Experimental research on mechanical properties of unbonded prestressed concrete simple beam at high temperature

The behaviors of the unbonded prestressed concrete simple beam were tested at high temperature. In the test the high temperature, the preloading and the designed prestressing degree of the beams were considered. The results show that at the beginning of heating, the prestress value of the beams increases within a small scale. Then, as the temperature continues increasing, the prestress value decreases. The deflection of the beams increases and the ultimate load decreases continuously with the rise of the temperature. Meanwhile, the higher the prestressing degree is, the greater the loss of prestress is when the beam destroyed, and the deflection of the beam is smaller with the prestressing degree increasing. The influence of preload on the beam is opposite to the prestressing degree. The ultimate load is decreased with the preload, which is more evident when the temperature is higher.