不同表面形态的黏砂变形GFRP筋与混凝土之间的黏结性能

Bond Behaviors between Sand-coated GFRP Rebar and Concrete in Different Surface Conditions

基于27个Losberg拉拔试验,对不同表面形态的黏砂变形玻璃纤维(GFRP)筋与混凝土之间的黏结性能进行了较为系统的研究.研究表明:GFRP筋与混凝土之间的黏结应力-滑移(τ-S)曲线可分为上升段、下降段和振荡段3段,其中上升段又可分为微滑移段和滑移段;黏砂变形GFRP筋的肋间距越大,则相应的τ-S曲线振荡段波谷之间的距离也越大;对于2种不同表面形态的黏砂变形GFRP筋(Aslan-1和Aslan-2),其破坏模式包括拔出和劈裂2种;黏砂变形GFRP筋试件的黏结强度约为钢筋试件的84.2%～98.6%;相比于黏砂变形Aslan-1 GFRP筋,Aslan-2 GFRP筋黏砂颗粒较细,且分布更均匀,黏砂层略厚,与混凝土之间的黏结强度略高10%左右;随着筋直径的增大和混凝土强度的降低,2种不同表面形态的黏砂变形GFRP筋试件与混凝土之间的黏结强度均有所降低.

Based on tests of 27 Losberg pull-out specimens, the bond behaviors between sand-coated GFRP rebar and concrete in dif- ferent surface conditions were systematically analyzed. Test results showed that the experimental bond stress-slip curves between GFRP rebar and concrete （r-S curve） was divided into ascending stage, descending stage and oscillating stage, and the ascending stage could be divided into the micro-slippage stage and slippage stage; with larger rib spacing of sand-coated GFRP rebar, higher spacing between troughs of the oscillating stage was obtained ; for two kind of the sand-coated GFRP rebar specimens with different surfaces, the failure modes included pullout failure and splitting failure; the bond strength of sand-coated GFRP rebar with concrete was 84.2% - 98.6% of that of the deformed steel; compared with the Aslan-1 sand-coated GFRP rebar, the bond strength of Aslan-2 sand-coated GFRP rebar with finer, better-distributed and thicker sand was 10% higher; the bond strengths of the two kinds of sand-coated GFRP rebar with different surfaces decreased along with the increase of the rebar diameter and the reduction of the concrete strength.