DAMAGES OF REINFORCED CONCRETE UNDER SYNERGISTIC EFFECTS OF CYCLIC FREEZE-THAW, DEICING-SALT ATTACK, REBAR CORROSION AND BENDING LOAD
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摘要: 采用自行研制的一套环境性能综合评估试验方法对钢筋混凝土试样成功地进行了冻融循环与除冰盐腐蚀协同作用(简称盐冻循环)、钢筋锈蚀与弯曲荷载协同作用下的失效试验。通过测量损伤演变过程中钢筋混凝土动弹性模量、钢筋应变和混凝土应变的变化,研究了盐冻循环、钢筋锈蚀与弯曲荷载协同作用下钢筋混凝土损伤失效的演变过程。结果表明,普通混凝土(C4 5 )和高强混凝土(C70 )在不同损伤因素协同作用下,损伤规律存在相似性,但损伤速率明显不同。相似性表现在:多因素协同作用下导致的损伤大于单因素损伤,特别是叠加上弯曲荷载后,混凝土动弹性模量下降速率大大增加,表明弯曲荷载对盐冻循环与钢锈协同作用下的钢筋混凝土的损伤有促进作用。在相同试验条件下,普通混凝土的损伤速率大于高强混凝土,表明普通混凝土的损伤阻力低于高强混凝土。另外,试验发现在给定的温差变化条件下,盐冻循环、钢锈与弯曲荷载协同作用导致钢筋混凝土中钢筋的应变幅值随着冻融循环次数的增加而逐渐增大。Abstract: The damage experiments of reinforced concrete samples under synergistic effects of cyclic freeze thaw, deicing salt attack, rebar corrosion and bending load were investigated using a comprehensive experimental method. Synergistic effects of these factors on the damage evolvement of the reinforced concrete was studied by measuring the change of dynamic modulus, rebar strain and concrete strain. Experimental results showed similar rule in damage evolvement,but different damage rate between the normal strength concrete (C45) and the high strength concrete (C70). The dynamic modulus of the reinforced concrete degraded with increasing effecting factors. Meanwhile, an interesting phenomenon is revealed that the amplitude of cyclic strains increase with the numbers of freeze thaw cycles within a fixed temperature difference.
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