Evaluation of FWD software and deflection basin for airport pavements

198 Pages·2016·7.32 MB·English

University of New Mexico
UNM Digital Repository
Civil Engineering ETDs Engineering ETDs
9-3-2010
Evaluation of FWD software and deflection basin
for airport pavements
Mesbah Uddin Ahmed
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Ahmed, Mesbah Uddin. "Evaluation of FWD software and deflection basin for airport pavements." (2010).
https://digitalrepository.unm.edu/ce_etds/30
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EVALUATION OF FWD SOFTWARE AND DEFLECTION BASIN
FOR AIRPORT PAVEMENTS

BY

MESBAH UDDIN AHMED

B. Sc. in Civil Engineering

Bangladesh University of Engineering and Technology, Dhaka, Bangladesh

THESIS

Submitted in Partial Fulfillment of the
Requirements for the Degree of

MASTER OF SCIENCE
Civil Engineering

The University of New Mexico
Albuquerque, New Mexico

July, 2010

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© 2010, Mesbah Uddin Ahmed

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DEDICATION
To my parents

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AKNOWLEDGEMENTS

I would like to thank Dr. Rafiqul A. Tarefder, my supervisor and thesis committee chair,
for his support, time and encouragement for this study. His guidance and professional
style will remain with me as I continue my career.
I would like to thank my thesis committee members: Dr. Tang-Tat Ng and Dr. John C.
Stormont for their valuable recommendations pertaining to this study.
I would like to express my gratitude to the Aviation Department, New Mexico
Department of Transportation (NMDOT) for the funding to pursue this research. I would
like to thank Jane Lucero, Administrator, Aviation Department and Robert McCoy of
Material Bureau, NMDOT for their assistance in field data collection.
Co-operation and encouragement from the team members of my research group are
highly appreciated. I thank Raju Bisht and Ryan W. Webb for their sincere effort in
laboratory testing for this study. Motivation from my friend, a graduate student Late
Mohammad Minhaz Mahdi is greatly acknowledged.

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EVALUATION OF FWD SOFTWARE AND DEFLECTION BASIN
FOR AIRPORT PAVEMENTS

BY
MESBAH UDDIN AHMED

ABSTRACT OF THESIS
Submitted in Partial Fulfillment of the
Requirements for the Degree of

MASTER OF SCIENCE
Civil Engineering

The University of New Mexico
Albuquerque, New Mexico

July 2010 

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EVALUATION OF FWD SOFTWARE AND DEFLECTION BASIN FOR
AIRPORT PAVEMENTS
by
Mesbah Uddin Ahmed
M. Sc. in Civil Engineering, University of New Mexico
Albuquerque, NM, USA 2010
B. Sc. in Civil Engineering, Bangladesh University of Engineering and Technology
Dhaka, Bangladesh 2007

ABSTRACT
Falling Weight Deflectometer (FWD) test data are processed by backcalculation software
to obtain modulus of layer materials of airport pavements. Currently, several
backcalculation software are available. However it is not known which software produces
accurate and consistence modulus values. In this study three backcalculation software;
namely, BAKFAA, EVERCALC, and MODULUS are evaluated for consistency and
accuracy. To examine accuracy, software predicted modulus values are compared to the
laboratory tested modulus values of soils, aggregate, and asphalts. Consistency is
examined by statistical analysis using three sets of FWD deflection data produced by
three loads with magnitudes of 9, 12, and 16 kip at an identical location of an airport
pavement. It is shown that EVERCALC software produces more consistent and accurate
modulus values than the BAKFAA and MODULUS software.
A concern with the available backcalculation software is that their analysis algorithms are
based on layered elastic theory with linear materials models. In addition, they consider
static loading, which is not the true representation of the dynamic loads applied in a FWD
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test in the field. To this end, this study performs a dynamic analysis of the FWD
deflection basin using a finite element method (FEM) with the consideration of non-
linear materials models. Results show that FEM predicted deflections have similar trends
of the field measured deflections. However, a number of trial combinations of inputs and
FEM models may be required to produce an identical match between the predicted and
measured deflections. It is recommended that this approach be the subject of future
studies.

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TABLE OF CONTENTS

ABSTRACT ................................................................................................................................. vii 
CHAPTER 1 .................................................................................................................................. 1 
INTRODUCTION ........................................................................................................................ 1 
1.1  Introduction ..........................................................................................................1 
1.2  Problem Statement ...............................................................................................1 
1.3  Hypothesis ............................................................................................................3 
1.4  Objectives .............................................................................................................4 
CHAPTER 2 .................................................................................................................................. 6 
LITERATURE REVIEW ............................................................................................................ 6 
2.1 Introduction ...............................................................................................................6 
2.2 FWD Test ..................................................................................................................6 
2.2.1 KUAB FWD ...........................................................................................................7 
2.2.2 Dynatest FWD ........................................................................................................7 
2.2.3 Carl Bro FWD ........................................................................................................7 
2.2.4 JILS FWD ..............................................................................................................8 
2.3 Current Applications of FWD test ............................................................................8 
2.4 Backcalculation of Layer Moduli ..............................................................................9 
2.4.1 Boussinesq’s Solution Method .............................................................................10 
2.4.2 Multi-Layered Elastic Theory ..............................................................................12 
2.4.3 Finite Element Method .........................................................................................15 
2.5 Overview of Backcalculation Software ...................................................................16 
2.5.1 BISDEF ................................................................................................................16 
2.5.2 BOUSDEF ............................................................................................................17 
2.5.3 CHEVDEF ...........................................................................................................17 
2.5.4 ISSEM4 ................................................................................................................18 
2.5.5 ELMOD ................................................................................................................18 
2.5.6 ELSEDEF .............................................................................................................19 
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