Assessment of Deflection Prediction Models for Cracked Prestressed Concrete Beams.

Variability of deflection prediction models is assessed for cracked prestressed concrete flexural members with bonded steel tendons. Current models for computing deflection are based on an effective moment of inertia (with or without an offset moment for the cracked section response) or a bilinear moment-deflection response using the moment of inertia of the uncracked section before cracking and moment of inertia of the cracked section after cracking. The accuracy of the approaches provided in ACI 318-19, the PCI Design Handbook, and elsewhere are examined for computing immediate deflection using a large database of 180 fully prestressed as well as partially prestressed beams. Parameters considered in the analysis include the effect of tension-stiffening, reinforcement ratio, prestressing type (fully or partially prestressed), cracking moment, concrete elastic modulus, modulus of rupture, and the use of transformed or gross section properties. Results highlight the need for a rational model that can be universally applied to reinforced as well as prestressed concrete flexural members. [ABSTRACT FROM AUTHOR]