(Solved): A pin connected structure is loaded and supported as shown in the Figure below. Member \( A B \) is ...

A pin connected structure is loaded and supported as shown in the Figure below. Member \( A B \) is rigid; \( C \) is a steel rod \( \left(E=200 \mathrm{Gpa}, A=600 \mathrm{~mm}^{2}\right. \), and \( \alpha=11.9\left(10^{-6 / 0} \mathrm{C}\right) \); and \( D \) is aluminium post \( \left(E=73 \mathrm{Gpa}, A=2500 \mathrm{~mm}^{2}\right. \), and \( \alpha=22.5\left(10^{-6} / \mathrm{C}\right) \). Initially, bar \( A B \) is horizontal and rod \( C \) is vertical, and there is a \( 0.09-\mathrm{mm} \) gap between the horizontal arm and post \( D \). If a \( 35-\mathrm{kN} \) force \( P \) is applied to the right end of the bar \( A B \) and the temperature of the system is raised by \( \Delta T= \) \( 40^{\circ} \mathrm{C} \), determine 1. The normal stresses in the steel rod \( C \) and aluminium post \( D \). 2. The changes in length of the steel rod \( C \) and of the aluminium post \( D \).