【摘要】 为研究混凝土收缩、徐变及预应力筋松弛耦合作用下长期预应力损失计算方法，以某预应力混凝土简支梁桥为背景，基于弹性徐变理论及积分中值定理，开展了桥梁结构长期预应力损失中值积分法研究，并给出了长期预应力损失中值积分法及中值系数计算公式。分别采用3种规范、数值计算法及中值积分法，计算了环境年平均相对湿度RH为60%、80%两种情况下，1、10、50年时长期预应力损失，并以数值计算值为参考值进行了对比。结果表明：按欧洲规范(EN 1992-1-1:2004)、《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)计算容易低估长期预应力损失，而按美国国家高速公路和交通运输协会标准(AASHTO 2012)计算则容易高估长期预应力损失；中值积分法计算值与数值计算值几乎相同，百分误差均小于0.5%;简化中值积分法计算公式与数值计算值相比略微偏小，计算误差随时间增加有减小的趋势，百分误差均在4%以内。更多还原

【Abstract】 A method to calculate the long-term prestress losses of concrete structures under the coupling effects of shrinkage, creep and prestressing tendon relaxation is proposed in this paper.Based on a simply-supported prestressed concrete bridge, research on the median integral method to calculate long-term prestress loss of bridge structures is carried out following the elastic creep theory and mean value theorem for integrals, and the related calculation formulas are presented.The methods suggested in three different codes and the median integral method were supplemented with numerical simulation to obtain the prestress loss values at one-,ten-and fifty-year′s service life of the bridge, when the annual average relative humidity RH was at 60% and 80%,respectively.The calculations were compared with the accurate numerical simulation.It is shown that the Eurocode(EN 1992-1-1:2004) and Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG 3362-2018)underestimate the predicted long-term prestress loss, while the AASHTO 2012 overestimates the predicted long-term prestress loss.The results calculated by median integral method agree well with the numerical simulation, with a percentage error less than 0.5%.The results calculated by the simplified median integral method proposed are slightly smaller than the numerical simulations, the calculation error is likely to rise over time, but the percentage errors are all within the range of 4%.更多还原