钢筋混凝土窄梁侧挂混锚碳纤维布加固受弯性能试验研究  

Experimental study on flexural strengthening of narrow RC beams with side-carried hybrid-anchored CFRP sheets

作　　者：周朝阳[1] 于亚男 郭宇轩 汪毅 ZHOU Chaoyang;YU Yanan;GUO Yuxuan;WANG Yi(School of Civil Engineering,Central South University,Changsha 410075,China;Central and Southern China Municipal Engineering Design&Research Institute Co.,Ltd.,Wuhan 430010,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中国市政工程中南设计研究总院有限公司,湖北武汉430010

出　　处：《建筑结构学报》2023年第5期232-239,共8页Journal of Building Structures

基　　金：国家自然科学基金项目(51878664,52178308)。

摘　　要：为了抑制纯粘片材加固窄梁的界面剥离破坏,采用与梁底同宽的纤维布,将其端部绕开缝板自锁,并用对穿锚栓和侧板挂住,协同粘贴形成侧挂混锚碳纤维布加固。对7根钢筋混凝土窄梁开展了受弯试验,结果表明:随着碳纤维布的加长,纯粘(仅采用纤维布全长粘贴)梁剥离破坏起始位置由端部转移到中部,剥离荷载略有增长;相比纯粘加固时的脆性剥离破坏,混锚加固梁表现出优越的受弯性能,短布混锚梁中部剥离和混凝土压碎基本同时发生,承载力达到黏结完好时的理论上限值,高于长布混锚梁;纤维布较长时,虽然出现剥离但之后荷载仍能持续增加,延性大幅提高,最终发生混凝土压碎;采用两层纤维布加固时,内长外短混锚加固比内短外长纯粘加固的抗剥离效果更好,前者承载力较未加固梁的提升率为后者的1.6倍,延性也有明显改善。Debonding is a common problem for reinforced concrete(RC)beams strengthened in flexure by externally bonded carbon fiber reinforced polymer(CFRP)sheets.To prevent the debonding failure of the strengthened narrow RC beams,a novel hybrid anchorage system was developed,by using which the CFRP sheet with the same width as the narrow RC beam was externally bonded to the bottom of the beam,while the effect of self-locking was formed by wrapping the ends of the CFRP sheet around a steel plate which has a gap in the middle;the steel plate was connected to the plates anchored to the two sides of beam by bolts.In total,seven RC beams were prepared for four-point bending tests.From the test results,the following findings can be reached.As the length of CFRP sheets increases,the initial position of the debonding changes from the end towards to the middle of CFRP sheets and the bearing capacity has only a marginal increase.In contrast to the brittle debonding failure of RC beams purely strengthened by externally bonding,the hybrid strengthened beams show excellent flexural behavior after yielding.For the specimens with a shorter CFRP sheet,the intermediate debonding and crushing of concrete occur at almost the same time;the bearing capacity reaches the theoretical upper limit of the beam with a perfect bond between the CFRP and the concrete,and is even higher than the case with a longer CFRP sheet.For the latter,after the debonding,the load can still increase and the ductility is largely improved.Finally,the failure mode is the crushing of concrete.For the beams strengthened with two layers of CFRP sheet,hybrid strengthening achieves a much better effect than pure bonding strengthening.The increase ratio of bearing capacity of the hybrid strengthened beam is about 1.6 times that of the unstrengthened beam,and the ductility of the beam also has obvious improvement by using hybrid strengthening.

关 键 词：钢筋混凝土梁 加固 碳纤维布 锚固 自锁 受弯试验 剥离 

分 类 号：TU375.1[建筑科学—结构工程] TU317.1