Structural Drawing — In steel fabrication practice, shop drawing dimensions and calculations are not rounded to the nearest 1/2 inch; critical features (holes, edge distances, copes, plate sizes) are typically controlled to much finer tolerances (for example 1/16 in or 1/8 in), with larger erection tolerances handled separately in codes and tolerancing notes.

Introduction / Context:
Structural steel shop drawings communicate to the fabricator exactly how plates, beams, columns, angles, and connections must be cut, drilled, welded, and assembled. The claim that these drawings are “usually calculated to the nearest 1/2 inch” oversimplifies industry practice and would be unacceptably coarse for most fabrication tasks.

Given Data / Assumptions:

• Shop drawings detail hole sizes and locations, copes, clip angles, stiffeners, base plates, and weld symbols.
• Fabrication requires repeatable accuracy so parts fit in the field.
• Erection tolerances are distinct from shop tolerances.

Concept / Approach:
Critical dimensions in steel fabrication (for example, gage lines, edge distances, bolt-hole centers) are commonly held to 1/16 in or 1/8 in accuracy. Coarser allowances (like overall frame fit-up) are addressed through erection tolerances and field-adjustment provisions. Conflating these two leads to the mistaken idea that all shop values round to 1/2 in.

Step-by-Step Solution:
1) Identify typical shop-controlled features: hole centers, copes, and plate dimensions.2) Note their standard tolerances (often 1/16 in or 1/8 in), which are finer than 1/2 in.3) Separate shop tolerances from erection tolerances (column plumb, beam camber).4) Conclude that “nearest 1/2 inch” is not the usual basis for shop calculations.

Verification / Alternative check:
Review any example shop drawing: bolt gage and edge distances are typically specified to two decimal places (in) or to fractional 1/16 in, confirming finer precision than 1/2 in.

Why Other Options Are Wrong:
“Correct” ignores common fabrication tolerances; “Only hole diameters use 1/2 in rounding” is still too coarse; “1 in is the norm” is even less realistic; “Dimensions are always given without tolerances” is false since tolerance control is essential.

Common Pitfalls:
Mixing erection and shop tolerances; assuming coarse rounding is acceptable for bolt placement; omitting tolerance notes on drawings.

Final Answer:
Incorrect