GATE 2019 CE (CE1) – Question 43
The T-section shown changes from fully elastic to fully plastic. By how much does the neutral-axis depth measured from the top decrease? The flange is 60 mm × 5 mm and the web below it 5 mm × 60 mm.
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Correct answer: (C) 13.75 mm
Explanation
Flange and web each have area 300 mm². Their centroids lie 2.5 mm and 35 mm from the top. Elastic neutral-axis depth is $[300(2.5)+300(35)]/600=18.75$ mm. Plastic neutral axis divides the total area equally, so it lies at the flange bottom, 5 mm from the top. Decrease is **18.75 − 5 = 13.75 mm, C**.