Answer Happy

A flat roof spanning 4.25 m is to be designed using C24 timber joists at 600 mm centres as shown in Figure Q1. Loads from the proposed roof construction are: Asphalt 20 mm thick : 0.45 kN/m2 Insulation : 0.10 kN/m2 Roof decking boards : 0.30 kN/m2 Timber firrings : 0.01 kN/m2 Suspended tile ceiling: 0.15 kN/m2 The building is at an elevation of 50 m above sea level and the roof is to be designed for a wind load of 0.6 kN/m². The height available from the supports to the underside of the decking is 150 mm, and the ends of the joist may have to be notched to fit this dimension Assuming that the roof decking provides full lateral restraint to the joist choose a suitable size for the joist timbers. Tasks required: (a) Loading analysis (5 marks) (b) Timber properties and parameters for design (5 marks) (c) Bending capacity check (ULS) (5 marks) (d) Shear capacity check (ULS) (5 marks) (e) Bearing capacity check (ULS) (5 marks) (1) Deflection limit check (SLS) (5 marks) [Total: 30 marks) 100 mm wide bearings Joists at 600 mm centres Joist span 4.25 m Figure Q1