【作者】 康孝先；

【导师】 强士中；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 我国在大跨度钢桥建设上某些指标已经赶超世界先进水平,但基础理论研究却落后较多,严重滞后于工程实践。随着我国桥梁建设的发展,钢桥跨径不断增大,广泛采用高强钢并向全焊形式发展,桥塔高耸化、箱梁薄壁化,使结构整体和局部的刚度下降,稳定问题显得比以往更为重要,迫切需要对钢桥结构稳定性和极限承载力等关键技术问题进行深入的理论研究和模型试验。20世纪70年代欧洲发生4次大型钢箱梁桥施工坠梁事故是桥梁稳定性问题研究的新起点,也说明应按极限承载力理论来指导设计。分析桥梁结构的极限承载力,不仅可以用于极限状态设计,而且可以了解桥梁结构的破坏形式,准确地知道结构在给定荷载下的安全储备和超载能力,为其安全施工和营运管理提供依据和保障。本文在总结和吸取前人对桥梁结构,特别是板钢结构极限承载力研究方面的成果和方法的基础上,采用理论分析和数值计算相结合的方法,对板、板钢结构的极限承载力进行了全面、系统的研究。本文的研究内容如下：1.钢桥稳定理论和板钢结构极限承载力研究的总结和评述：在对桥梁稳定理论和板钢结构极限承载力研究的历史与现状进行回顾和总结的基础上,就其基础理论、研究思路、分析方法、目前的研究水平等4方面,系统阐述已取得的成果,同时指出了目前板、板钢结构稳定性和极限承载力研究面临的问题,为大跨度钢桥极限承载力研究提供参考。2.板钢结构极限承载力研究：从含初始弯曲的大挠度方程出发,以薄板厚度的折减系数为摄动参数,将残余应力等效为边界荷载,将实用板(带初始弯曲和残余应力的板)比拟为理想板(完善板),得出板的厚度折减系数和板钢结构厚度折减方程。通过与数值方法和已有的试验数据对比分析验证了折减厚度法的正确性,并全面地分析了初始几何弯曲和残余应力对板钢结构极限承载力的影响。3.塑性佯谬的研究：回顾了塑性佯谬的研究历史和对可能造成塑性佯谬的原因进行了全面的总结。采用数值方法,对比分析了塑性增量理论和塑性全量理论对受压板塑性屈曲的影响,并对可能造成塑性佯谬的原因进行了分析和对比。根据对塑性屈曲试验的精细分析和理论研究,得出塑性佯谬是解析方法的近似造成的,塑性佯谬在塑性屈曲数值分析中是不存在的。4.板钢结构极限承载力统一理论研究：将有效宽度法推广到板钢结构的极限承载力分析,得到板钢结构极限承载力统一公式。通过对受压宽板的极限承载力分析验证了统一公式的适用范围；对简支板在均匀受剪、非均匀荷载和复杂荷载作用下的极限承载力分析,系统的研究了统一公式在板钢结构极限承载力分析中的应用；研究了简支板的弹性边界扭转刚度对承载力的影响,将简支板理论推广到板钢结构；与数值方法的对比验证了统一公式的完备性,并给出了适用于复杂板钢结构极限承载力分析的逐步破坏法。结合折减厚度法,考虑板钢结构抗力的随机性得出板钢结构的极限承载力统一理论。5.板钢结构极限承载力理论的应用研究：采用板钢结构极限承载力统一理论,研究工字形钢板梁在局压、受剪和复杂荷载作用下的极限承载力和受压加劲板的极限承载力,得出比已有理论更加优良的极限承载力公式。通过理论分析结果与试验的对比,验证了理论公式的合理性。6.基于可靠度理论的板钢结构极限承载力设计方法研究：回顾了我国公路钢桥设计理论的发展和现状,通过国内外主要钢桥设计规范的比较,提出了基于可靠度理论的板钢结构极限承载力设计方法和目标可靠度指标建议值。开发了基于Ansys软件的随机非线性有限元方法,采用该方法分析了板钢结构设计参数随机性对承载力的影响,得出了板钢结构极限承载力概率设计的分项系数。7.压杆极限承载力研究：采用统一理论研究钢压杆极限承载力,通过修正Shanly模型重新构建了钢压杆极限承载力公式。系统讨论了初始缺陷对钢压杆承载力的影响；对偏心压杆的控制方程进行解析分析,得出双模量理论解高于试验值的直接原因；对钢压杆极限承载力进行概率分析,得出了钢压杆稳定极限承载力概率设计的分项系数。8.试验验证：以珠江黄埔大桥施工稳定性的试验研究为依托,通过扁平钢箱梁节段试验研究了大跨度斜拉桥施工吊装阶段横隔板的稳定性,并通过局部试验研究了桁架式纵隔板的力学性能。通过试验和数值方法的对比分析,对本文提出的板钢结构极限承载力理论进行了验证。更多还原

【Abstract】 Some indicators of the China’s long-span steel bridge constructions had been catching up with the international advanced levels, but lagged behind in basic theoretical researches, which lagged behind engineering practice more seriously. Along with the development of China’s bridge constructions, the longer span of steel bridges, the taller height of bridge towers, the thinner plates of box girder, the extensive application of high-strength steels, as well as the development of whole welded in steel bridge fabrications, so that the local and overall structural stiffness declined, which made bridge stability is more important than ever. There is an urgent need for model tests and theoretical study in depth for steel bridges on the key technology, ie. stability and ultimate strength. Crashed of the four large steel box girder bridges during construction in the 1970s in Europe was the new starting point of the bridge stability research. It is also shown that the limit capacity theory should be guidelines to the bridge designings. Analyzed the ultimate strength of steel bridge structure, not only can be used to limit state design, but can understand its destructive forms, accurately know its overloading capacity and safety reserve with the given loads, provide the gist and guarantee for the security construction and operation.In this thesis, based on summarizing and learing from the achievements in the pioneer’s works on the bridge stability, the limit capacity of plate and steel plated structures. With theoretical and numerical analysis, the limit capacity of plate and steel plated structures had been investigated comprehensively and systematically. The study of this paper as follows:1. Summarized and commented the stability theories of steel bridges and the ultimate strength theories of steel plated structures. On the basis of its basic theories, research ideas, analysis methods and current level etc., systematically summarized its study history and current status, commented its achievements, and pointed out the questions on the ultimate capacity of plates and steel plated structures currently, which can give references to research on the ultimate capacity of long-span steel bridges. 2. Research on the ultimate capacity of steel plated structures. To analyze the ultimate capacity of steel plated structures finally can be idealized as investigated the ultimate capacity of a rectangular plate with arbitrary elastic boundaries loaded in plane. In this paper, considered residual stress as equivalent residual stress loads, researched on the large deflection equations of plates with initial imperfections, applied the thickness discounted quantity of plate as perturbation parameter, assimilated between the applied plate with initial imperfections and the perfect plate, acquired the thickness discounted quantity of perfect plates and the thickness discounted equations of steel plated structures. Validated by the results of nonlinear FEA and experiments, the thickness discounted method (TDM) is practical with good precision. According to nonlinear FEA, had comprehensive investigated the effect by initial imperfections of steel plated structures.3. Comprehensive summarized the research history and the possible reasons for the plastic paradox. Though numerical methods, contrasted the effect of plastic buckling by the flow theory and the deformation theory of plasticity, and the other reasons which may causes plastic paradox. According to detail analysis of the pastic buckling experiments and theoretic research, deemed that plastic paradox is not exist in numerical analysis, which was mainly caused by the approximate supposition in theoretic researches.4. Researched on the unified ultimate capacity theory(UUCT) for steel plated structures. Promoted the effective width theory to analysis the steel plated structures, gained the unification formula for the post-buckling ultimate strength of steel plated structures and the gradual destruction method to analysis the ultimate strength of complex steel plated structures, and validated the UUCT by nonlinear FEA. Through analyzed the ultimate capacity of simple-supported board plate with pressure loading, validated the application range of the UUCT. Research on the effect of torsion stiffness by elastic boundary, extended the results of simply supported plates to plates with elastic boundaries. Research on limit capacity of the simple-supported plate, loaded uniform shear load, non-uniform load and combination loads, systematically researched on how to apply the UUCT, and validated the reasonable of the UUCT by nonlinear FEA. Therefore, TDM, the unification formula and randomicity research on the limit capacity of steel plated structures be called by a joint name——the unified ultimate capacity theory. 5. Researched on the application of the UUCT for the steel plated structures. By the unified theory, researched on the limit capacity of I-section steel girders with shear loading, patch loading and combined loading, research on the stiffened plates with pressure loading. Through comparing research between tests result and nonlinear EFA, the new methods are reasonable than the known theoretical formulas.6. Reviewed the development of highway steel bridge design theories in China, through contrasted between domestic norms and overseas norms for the steel bridge designing, based on the reliability theories, brought forward the suggest value of reliable indicators and the ultimate capacity design methods for the steel plated structures. Stochastic nonlinear finite element method has been developed base on Ansys software. With it, researched on the effect by the stochastic design parameters of steel plated structures, received the sub-factor for the ultimate strength design.7. Researched on the ultimate strength of steel columns by the ultimate capacity theory. Systemically discussed the effect for strut’s bearing capacity by initial imperfection, rebuilt the new checking formula by amended Shanly model. By analytic method, research on the dominate equations of simple supported columns with eccentric loading, gained the direct reasons of that results of double-module theory is large than tests. Probability analyzed on the ultimate strength of steel struts, acquired the sub-factor for the ultimate strength design.8. Based on the flat steel box girder segment experiments of Huangpu Bridge, over Zhujiang river, studied the construction stability of the long-span cable-stayed bridges during suspender installation, and the mechanical properties of truss diaphragms. Through contrasted between the test and the finite element method, verified the unified ultimate capacity theory of steel plated structures proposed in this paper.更多还原