受力方式对活性粉末混凝土中钢筋黏结性能的影响

Influence of loading conditions on bond properties between steel bar and reactive powder concrete

采用拔出和梁式两种试验方法,对比分析了在不同受力状态下变形钢筋与活性粉末混凝土之间的黏结性能.研究表明:两种受力方式下的试件均有活性粉末混凝土劈裂、钢筋拔出与活性粉末混凝土劈裂共同发生、钢筋拔出3种破坏形式;钢筋在活性粉末混凝土中的黏结应力-滑移曲线都可分为4个阶段,但不同受力方式下每阶段特征略有差异;两种受力方式下,黏结强度都随钢纤维掺量的增加而增大,当钢纤维掺量由0%增加到2.0%时,拔出试验的黏结强度增长28.25%,而梁式试验的黏结强度增幅达到58.61%;当活性粉末混凝土中不掺加钢纤维时,梁式试验的黏结强度要小于拔出试验,但掺加钢纤维后,要大于拔出试验.

Influence of loading conditions on bond properties between reactive powder concrete and de- formed bar is studied through two different test methods. It is found that for different loading condi- tions, they all have three kinds of failure mode, reactive powder concrete splitting, reactive powder concrete splitting together with pullout and pullout. Bond stress-slip curves between reactive powder concrete and steel bars can fall into 4 stages, but the characteristics of each stage are different for dif- ferent loading conditions. Bond strength are all increased with the increase of steel fiber contents. When steel fiber contents increase from 0 % to 2.0 %, bond strength of pull-out specimens increases 28.25 % ,while beam specimens increases 58.61%. Bond strength of beam .specimens is smaller than pull-out specimens if the reactive powder concrete does not contain steel fibers, otherwise the former will larger.