A simply-supported post-tensioned pre-stressed concrete beam of span 18 m has the following properties: area of cross-section, 4 - 2800 x 10 mm; elastic section modulus, Wa=68800 10 mm and self-weight = 6.26 kN/m. The limiting design strengths are: (1) at transfer: 3 N/mm in tension; 20 N/mm in compression (ii) in service: zero tension; 18 N/mm in compression. Determine the initial pre-stressing force (Unit: kN), assuming that this is governed by both of the design strengths at transfer, when the beam carries only its own weight. Calculate also the corresponding eccentricity (Unit: mm) of the tendon profile at mid-span.