What Does ACI 318 Require for Structural Concrete Design?

ACI 318 requires engineers to design reinforced concrete members for factored load combinations using strength design, satisfy serviceability limits on deflection and cracking, meet durability requirements through exposure classes, and detail reinforcement — development, splices, hooks, spacing, cover — so the as-built member matches the design assumptions. Foundations, slabs, beams, columns, walls, and diaphragms each have dedicated chapters, and construction documents must show the design details the code's assumptions rest on. For owners, the practical takeaway is that concrete design doesn't end at member sizes. The mix design, the cover dimensions, the bar detailing, and the inspection of placement all carry code requirements, and the special inspection program under IBC Chapter 17 verifies them in the field. A complete concrete package addresses design, durability, detailing, and field verification together.

Detailing is the number-one source of plan-check corrections on concrete projects. Development lengths that don't fit in the joint, bars spaced tighter than concrete can flow through, missing confinement at frame joints — these are drawing problems, not analysis problems, and they cost weeks when caught late. We detail for constructability from the start: if the rebar can't physically be placed and consolidated, the design is wrong regardless of what the math says. Durability is the quiet second trap. A structural design that's perfect on strength but specifies the wrong exposure class delivers concrete that deteriorates in a decade — scaling, spalling, corroded reinforcement. And Chapter 18 seismic detailing is the third: special moment frame joints are congested by design, and the congestion has to be drawn, reviewed, and buildable. Flagging all three at kickoff is how we keep concrete projects out of correction cycles.

Cover these items in the structural documents and the concrete scope stays out of trouble.

• Confirm the Seismic Design Category early to know whether Chapter 18 detailing applies
• Assign exposure classes for every concrete element and carry them into the specifications
• Detail development lengths, splices, hooks, and confinement so they fit and can be built
• Show concrete cover dimensions that match the exposure class, not just minimums
• Coordinate the concrete mix submittal review with the specified strength and durability
• Align special inspection items for concrete with the statement of special inspections