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.