A one-way slab is simply supported over a span of 12m and is to be designed to carry a superimposed service load of 5 kPa in addition to its own self-weight. The slab has a rectangular cross-section and the loads do not need to be factored in your design. The slab is post-tensioned by regularly spaced tendons with parabolic profiles (zero eccentricity at ends, and a maximum eccentricity at the midspan). Each tendon contains 4x 12.7mm strands in a flat duct The material properties are: f'cp = 25 MPa, f'c = 40 MPa, Ecp = 26700 MPa, Ec = 32750 MPa fpb = 1870 MPa