Beam types – identification by support conditions A beam that is fixed at one end and free at the other is called:
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ASimply supported beam
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BFixed beam
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COverhanging beam
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DCantilever beam
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EContinuous beam
Answer
Correct Answer: Cantilever beam
Explanation
Introduction / Context:Structural analysis begins with recognizing beam support conditions, since bending moments, shear forces, slopes, and deflections depend on how the beam is restrained.
Given Data / Assumptions:
- One end built-in (encastré: zero slope and zero deflection).
- Other end free (no support reactions).
- Linearly elastic, prismatic beam.
Concept / Approach:Standard beam types include simply supported (pin–roller), fixed beam (both ends fixed), cantilever (one end fixed, other free), overhanging (span extends beyond a support), and continuous (more than two supports). Correct naming ensures correct use of formulas.
Step-by-Step Identification:Check restraints: fixed at one end implies encastré support.Opposite end is free → no restraint → classic cantilever configuration.
Verification / Alternative check:Moment and slope diagrams for standard loads (point load at free end, uniform load, etc.) match cantilever beam solutions: maximum moment at the fixed end, zero at the free end.
Why Other Options Are Wrong:Simply supported has rotation allowed at both ends; fixed beam is fixed at both ends; overhanging beams have spans extending beyond supports; continuous beams have three or more supports.
Common Pitfalls:Confusing cantilever with a propped cantilever (one end fixed, one end simply supported) or with an overhang case.
Final Answer:Cantilever beam