考虑剪滞效应下计算钢筋混凝土箱梁应力的换算截面法

Transformation-section method for stress calculation of reinforced concrete box beams with shear lag

基于换算截面的概念,提出利用变分原理进行钢筋混凝土箱梁剪力滞分析时,不改变换算前后截面的拉压性能及剪切性能,而将钢筋及混凝土组成的实际截面分别换算为拉压性能及剪切性能相同的假想材料所组成的匀质截面,对换算后截面按单一匀质材料进行剪力滞分析并得到换算截面应力分布,依据钢筋及混凝土两种不同材料的本构关系,得到实际截面应力分布.以钢筋混凝土简支箱梁受跨中集中力为例,说明换算截面进行考虑剪滞效应下截面应力计算的方法.算例与有限元分析结果的比较表明,该方法简便可行.

The tensile-compression and shear performance would not altered by using a concept of transformation-section when variation principle was used to analyze shear lag of box beams. Based on transformation-section method, the actual section composed of steel and concrete could respectively be transformed into a homogeneous section made of supposed material with identical tensile-compression or shear performance. The shear lag of supposed section was analyzed to calculate the distribution of normal stress, and then, according to the constitutive relation of steel and concrete, the stress of actual section could be obtained. An example of reinforced concrete simple-support beam subjected to concentrated load on middle span was given to illustrate this method. The result of comparison with its finite element analysis showed that this method was simple and feasible.