Design a marine crane for a container ship. The heaviest container for the crane to lift is 80 tons. The dimension requirement of the crane structure is given below. The whole structure is composed of four steel members connected to each other by pins. The density, Young's modulus and yielding stress of steel are respectively p = 7860 kg/m3, E = 200 GPa, 6Y = 250 MPa. Determine the size and cross section of each member to avoid buckling failure and yielding. Moreover, you need to reduce the product cost by using as few materials as possible, i.e. lightest crane. You also need to maintain the rigid. Propose two designs %3D %3D 15m K- 50m/