Three bars shown in the below figure are made of steel, brass and copper from left to right. The bars are connected to each other and fixed at both ends when the temperature is T1 = 12 ?C. Determine the force exerted on the rigid supports at both ends when the temperature becomes T2=28 ?C.

Steel Est = 200 GPa ast = 12(106)/C Brass Ebr = 100 GPa abr 21(10-6)/C Ast = 250 mm Abr = 300 mm- 500 mm -200 mm- Copper Ecu = 120 GPa acu = 17(10-6)/C Acu = 615 mm2 100 mm