Behavior of externally prestressed continuous beams with FRP/steel rebars under symmetrical/unsymmetrical loading: Numerical study

This study examines the use of fiber reinforced polymer (FRP) rebars as an alternative to steel rebars in externally prestressed concrete (EPC) continuous beams to alleviate the corrosion problem. To the best of the authors’ knowledge, this is the first study on continuous EPC beams with FRP rebars, taking into account the pattern of loading. By utilizing an experimentally verified computer model, numerical assessments are conducted on two-span EPC beams with carbon FRP (CFRP), glass FRP (GFRP) or steel rebars, subjected to symmetrical or unsymmetrical loading. The results show that providing a minimum FRP rebars is more effective in alleviating the cracking concentration than providing steel rebars. At ultimate, unsymmetrical loading leads to greater deflection in the critical midspan but lower tendon stress than symmetrical loading, while the deflection or stress difference highly depends on the type of rebars (FRP/steel). Several design codes for calculating the ultimate tendon stress are evaluated. Practical equations are proposed to predict the ultimate tendon stress in continuous EPC beams with FRP/steel rebars. The proposed equations exhibit much better predictions than the design codes.