This study proposes a novel method for evaluating the ultimate shear capacity of precast prestressed concrete columns post-tensioned by unbonded tendons. Through loading tests, the shear behavior of the columns under high compressive axial forces was investigated. Observing axial collapse near maximum load capacity led to the development of a truss-arch mechanism-based evaluation method, assuming axial force balancing. This method accurately evaluates the maximum load capacity of specimens in this study within a range of -5% to +12% with standard deviation of 0.051, aligning with the actual failure mode.
