Rigid beam ABC is supported as shown in Figure P4.10. The pin connections at B, C, and D are each double shear connections, and the ultimate shear strength of the pin material is 620 MPa. Tie rod (1) has a yield strength of 340 MPa. A uniformly distributed load of w = 15 kN/m is applied to the beam as shown. A factor of safety of 3.0 is required for all components. Assume a = 700 mm, b = 900 mm, c =300 mm, and d = 650 mm. Determine: (a) the minimum diameter required for tie rod (1). (b) the minimum diameter required for the double shear pins at B and D. (c) the minimum diameter required for the double shear pin at C.