Laced compression members: recommended inclination of lacing bars with the member axis Choose the suitable range for the angle that lacing bars make with the longitudinal axis.

Introduction:
Lacing systems connect components of a built-up compression member so that they act together. The angle of lacing bars ensures efficient shear transfer and stability while keeping bar forces reasonable.

Given Data / Assumptions:

• Built-up steel compression member with double lacing.
• Lacing bars primarily resist shear and provide lateral restraint.

Concept / Approach:

Design recommendations limit the inclination so that the axial and transverse components of bar forces are balanced. A commonly adopted range is 30° to 60° with the member axis.

Step-by-Step Solution:

Verification / Alternative check:

Check slenderness of lacing and node strength; connection design must also satisfy shear flow.

Why Other Options Are Wrong:

20°–50° admits too-flat lacing at the lower end; 40°–70° and 50°–80° skew the range upward; 15°–30° is excessively flat.

Common Pitfalls:

Ignoring out-of-plane buckling of lacing, inadequate end tie plates, and mismatched single vs double lacing assumptions.

Final Answer:

30° to 60°