BFRP筋与珊瑚混凝土粘结性能试验研究

EXPERIMENTAL STUDY ON THE BOND PERFORMANCE BETWEEN BFRP BARS AND CORAL CONCRETE

为研究玄武岩纤维增强复合材料筋(BFRP筋)与珊瑚混凝土的粘结性能,对不同直径(d=8 mm、12 mm)、不同粘结长度(2.5 d、5.0 d与7.5 d)及不同养护环境(标准养护室养护、20±2℃人工海水养护)的共24个BFRP筋与珊瑚混凝土粘结锚固试件进行了中心拉拔试验。结果表明:除直径为12 mm,粘结长度为7.5 d的拉拔试件出现珊瑚混凝土劈裂破坏外,其余试件均为BFRP筋从珊瑚混凝土中拔出破坏,其破坏形态与BFRP筋和普通混凝土粘结破坏形态无明显区别,只是更易发生劈裂破坏。其粘结滑移曲线可分为微滑移阶段、滑移阶段、剥离阶段、下降阶段和残余阶段共5个阶段。其最大平均粘结应力随直径与粘结长度的增加显著减小。标准养护条件下的BFRP筋与珊瑚混凝土的粘结强度明显高于20±2℃人工海水养护下的粘结强度。

To study of the bond performance between BFRP bars and coral concrete, pull-out tests were carried out for 24 anchorage specimens with FRP bars of different diameters（d=8 mm and d=12 mm）, different bonding lengths（2.5 d, 5.0 d and 7.5 d） and different curing conditions（standard curing room and artificial seawater immersion with the temperature of 20±2 ℃）. The results show that all the specimens fail due to the pull-out of the BFRP bars from the concrete except the specimens with 12 mm diameter bars and a bonding length of 7.5 d, which is identified by splitting failure of the concrete. The failure mode is similar to that between BFRP bars and ordinary concrete, but the splitting failure occurs more easily for the bond between BFRP bars and coral concrete. The bond-slip curve can be divided into five stages, i.e., micro slip stage, sliding stage, stripping stage, declining stage and residual stage. With the increase of the diameter and bond length, the maximum average bond stress decreases markedly. Moreover, the bond strength of the specimens under standard curing conditions is apparently larger than that of specimens immersed in 20±2 ℃ artificial seawater.