GATE 2024 CE (CE2) – Question 18
For a thin-walled section shown in the figure, points P, Q, and R are located on the major bending axis X−X of the section. Point Q is located on the web whereas point S is located at the intersection of the web and the top flange of the section.
[Figure: an I-section with a vertical web and equal top and bottom flanges. In each flange the part to the left of the web is 6 cm long and the part to the right is 3 cm long. P is on the axis X-X to the left of the web, Q is on the web and R is on the axis to the right. S is at the web-top flange junction.]
Qualitatively, the shear center of the section lies at
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Correct answer: (A) P
Explanation
The section is symmetric about the horizontal axis X-X but not about the web, so the shear centre is on X-X. The two flanges are longer on the left of the web (6 cm) than on the right (3 cm). A load through the shear centre must produce no twist: the flange shear forces, which are larger on the longer side, create a moment about the web, and the shear centre moves toward the longer flange side, to the left of the web, away from the centroid at the web. So it is at P.