줄눈 콘크리트 포장의 빌트인 온도 및 응력 발현에 미치는 영향 평가
Evaluation of Built-in Temperature and Its Influence on Stress Development in Jointed Concrete Pavements
- 주제(키워드) 도움말 Built-in temperature , Mechanistic approach , Concrete temperature , Concrete stress , Environmental loading , Creep or stress relaxation , Numerical model.
- 발행기관 Gangneung-Wonju National University
- 발행년도 2019
- 학위수여년월 2019. 8
- 학위명 박사
- 학과 및 전공 도움말 일반대학원 토목공학과
- 실제URI http://www.dcollection.net/handler/kangnung/000000010487
- UCI I804:42001-000000010487
- 본문언어 영어
초록/요약 도움말
Portland cement concrete (PCC) slab experiences volume changes in response to the temperature and moisture changes. Differential contraction and expansion caused by the differential temperature and moisture changes through the depth of the slab result in curling and warping. Curling and warping significantly affect the slab deformation, the location and magnitude of critical stresses in PCC slab, and the pavement performance. Built-in temperature (BIT) difference, defined as the temperature difference between the top and the bottom of the PCC slab at the final set, is one of the critical factors affecting curling and warping stress and deformation of PCC slab. However, the available methods for evaluating this parameter are very limited. The first objective of this research was to develop a mechanistic approach to predict BIT distribution in the PCC slab. To do this, a numerical model to predict the early-age concrete temperature distribution in a PCC slab was developed. An existing equation for predicting concrete final setting time was used and incorporated in the numerical model to establish the BIT distribution. The results of the numerical model showed good agreements with the field measured data. Using the proposed model, it was found that climatic conditions, placement time, concrete mix proportions, and pavement thicknesses have substantial effects on the magnitude of BIT difference. The second objective was to evaluate the effects of BIT distribution on stress development in a PCC slab. A numerical model to determine early-age and long-term stress development in PCC slab was therefore developed. The numerical model was validated with the field measured data. It was found that creep or stress relaxation could reduce concrete stresses about 33% to 40% in the first 20 days of the pavement age depending on the type of base materials. This finding indicated that the effects of creep or stress relaxation should be significantly considered in the analysis and design of the PCC pavement. BIT distribution obtained from the different concrete placement time within a day has a substantial effect on early-age stress development, but it has little effect on long-term stress development. It was expected that the findings from this study would provide the researchers and pavement engineers with useful and helpful information to improve the accuracy of stress estimation in PCC slab and to enhance the analysis and design of PCC pavement more mechanistic-based.
more목차 도움말
TABLE OF CONTENTS
ABSTRACT i
TABLE OF CONTENTS iii
LIST OF TABLES vi
LIST OF FIGURES vii
LIST OF ACRONYMS AND SYMBOLS xii
CHAPTER 1 INTRODUCTION
1.1 RESEARCH BACKGROUND AND MOTIVATION 1
1.2 OBJECTIVES 4
1.3 SCOPES 4
1.4 DISSERTATION OUTLINE 5
CHAPTER 2 LITERATURE REVIEW
2.1 BUILT-IN TEMPERATURE IN PCC SLAB 7
2.1.1 Definition of BIT 7
2.1.2 Behavior of Slab Curling/Warping with BIT 10
2.1.3 Factors Affecting BIT 14
2.1.4 Implication of BIT in PCC Pavement 17
2.1.5 Existing Methods for Determining BIT 19
2.2 STRESS DEVELOPMENT IN PCC SLAB 20
2.2.1 Factors Affecting Stress Development in PCC Slab 21
2.2.2 Existing Studies on Stress Development in PCC Slab 35
2.3 SUMMARY 41
CHAPTER 3 EVALUATION OF BUILT-IN TEMPERATURE
3.1 STRATEGY 43
3.2 MECHANISTIC APPROACH TO PREDICT BIT DISTRIBUTION 43
3.2.1 Concrete Temperature Model 44
3.2.2 Concrete Setting Time 58
3.2.3 Algorithm for Establishing BIT 60
3.3 VALIDATION OF BIT 62
3.3.1 Summary of Field Test Section 62
3.3.2 Input Data 67
3.3.3 Validation of Concrete Final Setting Time 68
3.3.4 Validation of Concrete Temperature and BIT 71
3.4 SENSITIVITY ANALYSIS OF BIT 74
3.4.1 Analysis Parameters 74
3.4.2 Effect of Concrete Placement Time 76
3.4.3 Effect of Concrete Mix Proportion 78
3.4.4 Effect of Pavement Thickness 79
3.4.5 Effect of Water to Cement Ratio 80
3.5 SUMMARY 81
CHAPTER 4 DEVELOPMENT OF NUMERICAL MODEL TO PREDICT STRESS IN CONCRETE PAVEMENT
4.1 STRATEGY 83
4.2 NUMERICAL MODELING OF JCP SLAB 83
4.2.1 Finite Element Analysis of JCP slab 83
4.2.2 Slab-Base Interaction Modeling 84
4.2.3 Finite Element Formulation 87
4.3 VALIDATION OF CONCRETE STRESS MODEL 93
4.3.1 Verification of Concrete Stress with the Theoretical Solution 93
4.3.2 Validation of Concrete Stress with Field Measurement 95
4.4 ZERO-STRESS TEMPERATURE 104
4.4.1 Definition of ZST 104
4.4.2 Determination of ZST 109
4.4.3 Sensitivity Analysis of ZST 110
4.5 SUMMARY 113
CHAPTER 5 EFFECTS OF BUILT-IN TEMPERATURE ON CONCRETE STRESS DEVELOPMENT
5.1 STRATEGY 115
5.2 SENSITIVITY ANALYSIS 115
5.2.1 Analysis Parameters 115
5.2.2 Results of Concrete Temperature Development 119
5.2.3 Effects of Creep or Stress Relaxation on Stress Development 122
5.2.4 Effect of Base Types on Concrete Stress Relaxation 127
5.3 EFFECT OF BIT ON CONCRETE STRESS DEVELOPMENT 128
5.3.1 Concrete Stress Development with Elastic Theory 128
5.3.2 Concrete Stress Development with Viscoelastic Theory 130
5.4 SUMMARY 132
CHAPTER 6 CONCLUSIONS
6.1 SUMMARY AND CONCLUSION 134
6.2 RECOMMENDATIONS FOR FUTURE STUDY 138
SUMMARY (IN KOREAN) 140
REFERENCES 142
APPENDIX 150
ACKNOWLEDGMENTS 164
CURRICULUM VITAE 165
