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GATE 2021 CE (CE1) – Question 32

Structural Analysis · Deflections of determinate beams, frames and trusses · 1 mark · Numerical answer

Square truss EFGH has side L=3 m, pin at E, roller at H and diagonal FH. All bars have axial rigidity R=500×10³ kN. Opposite outward forces P=150 kN act horizontally at F and G. Find horizontal displacement magnitude of G in mm, to one decimal.

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Correct answer: .9 to .9

Explanation

Joint equilibrium makes FG the only bar carrying force under the two equal and opposite top loads. All other members have zero axial deformation and F has zero horizontal displacement. Therefore $u_G=PL/R=150(3)/500000=0.0009$ m, or **0.9 mm**.