高温对建筑钢筋寿命的影响研究

The influence of high temperature on the life of building steel bar

为研究高温对建筑用钢筋寿命的影响,利用万能试验机对直径为12、25 mm的钢筋进行性能测试。结果表明:220℃时,钢筋试件表面出现明显的腐蚀坑,且分布不均,随着温度的升高,腐蚀产物分布均匀且致密,但无明显的腐蚀坑;温度继续上升,钢筋屈服强度降低,其氧化锈蚀和粘连锈蚀相互转化,使锈蚀量较大;直径为12 mm的钢筋比直径为25 mm的钢筋更快达到屈服点,退化程度更高。钢筋弹性模量、屈服强度和极限强度均随温度升高而退化,且温度越高,寿命越低。

In order to study the effect of high temperature on the lifespan of building steel bars,performance tests were conducted on steel bars with diameters of 12 mm and 25 mm using a universal testing machine.The results show that there are obvious corrosion pits on the surface of the steel bar specimen at 220℃,which are unevenly distributed.As the temperature increases,the corrosion products are evenly and densely distributed,but there are no obvious corrosion pit.As the temperature continues to rise,the yield strength of the steel bars decreases,and their oxidation corrosion and adhesion corrosion transform each other,resulting in a larger amount of corrosion.The steel bar with a diameter of 12 mm reaches the yield point faster and has a higher degree of degradation than the steel bar with a diameter of 25 mm.The elastic modulus,yield strength,and ultimate strength of steel bars all deteriorate with increasing temperature,following the rule that higher temperature leads to lower lifespan.