板件延性系数和面向抗震设计的钢截面分类

发布时间：2018-03-27 16:21

本文选题：抗震设计　切入点：非线性分析　出处：《浙江大学》2014年博士论文

【摘要】：抗震钢结构的构件截面通常要求其具有一定的塑性转动能力,实际工程中采用对截面进行分类,并对每一类截面的板件规定相应的宽厚比限值来满足结构的延性需求。目前常用的截面分类方法主要基于承载力和对达到承载力以后的变形能力的定性描述进行的,没有给出板件延性与宽厚比的关系,缺乏截面分类的具体定量指标。本文先对五种边界条件的均匀受压矩形板进行考虑几何非线性、材料非线性、残余应力、初始几何缺陷的非线性分析,得到各模型的压力—压缩变形曲线,并取承载力下降15%处的变形作为计算板件压缩延性从的依据。参数分析发现：不同分布模式的残余应力和残余应力幅值对μ。没有明显的影响；初始几何缺陷幅值增大,μc。会降低,但降低的幅度不大。μc随板件长宽比a/b的增加没有简单的单调增加或递减关系,μc最大值出现在a/b使屈曲半波数为1的范围,当a/b增大到使屈曲半波数大于1之后,μc的变化不大。对比不同边界条件的μc,当非加载边约束越强,μc越高。按照从和通用宽厚比兄的关系,拟合了不同边界条件的μc。计算公式。经过验证,这组公式可适用于不同屈服强度的钢材。对受弯和压弯状态下的四边简支矩形板以及受弯翼缘板进行弯矩—曲率分析,采用曲率定义受弯板件的延性,压弯板件的延性除了用曲率定义之外还采用了板件边缘纤维压应变来定义延性。通过分析发现板件边缘纤维压应变定义的μbc1不小于曲率定义的μbc2,且在纯弯情况下μbc1=μbc2,在纯压情况下μbc2=0,μbc1=μc。相同宽厚比的情况下,翼缘板受弯时的延性要远远大于受压时的延性。根据计算结果,拟合了受弯和压弯状态下的四边简支矩形板及受弯翼缘板的延性计算公式。为研究板件间相互作用对截面延性的影响,对压弯荷载作用下的工字形截面和箱形截面模型进行非线性分析,得到各模型的弯矩—曲率曲线,采用曲率定义截面延性。研究发现当轴压比一定时,固定翼缘或腹板的宽厚比,降低另一板件的宽厚比,截面延性会增加。另外截面高宽比和翼缘板与腹板的厚度比对截面延性也有很大的影响,在腹板宽厚比和翼缘宽厚比相同的情况下,不同高宽比或板件厚度比的截面延性并不相同。对轴压比在0-0.8之间的工形截面和箱形截面延性系数进行公式拟合,得到了截面延性系数与通用宽厚比λ的简洁关系式。最后尝试提出了面向抗震设计的钢构件截面分类方法。其出发点是：以计算地震力的结构影响系数的大小来确定截面的分类。先根据结构延性与截面延性的关系,区分考虑和不考虑结构的超强系数,反推出对各类截面的延性要求。然后利用前面得到的截面延性系数计算公式,按照各类截面的延性需求,分别给出各类截面的板件宽厚比分界。其中工字形截面和箱形截面的宽厚比分界采用了翼缘宽厚比和腹板宽厚比的相关关系来进行表示,并拟合了相关关系的计算式。
[Abstract]:The cross section of aseismatic steel structure usually requires a certain plastic rotation capacity , and the cross section is classified according to the actual engineering , and the corresponding wide - thickness specific limit value is specified for each type of cross - section plate to meet the ductility demand of the structure . The commonly used sectional classification method is mainly based on the bearing capacity and the qualitative description of the deformation capacity after the bearing capacity is reached , and the relation between the ductility and the aspect ratio of the plate is not given , and the specific quantitative index of the cross - section classification is lacking .

In this paper , the nonlinear analysis of geometric nonlinearity , material nonlinearity , residual stress and initial geometric imperfections are taken into account for the uniform compression rectangular plates with five boundary conditions . The deformation curves of the pressure - compression deformation curves of each model are obtained , and the deformation at 15 % of the bearing capacity is taken as the basis for calculating the compression ductility of the plate .
When a / b increases to a range where the number of buckling half waves is greater than 1 , 渭c is not large . When a / b increases to make the number of buckling half waves greater than 1 , the higher the 渭 c is . When a / b increases to make the number of buckling half waves greater than 1 , the higher the 渭 c is . By comparison with the general aspect ratio , the higher the 渭 c is . By verification , the formula can be applied to steels with different yield strength .

The ductility of the flexural plate is defined by curvature . The ductility of the flexural plate is defined by curvature , and the ductility of the bending plate is defined by the curvature definition . In the case of pure bending , 渭bc1 = 渭bc2 , the ductility of the flange plate is much larger than that of the compression . According to the calculation results , the formulas for calculating the ductility of the four - sided simple rectangular plate and the bent flange plate under the condition of bending and bending are fitted .

In order to study the influence of the interaction of the plates on the ductility of the cross section , the I - shaped cross section and the box - shaped cross section model under the action of bending load are analyzed non - linear to obtain the bending moment - curvature curve of each model .

In the end , the section classification method for seismic design is proposed . The starting point is to determine the classification of section by calculating the structure influence coefficient of seismic force . Firstly , according to the relationship between structural ductility and section ductility , the ductility requirements of various sections are given .

【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;TU352.11

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