Problem 1 (25 points) In the configuration shown, all members are at a uniform temperature and ABCD is vertical. Then the horizontal bars are subjected to different temperature changes: AT1= -50 K for EB and AT2=75 K for FC. The bars EB and FC have the same length L = 1.5 m, thermal expansion coefficient a = 12 x 10-6/K, cross-sectional area = 50 mm² and Young's modulus E = 200 GPa. Assuming that the vertical bar ABCD is rigid, find the displacement at point D and the forces in bars EB and FC. The length of the rigid bar ABCD is 3 m.

Fig: 1