基于不同黏结材的CFRP链-混凝土界面黏结性能试验研究

Experimental study on the bond behavior of CFRP strand sheet-concrete with different types of bond agents

为研究碳纤维增强复合链(CFRP Strand Sheet)与混凝土的界面黏结性能,共制作8组共24个试件并进行拉伸双剪试验,观测各组试件的破坏形态和应变分布规律,分析CFRP链与混凝土界面的黏结破坏机理,研究不同黏结材的力学性能和CFRP链加固层数对CFRP链-混凝土界面的剪切应力传递和黏结性能的影响。研究结果表明:CFRP链与混凝土的双剪试件均为表层混凝土的剪切破坏,随着CFRP链加固层数的增加,试件的剥离承载力增大,而CFRP链最大应变和界面断裂能均减小;当采用环氧树脂(EP)为黏结材时,CFRP链的材料利用率较大,而采用聚合物水泥砂浆(PCM)为黏结材时,虽单层CFRP链与混凝土界面间具有较优的抵抗剥离能力,但双层加固时,CFRP链的材料利用率却大幅降低。基于现有FRP片材-混凝土的双线性黏结滑移模型,并考虑CFRP链加固层数和黏结材力学性能的影响,建立了相应的界面黏结-滑移模型。

To investigate the bond behavior between carbon fiber reinforced polymer(CFRP)strand sheet and concrete,double-shear tests on a total of 24 specimens divided into eight groups were conducted.The failure modes and strain distribution of each group were observed,and then corresponding failure mechanism at the interface between two kinds of materials was analyzed.The influence on the stress transfer mechanism and bond behavior were evaluated based on different mechanical properties of bond agents and the number of CFRP strand sheet layers.The results show that all specimens tested in this program fail due to the debonding primarily induced by a very thin layer of concrete surface;as the number of CFRP strand sheet increases,the bearing capacity of specimens with the same bond agent increases as well,but both the maximum strain of corresponding CFRP strand sheet and fracture energy drop;the utilization of CFRP strand sheet is the largest among all specimens when epoxy is used as the adhesive;specimens with CFRP strand sheet of single layer,taking polymer cement mortar(PCM)as the bond agent,have superior the ability of resisting debonding,but the utilization of CFRP strand sheet reduce dramatically if the number of CFRP strand sheet layer is 2;a novel bond-slip model,which considers both mechanical properties of bond agents and the number of CFRP strand sheet layers,is established based on the existing bilinear bond-slip model of CFRP sheet-concrete.