外貼U型CFRP箍位置對RC梁受剪加固效果影響的參數(shù)研究
發(fā)布時間：2018-10-25 11:30
【摘要】：纖維增強復(fù)合材料(FRP)具有輕質(zhì)、高強、耐腐蝕等優(yōu)越的特性,在土木工程領(lǐng)域的應(yīng)用越來越廣泛。長期以來,FRP材料主要用于結(jié)構(gòu)的加固和修復(fù),而CFRP的U型粘貼是FRP抗剪加固鋼筋混凝土梁最常用的一種加固方式。本文首先回顧了目前纖維復(fù)合材料的應(yīng)用與研究現(xiàn)狀,然后提出一種新的思路:改變CFRP與箍筋的相對位置和CFRP的層數(shù),繼而研究加固后承載力的提升趨勢與CFRP的加固效率。研究的主要內(nèi)容如下:(1)在混凝土梁斜截面抗剪破壞的理論基礎(chǔ)上使用ANSYS數(shù)值模擬形式對五組箍筋間距分別為100mm、150mm、200mm、250mm和300mm的未經(jīng)過CFRP加固的混凝土梁進行了模擬,結(jié)果表明破壞模式與理論中斜截面抗剪破壞模式相同,且模擬值與理論計算值誤差在可接受范圍內(nèi),混凝土、鋼筋的應(yīng)力分布變化規(guī)律也與理論基本吻合,以上說明ANSYS模擬是可行的;(2)分別改變五組加固梁中CFRP與箍筋的相對位置,具體過程是從箍筋與CFRP中心重合的位置依次以25mm為單位移動,直到移動到CFRP的中心在兩箍筋的中間位置,得出每一組加固梁相對于未加固梁承載力提高的百分比和荷載-位移曲線以及CFRP的加固效率,最終發(fā)現(xiàn)隨著相對位置的改變,梁的承載力在不斷地提高,但是提高幅度呈下降趨勢,CFRP加固效率曲線也呈現(xiàn)相同的趨勢,可見CFRP在兩箍筋的中間位置時加固效果是最好的;(3)分別改變五組加固梁中CFRP的層數(shù),模型中層數(shù)分別設(shè)置為一層、兩層和四層,結(jié)論為:增加層數(shù)會提高承載力但承載力的增加幅度也是在逐漸減小的,而CFRP的加固效率呈下降的趨勢,所以CFRP對梁進行抗剪加固時層數(shù)為不超過四層為宜;(4)對比五組不同箍筋間距的梁,隨著CFRP與箍筋相對位置的改變,箍筋間距越大承載力提高的幅度越大,CFRP的加固效率也越高;(5)通過對比五組不同加固層數(shù)的梁的加固效果發(fā)現(xiàn)箍筋間距大的梁改變CFRP層數(shù)后的加固效果更明顯;
[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.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU375.1
本文編號：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.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU375.1
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