Difficulty: Easy
Correct Answer: 12 t
Explanation:
Introduction / Context:The outstand (projecting width) of a plate stiffener behaving as a compression element must be controlled to prevent local buckling. Design rules therefore limit the ratio of outstand to thickness for flats used as stiffeners in plate girders and similar built-up steel members.
Given Data / Assumptions:
Concept / Approach:Local plate buckling capacity improves with thicker plates and smaller outstands. Traditional steel design rules specify a simple limit—often expressed as a multiple of t—to keep the slenderness of the outstanding element within safe bounds without detailed plate-buckling checks.
Step-by-Step Solution:
Identify controlling limit for flat stiffeners in compression.Apply the customary outstand rule: maximum ≈ 12 t.Select '12 t' as the correct limit from the options.Verification / Alternative check:
This value aligns with long-used fabrication handbooks to preclude early local buckling and ensure effective stiffener action.Why Other Options Are Wrong:
6 t / 8 t / 10 t: more restrictive than necessary for standard stiffener design.15 t: too permissive; risks local buckling before the stiffener can fully develop capacity.Common Pitfalls:
Confusing outstand limits for flange plates with those for stiffener flats; the controlling multiples may differ.Final Answer:
12 t
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