纤维对GFRP筋与自密实混凝土基体粘结性能影响分析

Effect of fibers on bond behavior between GFRP bars and self-compacting concrete

通过18个中心拉拔试件试验,研究在基体中加入不同纤维（聚丙烯长纤维（PPA）、聚丙烯短纤维（PPB）、钢纤维（SF）以及混杂纤维）对玻璃纤维增强聚合物（GFRP）筋与混凝土基体粘结性能的影响,旨在寻找改善GFRP筋与混凝土基体粘结性能的有效途径。参照德国纤维混凝土标准DBV和国际材料与结构研究试验联合会标准R ILEM弯曲韧性评价方法,采用等效抗弯强度和变形能来评价粘结韧性。试验结果表明：与素混凝土（NC）基体相比,GFRP筋与掺入混杂钢纤维与聚丙烯长纤维以及各自单掺基体的粘结强度可提高13%~35%,还可改善粘结韧性;同时,GFRP筋与基体的粘结强度随钢纤维掺量增大而提高。根据试验结果拟合得出粘结滑移曲线上升段的模型参数,计算结果与试验结果吻合良好。

Based on the experiment of 18 pull-out samples,the influence of different types of fibers（macro steel fibers,macro PP-fibers and micro PP-fibers） on the bond behavior between GFRP bars and matrix was analyzed.In order to improve the bond behavior,a new method of using the equivalent bending strength and deformation energy to evaluate the bond toughness was proposed according to the flexural toughness measured by DBV and RILEM.The test results show that when adding suitable hybrid of steel fiber and macro PP-fiber or macro fiber into concrete,it can both enhance the bond strength by 13%～35% compared with NC matrix,and improve the bond toughness;the ultimate bond stress of GFRP bars is enhanced with increasing of steel fiber content.Finally,based on experimental results,the ascending branch of the bond-slip model is established,and the suggested model corresponds well with the testing curves.