| Unbonded partially prestressed concrete (UPC) is widely used in the structure such as bridge, industry workshop and ocean drilling platform. etc which endure repetitive load effect. At present foreign countries have progressed much study about static force properties of UPC beam,. But they still lack of the deep going study about fatigue properties of UPC beam, especially lack of the study about fatigue deformation of UPC beam and crack .We had the experiment of UPC beam of different pretressed strength and have studied deeply the development of fatigue deformation and how the crack come into being and expand under repeated load effect in this paper. This paper provides data and foundation of UPC structure fatigue deformation and crack checking computations. The following are the main contents of this paper:1 Based on 10 UPC experiment beams with different pre-stressed force, detailed research was emphasized on fatigue deformation and crack performance.2 According to experimental data, relation between average crack space, crack width, fatigue frequency and pre-stress value was studied. Then further studies on crack appearance and crack development mechanics was explored in detail. Inherent reason how fatigue frequency and pre-stress value affect fatigue crack was studied.3 According to experimental research, reinforced concrete crack width formula was amended with consideration in fatigue frequency and pre-stress value. Calculation data based on amended formula was compared to experimental data, concluding that the amended formula was feasible.4 Influencing factors on UPC beam deformation and residual deformation and deflection was summarized, and further research about the reasons of fatigue deflection.5 UPC beam fatigue deflection calculation formula was deduced, with main consideration in fatigue frequency and pre-stress value .The compared results indicated the deduced formula was basically accurate. |
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