BFRPC与预应力钢绞线黏结-滑移本构模型

Bond-slip Constitutive Model of BFRPC and Prestressed Steel Strand

预应力钢绞线与玄武岩纤维活性粉末混凝土BFRPC(Basalt Fiber Reactive Powder Concrete)之间的黏结性能,对预应力BFRPC桥梁结构的抗弯承载力、裂缝控制、刚度等性能具有显著影响。为了明晰预应力钢绞线与BFRPC之间的黏结-滑移失效过程,通过中心拉拔试验研究了钢绞线直径和黏结长度对预应力钢绞线与BFRPC之间黏结性能的影响。深入探讨了黏结应力-滑移曲线特征、黏结强度及影响因素;建立了BFRPC与预应力钢绞线的分段式双线型线性黏结应力-滑移本构关系模型;综合考虑钢绞线螺旋缠绕特征与旋转滑移失效模式,修正了预应力钢绞线与BFRPC的极限黏结强度计算模型。研究结果表明:对于相同直径的预应力钢绞线,黏结长度每增加100 mm,初始黏结应力下降15%~18%,极限黏结应力下降20%~23%;泊松效应会削弱混凝土和钢绞线之间的握裹力,使得黏结强度与钢绞线直径成反比;钢绞线与BFRPC的黏结-滑移本构关系模型可有效区分拉拔损伤的线性段和滑移段;建立的极限黏结强度修正模型精度良好,误差控制在理论计算控制线两侧±8%以内。

The bonding performance between prestressed strands and basalt fiber-reactive powder concrete(BFRPC)significantly affects the performance of prestressed BFRPC bridge structures in terms of flexural load capacity,crack control,and stiffness.Consequently,to clarify the bond-slip failure process between the prestressing strands and BFRPC,the effects of the strand diameter and bond length on the bonding performance between the prestressing steel strands and BFRPC were investigated using a central pull-out test.The bond stress-slip curve characteristics,bond strength,and influencing factors are discussed intensively.A segmented bilinear bond stress-slip constitutive model for the BFRPC and prestressing steel strands was established.The ultimate bond strength calculation model of the prestressed steel strand and BFRPC was modified by comprehensively considering the spiral winding characteristics of the steel strand and the rotational slip failure mode.The results show that for prestressing steel strands with the same diameter,the initial bond stress decreases by 15%to 18%,and the ultimate bond stress decreases by 20%to 23%per 100 mm increase in bond length.The Poisson effect weakens the grip between the concrete and the strand,so the bond strength is inversely proportional to the strand diameter.The bond-slip constitutive model of the steel strand and BFRPC can effectively distinguish the linear and slip segments of the pull-out damage.The accuracy of the established ultimate bond strength correction model is excellent,and the error is controlled within±8%on both sides of the theoretical calculation control line.