CFRP板加固RC&PPC梁抗剪性能试验研究

EXPERIMENTAL STUDY ON SHEAR PROPERTIES OF REINFORCED CONCRETE (RC) AND PARTIAL PRESTRESSED CONCRETE (PPC) BEAMS STRENGTHENED WITH EXTERNALLY BONDED CFRP STRIPS

通过10片普通钢筋混凝土(RC)梁及4片部分预应力混凝土(PPC)梁采用CFRP板抗剪加固的试验研究和非线性有限元分析,研究不同损伤程度、剪跨比、配箍率及预应力水平等因素对CFRP板加固RC&PPC梁抗剪性能的影响。结果表明:采用CFRP板对RC&PPC梁进行抗剪加固能够有效抑制斜裂缝的开展,提高加固梁斜截面抗剪承载能力,并改善梁的延性;RC梁损伤后加固,随着配箍率的增大以及剪跨比的减小,将提高加固RC梁的斜向开裂荷载、箍筋屈服荷载以及抗剪极限承载能力;随着预应力水平的提高,PPC加固梁的极限承载力增大,CFRP板抗剪加固效果比较显著;非线性有限元模型能够预测CFRP加固RC/PPC梁的抗剪性能,有限元计算结果与试验结果吻合良好;在进行CFRP板抗剪加固设计时,应对CFRP板的强度进行有效折减。

An experimental study and nonlinear finite element analysis including reinforced concrete （RC） beams and partial prestressed concrete （PPC） beams strengthened with CFRP strips were carried out under static loading. The influences of damage degree, ratio of shear span, stirrup ratio, and level of effective prestressing on the shear characteristics of these strengthened beams were investigated. Some important conclusions were extracted from the testing and numerical analysis and listed as follows： 1） The inclined cracking development can be effectively restrained using the proposed strengthening method with CFRP strips, and the shear load-carrying capacity and ductility of the strengthened RC＆PPC beams can be effectively improved. 2） The synclinal cracking load, yielding loads of the stirrup, and the shear load-carrying capacity of RC beams strengthened after the damage would be enhanced while the ratios of shear span becoming smaller and stirrup ratio becoming larger. 3） The improvements of shear carrying-capacity of PPC beams strengthened with CFRP strips would become larger if the level of effective prestressing increasing. 4） The proposed nonlinear finite element （FE） model can better predict the shear performance of strengthened RC＆PPC beams, and the results from FE model can correlate very well with those from testing. 5） The strength of CFRP strips should be effectively reduced during the shear strengthening design of the practical engineering cases.