The two-bay portal frame shown can be subjected to either of the following load systems: OA horizontal load of 2W at B and a vertical load of 3W at the

centre of span CD (b) A horizontal load of 2W at B and a vertical load of 3W at the centre of spanВС. If the plastic moment of the beams is 1.5 Mp and that of the columns M, calculate the minimum value of W which would cause collapse of the structure.Sketch the bending moment diagram of the structure at collapse indicating significant values.