Time-dependent behavior of concrete beams prestressed with bonded AFRP tendons

This paper presents a numerical study on the long-term performance of bonded aramid fiber reinforced polymer (AFRP) prestressed concrete beams. A computer model capable of predicting the service load long-term response of prestressed concrete beams with AFRP and steel tendons is developed. Model predictions agree well with the results of long-term tests on prestressed concrete beams. The time-dependent behavior of AFRP prestressed concrete beams is evaluated and the results are compared with those of steel ones. It is indicated that, when tendon relaxation is considered, AFRP tendons register a higher long-term prestress loss than steel tendons although the prestress loss contributed by concrete creep and shrinkage is significantly lower in AFRP tendons than in steel ones. As a consequence, AFRP tendons mobilize a lower prestressing camber and a higher downward load deflection compared to steel tendons. The analysis also shows that the influence of bottom nonprestressed steel on the time-dependent performance can be important or not so important, depending on the level of loading.