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

In order to study the relative dynamic modulus ofelasticity, deteriorated due to the accumulative fatiguedamage under the freeze-thaw enviorment, fatigue experiments werecarried out forfifteen prestressed or reinforced concrete beams underdifferent cycles of freeze-thawing. With the relative dynamicmodulus of elasticity as the damage variable, the influence on the damageof the freeze-thaw and the fatigue load is analyzed through thevariance analysis method. It is shown that the freeze-thawing isthe main damage factor at the initial stage and then the fatigue damagebecomes the mainfactor in this two-factor experiment, but the fatigue is the major factor ofdamage in the whole life of test beams. Applying prestress or enhancingprestress extent has an obvious inhibition effect on the damage of testbeams and will reducethe period in which the fatigue is the major damage factor in the lifetime of test beams.