Ultimate strength behavior of prestressed concrete beams at cryogenic temperatures
This paper investigates the ultimate strength behaviours of the unbonded prestressed concrete (PC) beams at cryogenic temperatures that aims to promote the applications of PC structures in cryogenic environments. Nineteen unbonded PC beams with different tension control stresses (0.4, 0.6, 0.75fptk) were tested at 20, 40, 70 and 100 degC. The structural performances of the unbonded prestressed reinforced concrete (RC) beams under cryogenic temperature were reported that included general load deflection behaviours, ultimate resistances, and failure modes. The test results indicated that at cryogenic temperatures, the plane section assumption for the prestressed RC beams under bending still worked, and the appearance of cracks can still be delayed by prestressing. The resistances corresponding to crack initiation, the yield of the non prestressed tensile reinforcements and the ultimate failure of the beams all increased linearly with the decrease of the temperature. The stiffness of specimens also increased as the temperature dropped. Analytical methods for predicting the resistance corresponding to the crack initiation and the ultimate resistance at low temperatures were developed and compared with the test results.