Factor de cálculo de flechas diferidas.Serviceability time-dependent analyiss of T and box shaped reinforce concrete cross-sections. Practical factos for obtaining delayed deflections

Abstract

In connection with a prior paper, this one prsents an approach to the time-dependent analysis of T or box shaped reinforced concrete cross-sections, with reinfocement at both sides, in serviceability conditions after cracking, considering shrinkage and creep under permanent load. Finally, as a result from this analysis, a formula for the factor permitting to obtain delayed deflections from instantanous ones is proposed for practical calculations. It could be an alternative to the one existing at the current Spanish reinforced concrete code (EH-91), almost equal in this to the prior version (EH-88), not distinguishing different kind of cross-sections. The formula has the important quality of making explicit the incidence of both shrinkage and creep, properties having big variations from one case to another. By other hand, in spite of having a similar formulation to the Spanish code one, it offers normally rather less conservative numerical results.