考虑海洋环境损伤的钢筋混凝土梁抗火性能试验研究

Experimental research on fire resistance performance for RC beams with damages caused by marine environment

为研究海洋环境造成的侵蚀损伤对钢筋混凝土梁抗火性能的影响,以氯侵蚀产生的初始裂缝最大宽度作为损伤指标,设计5根钢筋混凝土梁试件,先进行快速氯离子侵蚀试验,使其产生最大宽度为0.05、0.10、0.15、0.20 mm的侵蚀裂缝,然后对不同损伤程度的梁进行火灾试验。结果表明:侵蚀试验中箍筋比纵筋锈蚀严重,氧气浓度显著影响侵蚀速率;火灾试验后不同试件相同位置测点升温趋势大致相同,但截面历经最高温度相差较大,最大温差达到300℃;裂缝宽度越大,试件历经最高温度越高,挠度增长越快;侵蚀损伤指标对试件抗火性能影响显著,侵蚀裂缝宽度愈大试件受弯承载力损失越大,最大下降比例达到25.6%。

In order to study the effects of corrosion cracks caused by marine environment on fire resistance of RC beams,maximum value of crack width caused by chloride ion was taken as damage index,five RC beams were designed to develop different crack width ranging from 0. 05 mm to 0. 20 mm,which were caused by chloride ion erosion. Then the damaged RC beams with different crack width were set on fire in order to study their fire resistance.The results show that stirrups rust more seriously than longitudinal bars in rapid erosion test,and oxygen density has a great influence on erosion rate. The temperature rising trend of different members in the same location is roughly similar,but the temperature values have great difference,the maximum temperature difference reaches 300 ℃. Crack width has great effects on the deflection and temperature distribution of the members. The indicators of erosion damage have significant effects on the fire resistance of components. The larger the corrosion crack width is,the more the bending bearing capacity loss is. The highest percentage decline reaches 25. 6%.