T梁交接处剪应力传递与应力分布

发布时间：2018-02-16 09:19

本文关键词： 剪力滞效应 T形梁悬臂梁试验研究模型试验　出处：《华侨大学》2015年硕士论文　论文类型：学位论文

【摘要】：对于剪力滞问题的研究,是从上世纪20年代开始的。经过几十年的发展,对于剪力效应的研究取得了一些成果。虽然能够解决一定的实际问题,但还有许多问题需要进一步的研究。以往研究大多集中于对薄壁箱梁剪力滞的研究,而对于宽翼缘T梁剪力滞效应研究很少,对于T梁翼缘板宽度的改变对剪力滞研究更是少见;在试验研究方面,构件基本是水平放置,构件本身会产生自重,而在对于剪力滞效应的研究上没有考虑构件重力的作用,这样就会造成研究的不准确性,对于剪力滞效应的机理研究又有了不确定性。本文针对于以上两个问题进行了试验研究分析,最后得到了研究结论与展望。本文研究工作如下:(1)为了消除构件自重对剪力滞效应的影响,设计了一套试验装置,可以使T梁模型成为竖直悬臂结构,并且能够进行水平集中荷载的加载。(2)制作了不同翼缘宽度的有机玻璃T梁模型,纵向上分为4个截面,从下到上分别为A截面、B截面、C截面和D截面。在每个截面翼缘板上下表面和腹板左右表面同时粘贴应变片,并且在腹板和翼缘板交接处亦粘贴上应变片,这样可以把弯曲应变沿宽度方向测出来。(3)设计了四种加载方案——自由端加载,纯弯加载,反弯加载和跨中加载。在自由端加载下,随着弯矩和剪力的增加,剪力滞效应越来越明显;在纯弯段,A截面和B截面翼缘板剪力滞效应基本相同;在反弯点截面处,只受到剪应力的作用,翼缘板上下表面应变基本都为零;在跨中加载情况下,C截面翼缘板上出现了负剪力滞效应。(4)同时对四种加载方式下的交接处的应变研究,可以知道:在自由端加载情况下,沿着纵向方向,从固端到自由端,交接处应变逐渐减小;随着荷载的增大,A截面和B截面交接处应变逐渐增大;在纯弯加载情况下,A截面和B截面在相同荷载作用下翼缘板和腹板交接处应变基本相同;在反弯加载情况下,随着荷载的增大,A截面交接处应变数值逐渐增大;B截面交接处应变基本为零;在跨中加载情况下,沿着纵方向上,从固端到自由端,交接处应变逐渐减小,C截面交接处应变为负值。(5)通过对不同宽度翼缘T梁截面翼缘板上下表面应变曲线和剪力滞系数的对比,可以知道,在自由端加载下,A截面翼缘板剪力滞系数随着翼缘宽度的增加,剪力滞效应越来越明显;在纯弯加载情况下,A截面和B截面剪力滞效应程度不随翼缘板宽度的改变而改变。
[Abstract]:The study of shear lag began in -80s. After decades of development, some achievements have been made in the study of shear effect. Although it can solve some practical problems, However, there are still many problems that need further study. Most of the previous studies focused on the shear lag of thin-walled box girder, but the research on the shear lag effect of wide-flange T-beam is rare. In the experimental research, the members are basically placed horizontally, and the members themselves will produce self-weight, but in the study of the shear lag effect, the effect of the component gravity is not considered. This will lead to the inaccuracy of the research and the uncertainty of the mechanism of the shear lag effect. Finally, the conclusion and prospect of the study are obtained. The research work is as follows: 1) in order to eliminate the influence of the deadweight on the shear lag effect, a set of test device is designed, which can make the T-beam model become a vertical cantilever structure. And the model of PMMA T-beam with different flange width can be made by loading horizontal concentrated load. The model is divided into 4 sections longitudinally. From bottom to top are section A, section A, section B, section C, section D, respectively. Strain gauges are attached to the upper and lower surfaces of each section flange plate and to the left and right surfaces of the web plate, and to the junction of the web plate and the flange plate. In this way, the bending strain can be measured in the width direction.) four loading schemes are designed: free end loading, pure bending loading, reverse bending loading and mid-span loading. Under free end loading, with the increase of bending moment and shear force, The shear lag effect is more and more obvious, the shear lag effect is basically the same in pure bending section A section and B section flange plate, and at the reverse bending point section, only the shear stress acts on the upper and lower surface strain of the flange plate, and the surface strain of the flange plate is basically zero. In the case of mid-span loading, the negative shear lag effect appears on the flange plate of C section, and the strain at the junction of the four loading modes is also studied. It can be seen that under the loading of free end, along the longitudinal direction, from the fixed end to the free end, The strain at the junction gradually decreases, the strain at the junction of section A and section B increases with the increase of load, and the strain of section A and section B is basically the same at the junction of flange plate and web plate under the same load under pure bending loading. In the case of reverse bending loading, with the increase of load, the strain value at the junction of section A and section B increases gradually, and the strain at the junction of section B is basically zero. In the case of mid-span loading, along the longitudinal direction, the strain increases from the fixed end to the free end. The strain at the junction decreases gradually and the strain at the junction of C section is negative. (5) by comparing the upper and lower surface strain curves and shear lag coefficients of flange plates with different widths of flange T beams, we can know that, Under free end loading, the shear lag effect of flange plate of section A increases with the width of flange, but the shear lag effect of section A and section B does not change with the width of flange plate under pure bending loading.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU311

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