Ac '

;i +

where MT = MD + MSD + ML; P; is the initial prestress; Pe is the effective prestress after losses, where t denotes the top and b denotes the bottom fibers; e is the eccentricity of tendons from the concrete section center of gravity, cgc; r2 is the square of radius of gyration; and St/Sb is the top/bottom section modulus value of concrete section.

The decompression stage denotes the increase in steel strain due to the increase in load from the stage when the effective prestress Pe acts alone to the stage when the additional load causes the compressive stress in the concrete at the cgs level to reduce to zero. At this stage, the change in concrete stress due to decompression is fd ecomP _ a ' 1 + r2

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