持续荷载作用下疲劳损伤混凝土梁的变形性能分析OA北大核心CSTPCD

To clarify the development law of deformation of concrete beams under cyclic and sustained loads,the effect of fatigue damage on the creep development law of the compression concrete and the deformation properties of beams un-der sustained load were studied.First,fatigue damage was introduced by the bending fatigue test;next,four-beam creep tests with different degrees of fatigue damage were conducted by surcharge loading.Results showed that the maximum crack width of concrete in the tension zone,the total strain of concrete in the compression zone,and the total deflection of fatigue-damaged beams are larger and faster than those in the nondamaged beam under sustained load,and all indica-tors increase with increasing fatigue damage.The development of concrete microfractures is promoted under cyclic load.Fatigue advances and accelerates the development of creep deformation,implying that partial creep strain and creep de-flection are formed in the early fatigue loading.Based on the experimental results,the calculation models of total creep strain in the concrete compression zone and creep deflection of fatigue-damaged beams are established.When the cyclic loading cycles are 0.025,0.15 and 0.60 times the fatigue life,the residual fatigue deflections are equivalent to the creep deflection of the nondamaged beam for 128,800 and 1 180 days,respectively.