2. The members of the structures shown below are made of plain concrete. The compressive strength of concrete is 4000 psi. Calculate the maximum P that can be carried by these structures. (Don't use load and resistance factors.) (a-18.2 k, b-4.5 k, c-3.16 k) 10' c) P 10' TRO Cross-section of members: 6 x 6 in. 6 ft Diameter: 8 in. 10' T = P.1 ft b) 6 ft P 6 ft TO P/2 6 ft Cross-section of members: 8 x 16 in.