EXAMPLE 4.3 An unsymmetrical I-section beam is used to support an imposed load of 2 kN/m over a span of 8 m. The sectional details are top flange, 300 mm wide Copyrighted material Analysis of Prestress and Bending Stresses 89 and 60 mm thick; bottom flang, 100 mm wide and 60 mm thick; thickness of the web = 80 mm; overall depth of the beam = 400 mm. At the centre of the span, the effective prestressing force of 100 kN is located at 50 mm from the soffit of the beam. Estimate the stresses at the centre of span section of the beam for the following load conditions: (a) Prestress + self-weight (b) Prestress+self-weight + live load. -300 mm 400 mm 50 mm 80 mm 60 mm Live load=2 kN/m e=194 mm 8 m. 60 mm +100 mm Fig. 4.6 Prestressed Beam with Unsymmetrical I-Section Supporting Live Loads