Cálculo práctico de flechas diferidas en estructuras de hormigón armado

Practical calculation of long-term deflections in reinforced concrete structures

This work deals with long-term deflections due to creep and shrinkage in reinforced concrete structures. It extends previous work by the author on time-dependent analysis of reinforced concrete cross-sections under serviceability conditions, after cracking, considering shrinkage and creep in the compressed region. So, this work completes the approach, which proposes a practical formula for the delayed deflections, based on a factor that permits their determination from the instantaneous deflections. The basic formula is further examined, mainly to get better accuracy in one parameter, without abandoning the original theoretical framework. On the other hand, this analysis is complemented by checking the accuracy of the formula, which is shown to be good with reference to experimental results, for both normal and high strength concrete structures. Then, as a result from the analysis developed in this work, a formulation is proposed for practical calculations. The formulation has the advantages of being simple and giving explicit form for both creep and shrinkage, which vary from one case to another, in a compact and homogeneous way. In practice, it is general, applying also to T-section and similar cross-sections. After the conclusions, a practical example is developed.