表层嵌贴CFRP板条-混凝土界面粘结应力模型的试验与理论研究

为研究寒冷地区饱和砂岩的冻融损伤机理,采用DMA450伺服压机,在静载100N、动载80N、波动频率5～200Hz、温度-40～40℃的条件下,进行了饱和砂岩在不同频率正弦波单轴载荷作用下杨氏模量随温度变化的实验研究,获得滞(粘)弹性的弛豫衰减,以及有衰减引起的砂岩样品微结构变化情况。结果表明：饱和砂岩的杨氏模量和弹性波速度随温度升高而降低,随频率提高而增大; -40～20℃温度范围是冻融损伤最严重的区域。同时,在三种低频条件下(1.6Hz、2.8Hz和5.0Hz)用共振法在0℃获得相变衰减峰,反映了饱和砂岩的冻胀融缩效应,其产生的应力导致了饱和砂岩的损伤。从机理来看,前者是微观缺陷的演变,长期积累会导致破坏;后者是一种物理风化作用造成的宏观损伤。本文结果可为研究寒冷地区饱和岩石冻融损伤的机理及规律提供一定的参考。

Experimental and Theoretical Study on Model of Interfacial Bond Stress between Near-Surface Mounted CFRP Strips and Concrete

By taking into account the residual friction, a tri-linear bond-slip constitutive model is proposed in this paper based on bonding property experimental results of near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP) strips with concrete. Furthermore, the bond stress model between NSM CFRP strips and concrete is established. The general form of analytical solution for the model was obtained through solving the differential equations, and then distribution variation of the interfacial slip, the bond stress and CFRP tensile stress along with loading was derived, the calculation formula of bond capacity was also obtained. Based on above results, the bond stress model was validated by comparing with experimental data, and theoretical calculation results are in good agreement with experimental data. This proves that the bond stress model proposed in this paper can well predict the bond capacity of the NSM FRP-to-concrete interface and correctly describe the distribution of interfacial bond stress.