新型FRP-竹-混凝土组合梁的力学行为

Mechanical behavior of novel FRP-bamboo-concrete composite beams

提出一种新型FRP-竹-混凝土组合结构,其由FRP、竹材及混凝土组合而成,混凝土与竹材通过连接件连接。对采用销钉型连接件的FRP-竹-混凝土组合梁的力学行为进行试验研究。研究结果表明：混凝土-竹材的界面表现出一定的滑移,FRP-竹-混凝土组合梁为一种部分组合结构,组合梁因底部竹材纤维拉断而达到极限承载力,FRP筋因失去外部竹材包裹黏结而退出工作,FRP筋达不到极限强度,相对于对比竹梁,极限荷载Pmax提高1.84-2.06倍,对应挠度限值L/250的荷载PL/250提高3.33-3.82倍,承载力和刚度得到大幅度地提高,新型组合梁的力学性能介于完全组合和无组合之间,可通过组合效率系数E定量反映,为减小或避免混凝土承受拉力,应尽量保证组合梁截面中性轴接近竹-混凝土组合界面。

A new type of FRP-bamboo-concrete composite structures（FBCCS） was proposed, which is composed of FRP, bamboo and concrete. Concrete and bamboo were connected by connectors. The mechanical behavior of FBCCS with dowel type connections was investigated by testing and analysis. The results indicate that FBCCS are subject to a certain slip at the concrete-bamboo interface and the response of FBCCS was partially composite structures. The ultimate bearing capacity is achieved when the fracture in tension of bottom bamboo fiber occurs. The ultimate strength of FRP reinforcement is not obtained due to the bond loss of the external wrapped bamboo materials. The ultimate load Pmaxenhances by 1.84 to 2.06 times and the load PL/250 corresponding midspan deflection of L/250 increases by 3.33 to 3.82 times compared with those of the bamboo beam. The carrying capacity and cross-sectional rigidity are significantly improved. The mechanical performance of the novel composite beams is intermediate between those of full-composite and non-composite structures, and the composite efficiency can be estimated by the parameter E. In order to reduce or avoid concrete subjected to tensile stresses, the neutral axis of the composite cross-section should be designed to approach the bamboo-concrete interface.