锈蚀对钢管混凝土柱协同工作机理的影响

Effects of corrosion on collaborative mechanism of concrete filled steel tubular(CFST) columns

钢管锈蚀会对钢管本身的材料属性和套箍作用效果产生直接影响,也势必影响到钢管混凝土柱的力学性能和承载力。为了对钢管混凝土柱锈蚀后套箍力学机理有更清楚的认识,通过采用钢管壁厚和钢管刚度折减法,建立了钢管混凝土柱的锈蚀模型。在此基础上,根据弹性力学理论和钢管混凝土柱的协同工作原理,研究了轴向压力作用不同锈蚀程度下轴压钢管混凝土的套箍力学机理。分析结果表明,套箍力不但与核心混凝土的Poisson比、截面尺寸和弹性模量有关,而且还与外钢管的锈蚀程度、Poisson比、截面尺寸和弹性模量有关。随着锈蚀程度增加,钢管混凝土柱的组合弹性模量呈线性递减,外钢管对核心混凝土的套箍作用减弱,核心混凝土轴向压力分配系数呈线性增大。套箍力降低了核心混凝土轴向压力分配系数,提高了其轴向压承载力。

The corrosion on steel tube affects directly the properties and the confinement effect of the tube and thus impacts the mechanical performance and loading capacity of the concrete filled steel tubular（CFST ） columns. To understand the confinement mechanism of the steel tube after corrosion, a corrosion model for the column was proposed by a reduction method based on the thickness and stiffness of the steel tube. Subsequently,by means of the theory of elasticity and the collaborative mechanism of CFST column, the confinement mechanism of the CFST was studied under different corrosion levels. It shows that the confining force is related to not only the Poisson ratio, sectional size and elastic modulus of the core concrete but also the corrosion level, Poisson ratio, sectional size and elastic modulus of the steel tube. With the increase of the corrosion level, the composite elastic modulus of the CFST column decreases, but the axial compressive distribution coefficient increases. The confining force decreases the axial compressive distribution coefiicient, namely, increases its axial compressive bearing capacity.