TABLE OF CONTENTS
Title page
Abstract
Table of Contents
List of Symbols/Abbreviation
CHAPTER ONE
1.0 INTRODUCTION
1.1 Preamble
1.2 Problem Statement
1.3 Justification of Study
1.4 Aim and Objectives
1.4.1 Aim
1.4.2 Objectives
1.5 Scope and Limitation
1.5.1 Scope
1.5.2 Limitation
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Preamble
2.2 Basis of Fatigue
2.3 Classification of details in concrete structural component
2.4 Fatigue
2.4.1 Fatigue of concrete
2.4.2 Fatigue of reinforcement
2.4.3 Fatigue of reinforced concrete
2.5 Fatigue failure of reinforced concrete structures
2.5.1 Shear and Bond failures
2.6 Structural Reliability
2.7 Limit State Principles
2.7.1 Failure Events and Basic Random Variables
2.7.2 Reliability Index
2.7.3 Hasofer-Lind Reliability Index
CHAPTER THREE
3.0 RESEARCH METHODOLOGY
3.1 Estimation of parameters for reliability of bridge deck
3.2 Bridge Model
3.3 Structural Material
3.4 Load Combination
3.4.1 Dead Load Effect
3.4.2 Live Load Effect
3.5 Structural Resistance Models
3.6 Generation of Limit State Function
3.6.1 Failure of the Slab
3.6.1.1 Applied Dead Load
3.6.2 Failure Model for Beams
3.6.2.1 Interior Beams
3.6.2.1.1 Limit State Function for Shear in Interior Beam
3.6.2.2 Limit State Function for Moment Flexure in Interior Beam
3.7 Computer Analysis Procedure
3.7.1 MATLAB Program
CHAPTER FOUR
4.0 RESULT DISCUSSION
4.1 Failure due to moment flexure in Slab (Failure Mode One)
4.1.1 Effect of deck slab depth variation on the Safety Index
4.1.2 Effect of Coefficient of Variation due to concrete strength under bending on the Safety Index with respect to the stress cycle
4.1.3 Effect of Coefficient of Variation due to slab depth under bending on the Safety Index with respect to the stress cycle
4.2 Failure due to shear in deck beam(Failure Mode Two)
4.2.1 Effect of beam depth variation on the Safety Index with respect shear stress under stress cycle
4.2.2 Effect of concrete strength variation on the Safety Index with respect to stress cycle
4.2.3 Effect of coefficient of variation due to concrete strength under shear on the safety index with respect to the stress cycle
4.2.4 Effect of coefficient of variation due to beam depth under shear on the safety index with respect to the stress cycle
4.3 Failure due to Moment Flexure (Failure Mode Three)
4.3.1. Effect of beam depth variation on the Safety Index with respect to flexure under stress Cycle
4.3.2 Effect of concrete strength variation under bending on the Safety Index with respect to stress cycle
4.3.3 Effect of coefficient of variation due to concrete strength under flexure on the Safety Index with respect to the stress cycle
4.3.4 Effect of coefficient of variation due to beam depth under flexure on the Safety Index with respect to the stress cycle
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
5.1 Conclusion
5.2 Recommendation
REFERENCES
ABSTRACT
In this thesis the reliability analysis of reinforced concrete bridge decks subjected to high cycle fatigue was undertaken. A simply supported (single span) reinforced concrete bridge deck was specifically used for the investigation. The statistical models of capacity loss were derived. The uncertainties in structural resistance and the applied loadings were fully accommodated using probabilistic method. The limit state function(Failure Modes) for the flexural capacity of the deck slab, shear capacity of the deck beam and flexural capacity of the deck beam girder was developed and evaluated using the First Order Reliability Method(FORM). The entire process was implemented through a developed MATLAB program “dc_fatigue.m”. Analysis was carried out on all the failure modes considered by varying the geometrical and material properties of the system and their respective safety indices were determined. Failure due to shear in the deck beam gave the least safety index range of 6.06 to -2.11 at 3cycles/min for 10years and 40years respectively indicating the most critical section, when compared to the flexural failure with a safety index range value of 7.59 to 0.25 at 3cycles/min for 10years and 40years respectively. It was generally observed that the reliability index increased as the depth of section and concrete grade increased. Also, the coefficient of variation due to the concrete strength and depth of section decreased with increase in reliability index, from a safety index range of 7.61 to - 0.47 at 5% covariance and from 3.47 to -0.23 at 20% covariance under stress load of 3cycles/min. This trend is expected as quality control plays a very important role in achieving this level of safety in the system. Thus, for a single span bridge of 15m and less under high level of traffic load, a deck beam depth of 1200mm, deck slab of 250mm and concrete strength class of 30-35 are adequate for design and construction.
CHAPTER ONE
INTRODUCTION
1.1 Preamble
Researches on fatigue behaviour of concrete materials started at the end of the 19th century, due to failure in many concrete structures caused by fatigue rupture of the concrete (Rteil et.al, 2011). Results of experimental and theoretical studies of the fatigue properties of plain concrete, reinforcing bars, prestressing tendons, and also of structural concrete members, have been accumulating steadily over the past thirty years.
The assessment of existing structures will become a more frequent task for engineers in the near future due to the increasing age of existing infrastructure. These may be due to reasons such as(Jansen, 1996); Change in intended use of the structure, new regulations with higher load requirements for the structure, indications of ongoing deterioration in the structure, unusual incidents during use (e.g. vehicle impact, fire, earthquakes), inadequate serviceability, discovery of design or construction errors.
The purpose of reliability analysis in this research is to verify the overall stability and establishment of action effects, i.e. the distribution of internal forces and moments. In turn, this will enable the calculation of stresses, strains, curvature, rotation and displacements. In certain complex structures, the type of analysis used (e.g. finite-element analysis) will yield internal stresses and strains and displacements directly.
To carry out the analysis, both the geometry and the behaviour of the structure will need to be idealized. Commonly, the structure is idealized by considering it as made up of elements depicted....
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