基于准平面假定的内嵌CFRP筋加固宽缺口混凝土梁裂缝分析

为研究内嵌CFRP筋加固的宽缺口混凝土梁的裂缝特性，通过16根内嵌CFRP筋加固的混凝土梁静载试验，详细观测和研究了其开裂和裂缝扩展状况。基于FRP类材料加固混凝土梁应变协调的准平面假定，根据传统的钢筋混凝土裂缝研究理论，在充分考虑CFRP筋的力学贡献的前提下，对内嵌CFRP筋加固的普通混凝土梁、宽缺口混凝土梁的裂缝间距、裂缝宽度和最大裂缝宽度的计算式进行了理论推导。将理论算式的计算结果与试验实测结果进行了比对。研究结果表明：与对比梁相比，内嵌CFRP筋材加固的宽缺口混凝土梁和内嵌CFRP筋加固的普通混凝土梁的开裂裂缝和最大裂缝宽度均有大幅度降低，前者的裂缝宽度降低幅度要小于后者的。两类加固梁的最大裂缝宽度都随着CFRP加固量的增大而减小。裂缝间距、裂缝宽度和最大裂缝宽度的理论算式的计算结果与实测结果吻合较好。4个加固梁试件组的平均开裂裂缝均比对比梁的开裂裂缝宽度减少0.30mm。

Cracks of wide-notch concrete beams strengthened with near-surface mounted CFRP bars based on quasi-plane assumption

The static load tests of 16 concrete beams strengthened with near-surface mounted CFRP bars were completed, and the crack initiation and development were observed and studied. According to the traditional theory of reinforced concrete crack and on the premise of fully considering the mechanical contribution of CFRP bars, the theoretical derivation of the calculation formulas of the crack spacing, crack width and maximum crack width of wide-notch concrete beam with embedded CFRP bars was presented based on the quasi-plane assumption of strain compatibility of reinforced concrete beams strengthened with FRP. The calculation results of the theoretical formulas were compared with the measured results. The results indicate that the crack width and maximum crack width of wide-notch concrete beams and ordinary concrete beams strengthened with CFRP bars are greatly reduced in comparison with the un-strengthened beams, and that the reduction of maximum crack width of the strengthened wide-notch concrete beams is less than that of the strengthened ordinary concrete beams. The maximum crack width of two types of reinforced beams decreases with the amount of CFRP reinforcement. The calculation results of the theoretical formulas are in good agreement with the measured results in terms of the crack spacing, crack width and maximum crack width. The average crack width of the four series concrete beams strengthened with CFRP bars is 0.3mm lower than that of the comparison beams.