碳纤维板加固H型钢梁抗剥离夹具研制及应用试验  

Development and experiment of grippers to prevent debonding in H-shaped steel beams strengthened with carbon fiber reinforced polymer plates

作　　者：周朝阳[1] 樊文华 汪毅 周锦 ZHOU Chaoyang;FAN Wenhua;WANG Yi;ZHOU Jin(School of Civil Engineering,Central South University,Changsha 410075,China;Nanning Jinwanchang Enterprise Management Co.Ltd.,Nanning 530000,China)

机构地区：[1]中南大学土木工程学院,长沙410075 [2]南宁金万昌企业管理有限公司,南宁530000

出　　处：《工程科学学报》2024年第3期525-535,共11页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(51878664,52178308)。

摘　　要：外贴碳纤维板是钢梁抗弯加固的常用方法,但其端部易因界面应力集中导致剥离破坏,严重影响高性能材料的有效利用,特别是结构加固后的安全服役.为此开发出一种适用于H型钢梁的简易夹具——C形槽板夹,以加强碳纤维板的端部锚固.通过多根带夹碳纤维板加固梁的静力加载试验,验证了此夹具的可靠性,并考察了碳纤维板伸入剪跨段长度与剪跨段长度之比及锚固方式(纯粘、端锚和混锚)对加固效果的影响.研究发现端锚加固不同于纯粘,只要梁的控制截面仍在夹具之间,碳纤维板的极限应力、加固效果及利用效率均随其长度缩短而提高,当碳纤维板长度分别为600、750 mm时,前者极限应变和承载力比后者分别高27.3%和8.1%.由于钢梁表面处理质量较差,混锚加固梁均发生突然剥离,后期退化为端锚加固梁,因而相比端锚加固梁加固效果改善不大,需要提高表面处理质量再做类似研究.尽管如此,相比纯粘加固梁,混锚加固梁采用C形槽板夹后剥离破坏被延迟,抗弯性能大为改善.试验过程中还用压电阻抗法对界面剥离情况进行了检测,结果符合实际.External bonding of carbon fiber–reinforced polymer(CFRP)plates is a common method for the flexural strengthening of steel beams.However,the interfacial stress concentration at the CFRP plate end can easily cause premature debonding failure of strengthened beams.Consequently,the high performance of the materials is not fully utilized,and the safety of the strengthened beams may be threatened.To address this issue,the paper proposes a simple C-shaped plate gripper to strengthen H-shaped steel beams,which can improve the anchorage at the CFRP plate end.Four-point bending tests were conducted for strengthened beams to verify gripper reliability.The strengthening effect was examined by changing the ratio of the bond length(measured from load point to the CFRP plate end)to the shear span length and anchorage types.There are three types of anchorage:in the first type,the CFRP plate is bonded only on the tensile face of the beam;in the second type,the CFRP plate is attached to the tensile face of the beam and a gripper is attached to the end of the CFRP plate;in the third type,a combination of the above two types is utilized.These types are called pure bonding,end anchorage,and hybrid strengthening,respectively.The case with an anchorage at the CFRP plate end is considerably different from the case of pure bonding.The former relies on mechanical force transfer,while the latter relies on an epoxy resin for bonding.As long as failure does not occur first in the outer section of the CFRP plate,the strain and utilization ratio of the CFRP plate,along with the related strengthening effect,will increase as the length of the CFRP plate decreases.For a strengthened beam with a CFRP plate length of 600 mm,the ultimate strain and load are 27.3%and 8.1%higher than those of the case with a CFRP plate length of 750 mm,respectively.Notably,the hybrid strengthened beams debonded suddenly and degraded to beams with only end anchorage in the subsequent loading stage.There is no obvious improvement in beams with hybrid strengthening co

关 键 词：碳纤维板 抗弯加固 H型钢梁 剥离 C形槽板夹 压电阻抗法 

分 类 号：TU317.2[建筑科学—结构工程]