(a) A tied scaffold structure measures 9 m (H) and 9.1 m (W) shown in Fig. B2 supports a uniformly distributed load of 7 kN/m. Six horizontal forces ranging from 5 to 7 kN are acting simultaneously at each lift height as shown. Determine the overturning moment acting on the scaffold structure and calculate all leg loads without the stabilizing force provided by the tie provided. (10 marks) (b) Identify if any vertical member(s) are under tension. Use Table in Data Page 2 & 3 to check the axial loading capacity of the verticals against buckling under the maximum load calculated in (a). Assume the tubes and couplers comply with BS1139 and of "Used" condition. (5 marks) (c) If a tie is provided to stabilize the scaffold structure against lateral stability, determine the minimum tension required in the tie to keep the structure having a minimum factor of safety of 2.0 against overturning under the given horizontal loads. Uniformly Distributed Load 7 kN/m 7 kN 7 kN 5 kN 5 kN 5 kN Tie Ground Level 4.5 m 7 bays each 1.3 m wide Fig. B2 Cross Section of Wall Form (Not to Scale) 6 lifts each 1.5 m high Data Page 3 Maximum Permissible Compressive Loads in Steel Scaffolds (which are manufactured in accordance with BS 1139: Section 1.1:1990 with a yield stress of 225 N/mm) Effective Length Permissible Axial Compressive Load (kN) (mm) As "New" Tubes As "Used" Tubes 250 76.4 70.0 500 74.5 63.3 750 70.7 60.1 1000 64.3 54.7 1250 55.3 47.0 1500 45.3 38.5 1750 36.4 30.9 2000 29.3 24.9 2250 23.9 20.3 2500 19.8 16.8 2750 16.6 14.1 3000 14.1 11.9 3250 12.1 10.3 3500 10.5 8.9 3750 9.2 7.8 4000 8.1 6.9 4250 7.2 6.1 4500 6.4 5.5 4750 5.8 4.9 5000 5.2 4.4 5250 4.7 4.0 5500 4.3 3.7 5750 4.0 3.4 6000 3.6 3.1 8000 1.3 1.1 - End of Paper -