考虑拉伸刚化效应的FRP筋/混凝土轴拉构件变形计算方法

Deformation analysis method of FRP bar/concrete tension members by considering tension stiffening effect

考虑拉伸刚化效应是精确计算纤维增强树脂复合材料(FRP)筋/混凝土构件变形和裂缝的基础。提出了考虑拉伸刚化效应的FRP筋/混凝土拉伸构件变形计算的解析方法。首先,对修正Eligehausen黏结滑移模型(修正BPE模型)进行简化提出四线性黏结-滑移模型。根据该模型推导了拉伸构件在不同拉伸荷载阶段的FRP筋、混凝土应力和变形及黏结力和滑移量的分布表达式。结合混凝土开裂判别方法,提出了FRP筋/混凝土拉伸构件的全过程变形计算方法。通过与已有文献试验结果对比验证了本文方法的准确性。对影响拉伸刚化的一些参数进行了敏感性分析。结果表明,混凝土强度和配筋率对拉伸刚化效应影响不大,FRP筋弹性模量是影响拉伸刚化效应的主要因素。

The tension stiffening effect is the premise of accurate evaluation of the deformation and crack width of fiber reinforced polymer composite(FRP)bar/concrete members.An analytical method for determining the deformation of FRP bar/concrete tension member was proposed.A simplified four-linear model based on the modified Eligehausen model(modified BPE model)was presented.The distribution of stress,displacement of FRP bars and concrete and the distribution of bond force,slip between bars and concrete were established.By combining with the cracking criterion of concrete,an algorithm for the deformation of FRP reinforced tensive ties at different loading stages was proposed.After verification by comparing with experimental data in the literature,the effects of different parameters on the tension stiffening were analyzed.Parametric analysis results indicate that concrete strength and reinforcement ratio of FRP bars have a minor impact on the tension stiffening effect.However,the elastic modulus of FRP bars dominates the tension stiffening behavior of FRP reinforced concrete tensile elements.