Which roof type is described as being tensioned with a bottom metal cord?

Which roof type is described as being tensioned with a bottom metal cord?

• A. Panelized Arch
• B. Tied Arch Roofs
• C. Metal Arch Roof
• D. Lightweight Construction

Answer: (B)

A roof that uses a bottom cord in tension is a tied arch roof. In an arch, the shape naturally produces horizontal thrust at the supports. If you try to carry that thrust only with the abutments, you’d need very heavy walls. A tied arch solves this by putting a bottom chord (often a metal tie) across the springline that runs in tension. This tie pulls the arch ends inward, resisting the outward push and allowing the arch to act mainly in compression while the bottom cord handles the thrust in tension. The result is a roof that remains stable without massive supporting walls. The other options don’t describe this specific arrangement. A panelized arch is about assembling the arch from panels, but doesn’t necessarily involve a bottom tension cord. A metal arch roof refers to the material/shape, not the presence of a tying member. Lightweight construction is a general category that doesn’t specify the tensioned bottom cord concept.

A roof that uses a bottom cord in tension is a tied arch roof. In an arch, the shape naturally produces horizontal thrust at the supports. If you try to carry that thrust only with the abutments, you’d need very heavy walls. A tied arch solves this by putting a bottom chord (often a metal tie) across the springline that runs in tension. This tie pulls the arch ends inward, resisting the outward push and allowing the arch to act mainly in compression while the bottom cord handles the thrust in tension. The result is a roof that remains stable without massive supporting walls.

The other options don’t describe this specific arrangement. A panelized arch is about assembling the arch from panels, but doesn’t necessarily involve a bottom tension cord. A metal arch roof refers to the material/shape, not the presence of a tying member. Lightweight construction is a general category that doesn’t specify the tensioned bottom cord concept.