Investigation of Deterioration of Dowel Bars in Jointed Concrete Pavements Under Repeated Loading PDF Download
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Author: Iliya Yut
Publisher:
ISBN:
Category :
Languages : en
Pages : 418
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Author: Iliya Yut
Publisher:
ISBN:
Category :
Languages : en
Pages : 418
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Book Description
Author: Iliya Yut
Publisher:
ISBN:
Category : Dowels
Languages : en
Pages : 188
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Book Description
The Minnesota Department of Transportation (Mn/DOT) has selected a 316L stainless steel schedule 40 pipe as a new dowel bar to be used as a bid alternative for its high performance Portland Cement Concrete (PCC) pavements. Although this dowel bar should provide sufficient shear transfer capacity and low concrete bearing stresses, there was a concern that lack of a solid core may not provide sufficient resistance of the cross-section to distortion under a heavy axle loading. In this study, long-term performance of the 316L stainless steel schedule 40 pipe was investigated by subjecting a doweled joint to accelerated repeated loads through the use of the Minnesota Accelerated Loading Facility (Minne-ALF-2). Assessment of the new dowel bar performance was performed based on comparison with the standard 1.5 inch diameter epoxy -coated round steel dowel. The following tasks were accomplished: redesign, assembly and calibration of new version of Minne-ALF, development of experimental design matrix, conduct of accelerated full-scale testing, and post-testing evaluation. The results from the MinneALF-2 tests illustrated that while the LTE for the stainless steel dowel tubes was lower than the LTE for the epoxy-coated dowels, the stainless steel tubes are capable of providing over 70% LTE in the long-term when installed in concrete pavement joints. The ability to withstand deformation and corrosion while providing sufficient long-term performance suggests that the stainless steel tube dowel is an attractive alternative to the solid epoxy-coated dowel for use in long-life pavements.
Author: Wynand JvdM. Steyn
Publisher: Transportation Research Board
ISBN: 0309223660
Category : Technology & Engineering
Languages : en
Pages : 257
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"TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 433: Significant Findings from Full-Scale Accelerated Pavement Testing documents and summarizes significant findings from the various experimental activities associated with full-scale accelerated pavement testing (f-sAPT) programs that have taken place between 2000 and 2011. The report also identifies gaps in knowledge related to f-sAPT and where future research may be needed. NCHRP Synthesis 433 is designed to expand the f-sAPT base of knowledge documented in NCHRP Syntheses 325 and 235, both with the same title of Significant Findings from Full-Scale Accelerated Pavement Testing. f-sAPT is the controlled application of a wheel loading, at or above the appropriate legal load limit, to a pavement system to determine pavement response in a compressed time period. The acceleration of damage is achieved by one or more of the following factors: increased repetitions, modified loading conditions, imposed climatic conditions, and thinner pavements with a decreased structural capacity which have shorter design lives"--
Author: Cyril Levy
Publisher:
ISBN:
Category :
Languages : en
Pages : 146
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Book Description
Dowel bars in jointed plain concrete pavement (JPCP) have the important function of transferring wheel loads from one slab to the other, hence ensuring that the deflections on each side of the joint are kept almost equal. As well, the dowels should not impede the concrete pavement movements due to environmental effects (temperature and moisture). Dowel bar misalignment, attributed to deficient construction practice, is a major cause of joint distress or faulting by inhibiting the free movement of the slab at the joint. To prevent these issues, tolerance guidelines on misalignment levels are implemented by transportation agencies. Review of previous studies indicate that many researchers analysed the effects of dowel bar misalignment on pavement behaviour using a pull-out test, that is a forcebased opening of the joint. These approaches neglect that joints movements in the field are strain-governed by non-linear temperature and shrinkage actions, leading to combined axial movements and curling of the slab. In this study, the fundamental dowel bar behaviour under shrinkage and thermal loading was determined through detailed 3D finite element modelling (3D-FEM). To that end, models of dowel jointed concrete slabs were developed and subjected to realistic non-linear profiles of shrinkage and thermal strains. Studies were carried out on a single-bar model, taking into account bar-concrete friction and plastic concrete behaviour. The parameters that were investigated included different configurations and levels of bar misalignment and different friction coefficients between the steel and the concrete, simulating the use of bond-breakers. To interpret the results from the numerical analysis, criteria for concrete damage were developed and used in parallel with measures of joint load transfer efficiency; these were obtained by examining the response of the slab under a Falling Weight Deflectometer (FWD) drop at the joint. The results were verified by comparing the outputs of a model consisting of one half of a slab to published data. The analysis of the models revealead that none of the models showed signs of significant damage after the application of shrinkage and two thermal cycles. Analyses with up to ten thermal cycles did not indicate progressive accumulation of damage, suggesting that for the chosen parameters there is no the concrete around the dowel bar will not fail. Models with bars placed higher in the slab and bars with angular misalignment exhibited more damage than the non-misaligned models without reaching the damage criteria used in this study. The models did not exhibit the amount of damage reported in the studies on dowel bar misalignment having used pull-out tests. It was found that no significant difference existed between uncoated and coated dowel bars models results with regards to concrete damage at the joint. However, a high coefficient of friction between the dowel and the concrete, simulating dowel bar corrosion, proved to be the most detrimental to joint integrity. All of the models performed very well with respect to joint load transfer efficiency, suggesting that the plastic strains in the concrete around the dowel did not have a significant impact on joint performance for the realistic range of parameters investigated.
Author: Yi Bian
Publisher:
ISBN:
Category :
Languages : en
Pages : 638
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Author:
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 99
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Book Description
Load transfer across transverse joints has always been a factor contributing to the useful life of concrete pavements. For many years, round steel dowels have been the conventional load transfer mechanism. Many problems have been associated with the round steel dowels. The most detrimental effect of the steel dowel is corrosion. Repeated loading over time also damages joints. When a dowel is repeatedly loaded over a long period of time, the high bearing stresses found at the top and bottom edge of a bar erode the surrounding concrete. This oblonging creates multiple problems in the joint. Over the past decade, Iowa State University has performed extensive research on new dowel shapes and materials to mitigate the effects of oblonging and corrosion. This report evaluates the bearing stress performance of six different dowel bar types subjected to two different shear load laboratory test methods. The first load test is the AASHTO T253 test method for determining the modulus of dowel support, ko. The modified AASHTO test procedure was examined alongside an experimental cantilever dowel test. The modified AASHTO specimens were also subjected to a small-scale fatigue test in order to simulate long-term dowel behavior with respect to concrete joint damage. Loss on ignition tests were also performed on the GFRP dowel specimens to determine the resin content percentage. The study concluded that all of the tested dowel bar shapes and materials were adequate with respect to performance under shear loading. The modified AASHTO method yielded more desirable results than the ones obtained from the cantilever test. The investigators determined that the experimental cantilever test was not a satisfactory test method to replace or verify the AASHTO T253 method.
Author:
Publisher:
ISBN:
Category : Dowels
Languages : en
Pages : 192
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Author: Irene K. Battaglia
Publisher:
ISBN:
Category : Dowels
Languages : en
Pages : 52
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Author: Soonjun Ha
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 80
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The primary objective of this research project was to develop rational guidelines on the use of dowel bars in longitudinal construction joints (LCJs) for better-performing concrete pavements without potential longitudinal cracking problems. To thoroughly investigate the behavior of tied and/or doweled concrete pavements, field testing was conducted in several new continuously reinforced concrete pavement (CRCP) construction projects in Texas. Concrete strain gages, concrete displacement gages, and steel strain gages were installed in each test section. To achieve the primary objective of this study in a more effective way, theoretical analysis was performed along with field experimentation. It was found from field experimentation that subgrade drag theory (SGDT), currently used for tie bar design, is not adequate to accurately analyze the behavior of concrete pavements. Accordingly, an improved numerical model based on plane strain theory was developed to analyze a concrete pavement with tie bars at LCJs. To verify the validity of the numerical model, the analysis results were compared with the field data, transverse displacements across the LCJs, concrete stresses, and tie bar stresses. The comparison indicated a good correlation when both frictional restraint and curling effects were included in the analysis. The influences of multiple lane ties and pavement geometries on the stresses in concrete and tie bars were investigated through parametric studies using the numerical model. Although the stresses in tie bars and concrete increase as more lanes are tied together, the growth slows due to bond slip at the interface between tie bars and concrete. This means that the dowel bar placement instead of tie bars could reduce concrete stresses if it applies to wide pavements, while it could result in lane separation problems. On the other hand, concrete stresses do not increase any further if four or more lanes are tied together, and concrete stresses may not be high enough to cause longitudinal cracking. There are many miles of CRCP in Texas where more than four lanes and inside and outside concrete shoulders are tied together, with no longitudinal cracking. Accordingly, it is recommended from the findings in this study not to use dowel LCJs, as is the current practice.
Author: Wisconsin. State Highway Commission
Publisher:
ISBN:
Category : Bars (Engineering)
Languages : en
Pages : 14
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