Direct evaluation method for load-deformation curve of precast prestressed concrete frame with different tendon forces

Abstract

To establish a more accurate, flexible, and practical performance evaluation method for unbonded precast prestressed concrete (PCaPC) frames, a macro model was illustrated based on the exterior beam–column sub-assemblages of unbonded PCaPC frames, which considers different tensile forces of the post-tensioned tendons (i.e. unsymmetrical tendon forces) and high-strength concrete. Based on the macro model, closed-form equations of beam axial shortening were provided by precisely considering the deformation compatibility and force equilibrium conditions along the beam. In this study, the iteration method for the comprehensive evaluation of different performance limit states, as well as the load–deformation relationship of the beam–column sub-assemblages, were constructed and simplified. Accuracy and superiority of the proposed evaluation methods were verified by comparison with experimental data and evaluation results of previous methods. Both damage tolerance and self-centering performance of unbonded PCaPC frames can be more accurately measured by the proposed methods. Meanwhile, the consideration of unsymmetrical tendon forces makes the methods more flexible for different types of unbonded PCaPC frames. In addition, parametric study was conducted to understand the effects of critical design parameters on the performance limits. Preliminary design advices were given to show the application potential of this study.