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

北美的许多建筑结构和桥梁都是用焊接钢梁建造的，以抵抗重力荷载。这类梁的设计通常受其稳定性的影响，然而，各种参数都会影响其稳定响应，包括截面特性、端部和加载条件、内应力和初始几何缺陷。目前加拿大的设计标准是由研究支持的，这些研究不一定代表现代大梁的设计和制造实践。过去的实验研究和相应的数值模拟的有效性是值得怀疑的，因为它们依赖于不再实践的小规模测试样品和制造工艺。此外，很少有研究包括对影响参数的详细量化。为了更好地了解现代焊接钢梁的稳定性，设计人员需要基于反映构件在设计荷载下的实际行为的数据来改进指南。我们的研究项目集中于四个关键目标：1)彻底测量在现代制造和焊接过程中产生的残余应力的幅度和模式；2)根据残余应力的影响评估钢桥和建筑物中焊接梁的稳定性要求；3)评估加拿大当前对工字形焊接钢梁的稳定性设计要求；以及4)为加拿大钢结构和桥梁设计中的稳定性要求标准的变化提出设计建议。为了实现这些目标，研究小组将进行全尺寸的实验室实验，并采用数值模拟。我们还将为结构工程师的日常工作提供更好的设计工具，从而使结构更安全，降低建造成本。

Many building structures and bridges in North America are built with welded steel girders to resist gravityloads. The design of such girders is typically governed by their stability; however, various parameters canaffect their stability response, including cross-sectional properties, end and loading conditions, built-in stressesand initial geometric imperfections. Current Canadian design standards are supported by studies that do notnecessarily represent the design and fabrication practice of modern girders. The validity of past experimentalstudies and corresponding numerical simulations is questionable because of their reliance on small-scale testspecimens and fabrication processes that are no longer practiced. Additionally, few studies include detailedquantification 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 designloads. Our research project focuses on four key objectives: 1) to thoroughly measure the amplitude and patternof residual stresses that develop in the course of contemporary manufacturing and welding processes; 2) toevaluate the stability requirements for welded girders in steel bridges and buildings in light of the effect ofresidual stresses; 3) to evaluate current Canadian stability design requirements for I-shaped welded steelgirders; and 4) to generate design recommendations for changes to Canadian standards for stabilityrequirements in steel construction and bridge design. To achieve these aims, the research team will performfull-scale lab experiments and employ numerical modelling. We will also provide improved design tools tostructural engineers for their daily work, resulting in safer structures and reduced construction costs.