石材表层嵌埋CFRP筋粘结性能试验研究

EXPERIMENTAL STUDY ON BOND BEHAVIOR BETWEEN NSM CFRP RODS AND STONE FOR COMPOSITE STONE BEAMS

在花岗岩石梁受拉区嵌入CFRP筋以提高其抗弯承载力,对既有石结构加固和拓展现代石结构的应用范围具有重要意义。为研究石梁表层嵌埋CFRP筋组合石梁中CFRP筋、粘结剂与花岗岩的粘结性能,开展了26个直接拔出试件的试验研究。主要研究参数包括CFRP筋直径大小、CFRP筋嵌埋长度和粘结剂保护层厚度。试验现象揭示了3种典型破坏形式:CFRP筋拉断破坏、CFRP筋-粘结剂界面滑移破坏和石梁嵌埋槽角劈裂破坏。试验结果表明:1)试件破坏方式与嵌埋长度、CFRP筋表面粘结剂保护层厚度以及CFRP筋直径大小有关;2)CFRP筋表层粘结剂保护层最小厚度为0.5Db;3)极限荷载随着嵌埋长度的增加而增大,而平均粘结强度随着嵌埋长度的增加而减小;4)基本锚固长度与CFRP筋材直径有关,基本锚固长度与CFRP筋材直径的比值随直径的增加而有所增加。

It is a new technique to embed near-surface mounted（NSM） CFRP rods in a stone beam to improve the flexural performance of the beam,and it can be used for retrofitting existing stone structures.26 pull-out specimens were tested to investigate the bond behavior between CFRP rods and the stone.The main experimental parameters were the diameter of CFRP rod,the bonded length and the thickness of epoxy cover.Test results indicate that there are three typical failure modes,namely tensile rupture of CFRP rod,CFRP rod-epoxy interface-interfacial failure and fracture in the stone along the groove corner.The failure mechanism is influenced by the bonded length,the thickness of adhesive cover and the diameter of CFRP rod.An epoxy cover thicker than 0.5Db has no significant influence on the ultimate load of pull-out specimen.The ultimate load of pull-out specimen increases with the increase of bonded length,whereas the average bond strength decreases with the increase of bonded length.The basic anchorage length is related to the diameter of CFRP rod,which is 30Db and 35Db respectively for bars with diameter of 5mm and 7mm.