BFRP筋部分钢纤维增强混凝土梁挠度研究

Research on deflection of partial steel fiber reinforced concrete beams with BFRP bars

通过6根BFRP筋混凝土梁短期荷载作用下的四点弯曲试验,研究了钢纤维掺入率与钢纤维混凝土层高度对裂缝宽度、挠度以及裂缝闭合性能的影响,并对裂缝宽度、挠度以及卸载后裂缝闭性能进行了分析。研究结果表明:试验梁在极限荷载作用下,相同钢纤维掺入率下的BFRP筋部分钢纤维与全截面钢纤维增强混凝土梁所呈现出的裂缝宽度较为相近;试验梁在卸载后裂缝出现闭合,随着掺入率与钢纤维混凝土层高度的增加,裂缝的闭合性能越显著;在正常使用状态下,随着钢纤维掺入率与钢纤维混凝土层高度的增加,BFRP筋混凝土梁的抗弯性能提高明显。基于试验数据,通过修正梁截面有效惯性矩,提出适用于钢纤维作用下的BFRP筋混凝土梁的挠度计算公式,利用该计算公式得到的计算结果与试验结果进行对比,吻合效果较好。

Through the four-point bending test of 6 BFRP reinforced concrete beams under short-term load,the effects of the steel fiber incorporation rate and the height of the steel fiber concrete layer on the crack width,deflection and crack closure performance were studied,and the crack width,deflection and unloading were studied.The post-crack closure performance was analyzed.The research results show that under the ultimate load of the test beam,the crack widths of the steel fibers of the BFRP tendons under the same steel fiber incorporation rate and the full-section steel fiber reinforced concrete beams are relatively similar.The cracks of the test beams closed after unloading.With the increase of the incorporation rate and the height of the steel fiber concrete layer,the crack closure performance becomes more obvious.In normal use,with the increase of the steel fiber incorporation rate and the height of the steel fiber concrete layer,the resistance of the BFRP reinforced concrete beam the bending performance is significantly improved.Based on the experimental data and by modifying the effective moment of inertia of beam section,a formula for calculating the deflection of concrete beam with BFRP bars under the action of steel fiber is proposed.The calculated results are in good agreement with the experimental results.