外贴U型CFRP箍位置对RC梁受剪加固效果影响的参数研究
发布时间：2018-10-25 11:30
【摘要】：纤维增强复合材料(FRP)具有轻质、高强、耐腐蚀等优越的特性,在土木工程领域的应用越来越广泛。长期以来,FRP材料主要用于结构的加固和修复,而CFRP的U型粘贴是FRP抗剪加固钢筋混凝土梁最常用的一种加固方式。本文首先回顾了目前纤维复合材料的应用与研究现状,然后提出一种新的思路:改变CFRP与箍筋的相对位置和CFRP的层数,继而研究加固后承载力的提升趋势与CFRP的加固效率。研究的主要内容如下:(1)在混凝土梁斜截面抗剪破坏的理论基础上使用ANSYS数值模拟形式对五组箍筋间距分别为100mm、150mm、200mm、250mm和300mm的未经过CFRP加固的混凝土梁进行了模拟,结果表明破坏模式与理论中斜截面抗剪破坏模式相同,且模拟值与理论计算值误差在可接受范围内,混凝土、钢筋的应力分布变化规律也与理论基本吻合,以上说明ANSYS模拟是可行的;(2)分别改变五组加固梁中CFRP与箍筋的相对位置,具体过程是从箍筋与CFRP中心重合的位置依次以25mm为单位移动,直到移动到CFRP的中心在两箍筋的中间位置,得出每一组加固梁相对于未加固梁承载力提高的百分比和荷载-位移曲线以及CFRP的加固效率,最终发现随着相对位置的改变,梁的承载力在不断地提高,但是提高幅度呈下降趋势,CFRP加固效率曲线也呈现相同的趋势,可见CFRP在两箍筋的中间位置时加固效果是最好的;(3)分别改变五组加固梁中CFRP的层数,模型中层数分别设置为一层、两层和四层,结论为:增加层数会提高承载力但承载力的增加幅度也是在逐渐减小的,而CFRP的加固效率呈下降的趋势,所以CFRP对梁进行抗剪加固时层数为不超过四层为宜;(4)对比五组不同箍筋间距的梁,随着CFRP与箍筋相对位置的改变,箍筋间距越大承载力提高的幅度越大,CFRP的加固效率也越高;(5)通过对比五组不同加固层数的梁的加固效果发现箍筋间距大的梁改变CFRP层数后的加固效果更明显;
[Abstract]:Fiber reinforced composite (FRP) has been widely used in civil engineering due to its advantages of light weight, high strength and corrosion resistance. For a long time, FRP material is mainly used in the reinforcement and repair of structures, and the U-type bonding of CFRP is the most commonly used strengthening method for reinforced concrete beams strengthened by FRP. In this paper, the application and research status of fiber composites are reviewed at first, then a new way of thinking is put forward: to change the relative position of CFRP and stirrups and the number of layers of CFRP, and then to study the increasing trend of bearing capacity after strengthening and the strengthening efficiency of CFRP. The main contents of the study are as follows: (1) based on the theory of shear failure of concrete beams with oblique sections, five groups of concrete beams with a stirrups spacing of 100mm / 150mm / 200mm / 250mm and 300mm respectively, which are not strengthened by CFRP, are simulated by ANSYS numerical simulation. The results show that the failure mode is the same as the shear failure mode of the inclined section in theory, and the error between the simulated value and the theoretical calculation value is within the acceptable range, and the stress distribution of concrete and steel bar is basically consistent with the theory. The above results show that ANSYS simulation is feasible. (2) the relative positions of CFRP and stirrups in five groups of strengthened beams are changed respectively, and the concrete process is to move from the position where the stirrups coincide with the center of CFRP in turn to 25mm. Until the center of CFRP is moved to the middle of the two stirrups, the percentage of bearing capacity of each group of strengthened beams relative to the unstrengthened beams is obtained, the load-displacement curve and the reinforcement efficiency of CFRP are obtained. Finally, it is found that the relative position changes with the change of the relative position. The bearing capacity of beams is increasing, but the increasing amplitude is decreasing, and the efficiency curve of CFRP reinforcement is also showing the same trend. It can be seen that the strengthening effect of CFRP is the best in the middle position of two stirrups. (3) changing the number of layers of CFRP in five groups of strengthened beams, The middle layer of the model is set to one layer, two layers and four layers respectively. The conclusion is that increasing the number of layers will increase the bearing capacity, but the increasing range of the bearing capacity will gradually decrease, while the reinforcement efficiency of CFRP will decrease. Therefore, it is appropriate for CFRP to strengthen beams with no more than four layers. (4) comparing five groups of beams with different stirrups spacing, with the change of relative position of CFRP and stirrups, The larger the space between stirrups, the larger the bearing capacity, the higher the reinforcement efficiency of CFRP. (5) by comparing the reinforcement effect of five groups of beams with different reinforcement layers, it is found that the reinforcement effect of beams with large stirrups spacing is more obvious after changing the number of CFRP layers.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1
本文编号：2293578
[Abstract]:Fiber reinforced composite (FRP) has been widely used in civil engineering due to its advantages of light weight, high strength and corrosion resistance. For a long time, FRP material is mainly used in the reinforcement and repair of structures, and the U-type bonding of CFRP is the most commonly used strengthening method for reinforced concrete beams strengthened by FRP. In this paper, the application and research status of fiber composites are reviewed at first, then a new way of thinking is put forward: to change the relative position of CFRP and stirrups and the number of layers of CFRP, and then to study the increasing trend of bearing capacity after strengthening and the strengthening efficiency of CFRP. The main contents of the study are as follows: (1) based on the theory of shear failure of concrete beams with oblique sections, five groups of concrete beams with a stirrups spacing of 100mm / 150mm / 200mm / 250mm and 300mm respectively, which are not strengthened by CFRP, are simulated by ANSYS numerical simulation. The results show that the failure mode is the same as the shear failure mode of the inclined section in theory, and the error between the simulated value and the theoretical calculation value is within the acceptable range, and the stress distribution of concrete and steel bar is basically consistent with the theory. The above results show that ANSYS simulation is feasible. (2) the relative positions of CFRP and stirrups in five groups of strengthened beams are changed respectively, and the concrete process is to move from the position where the stirrups coincide with the center of CFRP in turn to 25mm. Until the center of CFRP is moved to the middle of the two stirrups, the percentage of bearing capacity of each group of strengthened beams relative to the unstrengthened beams is obtained, the load-displacement curve and the reinforcement efficiency of CFRP are obtained. Finally, it is found that the relative position changes with the change of the relative position. The bearing capacity of beams is increasing, but the increasing amplitude is decreasing, and the efficiency curve of CFRP reinforcement is also showing the same trend. It can be seen that the strengthening effect of CFRP is the best in the middle position of two stirrups. (3) changing the number of layers of CFRP in five groups of strengthened beams, The middle layer of the model is set to one layer, two layers and four layers respectively. The conclusion is that increasing the number of layers will increase the bearing capacity, but the increasing range of the bearing capacity will gradually decrease, while the reinforcement efficiency of CFRP will decrease. Therefore, it is appropriate for CFRP to strengthen beams with no more than four layers. (4) comparing five groups of beams with different stirrups spacing, with the change of relative position of CFRP and stirrups, The larger the space between stirrups, the larger the bearing capacity, the higher the reinforcement efficiency of CFRP. (5) by comparing the reinforcement effect of five groups of beams with different reinforcement layers, it is found that the reinforcement effect of beams with large stirrups spacing is more obvious after changing the number of CFRP layers.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1
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