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1.
二次受力下碳纤维布加固梁抗弯性能试验研究   总被引:1,自引:0,他引:1  
进行了4根不同二次受力条件下碳纤维布加固的钢筋混凝土梁和1根对比混凝土梁的抗弯性能试验研究。试验及分析结果表明,用粘贴碳纤维布的方法来提高梁的承载力十分有效,且预加载的存在使加固梁的极限荷载降低;碳纤维布能有效约束裂缝的开展,但裂缝的数量增加和分布区域变大,且预加载的大小会影响加固梁裂缝的开展和分布;碳纤维布加固可以增强梁的刚度,但延性有所降低。  相似文献   

2.
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   

3.
干湿交替与荷载作用下CFRP加固混凝土梁的耐久性   总被引:1,自引:0,他引:1  
对8根持载与恶劣环境作用后的碳纤维增强聚合物(CFRP)加固混凝土梁进行了试验研究.梁的尺寸为1700 mm×120 mm ×200 mm.首先采用4点分加栽方式对梁进行预裂,卸载后粘贴CFRP片材,然后放入腐蚀环境.影响因素考虑了干湿交替与持载水平(持载水平分别为30%和60%混凝土梁极限荷载).分析了干湿交替单一因素和荷载与干湿交替双重因素对CFRP加固梁的长期性能.试验结果表明:荷载与干湿交替双重因素对CFRP加固梁的承载力和破坏形态影响较大,这主要是由于CFRP与混凝土界面的劣化引起;对CFRP加固梁的刚度几乎没有影响.  相似文献   

4.
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   

5.
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   

6.
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   

7.
对15根玻璃纤维布加固的钢筋混凝土梁进行了试验研究。试验结果表明,玻璃纤维布加固的钢筋混凝土梁抗弯承载力显著提高,加固效果明显,但要有足够的粘贴长度以避免发生剥离破坏。  相似文献   

8.
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   

9.
通过利用大型通用有限元软件ANSYS,对不同卸载情况下碳纤维布加固的钢筋混凝土板的抗弯性能进行了非线性有限元分析.结果发现,对于施加了第一期荷载后须利用碳纤维布加固的钢筋混凝土板,加固前卸荷越多,板的极限承载力越大,越能尽量克服碳纤维布应变滞后,从而尽量发挥碳纤维布的作用。  相似文献   

10.
为研究民国时期钢筋混凝土梁抗弯性能的计算方法,首先对66根民国时期钢筋的力学性能、12个民国时期钢筋混凝土建筑的混凝土抗压强度以及9个民国时期钢筋混凝土梁柱构件的保护层厚度进行了测试分析,得出民国时期钢筋混凝土梁的真实材料强度和结构构造.然后结合案例分析,将民国时期钢筋混凝土梁的抗弯性能计算方法分别与中国、美国和欧洲当代钢筋混凝土梁的抗弯性能计算方法进行比较研究.结果表明:民国时期钢筋混凝土梁抗弯性能计算采用容许应力法,安全系数为3.55~4.0;当不考虑地震作用时,民国时期的钢筋混凝土梁抗弯性能计算方法要比中国、美国和欧洲当代钢筋混凝土梁的抗弯性能计算方法更加安全.结论可以为民国时期钢筋混凝土结构的安全评估提供依据.  相似文献   

11.
Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced 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   

12.
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   

13.
This paper presents the results of an experimental research on reinforced concrete beams strengthened with an external carbon fibre reinforced polymer(CFRP) layer under long-term load action that lasted for 330 d.We describe the characteristics of deflection development of the beams strengthened with different additional anchorages of the external carbon fibre composite layer during the period of interest.The conducted experiments showed that the additional anchorage influences the slip of the external layer with respect to the strengthened element.Thus,concrete and carbon fibre composite interface stiffness decreases with a long-term load action.Therefore,the proposed method of analysis based on the built-up-bars theory can be used to estimate concrete and carbon fibre composite interface stiffness in the case of long-term load.  相似文献   

14.
Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete (SFRSC) as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar’s stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.  相似文献   

15.
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   

16.
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   

17.
Extensive research has shown that externally bonded carbon fiber reinforced polymer (CFRP) laminates are particularly suitable for improving the fatigue behavior of reinforced concrete (RC) beams. This paper presents the research on flexural rigidity evolvement laws by testing 14 simple-supported RC beams strengthened with carbon fiber laminates (CFL) under cyclic load, and 2 under monotone load as a reference. The cyclic load tests revealed the peak load applied onto the surface of a supported RC beam strengthened with CFL is linear to the logarithm of its fatigue life, and the flexural rigidity evolvement undergoes three distinct phases: a rapid decrease from the start to about 5% of the fatigue life; an even development from 5% to about 99% of the fatigue life; and a succedent rapid decrease to failure. When the ratio of fatigue cycles to the fatigue life is within 0.05 to 0.99, the flexural rigidity varies linearly with the ratio. The peak load does not affect the flexural rigidity evolvement if it is not high enough to make the main reinforcements yield. The dependences of the flexural rigidity of specimens formed in the same group upon their fatigue cycles normalized by fatigue life are almost coincident. This implies the flexural rigidity may be a material parameter independent of the stress level. These relationships of flexural rigidity to fatigue cycles, and fatigue life may be able to provide some hints for fatigue design and fatigue life evaluation of RC member strengthened with CFL; nevertheless the findings still need verifying by more experiments.  相似文献   

18.
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   

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