Which system uses pre-stressed tendons within concrete that may fail when exposed to fire, causing loss of compression or torsion resistance?

• A. Tensioned framework within concrete
• B. Concrete
• C. Spalling
• D. Pre-Cast

Answer: (A)

Prestressed concrete is the system that uses tendons embedded in concrete and kept under tension to put the member into compression. When exposed to fire, the steel tendons can lose strength and relax, and the bond with the concrete can weaken, leading to a reduction or loss of the initial compressive force. Without that pre-compressed state, the concrete’s ability to resist tensile stresses, bending, and torsion drops, making the member much more vulnerable to cracking and failure. The description “tensioned framework within concrete” captures this prestressed setup. The other options don’t describe a system with pre-tensioned tendons: plain concrete lacks prestressing, spalling is a fire-related damage phenomenon, and pre-cast is a manufacturing method, not the prestressed system itself.