Research Article

Prediction of Long-Term Prestress Loss and Crack Resistance Analysis of Corroded Prestressed Concrete Box-Girder Bridges

Table 3

Statistical characteristics of parameters related to long-term prestress loss prediction.

Classification of parametersDescription of parametersDistribution(Mean, COV)Source

Material and dimension parametersInitial elastic modulus of concrete, Ec0 (MPa)Normal(3.55 × 104, 0.04)[41]
Concrete coverNormal(1.0178, 0.0496)
Initial elastic modulus of prestressing steel strand, Ep (MPa)Normal(1.95 × 105, 0.04)
Initial elastic modulus of HRB400 grade nonprestressing steel (MPa)Normal(2 × 105, 0.04)
Initial elastic modulus of HPB300 grade nonprestressing steel (MPa)Normal(2.1 × 105, 0.04)
Strength of HRB400 grade nonprestressing steel (MPa)Normal(434, 0.0791)
Strength of HPB300 grade nonprestressing steel (MPa)Normal(324.6, 0.1211)
Initial compressive strength of concrete, fc0 (MPa)Normal(55.2, 0.137)D
Environmental parametersAnnual relative humidity, RH (%)Normal(76.9, 0.061)CMA
Annual average temperature, T (°C)Normal(21.7, 0.251)
Model parametersUncertainty coefficient of concrete creep model, ΨcNormal(1, 0.339)[41]
Uncertainty coefficient of concrete shrinkage model, ΨsNormal(1, 0.541)
Load effect parametersDead load effect (bending moment), Mdle (kN·m)Normal(1.0148, 0.0431)
Live load effect (bending moment), Mlle (kN·m)Extreme I(0.7995, 0.0862)
Shear force, Vs (kN)Normal(1.0148, 0.0431)
Initial tension control stress, σcon (MPa)Normal(1, 0.04)[42]
Corrosion-related parametersSurface chloride concentration, CS (kg/m3)Normal(3.5, 0.5)[24]
Threshold chloride concentration, Ccr (kg/m3)Normal(0.9, 0.2)
Chloride diffusion coefficient, D0 (cm2/year)Log normal(0.631, 0.2)
Corrosion current density, icorr (μA/cm2)Normal(1, 0.2)
Penetration ratio, RNormal(6.0, 0.18)[39]

Note.The ratio of actual value to nominal value, D = design data, and CMA = china meteorological administration.