• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.155-162
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• 2006

Deflections of jointed concrete pavements at test road are monitored during 48 hours. And methods of calibration with respect to curling deflections are suggested. Relations between deflection ratio of center to joint at test time and deflection ratio of center at test time to center at reference time are described by regression. From deflections at test time, deflections transformed to reference time which gives minimum deflections in a day are estimated through regression curves and concluded to propose as a alternative method of curling calibration with more data accumulation.

• 한국도로학회:학술대회논문집
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• 2009.11a
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• pp.117-120
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• 2009

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.163-168
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• 2008

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.169-173
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• 2008

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.139-146
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• 2010

This research was conducted to analyze the behavior of the post-tensioned concrete pavement (PTCP) system in which weigh-in-motion (WIM) sensors were installed. One lane of PTCP was constructed after removing the existing asphalt pavement. The frictional resistance between the slab and the underlying layer should be small enough for the PTCP slab to properly have prestresses by tensioning. By performing an experimental construction of PTCP, the friction effects and the longitudinal displacements of PTCP under environmental loads were investigated. Based on the knowledge obtained from the experiments, the actual PTCP sections including WIM sensors were constructed and the curling behavior of the system was investigated. As a result, the behavior of the PTCP system was not affected by the existence of WIM sensors, and the appropriate PTCP system when installing WIM sensors in it could be developed.

• International Journal of Highway Engineering
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• v.9 no.1 s.31
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• pp.1-15
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• 2007

The objective of this paper is the establishment of finite element analysis frame work for pavement research. Finite element analysis results simulating various loading experiments are verified with sensor measurements obtained from the KHC Test Road. The accuracy of the finite element analysis can be supported by these efforts so that it helps spread out the finite element analysis to pavement research and design processes. The finite element model used in this research is the full 3D nonlinear model including concrete slab, lean concrete base, subbase, shoulder, dowel, and tie-bar. In order to accomplish the accurate verification, the loading condition and the pavement temperature distribution are exactly simulated with field measured data. The curling behavior and the strain distribution are compared with measured responses from the loading tests with a truck and the FWD. Strain and curling predictions from the concrete slab are matched well with measured responses but the strain prediction from the lean concrete base is not matched with measured response. In addition, the magnitude of permanent curling is evaluated with the finite element analysis.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.625-636
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• 2017

This study looked into the behavior of precast concrete track due to temperature variation and initial track deformation and examined the effect of initial deformation and deformation caused by temperature gradient on the stress distribution of slab under train load. In this paper, one of two papers in a series, a finite element analysis model for calculating deformation and stress of precast concrete track was proposed; the temperature distribution and displacements measured at the precast concrete track in the field were compared with the analytical results. The results show that the slab always curled up due to initial deformation; by comparing the measured displacements with the displacements calculated by taking measured temperatures at each depth as input, the effective built-in temperature (EBITD), the temperature difference between the top and bottom of the slab corresponding to the initial deformation, can be estimated. If EBITD is relevantly assumed, the calculated displacements correlate well with the measured ones.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.107-115
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• 2009

This study was conducted to investigate the effect of the slab thickness on the tensioning design and to determine the optimal slab thickness of the post-tensioned concrete pavement (PTCP). The tensile stresses due to the vehicle and environmental loads were obtained using a finite element analysis model and the tensioning stress was calculated employing an allowable flexural strength. The environmental loads of both the constant temperature gradient and the constant temperature difference between top and bottom of the slab were considered. The tensioning designs for various slab thicknesses were performed considering prestressing losses. The comparison results showed that generally as the thickness increased, the number of tendons became larger. Consequently, the design was not economical for a thicker slab thickness. Even though the number of tendons became smaller with an increase in the thickness under the small environmental load, a thicker PTCP slab was not economical because of a higher cost of concrete than that of steel. Therefore, the slab thickness should be kept in minimum within the construction available thicknesses.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.449-456
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• 2007

This research was conducted to analyze the features of the critical tensile stresses at the top and bottom of the concrete slab in the jointed concrete pavement (JCP) when subjected to both the environmental and vehicle loads. First, the stress distribution in JCP was analyzed when the system was subjected to only the environmental loads or the vehicle loads by using the finite element model of JCP. Then, the stresses were analyzed when the system was subjected to the environmental and vehicle loads at the same time. From this study, it was found that the critical tensile stresses at the slab bottom under the vehicle loads were almost constant regardless of the loading positions once the loads were applied at the positions having some distance from the transverse joint. The critical tensile stresses at the slab bottom could be obtained using the model consisting of normal springs for underlying layers by adding the critical stresses due to the environmental loads and the vehicle loads for the curled-down slab, and by subtracting the critical stress due to the environmental loads from that due to the vehicle loads for the curled-up slab. The critical tensile stresses at the top of the slab could be obtained using the model consisting of tensionless springs for underlying layers by adding the critical stress due to the environmental loads and the stress at the middle of the slab under the vehicle loads applied at the joint for the curled-up slab. An alternative to obtain the critical stresses at the top of the slab for the curled-up slab was to use the critical stresses under only the environmental loads obtained from the model having normal springs for underlying layers.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.59-68
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• 2009

Torsional behavior of concrete pavement slabs due to temperature and moisture effects is constrained by self weight and friction etc, and causes stress as the result. The stress due to humidity variation in the slab is difficult to calculate while that due to temperature variation can easily be calculated by a commercial structural analysis program. Thus, the slab behavior can be predicted more accurately if the humidity effect is converted to equivalent temperature and is used as an input of structural analysis. In this study, a concrete pavement slab was constructed and strains of the slab due to environmental loadings were measured for long-term period. Thermal strains were subtracted from the measured strains by using thermal expansion coefficient of the concrete measured in a laboratory. Shrinkage strains, the remained strains, was supposed as additional thermal strains to calculate imaginary temperature with equivalent effect of the shrinkage by dividing the shrinkage with the thermal expansion coefficient. An existing shrinkage model was modified by considering the self weight and friction to be used in another model which can convert differential shrinkage between top and bottom of the slab to equivalent temperature difference. Addition research efforts on tensile stress reduction according to steady increase in the compressive strains are warranted for more accurate stress calculation.