Please read the abstract in the section 00front of this documentThesis (PhD (Engineering))--University of Pretoria, 2006.Civil Engineeringunrestricte

Brink, Anna Catharina

Thesis (PhD (Engineering))--University of Pretoria, 2006.Please read the abstract in the section 00front of this documentCivil Engineeringunrestricte

UPSpace at the University of Pretoria

© University of Pretoria     THESIS SUMMARY MODELLING AGGREGATE INTERLOCK LOAD TRANSFER AT CONCRETE PAVEMENT JOINTS AC BRINK Supervisor: Prof Emile Horak Co-Supervisor: Prof Alex Visser Department: Civil Engineering University: U ni versity of Pretoria Degree: Philosophiae Doctor (Engineering) The South African concrete pavement community recognized the need to upgrade the South African Concrete Pavement Design and Construction Manual, to a manual based on mechanistic design principles. During a re­evaluation of factors affecting riding quality, structural service life, maintenance and rehabilitation needs, the prominent influence of joint performance in jointed concrete pavements (JCP) was re-confmned. It was identified that the analytical equation used in the manual to predict relative movement at joints was only applicable to a small range of aggregate sizes. Further research was therefore needed, which resulted in the study presented in this thesis. The primary objective of this research was to evaluate pavement response in terms of deflections, to static and moving impulse or dynamic loads (equivalent to traffic loads), and to take into account existing methods for modelling aggregate interlock shear transfer. This was in order to develop a fundamental model that reflects variations in joint load transfer with joint opening, load magnitude and concrete properties to replace an existing equation in the new South African mechanistic concrete pavement design manual. In the context of this thesis, modelling can be defined as the execution of pre-planned tests in a laboratory under controlled conditions using materials commonly used in the construction of concrete pavements in South Africa in order to develop an equation simulating performance in the field. Theoretical analyses of concrete pavement models were first done by the author using the three-dimensional finite element computer software programme EverFE. This was in order to determine the ranges for the    different input variables that could be expected during modelling in the laboratory. Both aggregate interlock and dowel/concrete interaction were evaluated using EverFE. The focus of subsequent laboratory testing was to measure relevant responses during testing of instrumented concrete pavement models. Instrumentation included load cells, actuators, linear variable displacement transducers, as well as horizontal strain displacement transducers to collect fast responses induced by dynamic loads. Thennocouples collected further infonnation on the influence of environmental temperature. The preliminary testing also included detennining the relevant engineering properties for the typical South African aggregates used in the study. The laboratory concrete pavement test sections were constructed on rubber mats to simulate a Winkler foundation. Constructing the models on rubber mats made it possible to repeat experiments with the same founding conditions, which reduced the number of variables that had to be taken into consideration during analysis of the data. Conclusions reached from the study were inter alia that there was no significant deterioration of the crack face during the application of up to two million dynamic load cycles, which indicated that little abrasion took place at the initial crack width. It also indicated that fatigue of the aggregates at the joint face did not playa significant role, which could be attributed to the high quality of the crushed stone used in South Africa, as well as to the fact that testing was conducted inside the controlled environment of a laboratory. Moment and inertia in the slab contributed to greater load transfer efficiency under dynamic loading, than under static loading. A specific relationship detennined from laboratory results was used to refine the aggregate interlock load transfer model in the software developed for the new mechanistic design manual. Data from field investigations of in service concrete pavements in southern Africa was used to calibrate the laboratory data.    ABSTRACT Title: 	 Modelling Aggregate Interlock Load Transfer at Concrete Pavement Joints Author: 	 Anna-Carin Brink Supervisor: 	 Prof Emile Horak Co-Supervisor: 	 Prof Alex Visser Department: 	 Civil Engineering University: 	 University of Pretoria Degree: 	 Philosophiae Doctor (Engineering) Keywords: 	 Aggregate interlock, Load transfer efficiency, Jointed concrete pavement, Winkler foundation, Dynamic and static loading, Relative movement. The South African concrete pavement fraternity recognized the need to upgrade the South African Concrete Pavement Design and Construction Manual, to a manual based on mechanistic design principles. During a re­evaluation of factors affecting riding quality, structural service life, maintenance and rehabilitation needs, the prominent influence of joint performance was re-confirmed. Further research was needed to enable modelling of aggregate interlock load transfer at concrete pavement joints, which resulted in the study presented in this thesis. The primary objective of this research was to evaluate pavement response in terms of deflections, to static and moving impulse or dynamic loads (equivalent to traffic loads), and to take into account existing methods for modelling aggregate interlock shear transfer (In the context of this thesis, modelling .can be defmed as the execution of pre-planned tests in a laboratory under controlled conditions using materials commonly used in the construction of concrete pavements in South Africa in order to develop an equation simulating performanc.e in the field). This was in order to develop a fundamental model that reflects variations in joint load transfer with joint opening, load magnitude and concrete properties to replace an existing equation in the new South African mechanistic concrete pavement design manual. During modelling the focus was to measure relevant responses during testing of instrumented concrete pavement models. Instrumentation included load cells, actuators, linear variable displacement transducers, as well as horizontal strain displacement transducers to collect fast responses induced by dynamic loads. Thermocouples collected further information on environmental influences. The preliminary testing also    included determining the relevant engineering properties for South African materials. The concrete pavement models were constructed on rubber mats to simulate a Winkler foundation with or without inter-layers. Conclusions reached from the study were inter alia that there was no significant deterioration of the crack face during dynamic loading, which indicated that little abrasion took place at the initial crack width. It also indicated that in this instance fatigue of the aggregates at the joint face did not playa role, which could be attributed to the high quality of the crushed stone used in South Africa. Moment and inertia in the slab contributed to the greater load transfer efficiency under dynamic loading, than under static loading. A specific relationship determined from laboratory results was used to refine the aggregate interlock load transfer model in the software developed for the new mechanistic design manual. Data from field investigations of in service concrete pavements in southem Africa was used to calibrate the laboratory data.    To my children Annica and Dawid and my parents Danie and Annetjie Brink    ACKNOWLEDGEMENTS I wish to express my gratitude to God, my Father, that I have had the opportunity to do this research and that He has kept my mother alive to pray for me, despite being seriously il1. Further, I wish to express my appreciation to the following organisations and persons who made this thesis possible: a) 	 BKS (Pty) Ltd for allowing me two years' study leave, and for paying my salary while doing so. b) 	 The Cement and Concrete Institute (C&CI) for financial support and the use of their library facilities during the course of the research. c) 	 The Technology and Human Resources for Industry Program (THRIP) and the Centre for Transport Development for fmancial support. d) 	 Professor Emile Horak and Professor Alex Visser, my supervisors, for their guidance and support. e) 	 Prof Christo van As for assistance with the development of the mathematical equation used in the CncRisk software. f) 	 Investmech for the use of their laboratory facilities and their mechanical engineering input to assist in sorting out testing procedures and for generating data for analysis of the experimental concrete slabs. g) 	 Alpha Stone, Lyttleton (Pty) Ltd, and Lafarge Readymix for supplying materials for casting the concrete slabs. h) 	 My daughter, Annica and my son, Dawid for their love and enthusiasm to see their mother complete this study.    CONTENTS CHAPTER 1: INTRODUCTION CHAPTER 2: LITERATURE REVIEW AND GUIDANCE FOR MODELLING CHAPTER 3: LABORATORY AND FIELD PROGRAMMES CHAPTER 4: ANALYSIS AND MODELLING CHAPTER 5: APPLICATION OF LABORATORY AND FIELD MODELLING CHAPTER 6: SUMMARY, CONCLUSIONS AND RECOMMENDATIONS REFERENCES APPENDIX A: WESTERGAARD SOLUTIONS APPENDIX B: WESTERGAARD-TYPE SOLUTION FOR EDGE LOAD TRANSFER PROBLEM APPENDIX C: DOWEL MODELLING APPENDIX D: THEORETICAL MODELLING RESULTS APPENDIX E: TEST METHODS USED APPENDIX F: TEST RESULTS APPENDIX G: PHOTOS    

Modeling aggregate interlock load transfer at concrete pavement joints

https://repository.up.ac.za/bitstream/2263/28110/1/00front.pdf

Modeling aggregate interlock load transfer at concrete pavement joints

Abstract

Similar works

Full text

Available Versions

UPSpace at the University of Pretoria