一种计算支座约束影响下连续组合梁徐变次内力的解析方法

为合理方便地计算支座约束影响下连续组合梁的徐变效应，预估组合梁长期力学性能，基于力法基本原理和混凝土徐变本构方程，分解了连续组合梁截面应力重分布和结构支座约束内力重分布的耦合关系，推导了连续组合梁在支座快速约束和缓慢约束两种情况下的徐变次内力解析公式，并通过理论和数值方法对算例进行分析.计算表明:徐变对支座沉降约束起有利作用，组合梁徐变次弯矩受截面内部应力重分布影响，受重分布系数控制，随组合梁截面混凝土与钢梁的刚度比变化，内部应力和外部内力相互影响，且与徐变系数和老化系数相关.采用该方法可较方便地计算连续组合梁在支座约束变化下的内力，公式推导建立在清晰的力学基础上，计算结果能较有效地反映组合梁力学特征，是对组合梁长期力学性能计算方法的一种有效补充. 

Analytical Method for Computing Creep Secondary Internal Forces of Continuous Composite Beams Influenced by Support Constraints

To calculate the creep effects of steel-concrete composite beams under support constraints, and to predict the long-term mechanical properties, the coupling relationship between sectional stress redistribution in the continuous composite beams and restrained internal force redistribution of structural supports was unlocked based on the principle of force method and creep constitutive equation of concrete. The analytical formulas for computing the creep secondary internal forces of the composite beam under the two conditions of fast and slow support constraints were deduced. Then, both of theoretical and numerical methods were adopted to analyze an example. The calculation results show that, the creep plays a beneficial role in restricting the settlement of support. The creep secondary moment in the steel-concrete composite beam is affected by the internal stress redistribution, can be controlled by the redistribution coefficient, and varies with the stiffness ratio between concrete and steel beam. The internal stress and external internal force can influence each other. This change process is related to the creep coefficient and aging coefficient. These formulas derived in this paper are proposed based on clear mechanics concepts. Therefore, this method can be more conveniently used to calculate the internal forces of the steel-concrete composite beams under the influence of bearing changes. The obtained results can effectively reflect the mechanics characteristics of steel-concrete composite beams. This method is an effective supplement to evaluate the long-term mechanical characteristics of the composite beams.