因此广泛应用于工业和商业结构、炼油厂、电力和石化厂、管架、高层建筑、体育场、竞技场和桥梁。当横向无支撑构件在荷载作用下发生弯曲时，它们往往会失去稳定性，并最终倾向于发生横向扭转屈曲。现行的加拿大设计标准承认横向扭转屈曲是控制中长跨构件承载力的一种失效模式。标准中规定的设计程序有以下局限性：（a）导致构件强度估计不准确，或（B）使其在某些实际设计情况下不适用。研究计划的长期目标是：（1）改进加拿大标准中钢梁弹性/非弹性侧向扭转屈曲的现行设计规则;（2）开发加固梁弹性/非弹性侧向扭转屈曲的新设计解决方案。短期目标（1）量化初始不直度和残余应力对钢梁弹性/非弹性抗侧扭屈曲的影响;（2）确定用盖板或翘曲加劲肋加固的钢梁的弹性/非弹性抗侧扭屈曲强度。HQP培训：该研究计划将导致9名HQP（3 PhD，3 MSc和3BSc）在钢结构分析/设计方面的培训，为他们提供力学/FEA的坚实基础，提高他们的沟通技巧，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成本效益高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)制定加强构件的设计建议将使设计人员能够避免过早拆除/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)研究产生的计算机实现将免费提供。将努力向加拿大结构分析软件公司转让/修改/改进所开发的数值解决方案，以便在商业上加以实施。(4)从研究计划中获得的专业知识和知识适用于/可修改其他建筑材料的梁（例如，胶合木梁、木质I型托梁、拉挤FRP梁和复合梁）。

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).