钢筋混凝土框架结构伸缩缝间距计算

《混凝土结构设计规范》给出的钢筋混凝土框架结构中伸缩缝间距取值比较原则化，因而其应用效果不尽人意．为此，提出伸缩缝间距应能保证温度及收缩应力不大于容许应力，且使综合裂缝宽度处于规范允许范围内的思想．以此为基础，对由多层简化为单层的规则框架中跨梁板截面考虑徐变和开裂影响的平均轴拉应力进行了验算，并从中推导出与温度及收缩自由应变、结构约束、截面配筋率、荷载标准组合下的钢筋应力等主要因素有关的伸缩缝间距计算公式．算例表明公式具有一定的合理性和参考价值．

Calculating of Expansion Joint Spacing of Reinforced Concrete Frame Structures

The values of expansion joint spacing of reinforced concrete structures are given by some standards. But the effect of using these values is not very safisfactory. To find the reasonable values it is necessary to take account of two factors: 1) the stresses caused by temperature and shrinkage are less than the allowable stresses; 2) the composite cracking width has to be within the allowable range. On the basis of the above-named analysis the average tension stresses with including the effect of creep and cracking were examined in the middle sections of regular single layer frame simplified from multilayer frame. By the examining a formula calculating the expansion joint spacing of reinforced concrete frame structures was deduced. In the formula the several main factors, such as the free strain induced by temperature and shrinkage, structure restraining, steel ratio of cross section and the characteristic combination stress in reinforcements, were taken into consideration. Two calculating examples indicate that the formula is rational and usable.