GATE 2021 CE (CE1) – Question 48
The illustrated symmetric truss has all member lengths L=2 m. Sloping and bottom members have area A=10⁴ mm², while QR has area 2A. A downward force F=10√3 kN acts at T. Find compressive stress in QR in kN/m² (integer).
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Correct answer: 490 to 510
Explanation
The equilateral triangular panels have 60° diagonals. Each support reaction is F/2=5√3 kN; joint equilibrium gives 10 kN compression in an outer diagonal. At Q, the two diagonal horizontal components sum to 10 kN, so QR carries 10 kN compression. Its area is 2A=0.02 m², giving **500 kN/m²**. The supplied second moment is unnecessary for axial stress.