Comparison of Concrete Creep-Induced Structural Prestress Loss Calculated by Codes from Different Countries

Xu, Feiping; Li, Da-fang; Zhang, Zhong-tian; Zhang, Qingtao; Liang, Kang; Wei, Ya

doi:10.1061/jhtrcq.0000701

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…In the process of deducing the formula of long-term prestress loss, the following basic assumptions are satisfied [ 33 , 34 , 35 ]: At any time, the elastic stress and elasticity of concrete should become linear; The assumption of flat section deformation of the beam body is valid; The creep deformation is linear, satisfying the superposition principle; Ordinary reinforcement and prestressed reinforcement are completely bonded to the concrete without slip; There is no cracking phenomenon in the concrete section. …”

Section: Calculation Methods Of Long-term Prestress Loss Considering ...mentioning

confidence: 99%

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

Han

Tian

et al. 2023

Materials

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In order to accurately calculate the long-term prestress losses of prestressed tendons, a time-varying model of long-term prestress loss considering the interaction between concrete shrinkage, creep, and the stress relaxation of prestressed tendons was constructed. Then, a method for calculating the long-term prestress losses of concrete structures was developed. A long-term prestress loss test of a prestressed concrete T-beam in a long-term field test environment was carried out. The measured values of long-term prestress losses are compared with the calculated results of JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model. The results show that the long-term effective tension of the T-beam decreases gradually with the increase in the load holding time. At the beginning of loading, the tensile force changes rapidly and then gradually slows down. The later the tensile age or the higher the initial loading stress level, the smaller the long-term prestress losses of the prestressed tendons. The long-term prestress loss values calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model increase with the increase in the load holding time. In the early stage of loading, the rate of change slows down and tends to be stable. The calculated results of JTG 3362-2018 and AASHTO LRFD-2007 are significantly different from the measured values. However, the calculated results of the time-varying law model are in good agreement with the measured values. The average coefficients of variation of the long-term prestress loss calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model are 17%, 10%, and 5%, respectively. The time-varying law model of the long-term prestress losses of prestressed tendons is accurate, and the long-term prestress loss of prestressed reinforcement can be predicted effectively.

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Section: Calculation Methods Of Long-term Prestress Loss Considering ...mentioning

confidence: 99%

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

Han

Tian

et al. 2023

Materials

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“…where, max F is the concrete failure load , cc f is the axial compressive strength design value of plain concrete and A is the pressure-bearing area [15][16][17][18], then the concrete was crushed.…”

Section: Structural Design Of Locking Wedge Concrete Fixed Piermentioning

confidence: 99%

Structural Design of Pressure Pipeline Wedge-Shaped Concrete Piers

2023

Teh. vjesn.

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This paper proposed a wedge concrete fixed pier device based on self-locking to solve the problems existing in the fixed pier of water supply pipeline in utility tunnels. The system converted the horizontal thrust, originally applied to the weld seam in the pipeline, into oblique downward pressure by bending the pipeline upward. When the pipeline was bent upward at an angle equal to twice the horizontal angle of the wedge concrete fixed pier, then the fixed pier achieved the variable pressurebearing effect in the horizontal direction through the self-locking between the concrete pier and the bottom plate of the utility tunnels. In addition, this avoided the damage to the fixed pier device, caused by the instantaneous pipeline internal pressure exceeding the maximum bearing thrust of the weld seam. The wedge fixed pier could be poured twice when the pipeline entered the utility tunnels, saving the rework cost of pouring the concrete again due to the changes of the design positioning of the water supply pipeline. As long as the area of the built-in steel fittings in the wedge concrete exceeded a certain range, the wedge concrete pier would not be crushed.

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