Slenderness control under load reversal: A tension member that may be subjected to stress reversal due to wind (i.e., may experience compression at times) should have its slenderness ratio limited to which maximum value?
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A180
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B200
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C250
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D300
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E350
Answer
Correct Answer: 180
Explanation
Introduction / Context:Tension members designed primarily for tension can sometimes experience compression under wind or seismic load combinations. Codes place a stricter slenderness limit in such cases to avoid excessive flexural buckling susceptibility.
Given Data / Assumptions:
- Member is usually in tension but may see compression due to load reversal.
- Slenderness ratio is L/r (effective length over radius of gyration).
Concept / Approach:Where reversal of stress is possible, the member must satisfy not only tensile limit states but also the serviceability and stability requirements applicable to compression. A commonly used upper limit for such “tension members liable to reversal” is about 180 to provide adequate stiffness against buckling in compression.
Step-by-Step Solution:Recognize potential compression under wind.Adopt conservative slenderness limit to control buckling risk.Select 180 as the maximum recommended value.
Verification / Alternative check:Historic working stress provisions and many exam references cite 180 as the limit for tension members subject to reversal; pure tension members may be allowed higher limits for appearance or vibration only.
Why Other Options Are Wrong:
- 200–350: too slender, offering inadequate compression stability under reversal.
Common Pitfalls:
- Treating potentially reversible members as pure tension without checking buckling.
Final Answer:180