Lacing bars — minimum width rule in riveted/bolted construction In riveted/bolted steel construction, the minimum width of a lacing bar is generally taken as:

Difficulty: Easy

Correct Answer: Thrice the nominal rivet diameter

Explanation:


Introduction / Context:
Lacing bars connect components of built-up compression members and must be wide enough for practical drilling/bolting and to avoid local bearing failures at end connections. Codes give a simple minimum width rule tied to fastener size.


Given Data / Assumptions:

  • Lacing is riveted or bolted (not welded).
  • Nominal diameter d of end rivet/bolt is known.
  • We need the minimum bar width requirement.


Concept / Approach:
A widely used rule states: minimum width b_min ≥ 3d, where d is the nominal diameter of the end connector. This ensures adequate edge distance, hole clearance, and bearing area without resorting to overly thick plates. Rounding to stock sizes is permitted, but the rule itself is 3d.


Step-by-Step Solution:
Step 1: Identify connector diameter d.Step 2: Compute b_min = 3 × d.Step 3: Select nearest available plate width ≥ b_min, keeping standard rounding separate from the rule.


Verification / Alternative check:
IS-style summaries and training problems consistently cite the 3d rule for riveted/bolted lacing bars.


Why Other Options Are Wrong:
Equal to d or 2d: Too narrow; risks poor edge distances and bearing.
Maximum of the above rounded: Mis-states the rule; rounding does not replace the 3d minimum.
4d: Overly conservative as a blanket minimum; not required.


Common Pitfalls:

  • Confusing bar width (3d) with thickness rules (l/40 or l/60).
  • Ignoring edge distance and hole spacing checks alongside the width rule.


Final Answer:
Thrice the nominal rivet diameter

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