Análisis en el tiempo de secciones de hormigón pretensado: Pérdidas de pretensado por retracción y fluencia. Influencia de la armadura pasiva

Time-dependent analysis of prestressed concrete cross-sections: Creep and shrinkage prestressing lasses, and the influence of passive reinforcement

This paper studies the time-dependent behaviour due to creep and shrinkage of prestressed concrete cross-sections, in a simple hut accurate way. The analysis is an extension of a previous work for non-cracked reinforced concrete cross-sections. It focuses mainly on the evaluation of the creep and shrinkage prestressing losses. One conclusion is that passive reinforcement has a certain significance for such losses. However. normally, this tactor is not taken into account in their calculation: specially for compression reinforcement. which tends to increase these losses. The present analysis includes this factor in an inherent way and finally leads to several formulae for the losses: one more accurate and other two simplified. Results from the proposed formulae are compared with those derived from another well-known formulae for different reinforcement ratios.