FRP筋再生混凝土梁受弯性能试验研究

Experimental study on flexural behavior of FRP bars recycled concrete beams

为了研究FRP筋再生混凝土(RAC)梁受弯性能,试验制作八根FRP筋再生混凝土梁(其中GFRP筋和BFRP筋再生混凝土梁的数量分别为六根和两根),通过四点弯曲试验研究再生骨料(RA)替代率与FRP筋类型对梁破坏模式、挠度和承载力等性能的影响。试验结果表明:(1)梁的开裂荷载和极限承载力均随着再生骨料替代率的增加而下降,且破坏模式也逐渐由正截面混凝土受压破坏转为斜拉破坏;(2)BFRP筋弹性模量的提高使梁的混凝土受压区高度增加,正截面承载力增加,而斜截面承载力提高较少,从而使BFRP筋再生混凝土梁发生斜拉破坏;(3)规范计算得到的FRP筋再生混凝土梁承载力安全储备略显不足,建议实际配筋率为平衡配筋率ρfb的1~1.5倍时,设计值取规范计算值的0.8倍;(4)GB与ACI挠度计算值均与试验值拟合程度较好,能很好地预测FRP筋再生混凝土梁的挠度值。

In order to study the flexural performance of FRP bars RAC(recycled aggregate concrete)beams,8 FRP bars RAC beams were experimentally fabricated,of which the number of GFRP bars and BFRP bars RAC beams was 6 and 2,respectively.The effects of RA(recycled aggregate)replacement rate and FRP bars type on the failure mode,deflection and bearing capacity of beams were studied by four-point bending test.The test results show that:(1)The cracking load and ultimate bearing capacity of the beam both decreased with the increase of RA replacement rate,and the failure mode gradually changes from the compression failure of normal section concrete to the diagonal tensile failure;(2)The increase in the elastic modulus of BFRP bars increases the height of the RAC compression zone of the beam,which improves the bearing capacity of the normal section of the beam,but the bearing capacity of the oblique section increases less,so that the diagonal tensile failure of the RAC beam with BFRP bars occurs;(3)The safety reserve of the bearing capacity of FRP reinforced RAC beams calculated by the specification is slightly insufficient.It is suggested that when the actual reinforcement ratio is 1~1.5 times of the equilibrium reinforcement ratioρ_(fb),the design value is 0.8 times of the calculated value of the specification;(4)The calculated deflection values of GB and ACI are in good agreement with the experimental values,which can well predict the deflection value of FRP reinforced RAC beams.