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Sang Yum Lee - One of the best experts on this subject based on the ideXlab platform.

  • Permanent Deformation Model Based on Shear Properties of Asphalt Mixtures: Development and Calibration
    Transportation Research Record, 2011
    Co-Authors: Hyun Jong Lee, Sang Yum Lee
    Abstract:

    A permanent Deformation Model of asphalt concrete based on shear properties is developed and calibrated. This Model is extended and improved from previous work with the use of laboratory test results. Tri-axial compressive strength and repeated-load permanent Deformation (RLPD) tests on three types of asphalt mixtures are performed at various loads and temperatures to correlate the shear properties of asphalt mixtures with rutting performance. Test results indicate that the cohesion and friction angle of a given asphalt mixture decrease with increased temperature. Also, the results of RLPD tests indicate that loading and environmental conditions such as deviatoric stress, confining pressure, test temperature, and load frequency significantly affect the permanent Deformation of asphalt mixtures and must be incorporated into the prediction Model. Three versions of the permanent Deformation Model based on different input levels are proposed and verified by the test data. Then, the Model is calibrated by an a...

  • Development of a Permanent Deformation Model of Asphalt Mixtures for South Korean Pavement Design Guide
    Transportation Research Record, 2009
    Co-Authors: Hyun Jong Lee, Hee Mun Park, Sang Yum Lee
    Abstract:

    The Korean Pavement Design Guide (KPDG) was developed based on a mechanistic-empirical approach. This paper presents the permanent Deformation Model of asphalt mixtures in the KPDG. The permanent Deformation Model for various types of asphalt mixtures was developed by using the results of triaxial repeated loading tests. This Model was calibrated with the accelerated pavement test (APT) and the Long-Term Pavement Performance (LTPP) database. Through the triaxial repeated loading tests, the permanent Deformation Model of asphalt mixtures was developed to address the effects of temperature and initial air voids. The Model coefficients for the temperature and air voids obtained from the triaxial tests do not need to be calibrated. However, the Model coefficients for the shift factor and number of load repetitions should be calibrated with APT data. This study found that the Model requires a correction factor to consider the effects of total asphalt concrete (AC) layer thick-nesses. The correction factor is u...

Hyun Jong Lee - One of the best experts on this subject based on the ideXlab platform.

  • Permanent Deformation Model Based on Shear Properties of Asphalt Mixtures: Development and Calibration
    Transportation Research Record, 2011
    Co-Authors: Hyun Jong Lee, Sang Yum Lee
    Abstract:

    A permanent Deformation Model of asphalt concrete based on shear properties is developed and calibrated. This Model is extended and improved from previous work with the use of laboratory test results. Tri-axial compressive strength and repeated-load permanent Deformation (RLPD) tests on three types of asphalt mixtures are performed at various loads and temperatures to correlate the shear properties of asphalt mixtures with rutting performance. Test results indicate that the cohesion and friction angle of a given asphalt mixture decrease with increased temperature. Also, the results of RLPD tests indicate that loading and environmental conditions such as deviatoric stress, confining pressure, test temperature, and load frequency significantly affect the permanent Deformation of asphalt mixtures and must be incorporated into the prediction Model. Three versions of the permanent Deformation Model based on different input levels are proposed and verified by the test data. Then, the Model is calibrated by an a...

  • Development of a Permanent Deformation Model of Asphalt Mixtures for South Korean Pavement Design Guide
    Transportation Research Record, 2009
    Co-Authors: Hyun Jong Lee, Hee Mun Park, Sang Yum Lee
    Abstract:

    The Korean Pavement Design Guide (KPDG) was developed based on a mechanistic-empirical approach. This paper presents the permanent Deformation Model of asphalt mixtures in the KPDG. The permanent Deformation Model for various types of asphalt mixtures was developed by using the results of triaxial repeated loading tests. This Model was calibrated with the accelerated pavement test (APT) and the Long-Term Pavement Performance (LTPP) database. Through the triaxial repeated loading tests, the permanent Deformation Model of asphalt mixtures was developed to address the effects of temperature and initial air voids. The Model coefficients for the temperature and air voids obtained from the triaxial tests do not need to be calibrated. However, the Model coefficients for the shift factor and number of load repetitions should be calibrated with APT data. This study found that the Model requires a correction factor to consider the effects of total asphalt concrete (AC) layer thick-nesses. The correction factor is u...

Qing-po Yang - One of the best experts on this subject based on the ideXlab platform.

  • A simple permanent Deformation Model of rockfill materials
    Water Science and Engineering, 2018
    Co-Authors: Degao Zou, Jingmao Liu, Xianjing Kong, Chenguang Zhou, Qing-po Yang
    Abstract:

    Abstract Existing experimental results have shown that using a semi-log linear relationship between the permanent volumetric strain and cyclic number underestimates the volumetric Deformation of rockfill materials with a large cyclic number, and that the error increases with the confining pressure. The existing permanent Deformation Models are not suitable for the seismic safety analysis of high dams during strong earthquakes. In this study, a series of large-scale triaxial cyclic loading tests of rockfill materials were performed, and a new permanent Deformation Model of rockfill materials was developed and validated with three kinds of rockfill materials. The results show that the proposed Model can properly reflect the general features of the permanent Deformation of rockfill materials. The main features of the Model are as follows: (1) relations between the cyclic number and permanent volumetric/shear strain are described by hyperbolic functions, which can avoid underestimating the volumetric Deformation occurring during strong earthquakes; (2) the Model can capture the effect of the mean effective stress on the permanent volumetric strain, with greater confining pressure correlating to greater permanent volumetric Deformation, and the permanent volumetric strain under low confining pressure near the dam crest can be well represented; and (3) the Model can reflect the effect of the consolidation stress ratio on the permanent shear strain.

  • A simple permanent Deformation Model of rockfill materials
    Elsevier, 2018
    Co-Authors: Degao Zou, Jingmao Liu, Xianjing Kong, Chenguang Zhou, Qing-po Yang
    Abstract:

    Existing experimental results have shown that using a semi-log linear relationship between the permanent volumetric strain and cyclic number underestimates the volumetric Deformation of rockfill materials with a large cyclic number, and that the error increases with the confining pressure. The existing permanent Deformation Models are not suitable for the seismic safety analysis of high dams during strong earthquakes. In this study, a series of large-scale triaxial cyclic loading tests of rockfill materials were performed, and a new permanent Deformation Model of rockfill materials was developed and validated with three kinds of rockfill materials. The results show that the proposed Model can properly reflect the general features of the permanent Deformation of rockfill materials. The main features of the Model are as follows: (1) relations between the cyclic number and permanent volumetric/shear strain are described by hyperbolic functions, which can avoid underestimating the volumetric Deformation occurring during strong earthquakes; (2) the Model can capture the effect of the mean effective stress on the permanent volumetric strain, with greater confining pressure correlating to greater permanent volumetric Deformation, and the permanent volumetric strain under low confining pressure near the dam crest can be well represented; and (3) the Model can reflect the effect of the consolidation stress ratio on the permanent shear strain. Keywords: Rockfill materials, Permanent Deformation, Triaxial test, Cyclic loading, Consolidation stress rati

Yi Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Natural frequency analysis of a sandwich panel with soft core based on a refined shear Deformation Model
    Composite Structures, 2006
    Co-Authors: Qunli Liu, Yi Zhao
    Abstract:

    The natural frequency of a thick rectangular sandwich panel composed of orthotropic facesheets and a soft core was studied based on a refined shear Deformation Model. The shear Deformation of the sandwich panel was described by a polynomial function. The effect of transverse shear modulus of the facesheets and core on flexural vibration of the panel was investigated. Comparison was made among classical thin plate theory, linear shear (low order) Deformation theory and the refined shear (high order) Deformation Model. Results from finite element analysis were also provided to verify the theoretical predictions. It was shown that the refined shear Deformation Model provided a better prediction on the natural frequency of vibration of a sandwich panel than thin plate Model or low order Deformation Model.

J.-p. Guillerault - One of the best experts on this subject based on the ideXlab platform.

  • Experimental validation of a rolling stand elastic Deformation Model
    Journal of Materials Processing Technology, 1994
    Co-Authors: A. Hacquin, Pierre Montmitonnet, J.-p. Guillerault
    Abstract:

    Abstract Predicting strip profile due to roll Deformation is a major concern in the rolling industry. We are developing a numerical Model coupling iteratively a semi-analytical elastic rolling stand Deformation calculation with a three-dimensional Finite Element Method for the strip Deformation and rolling force distribution predictions. The present paper describes a comparison with experiments on a 4-high pilot mill, consisting in cold rolling various rake-shaped assemblies of aluminum rods. Under such conditions we may assume the rolling force to be equally distributed among the rods. Therefore, off-line measurements of rod exit thicknesses yield the loaded roll profile as elastic recoveries of rods are identical. Measured and predicted rolling forces of a single rod are also compared.