不锈钢焊接截面梁局部稳定与非线性变形性能研究

The key advantages of stainless steel structures are their remarkable corrosion resistance and durability, which have raised their promising prospect in structural applications. In view of the disparities in material properties between stainless steel and carbon steel, the existing design approaches for carbon steel structures may not be directly extended to cover stainless steels, calling for separate investigations. The experimental studies on local buckling and nonlinear deformation behaviour of welded stainless steel flexural members will be carried out, based upon which the inherent load-carrying mechanism and comprehensive design methods could be investigated. The local buckling behaviour of web plates in flexural members under shear, bending and patch loading will be separately described by simplified mechanical models, and the interaction effects between the various forces can also be studied. The load versus deformation curves of simply supported and continuous flexural members will be analysed theoretically. Finite element models will be set up to conduct numerical simulations on the local buckling and nonlinear deformation behaviour parallel to the experimental tests, upon the validation of which, systematic parametric studies would be conducted. Analysis of the key parameters can reveal their influences on the buckling resistances and flexural deformations. Consequently, the design principle for the various stiffeners will be presented, and design methods for predicting local buckling and postbuckling resistances will be proposed. Moreover, the design approach to flexural deformation calculation and residual deformation restriction will also be provided. The expected research achievements could play an important role in developing design methods for stainless steel structures and promoting the use of stainless steel in structural applications.

不锈钢结构由于其优良的耐腐蚀性和耐久性，在建筑结构中具有可观的应用前景；不锈钢材的基本力学性能与普通钢材存在明显区别，现有的普通钢结构设计方法不再适用，需要针对不锈钢结构开展专门研究。本项目将以不锈钢焊接截面梁的局部稳定与变形性能试验为基础，系统开展梁局部稳定与非线性变形受力机理和设计方法研究：建立准确描述不锈钢梁腹板在剪力、弯矩、局部压力单独作用以及共同作用下的局部屈曲机理的简化力学模型，以及确定不锈钢焊接简支梁和连续梁的荷载-挠度发展定量关系式；建立能够准确可靠模拟不锈钢焊接截面梁局部稳定和非线性变形性能的精细有限元数值模型，开展系统性参数分析确定各关键参数的影响规律；确定不锈钢焊接截面梁腹板加劲肋配置与设计原则，提出腹板局部稳定和屈曲后强度利用的设计方法，建立弯曲挠度计算和残余变形控制设计方法。项目研究成果对于完善不锈钢结构设计方法和理论，促进不锈钢结构工程应用具有重要的积极意义。

不锈钢结构具有优良的耐腐蚀性、耐久性和建筑表现力，可以从结构材料层面解决普通钢结构的腐蚀问题，但不锈钢的非线性材料力学特性使得构件的受力性能与普通钢结构构件存在明显区别，不能直接沿用现有的计算方法。本项目采用了试验研究、数值计算和理论分析的手段，对不锈钢焊接截面梁的局部稳定性能和变形性能进行了深入研究。主要研究内容包括：完成了108组奥氏体型S30408和双相型S22253两种牌号不锈钢材料的拉伸和压缩力学性能试验，32组不锈钢焊接截面梁的剪切、弯曲、弯剪和局部承压的局部稳定加载试验，以及10组简支梁和连续梁的变形性能试验，所得出的不锈钢梁受力特性和失效破坏形态是开展不锈钢结构技术研究的基础试验数据；分别建立了准确模拟不锈钢焊接截面梁局部稳定性能和变形性能的精细化有限元数值模型，并基于试验结果对模型的准确可靠性进行了验证；系统分析了梁腹板在纯剪、纯弯和局部压应力单独作用以及多种应力组合作用下的局部屈曲受力机理，探究了梁腹板上配置的横向加劲肋、斜向加劲肋和纵向加劲肋的影响，研究了简支梁和连续梁的荷载-挠度发展关系，基于试验研究和数值分析结果揭示了各关键参数对梁局部稳定性能和变形性能的影响规律；提出了不锈钢焊接截面梁腹板加劲肋配置原则，得出了不锈钢梁局部稳定承载力和变形计算方法，包括梁的局部屈曲承载力和在不同加劲肋配置方案下考虑屈曲后强度的承载力计算公式。项目研究成果为我国正在开展的《不锈钢结构技术规程》修订工作和相关工程实践提供了重要的试验和理论研究基础。