Accounting for the seasonal variations in the design of flexible pavements.
Item
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Title
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Accounting for the seasonal variations in the design of flexible pavements.
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Identifier
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AAI9720071
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identifier
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9720071
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Creator
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Ali, Hesham A.
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Contributor
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Adviser: Neville A. Parker
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Civil
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Abstract
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The first main objective of the work reported here, is to investigate and quantify the relationship between climatic variables and pavements' structural properties, in light of the data collected under the Seasonal Monitoring Program of the Long Term Pavement Performance Program. A series of bivariate and multivariate graphs are plotted to visually explore the spatial and temporal distribution of the pavement structural properties, and to graphically express the relationships between pairs of variables. Semivariogram analysis and ANOVA are used to analyze the spatial variation of the pavement layer moduli. Multivariate correlation analysis is used to correlate changes in pavement structural properties to climatic factors. Principal components and regression analyses are used to formulate and calibrate linear models that correlate climatic factors to the pavement's layer moduli. Nonlinear exponential models are developed to correlate the AC layer modulus to pavement temperature. Sinusoidal models are developed to correlate the layer moduli to the month of the year. Time series analysis is used to quantify the temporal and the spatial variations in pavement layers' moduli.;The second main objective is to develop a methodology to account for the seasonal changes in pavements' structural properties in the design of flexible pavements. Time series approach is used to incorporate the seasonal variations of pavement layers' stiffnesses in both empirical and mechanistic-empirical pavement design methods. A computer program was written to carry out the required calculations based on the proposed methods, and to compare the outputs to those of existing design methods. A sensitivity analysis was performed to examine the sensitivity of the program output (the required Structural Number (SN)), to each of the input parameters and to correlate the required structural number based on the AASHTO method, to that of the proposed method.;The concept of The Equivalent Constant Moduli is proposed to back-calculate the moduli of equivalent pavement layers that: have constant moduli with time, have the same set of thicknesses as the original pavement and will last the same performance life as the original pavement. The concept has the potential of simplifying the design method and evaluating the consequences of the design assumptions in relation to the stiffnesses of the pavement layers.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
