Anjali Engineering

Effect of Fire on Building Structures
-Concrete:
Exposure to high temperature causes loss of moisture, leading to cracking, spalling, and reduction in compressive strength.

At extreme temperatures, chemical changes (such as decomposition of calcium hydroxide and C-S-H gel) further weaken the concrete.

-Steel Reinforcement:
Prolonged heating results in thermal expansion (elongation) and significant reduction in tensile strength and yield strength.
At around 500–600 °C, reinforcing steel loses much of its strength and stiffness.

-Final Consequences:
a) Overall load-bearing capacity decreases significantly.
b) Structural vulnerability to earthquakes increases, as residual strength and ductility are compromised.

-Recommendations:
I) Engineering inspection of all fire-affected buildings before starting any interior repair/finishing works.
II) Retrofitting and strengthening measures (such as jacketing, fiber-reinforced polymers, or replacement of damaged elements) must be carried out to restore safety and performance.