Rigid bar ABC is supported by two identical solid bronze [oy = 331 MPa; E = 105 GPa; a = 22.0 x 10-6/°C] rods and a single solid steel [oy = 250 MPa; E = 200 GPa; a = 11.7x10-6/°C] rod. Bronze rods (1) each have diameters of d₁= 16 mm and lengths of L₁ = 3.1 m. Steel rod (2) has a length of L₂ = 4.2 m. (a) Calculate the diameter d2 required for steel rod (2) so that the deflection of joint B is zero for any change in temperature. (b) Using the value of d2 determined in part (a), determine the maximum temperature decrease that is allowable for this assembly if a factor of safety of 2.5 is specified for the normal stress in each rod. Since the temperature is decreasing, the answer should be negative. (1) (1) L₁ A C Answer: (a) d₂= (b) ΔT = i Mi (2) B a L2 mm °℃