Constraint Relief Gap is designed to provide localized relief to what?

• A. A gap for water drainage
• B. A gap to reduce weight
• C. A gap to provide localized relief to tri-axially restrained details
• D. A gap for thermal expansion in joints

Answer: (C)

The idea behind a constraint relief gap is to give a small amount of freedom where a component is fixed in more than one direction. When a detail is restrained in three axes, any temperature change, load, or shrinkage can generate internal stresses because the parts can’t move where they are tightly held. A constraint relief gap creates just enough clearance to let those pieces move slightly relative to one another, in at least one direction, so the restraint isn’t as severe. This helps prevent binding, excessive stresses, or cracking at tri-axially restrained details.

This isn’t about drainage, reducing weight, or a general thermal expansion gap in joints. Those serve different purposes: drainage gaps handle water, weight isn’t saved by a gap, and typical joint expansion gaps address deck or member thermal expansion, not localized restraint in tri-axial connections.