BEHAVIOUR OF HIGH STRENGTH REINFORCED CONCRETE BEAMS EXPOSED TO DIRECT FIRE

The performance of high strength reinforced concrete beams at elevated temperatures is critical especially in case of the evaluation of building behavior in fire conditions. Many researches reported and explained the fire effect on the mechanical properties of the normal concrete and reinforcement. As the need of high strength concrete arises with increasing demands for an unproved efficiency and reduced concrete construction cost, the effect of fire on high strength concrete beams were studied in this research. In this research twelve high strength concrete beams were casted to study the factors affecting this behavior. The factors taking into consideration in this research were the thickness of concrete cover and time exposure to fire. The cover thicknesses taking in this research were 1.5 cm, 3.0 cm and 4.5 cm. Time exposures to fire taken into account in this research were 0, 30 minutes, 60 minutes and 120 minutes. The temperature inside the oven used was 650°C. The tested beams were exposed to direct flame for the test time, beams were left to cool gradually. The temperature inside the oven was raised till 650°C in 3 minutes. The results of testing were illustrated in charts for load - deflection relationship, load maximum - tensile strains, load - maximum compressive strains. Deformation shapes and the modes of failures were presented. Conclusions according to the test results were drawn.

• INTRODUCTION

• EXPERIMENTAL PROGRAM

• ANALYSIS AND TEST RESULTS

• CONCLUSIONS

• REFERENCES