Which feature refers to pre-stressed tendons within concrete that may fail when exposed to fire, affecting the structural strength?

• A. Wood Construction
• B. Cast in Place
• C. Tensioned framework within concrete
• D. Type I - Fire Resistive

Answer: (C)

Pre-stressed tendons inside concrete are designed to keep the member in compression, which greatly boosts its ability to resist bending and cracking. When such a member is exposed to fire, the heat weakens the steel strands and reduces the prestressing force. As the tendons lose tension, the concrete loses part of its compressive advantage, causing cracks to open more readily, stiffness to drop, and the overall structural strength to diminish. This makes the feature referring to a tensioned framework within concrete the best answer, because it directly relates to how prestressing affects fire performance and strength.

The other descriptions don’t address this internal mechanism: wood construction implies a different material system; cast-in-place describes the method rather than the presence of prestressed tendons; a Type I fire-resistive rating speaks to overall fire resistance, not to the behavior of prestressed tendons under heat.