复合内嵌碳纤维筋和预应力螺旋肋钢筋加固混凝土梁试验

对高强度的螺旋肋钢筋施加预应力,将螺旋肋钢筋和非预应力的碳纤维筋用不同的组合方式嵌入混凝土梁受拉区混凝土保护层中进行弯曲试验。结果表明:内嵌2根螺旋肋钢筋和1根碳纤维筋(BF1P2梁)或内嵌1根螺旋肋钢筋和2根碳纤维筋(BF2P1梁),且对螺旋肋钢筋施加的预应力水平分别为其极限强度的30%,45%和60%,加固混凝土梁的极限承载能力、刚度及抗裂性能均有显著改善。与对比梁相比,BF1P2梁的开裂荷载提高了86.70%~133.33%,屈服荷载提高了32.25%~72.04%,极限荷载提高了72.73%~90.00%;BF2P1梁的开裂荷载、屈服荷载和极限荷载则分别提高了50.00%~133.33%,50.54%~136.56%和72.20%~173.60%;BF2P1梁的加固效果优于BF1P2梁,且对螺旋肋钢筋施加预应力的水平为45%时,混凝土梁的加固效果最佳。

Experiment of RC beams strengthened with near-surface mounted carbon fiber reinforced plastic bar and pre-stressed helical rib rebar

According to different combinations of carbon fiber reinforced plastic(CFRP) and pre-stressed helical rib rebar(HRR),grooves were opened in the concrete cover of the tensile region in the concrete beams.CFRP and pre-stressed HRR were inserted in the grooves and then filled with resin.The bending test results show that the limit bearing capacity,rigidity,and crack resistance of the beams strengthened with near-surface mounted two HRRs and one CFRP(BF1P2) bar or with one HRR and two CFRP(BF2P1) bars,in which HRR was pre-stressed to 30%,45%,and 60% of its limit strength,were improved significantly.In comparison with the un-reinforced beams,for the BF1P2 beams the crack loads increased by 86.70% to 133.33%,the yield loads increased by 32.25% to 72.04%,and the limit bearing capacities increased by 72.73% to 90.00%;and for the BF2P1 beams the crack loads increased by 50.00% to 133.33%,the yield loads increased by 50.54% to 136.56%,and the limit bearing capacities increased by 72.20% to 173.60%.The reinforcing result of BF2P1 was better than that of BF1P2.The beam strengthened with HRR that was pre-stressed to 45% of the limit strength was the best.