温度-荷载耦合作用下端锚CFRP加固RC梁受弯性能研究

Flexural behavior of end-anchored CFRP strengthened RC beams subjected to combined effects of load and temperature

为研究端部锚固对碳纤维增强聚合物(CFRP)加固钢筋混凝土(RC)梁高温性能的影响,进行了温度和荷载耦合作用下带有端部锚固的CFRP加固梁受弯性能试验,采用纯外贴、钢压板锚固和自锁式锚固等不同端锚形式,对比分析端部锚固措施对加固梁受弯性能的影响。结果表明:与纯外贴CFRP加固梁相比,端部锚固提高了加固梁常温及高温下的受弯性能;钢压板锚固在常温下可以有效限制CFRP端部剥离,CFRP强度利用率由43.6%提高至79.3%,极限荷载提高12%左右;但是温度达100℃后钢压板锚固无法限制CFRP剥离,承载力退化至未加固水平,加载过程中最大强度利用率只有50.5%;自锁式锚固法在任何温度下均可限制CFRP剥离,其破坏形式多为CFRP拉断,可以最大限度地提高CFRP强度利用效率;在试验温度100℃下极限荷载相比纯外贴形式的提高了22.7%,在试验温度120℃下极限荷载相比钢压板锚固试件仍提高10%。引入了承载力退化系数,给出了温度-荷载耦合作用下端锚CFRP加固梁正截面受弯承载力计算公式,计算结果与试验结果吻合较好。

To study the effect of end anchorage on the structural performance of carbon fiber reinforced polymer(CFRP) strengthened reinforced concrete(RC) beams under high temperatures, the flexural tests of end-anchored CFRP strengthened RC beams under temperature and load were carried out. Different end-anchored measures including external bonding, steel plate anchoring and self-locking anchoring were used to investigate the flexural behavior of the strengthened beams. Compared with the external bonding specimens, the end-anchored measures significantly improve the flexural performance of the strengthened beam at normal temperature or high temperature. Steel plate anchoring can effectively limit CFRP end peeling at normal temperature, where the CFRP utilization rate is increased from 43.6% to 79.3%, simultaneously its ultimate load is increased by about 12%. However, the steel plate does not restrict the peeling failure of CFRP when the temperature exceeds 100 ℃. The bearing capacity of steel plate anchoring specimens is degraded to the unreinforced level, and the maximum CFRP utilization rate during the loading process is only 50.5%. The self-locking anchoring specimens can limit CFRP peeling at any temperature, and the failure modes are mostly CFRP tensile fracture. The self-locking anchoring specimens maximize the utilization efficiency of CFRP material. The ultimate load at 100 ℃ increases by 22.7% in comparison with the external bonding specimen, while the ultimate load at 120 ℃ is increased by 10% compared with steel plate anchoring specimens. The bearing capacity degradation coefficient was introduced, and the design formula for the flexural bearing capacity of end anchored CFRP-RC beam under temperature was given, which agreed well with test result.