Long-term deformation of prestressed concrete beams

This paper presents a method for calculating camber and deflection of underacked prestressed concrete beams subjected to long-term loading. The method are adaptable to calculation of statically determinate or statically indeterminate, pre-tensioned or post-tensioned beams, with bonded or unbonded tendons and multi-layers of tendons mixed with non-prestressed steel etc. 32 beams have been observed in the long-term experiment. All theoretical values are in good agreement with the experimental ones. Meanwhile, it has been found that the time-dependent camber of beams will increase, keep constant or even decrease as time goes on according to their different arrangements of multi-layers of tendons and non-prestressed steel.