Effect of fire on some mechanical properties and behavior of reinforced concrete rigid beams

الملخص EN

In this study, some mechanical properties and deflection behavior of rectangular reinforced concrete rigid beams under the effect of fire flame exposure is presented.

The properties investigated were compressive strength and two non-destructive tests, the ultrasonic pulse velocity and rebound number.

The concrete specimens and beams were subjected to fire flame temperatures ranging from (23 – 600 C° ) at different ages of 30, 60 and 90 days , two temperature levels of 400 C° and 600 Cº were chosen with two different exposure duration of 0.5 and 1.0 hour.

The rectangular reinforced concrete beam (2250 × 375 × 375 mm) (length * width * height respectively) were cast and subjected to fire.

Based on the results of this work, the properties investigated of concrete were very sensitive to fire flame exposure.

The beams were deteriorated when the fire flame intensity was increased, for all ages and periods of exposure.

The residual compressive strength ranged between (68-84 %) at 400 C°.

and (52-63%) at 600 C°.

Cooling by water caused further reduction in the compressive strength, ultrasonic pulse velocity and rebound number, compared with specimens cooled in air.

The percentage reduction in compressive strength, ultrasonic pulse velocity and rebound number of the specimens cooled in water were (2-10 %) more than the specimens cooled in air.

Also, it was found that the temperature distribution through the thickness of beam is similar for all beams, which have the same thickness and exposure period to fire flame.