Horizontal restraint can stiffen a column by providing horizontal supports or restraints or stretchers. Which term describes this?

• A. Horizontal restraint
• B. Diaphragm reaction
• C. Vertical expansion
• D. Slab on grade

Answer: (A)

The concept being tested is how a column is stiffened against lateral movement by tying it into horizontal supports. The term that describes this exact idea is horizontal restraint. It refers to adding horizontal members or connections that limit sway and increase stiffness of the column by restraining it laterally, often through links, braces, or connections to a floor diaphragm or other horizontal elements.

Diaphragm reaction is about the forces generated and transmitted by a floor diaphragm as it distributes lateral loads to the vertical resisting elements—not the restraint mechanism itself. Vertical expansion isn’t a standard term for this concept, and slab on grade describes a type of floor, not the restraint action affecting a column.