A simple beam is defined as a beam supported at its ends with no moments at the supports.

A simple beam is defined as a beam supported at its ends with no moments at the supports.

• A. Cantilever beam
• B. Simple beam
• C. Continuous beam
• D. Fixed-ended beam

Answer: (B)

The defining idea here is how support conditions control bending moments. A beam that is simply supported at its ends is free to rotate at those supports, so the bending moment at each end is zero. This is why it carries only vertical reactions and has zero moment at the supports, with the moment peaking somewhere in the interior (for example, under a uniform load the maximum moment occurs at midspan). In contrast, a cantilever has a fixed end that resists rotation, so a nonzero moment exists at that end. A fixed-ended beam has ends that resist rotation as well, producing moments at the ends. A continuous beam spans over multiple supports and develops moments at internal supports due to the continuity of the member. So the statement describes a simply supported, or simple, beam.

The defining idea here is how support conditions control bending moments. A beam that is simply supported at its ends is free to rotate at those supports, so the bending moment at each end is zero. This is why it carries only vertical reactions and has zero moment at the supports, with the moment peaking somewhere in the interior (for example, under a uniform load the maximum moment occurs at midspan).

In contrast, a cantilever has a fixed end that resists rotation, so a nonzero moment exists at that end. A fixed-ended beam has ends that resist rotation as well, producing moments at the ends. A continuous beam spans over multiple supports and develops moments at internal supports due to the continuity of the member. So the statement describes a simply supported, or simple, beam.