Seismic Performance at Beam Ends of Unbonded Prestressed Precast Concrete Frames

Abstract

 Numerical modelling was conducted to investigate the seismic performance at beam ends of unbonded prestressed precast concrete frames. The established finite element model was verified by the test results. Through numerical simulation, the influence of such factors as the presence or absence of energy-dissipating reinforcement, the length of the unbonded section of energy-dissipating bars, the amount of prestressed or non-prestressed reinforcement on the seismic performance at beam ends of unbonded prestressed precast concrete frames were further analyzed. The results show that all prestressed precast beam-end models have similar initial stiffness. The bearing capacity and energy-dissipating performance of beam-end models without energy-dissipating bars are the lowest. The length of the unbonded section of energy-dissipating bars has no significant effect on the bearing capacity and energy-dissipating capacity of beam-end models, though the yield displacement increases obviously with the increase of the length of the unbonded section, as the local stress of energy-dissipating bars is reduced by setting the unbonded section. The bearing capacity of beam-end models can be improved by increasing the amount of prestressed or non-prestressed reinforcement. In the case of the same amount of prestressed reinforcement, increasing the amount of energy-dissipating bars can significantly improve the energy-dissipating capacity.