What Are Structural Drawings?

IBC Section 1603 requires the construction documents to show design loads and criteria: floor and roof live loads, ground snow load, wind design data such as the ultimate design wind speed and exposure category, the seismic design category and seismic force-resisting system, and soil bearing values. The structural general notes are where those live.

The notes also set material grades, such as ASTM A992 for wide-flange steel and concrete strength by element, and they carry or reference the statement of special inspections required by IBC Chapter 17. An inspector with a question about a material grade often finds the answer there before reaching the specification.

Foundations come first, then each framing level from the bottom up, then the roof. Elevations of braced frames or shear walls follow, then sections and details, then schedules. That order mirrors the construction sequence, so the field can find the next sheet they need.

Typical details carry a lot of weight. A typical beam-to-column connection or typical slab edge detail applies everywhere it is not specifically overridden, so a missing exception on the plan means the typical governs.

Gravity framing carries weight down. The lateral system carries wind and seismic loads to the foundation through braced frames, moment frames, or shear walls, and it is documented with frame elevations, shear wall schedules, and collector and drag strut details.

An architectural change that cuts an opening in a shear wall or moves a braced frame bay changes the lateral design, so it needs the structural engineer and not only a drafting update. Penetrations through shear walls and frame bays are a routine coordination check for that reason.

Steel connections, steel joists, metal deck, cold-formed steel framing, precast concrete, stairs and railings, and post-tensioning are often delegated to engineers working for the fabricator or subcontractor. The structural drawings set the criteria and loads, and the delegated design comes back as a stamped submittal.

The engineer of record reviews delegated submittals for conformance with the design intent and the criteria given. Clear criteria on the drawings, such as reactions, deflection limits, and loads from hung equipment, keep that review short and the resubmittals few.

Slab edges, depressions, openings, and embeds come from other drawings: the architect's floor plans and wall sections, the mechanical shafts, the plumbing floor drains, the elevator pit. A structural set issued on last month's architectural background shows those items in last month's locations.

Equipment weights and locations from the MEP schedules, especially rooftop units, generators, and cooling towers, set support framing and housekeeping pads. A heavier unit selected after the structural set is issued is a frequent source of bulletins.