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沿海环境下的钢筋混凝土(RC)结构处于荷载作用和环境作用同时存在的工作状态且在正常条件下会出现不同程度的荷载损伤。为了在实验室内模拟其工作状态,对RC梁试件施加幅值分别为0.3P_u、0.4P_u、0.5P_u、0.6P_u和0.7P_u(P_u为单调加载梁的极限荷载)的初始荷载造成不同程度的损伤,经历120次海水干湿循环作用后,进行单调加载试验测试剩余力学性能,并对梁试件钻芯取样测试不同位置及深度处混凝土的氯离子含量。试验结果表明,不同程度初始损伤RC梁经历120次海水干湿循环后,其屈服荷载、极限荷载和延性均随初始荷载幅值的增加而降低;与无损伤梁试件相比,当初始损伤荷载为0.4P_u时,梁试件的屈服荷载和极限荷载降幅分别为10.4%和7.9%,随着初始荷载增大,屈服荷载和极限荷载快速下降,当初始损伤荷载为0.7P_u时,屈服荷载和极限荷载降幅分别达33.7%和32.4%。氯离子含量测试结果表明,梁试件混凝土受拉区氯离子含量均大于受压区氯离子含量;当初始损伤荷载小于0.5P_u时,受拉钢筋表面混凝土的氯离子含量差别不大且小于0.1%,当初始损伤荷载为0.7P_u时,钢筋表面氯离子含量最大达到0.14%。可见,初始荷载损伤与海水干湿循环综合作用对RC梁力学性能及耐久性劣化影响显著。
Reinforced concrete (RC) structures in coastal environment are in a working condition where both loading and environmental effects exist, and under normal conditions, varying degrees of load damage occur. In order to simulate their working conditions in the laboratory, the initial load of RC beams with different amplitudes of 0.3P_u, 0.4P_u, 0.5P_u, 0.6P_u and 0.7P_u respectively (P_u is the ultimate load of monotonic loading beam) After 120 cycles of wet and dry seawater circulation, the monotonous loading test was carried out to test the remaining mechanical properties, and the core sample of the beam specimen was taken to test the chloride ion content of the concrete at different positions and depths. The experimental results show that the initial load, the ultimate load and the ductility of RC beams with different degrees of initial damage after 120 cycles of seawater wet-dry cycle both decrease with the increase of initial load amplitude. Compared with the specimens without damage, when initial damage When the load is 0.4P_u, the yield load and ultimate load drop of beam specimens are 10.4% and 7.9% respectively. With the increase of initial load, the yield load and ultimate load decrease rapidly. When the initial damage load is 0.7P_u, And the limit load decreased by 33.7% and 32.4% respectively. The test results of chloride ion content show that the content of chloride ion in the concrete tensile zone of beam specimen is larger than that of the chloride zone in the compression zone. When the initial damage load is less than 0.5P_u, the difference of chloride ion content on the concrete surface is less than 0.1 %, When the initial damage load is 0.7P_u, the maximum chloride ion content on the steel surface reaches 0.14%. It can be seen that the combined effect of initial load damage and seawater wet-dry cycle has a significant effect on the mechanical properties and durability degradation of RC beams.