Some conclusions for the time-dependent analysis of reinforced concrete structures concerning the calculation of delayed deflections

Abstract

When designing reinforced concrete structures, taking into account the effects of shrinkage and creep. an actual time.-dependent analysis is normally not performed. In practice, nothing but delayed deflections are calculated are calculated. These deflections are obtained by multiplying the initial (instantaneous) ones by a factor that is linked to the creep coefficient. Using a simple but accurate reasoning, this paper dealts with the aforementioned matter in order to establish its limits. In particular, it is shown that in most cases such a procedure is justified for reinforced concrete. Although the factor that is proposed to obtain the deflections is normally less and depends on both creep and shrinkage. To this purpose, an analytical approach to predict the behaviour of the cracked structural parts has been developed. This approach extrapolates to the time -dependency range a method of cross- sectional calculation that considers separately the pure concrete and steel areas.