冻融和疲劳对预应力受弯构件损伤的影响

通过15根预应力及普通混凝土试验梁在经历不同冻融循环次数后的疲劳试验, 探索试验梁 相对动弹模衰减规律, 以相对动弹模为损伤变量, 通过方差分析方法定量分析冻融和疲劳两 种因素对构件损伤的影响. 研究表明试验梁在冻融和疲劳荷载双因素作用下, 初期以冻融损 伤为主, 之后很快发展为以疲劳损伤为主, 疲劳损伤是构件的主要损伤因素. 施加预应力或 提高预应力度对试验梁疲劳损伤有较明显的抑制作用, 将缩短试验梁全寿命中以疲劳损伤为 主的时间.

THE INFLUENCE OF FREEZE-THAWING AND FATIGUE LOAD ON THE DAMAGE OF PRESTRESSED CONCRETE BEAMS

In order to study the relative dynamic modulus of elasticity, deteriorated due to the accumulative fatigue damage under the freeze-thaw enviorment, fatigue experiments were carried out for fifteen prestressed or reinforced concrete beams under different cycles of freeze-thawing. With the relative dynamic modulus of elasticity as the damage variable, the influence on the damage of the freeze-thaw and the fatigue load is analyzed through the variance analysis method. It is shown that the freeze-thawing is the main damage factor at the initial stage and then the fatigue damage becomes the main factor in this two-factor experiment, but the fatigue is the major factor of damage in the whole life of test beams. Applying prestress or enhancing prestress extent has an obvious inhibition effect on the damage of test beams and will reduce the period in which the fatigue is the major damage factor in the life time of test beams.