In which of the following cases is the compression flange most su
A. An I-section supporting a roof slab with shear connection
B. Purlin of a roof supporting dead and live loads
C. Encased beam
D. A steel I-section supporting a point load when acting as a cantilever
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Right Answer is: D
SOLUTION
Concept:
The beam is not get failed in bending due to which flange start buckle in the lateral direction this is known as the lateral buckling, As the web and the tension flange is stable they try to resist the buckling of the beam and due to which the a eccentricity is produce between the shear center and the applied load resulted due to which a couple is get generated which produce the torque due to which warping take place. This complete phenomenon is known as lateral torsional buckling.
This occurs because compression flange is not laterally restrained so, it can be prevented if adequate restraints are provided in the plane of compression flange. This can be done in following ways:
1. An I-section supporting a roof slab with shear connection.
2. Purlin of a roof supporting dead and live loads are laterally restraints due t o presence of sag rod.
3. Steel Beam is encased in concrete.