고체역학 (Beer) — Torsion: Problem 3.138

3.138 An 8-ft-long steel member with a W8 x 31 cross section is subjected to a 5-kip·in. torque. The properties of the rolled-steel section are given in Appendix E. Knowing that \(G = 11.2 \times 10^6\) psi, determine (a) the maximum shearing stress along line a-a, (b) the maximum shearing stress along line b-b, (c) the angle of twist. (See hint of Prob. 3.137.)