薄壁不锈钢轴压构件的极限承载力

发布时间：2018-04-12 00:38

本文选题：不锈钢 + 材料非线性　；参考：《浙江大学》2014年博士论文

【摘要】：不锈钢材料不锈耐蚀,外观精美,具有良好的力学和工艺性能,是一种外观及使用性能优异的建筑材料,但其受力性能与普通碳素钢存在显著不同：应力—应变关系表现为典型非线性,无屈服平台,比例极限较低,应变硬化性能显著。目前国内对不锈钢结构力学性能方面的研究相对较少,又无相关设计标准,极大地限制了不锈钢材料在建筑结构中的应用与发展。本文对薄壁不锈钢轴压构件的极限承载力进行了深入研究。首先对国内外不锈钢应力—应变关系模型的研究成果进行梳理,通过介绍、分析、比较和验证,筛选最佳不锈钢材料应力—应变关系模型。结果表明Quach提出的三段式模型具有较高精度且可采用Ramberg-Osgood三参数表示,是目前可供选用的最佳模型。然后针对不锈钢材料,利用广义梁理论基本原理,推导出适用于非线性材料的修正广义梁理论平衡方程,提出不锈钢薄板受压局部屈曲、卷边槽形截面柱畸变屈曲及箱形截面柱弯曲屈曲荷载计算公式。结果表明其计算值与既有试验结果吻合良好,具有较高精度,可用于不锈钢薄板受压局部屈曲荷载、卷边槽形截面柱畸变屈曲荷载及箱形截面柱弯曲屈曲荷载的确定。接下来基于既有试验结果建立有限元分析模型,对四边简支不锈钢薄板均匀受压的局部稳定性能进行研究,结合大量参数分析对Winter稳定曲线进行修正,提出适用于不锈钢材料的薄板均匀受压极限承载力和箱形截面构件局部屈曲承载力计算公式。之后对薄壁不锈钢圆管柱轴心受压性能进行试验研究,包括标准材料拉伸试验、短柱轴向受压试验和长柱轴向受压试验,并基于试验结果对材料性能、破坏形态、位移、应力分布和初始缺陷等进行分析。接着利用有限元软件对上述试验进行数值模拟,建立精确的有限元模型,并通过大量参数分析考察包括长细比、壁厚、直径、径厚比、初始缺陷、材料性能等因素对薄壁不锈钢圆管柱轴心受压极限承载能力的影响,提出临界修正长细比和容许径厚比计算公式。最后对薄壁不锈钢圆管柱轴心受压的屈曲性能进行理论分析,并就几种国外不锈钢结构设计规范中的轴压构件极限承载力计算方法进行介绍,最终基于大量有限元分析结果提出薄壁不锈钢圆管长柱、短柱轴心受压极限承载力计算方法。结果表明其计算值与有限元结果吻合良好,与国外规范计算方法相比具有较高精度且偏于安全,可用于薄壁不锈钢圆管柱轴心受压构件极限承载力的确定。
[Abstract]:Stainless steel is a kind of building material with excellent appearance and good mechanical and technological properties.However, the mechanical properties of the steel are obviously different from those of common carbon steel. The stress-strain relationship is typical nonlinear, has no yield platform, has low ratio limit, and has remarkable strain-hardening properties.At present, there are few researches on the mechanical properties of stainless steel structures in China, and there is no related design standard, which greatly limits the application and development of stainless steel materials in building structures.In this paper, the ultimate bearing capacity of thin-walled stainless steel members under axial compression is studied.Firstly, the research results of stress-strain relationship model of stainless steel at home and abroad are combed out, and the best stress-strain relationship model of stainless steel material is selected by introducing, analyzing, comparing and verifying.The results show that the three-segment model proposed by Quach has high accuracy and can be expressed by Ramberg-Osgood three parameters. It is the best model available at present.Then, based on the basic principle of generalized beam theory for stainless steel material, the modified generalized beam theory equilibrium equation suitable for nonlinear material is derived, and the local buckling of stainless steel thin plate under compression is proposed.The formulas for calculating buckling load of curved grooved column and box section column are presented.The results show that the calculated values are in good agreement with the experimental results and have high accuracy. It can be used to determine the local buckling load of stainless steel thin plate, the distorted buckling load of curved grooved column and the bending buckling load of box section column.Then the finite element analysis model is established based on the existing test results, and the local stability behavior of the thin stainless steel sheet with four edges simply supported under uniform compression is studied, and the stability curve of Winter is modified by a large number of parameter analysis.The formulas of uniform compressive ultimate bearing capacity and local buckling capacity of box section members suitable for stainless steel materials are presented.Then the axial compression performance of thin wall stainless steel round pipe string is studied, including the tensile test of standard material, the axial compression test of short column and the axial compression test of long column. Based on the test results, the properties of material, failure form and displacement are studied.Stress distribution and initial defects are analyzed.Then the finite element software is used to simulate the above experiments, and an accurate finite element model is established, and through a large number of parameter analysis, including the aspect ratio, wall thickness, diameter, diameter to thickness ratio, initial defect, etc.The influence of material properties on the ultimate bearing capacity of thin-walled stainless steel circular string under axial compression is discussed. The critical modified aspect ratio and the allowable diameter to thickness ratio are presented.Finally, the buckling behavior of thin-walled stainless steel circular tubular columns under axial compression is analyzed theoretically, and the calculation methods of ultimate bearing capacity of axial compression members in several foreign stainless steel structural design codes are introduced.Finally, based on a large number of finite element analysis results, the ultimate bearing capacity of thin-walled stainless steel tube columns under axial compression is proposed.The results show that the calculated values are in good agreement with the finite element results and have higher accuracy and safety than those of the foreign codes. It can be used to determine the ultimate bearing capacity of thin-walled stainless steel tubular columns under axial compression.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU391

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