局部腐蚀圆中空夹层钢管混凝土短柱偏压力学性能研究

Eccentric compression performance of CFDST stub columns under local corrosion

为研究局部腐蚀圆中空夹层钢管混凝土短柱偏心受压的力学性能,以局部腐蚀的腐蚀率及荷载偏心率为参数,建立数值模型,分析了腐蚀率与荷载偏心率对该类构件承载力的影响规律及破坏机理.结果表明,外钢管局部腐蚀导致弹性范围内刚度减小,腐蚀率越大,腐蚀区域越早产生局部屈曲,导致塑性破坏,进而导致承载力降低.荷载偏心率对承载力影响较大,当偏心率小于1.5时,承载力随偏心率的增大而急剧减小;当偏心率大于1.5时,承载力减小的趋势逐渐趋于平缓.同时,外钢管对内部结构的约束效应受偏心率影响较大,当偏心率较小时,约束效应明显,外钢管只产生环向拉应变;随着偏心率的增大,腐蚀区域靠近加载点一侧的钢管首先产生局部屈曲,同时腐蚀区域远离加载点一侧的钢管出现环向压应变.

In order to study the eccentric compression performance of concrete filled double skin steel tubular(CFDST) stub columns under local corrosion, the numerical model was established with the parameters of corrosion rate of local corrosion and eccentricity of load. The influence of corrosion rate and eccentricity of load on the bearing capacity and failure mechanism of such members were analyzed. Results show that the local corrosion of the outer steel tube resulted in a decrease of stiffness in the elastic range. The greater the corrosion rate was, the earlier the local buckling of the corrosion area occurred, which caused plastic failure and reduced the bearing capacity. Load eccentricity had a greater effect on bearing capacity, the bearing capacity decreased sharply with the increase of eccentricity when eccentricity ratio was less than 1.5, and the decreasing tendency of the bearing capacity gradually became flat when the eccentricity ratio was greater than 1.5. The restraint effect of the outer steel tube on the internal structure was greatly affected by eccentricity ratio. The constraint effect was obvious when the eccentricity ratio was minor, and the outer steel tube only generated a circumferential tensile strain. With the increase of eccentricity ratio, local buckling first appeared in the steel tube on the side close to the load point in the corrosion area, while the circumferential compress strain occured on the steel tube on the side far from the load point in the corrosion area.