【作者】 张彩然；

【导师】 朱尔玉；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2012， 博士

【摘要】 摘要：单轨应急梁三面受力、曲线半径小,且线形多样化,采用了倒T形钢箱梁的结构形式,本文在总结国内外学者研究成果和相关设计规范的基础上,通过理论推导和有限元分析,并结合相关试验研究,对应急梁结构设计中的稳定问题展开较为系统的研究,主要完成了以下工作：(1)以侧向屈曲为控制因素,对应急梁在三种常见荷载作用下整体稳定的临界荷载计算公式进行了推导。对不同曲线半径的应急梁进行整体稳定的理论计算和数值分析,结果表明,应急梁侧向屈曲的临界荷载受曲线半径变化的影响不明显,可以按照直线梁的屈曲特性进行分析。(2)对影响应急梁侧向屈曲的重要因素进行参数分析,并推导了应急梁受压翼缘自由长度与其宽度之比的临界值计算公式,并由此给出了常见荷载作用下,不同截面尺寸比值时应急梁的最大跨宽比。(3)基于能量原理,对轴向压力、弯矩和剪力共同作用下,不等间距开口肋加劲板弹性屈曲的临界应力计算公式进行推导,将等间距布置的开口肋加劲板作为它的一种特殊情况,对公式进行了简化。(4)考虑截面实际形心轴的位置和闭口截面的抗扭刚度,单独计算母板与加劲肋的抗弯刚度,利用能量原理对不等间距闭口肋加劲板弹性屈曲的临界应力计算公式进行了推导。与目前文献中梯形肋加劲板屈曲的计算方法相比,本文方法能更准确地反映母板和加劲肋对截面抗弯刚度的贡献。(5)基于加劲板的弹性稳定理论,分别对影响开口肋和闭口肋加劲板屈曲临界应力的影响因素进行参数分析,根据应急梁加劲板的结构形式和纵向加劲肋的受力特点,推导得到了开口加劲肋和闭口加劲肋各自对应的最大尺寸限值和合理刚度的计算公式。(6)建立不同尺寸参数的矩形肋加劲板有限元模型,分别对其进行焊接残余应力的数值分析,并对影响矩形肋加劲板残余应力分布的影响因素进行了参数分析,在此基础上,对加劲板残余应力的数值计算结果进行分析处理,提出了矩形肋加劲板残余应力的简化计算模式。(7)同时考虑材料非线性和几何非线性,并计入初始几何缺陷和残余应力的影响,对采用不同尺寸参数的开口肋加劲板和矩形肋加劲板分别进行稳定极限承载力的有限元分析,并对影响其极限承载力的影响因素进行了参数分析。更多还原

【Abstract】 ABSTRACT:Due to the properties:three sides loading, small curve radius and various linear of Monorail tracts, inverted T-shaped steel box girders are used for emergency beams. Based on the domestic and abroad researches, design rules and experiments, this paper investigate the stability issues in the design of emergency beams by theoretical and finite element analyses. The main works involved in this research are follows:(1) Lateral buckling as the controlling factor, the formulas used for calculating overall stability of emergency beams under different kinds of load were derived. The overall stabilities of the emergency beams with different radiuses were theoretically and numerically analyzed. The results showed that, the effect of radius on the critical buckling load was insignificant, and it can be calculated according to the characteristics of the buckling properties of linear beam.(2) A parametric study involving main factors which affect the lateral buckling of emergency beam was applied, and the formulas used for calculating critical values of the ratio (flange length/width, emergency beam) were deduced. So, the maximum ratios (span/width, emergency beam) under three kinds of load were presented for various emergency beams’cross-sections.(3) Based on the energy principle, the formulas used for calculating critical stress of elastic buckling of stiffened plates with unequal interval opening stiffeners were derived. The formulas were simplified later, regarding the stiffened plates with equal interval opening stiffeners as a special case.(4) Taking into account the actual position of the centroidal axis and tensional rigidity of the section, and considering the flexural rigidity of the stiffeners separately, the formula used for critical buckling stress of stiffened plates with unequal interval closed stiffeners was derived, using the energy theory. Comparing the current calculation methods of stiffened plates with trapezoidal stiffeners, the above formula can more accurately reflect the contribution of panels and stiffeners on bending stiffness of the cross-section.(5) Based on the elastic theory of stiffened plates, the main factors, which affect critical buckling stress of the stiffened plates with opening stiffeners and closed stiffeners, were parametric studied respectively. According to stiffened plates structures and force characteristics of the longitudinal stiffeners, the maximum limited sizes and reasonable stiffness formulas for opening stiffeners and closed stiffeners were derived.(6) Finite element models for the different size stiffened plates with rectangular stiffeners were established, for analyzing the welding residual stress of models. The factors which affect the residual stress profiles of the models were parametric studied. At last, the simplified diagrams for calculating residual stress profiles of the stiffened plates were presented.(7) Taking into account the material nonlinearly and geometric nonlinearity, and considering the initial geometric imperfections and residual stresses, the ultimate strength of stiffen plates with opening stiffeners and rectangular stiffeners, which are different on size, were analyzed by finite element models and, the factors affecting the ultimate strength were parametric studied.更多还原