一种计算组合梁徐变和收缩效应的新方法

A new algorithm for creep and shrinkage effects of composite beams

为准确方便计算钢-混凝土组合梁徐变和收缩效应,预估组合梁的长期力学性能,采用直接法推导了组合梁材料换算系数、徐变调整系数和收缩调整系数,获得组合梁时随应力公式,可根据材料力学中单一材料的力学公式计算组合梁截面应力.算例分析表明:采用直接法计算组合梁截面纤维应力结果与采用内力分配法计算的结果符合性很好.直接法适用性非常广,适用于正弯矩下的简支组合梁、框架组合梁和预应力组合梁等,根据不同的约束形式和荷载类型给定组合梁截面形心处的内力值,可计算相应的时随调整系数、截面应力和应变.该方法简单实用,是对组合梁长期力学计算方法的一种有效补充,可直接应用于工程实用计算.

To calculate creep and shrinkage effects of steel-concrete composite beams to forecast their long-term mechanical performances,a new algorithm named direct method was adopted.The material ratios,creep adjustment coefficients and shrinkage adjustment coefficients were derived.The formulas of time dependent stresses were obtained.Hence,cross section stresses of composite beam can be calculated similar to a single material section based on material mechanics theory.The analysis indicates the results of cross section stresses of composite beam by direct method are consistent with that by internal force distribution method.The direct method can be used in a wide range,such as simply supported composite beams,composite beams in frame and pre-stressed composite beams under actions of positive bending moment.It can be adopted to obtain adjustment coefficients,stresses and strains according to the internal force at the composite beam centroid with different constraint and load forms.It is a simple-useful method and supplement for a long-term mechanical calculation theory of composite beam.It can be directly applied in practical engineering calculations.