共查询到20条相似文献，搜索用时 26 毫秒
1.
Carbon fiber reinforced polymer （CFRP） bars were prestressed for the structural strengthening of 8 T-shaped reinforced concrete （RC） beams of a 21-year-old bridge in China. The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory. The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit. The field construction processes of strengthening with CFRP bars including grouting cracks, cutting groove, grouting epoxy and embedding CFRP bars, surface treating, banding with the U-type CFRP sheets, releasing external prestressed steel tendons-were introduced in detail. In order to evaluate the effectiveness of this strengthening method, field tests using vehicles as live load were applied before and after the retrofit. The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge, including the bending strength and stiffness, is enhanced. The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges. Therefore, the proposed strengthening technology is feasible and effective. 相似文献
2.
为研究碳纤维布(CFRP)对加固后钢筋混凝土梁的抗弯疲劳性能的影响,进行了3根CFRP加固梁及1根对比梁的抗弯疲劳试验.研究了碳纤维布加固方式、构件使用荷载等参数对碳纤维布加固损伤钢筋混凝土吊车梁的抗弯疲劳性能影响.试验研究表明:采用碳纤维布加固后,构件裂缝的宽度减小50.2%~66%,发展速度也得到控制,钢筋应力减小24.1%~28.2%,构件的刚度提高14.9%~16.1%.依据试验结果,从现有规范中关于构件刚度计算方法出发,进行了CFRP加固钢筋混凝土吊车梁的疲劳刚度计算分析,该计算方法可用于吊车梁加固工程设计.最后给出了CFRP加固梁的疲劳设计的合理化建议. 相似文献
3.
Reinforced concrete （RC） columns lacking adequately detailed transverse reinforcement do not possess the necessary ductility to dissipate seismic energy during a major earthquake without severe strength degradation. In this paper, a new retrofit method, which utilized fiber-reinforced plastics （FRP） confinement mechanism and anchorage of embedded bars, was developed aiming to retrofit non-ductile large RC rectangular columns to prevent the damage of the plastic hinges. Carbon FRP （CFRP） sheets and glass FRP （GFRP） bars were used in this test, and five scaled RC columns were tested to examine the function of this new method for improving the ductility of columns. Responses of columns were examined before and after being retrofitted. Test results indicate that this new composite method can be very effective to improve the anti-seismic behavior of non-ductile RC columns compared with normal CFRP sheets retrofitted column. 相似文献
4.
INTRODUCTION The aging or deterioration of existing R. C.(reinforced concrete) or P. C. (prestressed concrete)structures is one of the major problems that modernengineers have to face. If the flexural or shear strengthof R. C. or P. C. structures is not sufficient to maintaintheir service functions, strengthening of these struc-tures becomes necessary. To date, steel plates havebeen used to strengthen concrete members. Usingcomposite plates to strengthen R.C. or P.C. structures… 相似文献
5.
Strengthening reinforced concrete beams using prestressed glass fiber-reinforced polymer-Part Ⅰ: Experimental study 总被引：2，自引：0，他引：2
This work is aimed at studying the strengthening of reinforced concrete (R. C.) beams using prestressed glass fiber-reinforced polymer (PGFRP). Carbon fiber-reinforced polymer (CFRP) has recently become popular for use as repair or rehabilitation material for deteriorated R. C. structures, but because CFRP material is very stiff, the difference in CFRP sheet and concrete material properties is not favorable for transferring the prestress from CFRP sheets to R. C. members. Glass fiber-reinforced polymer (GFRP) sheets with Modulus of Elasticity quite close to that of concrete was chosen in this study. The load-carrying capacities (ultimate loads) and the deflections of strengthened R. C. beams using GFRP and PGFRP sheets were tested and compared. T- and ⊥-shaped beams were used as the under-strengthened and over-strengthened beams. The GFRP sheets were prestressed to one-half their tensile capacities before being bonded to the T- and l-shaped R. C. beams. The prestressed tension in the PGFRP sheets caused cambers in the R. C. beams without cracks on the tensile faces. The PGFRP sheets also enhanced the load-carrying capacity. The test results indicated that T-shaped beams with GFRP sheets increased in load-carrying capacity by 55% while the same beams with PGFRP sheets could increase load-carrying capacity by 100%. The ⊥-shaped beams with GFRP sheets could increase load-carrying capacity by 97% while the same beams with PGFRP sheets could increase the loading-carrying capacity by 117%. Under the same external loads, beams with GFRP sheets underwent larger deflections than beams with PGFRP sheets. While GFRP sheets strengthen R. C. beams, PGFRP sheets decrease the beams' ductility, especially for the over-strengthened beams (⊥-shaped beams). 相似文献
6.
Feras ALZOUB ZHANG Qi LI Zheng-liang 《重庆大学学报(英文版)》2007,6(4):305-310
This paper presents the results of an experimental investigation on the response of pre-damaged reinforced concrete (RC) beam strengthened in shear using applied-epoxy unidirectional carbon fiber reinforced polymer (CFRP) sheet. The reasearch included four test rectangular simply supported RC beams in shear capacity. One is the control beam, two RC beams are damaged to a predetermined degree from ultimate shear capacity of the control beam, and the last beam is left without pre-damaged and then strengthened with using externally bonded carbon fiber reinforced polymer to upgrade their shear capacity. We focused on the damage degree to beams during strengthening, therefore, only the beams with side- bonded CFRPs strips and horizontal anchored strips were used. The results show the feasibility of using CFRPs to restore or increase the load-carrying capacity in the shear of damaged RC beams. The failure mode of all the CFRP-strengthened beams is debonding of CFRP vertical strips. Two prediction available models in ACI-440 and fib European code were compared with the experimental results. 相似文献
7.
为研究无机胶粘贴碳纤维布对钢筋混凝土梁高温性能的影响,对3根不同加固方式及防火方式的钢筋混凝土梁进行高温试验。试验结果表明,无机胶及防火涂料对钢筋混凝土梁温度场及跨中挠度有重要作用;与防火性能较差的有机胶相比,无机胶具有较好的耐高温性能,可应用于碳纤维布加固混凝土工程中;防火涂料在火灾过程中具有较好的防火和隔热作用,在防火设计中不可忽略。 相似文献
8.
INTRODUCTION Externally bonded fiber reinforced polymer (FRP) composites can be used to improve the flexural strength of structural members. To evaluate the flex-ural performance of the strengthened members, it is necessary to study the flexural stiffness of FRP- strengthened RC members at different stages, such as pre-cracking, post-cracking and post-yielding. Up to now, only very few studies were focused on the structural members strengthened under pre-loading or pre-cracking (Arduin… 相似文献
9.
通过9根表层嵌入碳纤维增强塑料板条抗剪加固的钢筋混凝土梁和4根对比梁的静载试验,分析了构件的破坏形态、斜截面纤维应变分布特征及加固后极限承载力的影响因素。研究结果表明：嵌入式加固与外贴加固相比,可以明显地提高钢筋混凝土梁的抗剪承载力,并改变构件的变形性能。最后,在国内外研究资料的基础上,提出了加固后混凝土梁的受剪承载力计算公式,并对计算值与试验值进行了比较,结果吻合较好。 相似文献
10.
玻璃纤维布加固的钢筋混凝土梁试验研究与抗弯承载力计算 总被引：1，自引：0，他引：1
对9根玻璃纤维布加固的钢筋混凝土梁和3根对比梁进行了抗弯性能试验研究. 试验中考虑了配筋率、加固量、剪跨比与混凝土强度等级4个参数. 试验结果表明, 经玻璃纤维布加固的钢筋混凝土梁抗弯承载力有显著提高; 混凝土强度、配筋率、加固量对极限荷载有显著影响; 剪跨比对加固梁的破坏形态有影响. 根据不同的破坏模式, 提出了抗弯承载力计算方法. 相似文献
11.
INTRODUCTION There is increased need in recent years for strengthening or rehabilitation of existing reinforced concrete structures adversely affected by overloading, construction material deterioration, seismic loads, structural deformation, etc. An effective method for increasing the shear capacity of reinforced concrete columns is the use of externally bonded carbon fiber reinforced plastic (CFRP) systems (ACI, 2002). FRP systems were first applied to reinforced concrete col-umns i… 相似文献
12.
基于ANSYS程序的钢筋混凝土梁非线性数值模拟 总被引：2，自引：0，他引：2
采用商用程序ANSYS对不同配筋率的钢筋混凝土梁进行非线性数值分析，以考察不同配筋率对钢筋混凝土梁受弯性能的影响。结合数值模拟分析过程，详细介绍了基于ANSYS程序的钢筋混凝土构件非线性数值分析的关键技术，分析了对不同配筋率的钢筋混凝土粱的刚度变化、破坏特征、截面应力分布、裂缝发展和钢筋、混凝土应力及应变发展过程。 相似文献
13.
The earthquake-resistant property of reinforced concrete members depends on the interaction between reinforcing bars and surrounding concrete through bond to a large degree,In this paper a general system aimed at dealing with the failure analysis of reinforced concrete columns strengthened with carbon-fiber-reinforced plastic(CFRP) sheets including bond-slip of the anchored reinforcing bars at the foot of the columns is presented.It is based on the yield design theory with a mixed modeling of the structue,according to which the concrete material is treated as a classical two-dimensional continuum ,whereas the longitudinal reinfocing bars are regarded as one-dimensional rods including bond-slip at the foot of the columns,In shear reinforced zones both the shear CFRP sheets and transvers reinforcing bars are incorporated in the analysis throuth a homogenization procedure and they are only in tesion ,The approach is then implemented numerically by means of the finite-element formulation,The numerical procedure produces accurate estimates for the loading-carrying capactiy of the shear members taken as an illustrative application by correlation with the experimental results,so the proposed approach is valid. 相似文献
14.
EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS 总被引：1，自引：0，他引：1
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｉｓｇｒｏｗｉｎｇｃｏｎｃｅｒｎｆｏｒｃｏｒｒｏｓｉｏｎｄａｍ ａｇｅｉｎｒｅｉｎｆｏｒｃｅｄｃｏｎｃｒｅｔｅ (ＲＣ)ｓｔｒｕｃｔｕｒｅｓｗｉｔｈｓｅｖｅｒａｌｄｅｃａｄｅｓ’ｓｅｒｖｉｃｅ.Ｔｈｅｒｅｉｎｆｏｒｃｅｍｅｎｔｃｏｒ ｒｏｓｉｏｎｏｆＲＣｃｏｎｓｔｒｕｃｔｉｏｎｓｐｒｏｂａｂｌｙｉｓｔｈｅｍｏｓｔｓｉｇｎｉｆｉｃａｎｔｐｒｏｂｌｅｍａｎｄｏｕｔｗｅｉｇｈｓｏｔｈｅｒｆｏｒｍｓｏｆｄｅｔｅｒｉｏｒａｔｉｏｎ .ＳｔｕｄｉｅｓｂｙＰｅａｔｔｉｅｅｔａｌ.( 1 9… 相似文献
15.
苏州胥江桥为预应力桥梁 ,桥型由预制梁形成连续梁和组合梁 ,本文主要介绍预应力铺束、张拉工艺、灌浆工艺。 相似文献
16.
There is growing concern for corrosion damage in reinforced concrete structures with several decades’ service. Pullout tests
and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of
reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then
declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete
increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases,
and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength
coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to
easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper
can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded
reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam
is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between
steel bar and concrete.
Project supported by Cao Guanbiao Key Technology Development Founding of Zhejiang University and Construction Ministry of
China. 相似文献
17.
有粘结预应力FRP筋混凝土梁受弯有限元模拟 总被引：1，自引：0，他引：1
庄金平 《福建工程学院学报》2011,9(4)
采用有限元软件ABAQUS对预应力FRP筋混凝土梁受弯性能进行模拟。通过降温法施加预应力,忽略预应力筋与混凝土之间的粘结滑移。在收敛度差调整到3%、线性受拉损伤值dt的峰值取为0.9时,模拟结果与他人的试验结果比较基本吻合。 相似文献
18.
碳纤维布与钢构套复合加固锈蚀钢筋混凝土柱抗震性能研究(英文) 总被引：1，自引：0，他引：1
为改善锈蚀钢筋混凝土柱的抗震性能, 利用碳纤维布与角钢对锈蚀柱进行复合抗震加固. 试验共对12根试件进行了低周反复加载试验, 研究参量包括钢筋锈蚀程度、轴向荷载、碳纤维布层数和角钢用量. 试验结果表明, 利用碳纤维布和角钢复合加固锈蚀柱可以显著改善锈蚀柱的承载能力、延性和耗能能力. 复合加固后, 加固柱的强度和延性与锈蚀柱相比, 可分别提高0.9倍和1倍以上. 基于试验结果, 提出了计算加固构件屈服荷载、最大荷载和位移延性系数的简化公式, 计算结果与试验结果极为吻合. 相似文献
19.
采用Ansys有限元软件对8根不同锈蚀率的FRP片材加固钢筋混凝土梁的受弯性能进行数值分析,研究纵筋锈蚀率对FRP加固梁的裂纹开展、破坏模式、承载能力以及延性和变形能力的影响.研究结果表明:低钢筋锈蚀率的梁发生受压区混凝土压碎破坏;中等锈蚀率的梁钢筋屈服后,钢筋与混凝土界面发生黏结滑移,最后FRP剥离破坏;高锈蚀率的梁钢筋没有达到屈服强度便发生黏结滑移,最后发生受压区混凝土压碎破坏.钢筋锈蚀越严重,FRP加固钢筋混凝土梁的承载力降低得越多.试件RCB-1(锈蚀率为0)的承载力为115 kN,而试件RCB-7(锈蚀率为20%)的承载力仅为42 kN.与FRP加固未锈蚀的钢筋混凝土梁相比,FRP加固锈蚀钢筋混凝土梁的变形能力较高.试件RCB-1和试件RCB-7的最大跨中挠度分别为20 mm和35 mm,而试件RCB-5(锈蚀率为10%)的最大跨中挠度达到了60 mm. 相似文献
20.
为了解玻璃纤维(GFRP)布与钢筋混凝土梁界面之间的粘结性能,进行了7根GFRP布加固的钢筋混凝土梁与2根对比梁的试验研究.试验的变化参数为GFRP布层数、粘结长度及配筋率.试验结果表明,GFRP布加固的钢筋混凝土梁极限荷载显著提高,但是发生剥离破坏的试验梁极限荷载有所降低,粘结长度是影响加固梁剥离破坏的主要因素.根据试验结果提出了GFRP布与钢筋混凝土梁界面粘结剪应力的试验分析方法并分析了界面间粘结剪应力的分布.同时,提出了GFRP布加固的钢筋混凝土梁剥离正应力与粘结剪应力的理论分析方法.最后,给出了GFRP布加固钢筋混凝土梁剥离荷载的计算方法.为验证理论分析方法的正确性,计算了试验梁界面间的粘结剪应力、剥离正应力及剥离荷载.计算结果表明,所提出的理论分析方法与试验值吻合较好. 相似文献