Definition of a fixed beam: a beam that is rigidly fixed at both of its ends (no rotation and no translation at supports).
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Aone
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Bboth
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Cneither end (simply supported)
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Donly one end but guided at the other
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Evaries with loading
Answer
Correct Answer: both
Explanation
Introduction / Context:Support conditions dictate bending moments and deflections in beams. A fixed (built-in) support restrains both rotation and translation, producing end moments even under uniform loading.
Given Data / Assumptions:
- Linear elastic, prismatic beam.
- Ideal fixed ends with zero slope and zero deflection at supports.
- Transverse loading.
Concept / Approach:A fixed beam has both ends built-in. This contrasts with simply supported beams (pinned/roller) where rotations are free, and cantilevers where one end is fixed and the other is free.
Step-by-Step Solution:
Identify end conditions: fixity at both ends ⇒ redundant end moments develop.Use fixed-end moment formulas for standard loads to analyze.Deflection is smaller than an equivalent simply supported beam due to added restraint.Verification / Alternative check:Compare slopes: in a fixed beam, slope at ends is zero; in simply supported beam, slope is generally non-zero.
Why Other Options Are Wrong:One fixed end only defines a cantilever.Support type does not vary with loading for a given structural detail.
Common Pitfalls:Confusing fixed with guided supports; assuming zero moment at ends when fixity exists.
Final Answer:
both