高抗剪强度FRP型材组合梁成型工艺及试验研究

High shear strength post-forming FRP profiles: manufacture and testing

纤维单向布置导致FRP拉挤型材抗剪强度极低、易在腹板发生纵向剪切破坏,为有效克服这一缺点,提出一种针对FRP拉挤型材的二次成型工艺。该工艺以FRP拉挤型材、FRP纤维布和树脂为原料;在两个FRP拉挤型材腹板间手糊中间夹层,施加法向螺栓预紧力以保证各部分共同工作。为检验二次成型FRP拉挤型材构件及FRP-混凝土组合梁的力学性能,文中共测试20个直剪试件、2根短梁和4根FRP-混凝土组合梁,试验结果表明二次成型FRP腹板剪切强度较原FRP拉挤型材提高28%,极限剪应变达到原FRP拉挤型材的2.8倍,剪力达到峰值后只下降约20%。基于层合板理论和最大剪应变失效准则,推导出适用于此工艺的剪切刚度和剪切强度计算方法,计算结果和试验值吻合良好。利用适合于FRP的强度储备指标对二次成型FRP剪切破坏的强度储备进行计算,给出设计建议。

The unidirectionally reinforced fibers in FRP pultruded profiles may lead to the low shear strength and the phenonenon that shear failure in the longitudinal direction may readily occur at webs. To overcome the shortcomings described above,a post-forming process for FRP profiles was proposed,in which a multi-directional hand lay-up interlayer was added between two pultruded FRP webs. Direct shear tests on 20 specimens revealed that the web shear strength of post-forming profiles was improved substantially over the pultruded profiles, and shear stresses was redistributed after a higher level to avoid brittle failure mode. As a result,based on the characteristics of the post-forming process,a simplified calculation method for stiffness and strength was derived based on laminated plate theory.