고체역학 (Beer) — Stress and Strain—Axial Loading: Problem 2.54

2.54 The steel rails of a railroad track (\(E_s = 200 \text{ GPa}\), \(\alpha_s = 11.7 \times 10^{-6}/^{\circ}\text{C}\)) were laid at a temperature of \(6^{\circ}\text{C}\). Determine the normal stress in the rails when the temperature reaches \(48^{\circ}\text{C}\), assuming that the rails (a) are welded to form a continuous track, (b) are 10 m long with 3-mm gaps between them.