A steel two hinged circular arch rib has a span of 30m and a rise of…

Question

A steel two hinged circular arch rib has a span of 30m and a rise of 3m. The rib section is uniform throughout with an overall depth of 0.7m. Neglecting all effects except those due to bending, find from first principles, the bending stress at the crown due to a temperature change of 30K. Take $E = 2 \times 10^5 \text{ N/mm}^2$ and $\alpha = 11 \times 10^{-8} \text{ per } \text{K}$.