薄壁卷边H型钢受弯构件局部屈曲与畸变屈曲的性能分析

发布时间：2018-08-26 13:00

【摘要】：最近几年,薄壁型钢在我国越来越流行,各种截面形式的薄壁型钢大量用于各个工程之中,国家也颁布了相应的规范进行指导工程人员进行设计施工。但是,对于薄壁型钢来说,由于自身比较薄,一旦做成一定长度的构件,就容易发生屈曲失稳。因此,想要更加完美的使用薄壁型钢就必须对屈曲失稳具有足够的了解。对于普通的H型钢来说,其翼缘和腹板容易出现屈曲失稳导致构件的承载力下降,因此必须限制翼缘板的宽厚比和腹板的高厚比,最直接的做法就是增大翼缘和腹板的厚度,但用钢量也就增加了。在这种情况下,一种新型截面形式的型钢出现了即薄壁卷边H型钢,由于这种构件的卷边起到了加劲的作用,约束了翼缘板的屈曲失稳从而提高了构件屈曲后的强度。本文简单介绍了用于求解薄壁型钢局部屈曲与畸变屈曲极限承载力的直接强度法与有效宽度法,并通过分析它们之间的优缺点,建议使用更为简单可行的直接强度法。然而,使用直接强度法求解薄壁卷边H型钢受弯构件发生屈曲时的极限承载力需要求得构件的弹性屈曲应力。一般求解构件的弹性屈曲应力是通过数值解法,但是该方法操作复杂、十分不便。因此,本文将通过有限条软件CUFSM和有限元软件ABAQUS对薄壁卷边H型钢受弯构件的局部屈曲和畸变屈曲的性能进行分析,研究各个参数对受弯构件的影响,然后建立局部屈曲应力公式和畸变屈曲应力公式,便于快速手算出薄壁卷边H型钢受弯构件发生局部屈曲与畸变屈曲时的极限承载力。其中,主要完成了以下主要的创新研究工作:(1)利用有限条CUFSM软件建立了大量不同尺寸的薄壁卷边H型钢受弯构件的模型,求出了构件的屈曲应力从而得到构件发生屈曲时的抗弯承载力,然后通过观察其不同卷边宽厚比、截面宽高比、腹板高厚比、翼缘宽厚比的变化,分析出其对薄壁卷边H型钢受弯构件的影响,从而得到参数的最佳取值范围将其应用于工程之中。(2)通过分析不同参数对薄壁卷边H型钢受弯构件的畸变屈曲影响,建立了适于求解薄壁卷边H型钢受弯构件临界畸变屈曲的半波长公式,并通过验证发现,该公式能够很好的求出薄壁卷边H型钢受弯构件临界畸变屈曲的半波长,为今后研究薄壁卷边H型钢受弯构件的畸变屈曲提供了支持。(3)利用有限条CUFSM软件得到了大量薄壁卷边H型钢的局部屈曲应力和畸变屈曲应力,然后利用经典板件屈曲应力公式求出构件的屈曲系数,再用1stopt拟合软件分别对局部屈曲系数以及畸变屈曲系数进行拟合从而得到相应的屈曲系数公式,最后将拟合得到的屈曲系数公式带入到经典板件屈曲应力公式中,继而得到适合求解薄壁卷边H型钢的弹性局部屈曲应力公式和弹性畸变屈曲应力公式,最后用有限元软件ABAQUS验证简化公式的正确性。
[Abstract]:In recent years, thin-walled section steel is becoming more and more popular in China, various types of thin-walled section steel are widely used in various projects, the country also issued the corresponding code to guide engineers to design and construction. However, for thin-walled steel, the buckling instability is easy to occur once a certain length of member is made. Therefore, in order to use thin-walled steel more perfectly, it is necessary to have a good understanding of buckling instability. For ordinary H-section steel, the flange and web are prone to buckling instability, which leads to the decrease of the bearing capacity of the member. Therefore, the width-thickness ratio of the flange plate and the ratio of the height to thickness of the web must be restricted, and the most direct way is to increase the thickness of the flange and the web. But the amount of steel used increased. In this case, a new type of section steel, that is, thin-walled crimped H-section steel, appears. Because of the stiffening effect of this kind of member, the buckling instability of flange plate is restrained and the strength after buckling of the member is improved. In this paper, the direct strength method and the effective width method for calculating the ultimate bearing capacity of local buckling and distortion buckling of thin-walled steel are briefly introduced. By analyzing the advantages and disadvantages between them, a more simple and feasible direct strength method is suggested. However, the direct strength method is used to calculate the ultimate bearing capacity of thin-walled crimped H-beam members when buckling occurs, and the elastic buckling stress of the members should be obtained. In general, the elastic buckling stress of members is solved by numerical method, but the operation of this method is very complicated. Therefore, through finite strip software CUFSM and finite element software ABAQUS, the local buckling and distortion buckling of thin-walled crimped H-section members are analyzed, and the effects of various parameters on the bending members are studied. Then, the local buckling stress formula and the distorted buckling stress formula are established, which is convenient to calculate the ultimate bearing capacity of thin-walled crimped H-beam bending members under local buckling and distortion buckling. The main contributions are as follows: (1) A large number of thin-walled crimped H-section members with different sizes have been modeled by using finite strip CUFSM software. The buckling stress of the member is obtained to obtain the flexural bearing capacity of the member when buckling occurs, and then the variation of the ratio of width to thickness, the ratio of width to height of section, the ratio of height to thickness of web, and the ratio of width to thickness of flange are observed. The influence of different parameters on the bending member of thin-walled crimped H-section steel is analyzed, and the optimum range of parameters is obtained. (2) the effect of different parameters on the distortion buckling of thin-walled crimped H-section member is analyzed. A half-wavelength formula for calculating the critical distortion buckling of thin-walled crimped H-beam bending members is established, and it is found that the formula can well obtain the half wavelength of the critical distortion buckling of thin-walled crimped H-beam bending members. It provides the support for the study of the buckling distortion of thin-walled crimped H-beam members in the future. (3) A large number of local buckling stresses and distorted buckling stresses of thin-walled crimped H-section steel are obtained by using finite strip CUFSM software. Then the buckling coefficient of the member is obtained by using the classical buckling stress formula, and then the local buckling coefficient and the distortion buckling coefficient are fitted by 1stopt fitting software to obtain the corresponding buckling coefficient formula. Finally, the fitted buckling coefficient formula is introduced into the classical buckling stress formula, and then the elastic local buckling stress formula and the elastic distortion buckling stress formula are obtained, which are suitable for solving thin-walled crimped H-section steel. Finally, the correctness of the simplified formula is verified by finite element software ABAQUS.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU392.1

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