The members EJ and IJ of steel truss shown in the figure below are subjected to a temperature rise of 30° C. The coefficient of thermal expansion of steel is 0.000012 per °C per unit length. The displacement (mm) of joint E relative to joint H along the direction HE of the truss, is

ANS:C - 0.764

Stresses due to thermal expansion = Esteel *α * T = 2.10*10^5 * 0.000012 * 30 = 75.6 Mpa.

Displacement between two point E, H is diagonal JG which has length = 4.24 m.
Displacement = F*L/AE = stresses * (L/E) = 75.60 MPA * 4240 / 2.1 * 10^5 = 1.5264 mm in Diagonal which expansion tow joint E,H 1.52/2 = 0.763 mm.