In seismic zones, the brace for risers longer than 3 feet is a which type?

In seismic zones, the brace for risers longer than 3 feet is a which type?

• A. 2 way brace
• B. 3 way brace
• C. 4 way sway brace
• D. No brace

Answer: (C)

In seismic zones, longer risers need restraint that stops movement in all directions. A four-way sway brace does this by bracing the riser on opposite sides with a cross member, forming a secure, box-like restraint. This setup prevents sway in both horizontal directions and helps control any vertical movement during an earthquake, which is why it’s required when the riser length exceeds three feet. A two-way brace only controls sway in a single plane, and a three-way brace leaves one direction only partially restrained, which isn’t sufficient for longer risers. No brace would leave the riser free to move and fail under seismic shaking.

In seismic zones, longer risers need restraint that stops movement in all directions. A four-way sway brace does this by bracing the riser on opposite sides with a cross member, forming a secure, box-like restraint. This setup prevents sway in both horizontal directions and helps control any vertical movement during an earthquake, which is why it’s required when the riser length exceeds three feet. A two-way brace only controls sway in a single plane, and a three-way brace leaves one direction only partially restrained, which isn’t sufficient for longer risers. No brace would leave the riser free to move and fail under seismic shaking.