Transfer length in pretensioned prestressed concrete structures composed of high performance lightweight and normal-weight concrete

This article discusses an analytical model that relates the transfer length and the prestressing strand draw-in immediately after transfer; the model is based on the elastic confinement hypothesis of the prestressing strand using concrete and/or confining reinforcement. Two expressions are proposed to estimate upper and lower bounds on the transfer length, which consider the prestressing strand draw-in and the transferred effective prestress. The analytical model and the proposed expressions are compared with the experimental results obtained at the University of La Coruña, in which precast pretensioned prestressed concrete members were fabricated from conventional concretes and lightweight concretes. Strand Y1860 S7, db = 15.2 mm, was used in this research. The tested pretensioned lightweight concrete members exhibit structural insecurity because of the splitting cracks detected after the prestress release.