Automation of the evaluation of bonded and unbonded prestressed concrete beams, according to brazilian and french code specifications

This paper presents a suggestion for the automation of the design procedures of bonded and unbonded prestressed concrete flexural members, according to the Brazilian (NBR 6118:2007) and French (Règles BPEL 91) norm specifications. Prestressing of concrete structures has been increasingly used, mainly due to its building advantages, as well as allowing reducing crack incidence and element dimensions by the use of more resistant materials. Structure is analyzed by a numerical model that employs a hybrid type finite element for planar frames, considering geometric nonlinearity, cyclic loading and composite construction. The computational algorithm implemented considers full, partial and limited prestressing situations, evaluating in each case decompression limit state, limit state of cracking, ultimate limit state and final prestressing state. Finally, two examples comparing design situations according to the Brazilian and French norms are presented.