Análise das perdas progressivas em uma viga de concreto protendido pós-tracionada

Abstract

The prestressed concrete has been gaining space in the civil construction market, as well as in projects of special art works, due to the need for lighter, slimmer structures and large spans. To ABNT NBR 6118:2014 indicates that the losses of the protrusion force in relation to the initial tension value applied by the tensioning device should be foreseen in the project. This work aims to study the calculation methodologies for progressive losses according to ABNT NBR 6118:2014, Eurocode 2 (2004) adapted by Bastos (2019), alternative method adapted by Bastos (2019) and the method of Vasconcelos (1980), considering variations in humidity, fictitious thickness, starting time of the protection force and tension properties of steel in order to make an analysis and compare these results. The values obtained by the progressive loss calculation methods, in general, showed great variations, where the alternative method adapted by Bastos (2019) and the vasconcelos method (1980), in general have a sensitivity for variations of retraction, fluency and steel relaxation as a function of the prestressing start time, in addition to that, the results obtained from progressive losses are more costly compared to other methodologies for calculating progressive loss. The simplified method of ABNT NBR 6118:2014, was less susceptible to variations in the results obtained from progressive losses, as well as the approximate method of ABNT NBR 6118:2014, where it remained with little variation in progressive losses, showing itself conservative in the results of progressive losses. The simplified Eurocode 2 method adapted by Bastos (2019), in general, was the method that came closest to the results of progressive losses by the methodologies indicated in ABNT NBR 6118: 2014 for the calculation of progressive losses.