What must be done to column vertical bars to prevent buckling under compression?

What must be done to column vertical bars to prevent buckling under compression?

• A. Restrained
• B. Left free
• C. Bent to shape
• D. Painted

Answer: (A)

When a column or vertical reinforcement is loaded in compression, it tends to buckle if it can move sideways. Providing lateral restraint along the length of the bar—by tying, bracing, or encasing it to form a stable column—raises the load at which buckling occurs and keeps the member from bowing. That’s why the vertical bars must be restrained to prevent buckling under compression. Leaving them free would allow sideways deflection and failure. Simply bending them to shape doesn’t address the need for continuous lateral support. Painting has no effect on their structural stiffness or stability.

When a column or vertical reinforcement is loaded in compression, it tends to buckle if it can move sideways. Providing lateral restraint along the length of the bar—by tying, bracing, or encasing it to form a stable column—raises the load at which buckling occurs and keeps the member from bowing. That’s why the vertical bars must be restrained to prevent buckling under compression.

Leaving them free would allow sideways deflection and failure. Simply bending them to shape doesn’t address the need for continuous lateral support. Painting has no effect on their structural stiffness or stability.