Laced compression members — effective length of lacing bars Identify the correct definition(s) of the effective length for lacing bars in different connection types and patterns.

Introduction / Context:
Accurate effective length definitions for lacing bars are vital because slenderness checks, minimum thickness, and width rules depend on it. Different connection types (riveted/bolted versus welded) and lacing patterns (single versus double) alter the effective length used for detailing and stability checks.

Given Data / Assumptions:

• Single and double lacing in riveted/bolted construction are considered.
• Welded lacing uses effective weld lengths at each end.
• Standard detailing reduction factor of about 0.7 applies for double/welded cases.

Concept / Approach:
In single lacing, the bar spans the clear distance between inner end connectors; that is its effective length. In double lacing, each diagonal system shares shear, so a reduced factor (≈0.7) is used. For welded lacing, the welds provide end fixity over their effective lengths, so the clear distance between inner ends of effective welds defines the bar's effective length, with a similar 0.7 factor in many detailing guides.

Step-by-Step Solution:
Step 1: State single lacing effective length: distance between inner end connectors.Step 2: Apply 0.7 reduction for double lacing (riveted/bolted).Step 3: For welded lacing, use distance between inner ends of effective weld lengths; a 0.7 factor is often adopted similarly.Step 4: Hence, all listed statements are correct.

Verification / Alternative check:
Classic steel design Q&A and summaries reproduce these definitions consistently, reflecting long-standing shop practice and codal commentary.

Why Other Options Are Wrong:
Any single item alone omits the others; the comprehensive choice is 'All the above'.

Common Pitfalls:

• Using the panel length instead of connector-to-connector (or weld-to-weld) gauge.
• Forgetting the 0.7 factor for double or welded lacing when sizing thickness.

Final Answer:
All the above