Which term denotes the bending moment that causes tension in the top fiber and compression in the bottom fiber of a beam?

• A. Negative Moment
• B. Positive Moment
• C. Sagging Moment
• D. Torsional Moment

Answer: (A)

When a beam bends, the sign of the bending moment tells you which side of the section is in tension. If the top fibers are in tension and the bottom fibers are in compression, the curvature is concave down, known as hogging. This corresponds to a negative bending moment under the usual sign convention. So the term describing this condition is negative moment (also called hogging moment). Positive or sagging moments produce the opposite stress pattern (top in compression, bottom in tension), and torsional moment relates to twisting, not bending.