钢管混凝土受压构件徐变分析

Creep Analysis of Concrete Filled Steel Tubular Compressed Member

混凝土徐变使钢管混凝土构件发生应力重分布。根据弹性徐变理论,按龄期调整的有效模量法,导出了轴心受压和小偏心受压构件长期作用下钢管与核心混凝土徐变应力增量计算公式,计算值与试验结果吻合较好。进一步的数值分析表明,截面含钢率变化会显著影响钢管应力增量值的变化,但对核心混凝土应力增量影响不大;随着偏心率的增大,相同含钢率下钢管与核心混凝土应力增量几乎均呈线性变化。增大截面含钢率可降低钢管由徐变产生的附加内力,但根据截面内力按刚度分配的原则,钢管更多地承担外力,使钢管的总内力呈增大趋势,核心混凝土承受的外力显著减小,不利于钢管混凝土构件性能的发挥。

Creep leads to the stress redistribution of Concrete Filled Steel Tubular （CFST） member. According to elastic creep theory and aging-adjustment effective module method, creep stress increment formulas of both steel tube and core concrete for CFST uniaxially and small eccentrically member under long-term action have been put forward. The result of computation is in accordance with that of experiment. The further numerical analysis shows that sectional steel ratio has obvious influence on stress increment of steel tube, but less effect on core concrete. Stress increments of both steel tube and core concrete are linearly changed at same sectional steel ratio while eccentric ratio is raised. Although larger sectional steel ratio could reduce additional internal force of steel tube, steel tube still afford more external force based on the principle of stiffness distributing internal force ,which makes total internal force of steel tube still increase and the external force of core concrete obviously reduce. It isn＇ t beneficial for CFST to take full advantage of its performance.