冻融后预应力混凝土构件疲劳损伤模型

通过7根预应力混凝土梁进行不同冻融循环次数后的疲劳试验,研究冻融环境下构件由于疲劳累积损伤而造成的刚度衰减规律,试验结果表明冻融作用对构件在疲劳荷载下挠度的发展起加剧作用,且随着冻融次数增多作用愈明显.在冻融循环和疲劳荷载的共同作用下,试验梁的剩余刚度在弯曲疲劳过程中呈现三阶段衰减规律,并且在第2阶段近似呈线性衰减,构件发生疲劳破坏时,其剩余刚度衰减至初始刚度的66%左右.根据损伤理论得到试验梁基于刚度衰减的累积损伤值D与循环寿命比n/Nf之间的关系模型,该模型考虑了冻融效应对疲劳累积损伤的影响,可为寒区预应力混凝土梁疲劳寿命预测提供有价值的参考.

Fatigue damage model of prestressed concrete beams suffered freeze-thawing

In order to inverstigate the rigidity deterioration regulation of the accumulative fatigue damage under freeze-thaw enviorment,a fatigue experiment of seven prestressed concrete beams was conducted for different freeze-thawing times.The experiment results indicate that freeze-thawing effect can aggravate the deflection development of test beams in fatigue experiment.The remaining rigidity of test beams shows a course of a three-stage deterioration characteristic,and displays a linear deterioration during the second stage with 66% initial rigidity at fracture.A model was proposed to describe the relation between accumulative damage of D and cycling life ratio of n/Nf.The freeze-thawing effect on accumulative damage was considered to provide valuable reference in fatigue life prediction of prestressed concrete beams in cold region.