钢绞线腐蚀对部分预应力混凝土梁疲劳寿命的影响分析

摘要

为研究钢绞线腐蚀对部分预应力混凝土梁疲劳寿命影响,对实际公路工程中的部分预应力混凝土梁的疲劳破坏进行了模型试验.基于分段线性的原理,考虑应力重分布修正及残余应力的影响,以混凝土弯曲受压变形模量和钢筋有效面积为疲劳损伤参数并对疲劳循环控制截面进行应力分析并计算试验梁的疲劳寿命.结果表明:钢绞线受腐蚀的部分预应力混凝土梁的失效往往源于钢绞线的疲劳断裂,钢绞线腐蚀率影响着部分预应力混凝土梁的疲劳寿命;分析计算得到的钢筋和钢绞线应力值与试验结果基本吻合;考虑钢绞线腐蚀疲劳强度折减的试验梁的疲劳寿命计算值与试验结果误差较小.%In order to analyze the effect of corroded strand on fatigue life of partial prestressed concrete (PPC) beams,experiments on fatigue performance of PPC beams with corroded strands are carried out in this paper.Considered fatigue flexural compressive deformation modulus of concrete and effective area as the damage parameters for concrete and rein-forcement respectively,the cross-sectional stress and the fatigue life of experimental beams are analyzed by taking the ef-fect of steel stress redistribution and the residual strain of reinforcement into account.The experiment results show that the initiation of fatigue failure of experimental beams is owing to the fracture of the corroded strands and the corrosion rate of stress strands has an obvious influence on the fatigue life of experimental beams.Reasonable agreement of the calculat-ed results of the steel stress with experimental results verified the reliability of the nonlinear analysis.When the reduction factor of fatigue strength of corroded strand is considered,the calculated results of fatigue life fit favorably with the exper-imental results.