黏砂变形GFRP筋黏结性能研究

基于18个梁式试验、42个Losberg拉拔试验以及6个标准拉拔试验,对黏砂变形GFRP筋与混凝土之间的黏结性能进行了较系统的研究。研究表明:黏砂变形GFRP筋梁式试件和拉拔试件的破坏形态均可分为拔出破坏和劈裂破坏两种,黏结长度大于5倍直径的GFRP筋试件发生劈裂破坏,小于5倍直径的试件发生拔出破坏,而对于黏结长度为5倍直径左右的试件,两种破坏形态均有可能发生;GFRP筋与混凝土之间的黏结强度约为相应带肋钢筋的0.64～1.27倍;随着黏结长度和直径的增加,GFRP筋与混凝土之间的黏结强度有所降低;基于梁式试验、Losberg拉拔试验与标准拉拔试验得到的GFRP筋与混凝土之间的黏结强度无显著差异。最后,综合考虑GFRP筋直径、表面形态、黏结长度等因素影响,提出GFRP筋与混凝土之间黏结强度、锚固长度的设计建议。

A study on the bond behavior of sand-coated and deformed GFRP rebars

Based on 18 beam tests,42 Losberg pullout tests and 6 standard pullout tests,the bond behavior of sand- coated and deformed GFRP rebars in concrete is systematically analyzed.The test results showed that for the sand- coated and deformed GFRP rebars both in beam tests and in pullout tests,the failure modes included pullout failure and splitting failure.The pullout failure occurs in the specimens of embedment length greater than 5 times the rebar diameter,for those with the embedment length less than 5 times the rebar diameter,splitting failure occurs,and for those with embedment length around 5 times the rebar diameter,either of the two failure modes may occur.The study also showed that the bond strength of GFRP rebars in concrete is 0.64-1.27 of that of deformed steel rebars. With the rebar diameter and the embedment length increasing,the bond strength of GFRP rebars to concrete decreases.Furthermore,the type of bond tests did not significantly affect the bond strength of GFRP rebars in concrete.The design guidelines for bond strength and development length were provided,considering the effects of rebar diameter,embedment length,and outer surface.