Transverse Cracking Of Bridge Decks Influence Of Temperature And Restrained Shrinkage
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Transverse Cracking Of Bridge Decks Influence Of Temperature And Restrained Shrinkage
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Author :
language : en
Publisher:
Release Date : 2003
Transverse Cracking Of Bridge Decks Influence Of Temperature And Restrained Shrinkage written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
Ohio Department of Transportation started a program of replacement of bridge decks by high performance concrete decks but the decks started showing cracks after just six to eight months or a season of construction. This study was taken up to ascertain the causes of this early cracking with emphasis on the study of the role of temperature and restrained shrinkage in cracking. Analysis of data from ODOT about its previously cast decks about their location, mix design, slump, compressive strength, average shrinkage, month of casting, ninety day chloride penetration values and temperature differential showed vast scatter, indicating that deck cracking is the compounded effect of several factors acting together and implied an in-depth study in various directions. To gain an insight into the role of temperature and restrained shrinkage in cracking, an experiment was done in an ODOT project involving a phased replacement of deck of a bridge (on US 127) over still water in Richland Township of Darke County in Ohio. Prior to casting, four pairs of vibrating wire gages were placed at the top and bottom of the reinforcement cage of deck at following locations * On the mid-span between two beams * Over the pier * Over the beam * Over the beam pier intersection. Hourly strains and corresponding Temperatures were measured and recorded for fifteen months. Numerical analysis and analytic study was done on the data obtained from site. Both phases of construction showed a different behavior so far as the pattern of strain generation is concerned. It was observed that the gages having least external restraint developed highest strains. The deck showed a wavy behavior with upward curvature at locations where deck had a beam below and downward curvature for locations where deck has no beam (restraint) below it. The temperature was seen to become a potential source for cracking only when a vast difference of temperature existed along the cross section of deck. Even after one year of casting the deck, only minor cracking was observed. This unexpected behavior of deck was attributed to good construction practices, especially proper curing.
Transverse Cracking Of High Performance Concrete Bridge Decks After One Season Or Six To Eight Months
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Author :
language : en
Publisher:
Release Date : 2006
Transverse Cracking Of High Performance Concrete Bridge Decks After One Season Or Six To Eight Months written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Concrete categories.
Cracking is a major problem with newly placed concrete decks. These decks tend to develop full depth, transverse cracks and partial depth longitudinal cracks within a few months of the concrete being placed. A literature review showed that several other states had experienced similar problems. A review of data from Ohio bridge decks showed weak correlations between deck cracking and slump, time of year when the deck was placed, shrinkage, chloride permeability and compressive strength, but there was no clear relationship between cracking and any of these properties. Data also suggested that using a coarse aggregate with an absorption> 1% may help mitigate deck cracking but will not always stop it. As part of this study, 3 bridge decks were instrumented. One was a standard class "S" concrete deck and the other two were high performance concrete. The class "S" deck showed only hairline cracking after 1 year, but transverse cracking occurred in the HPC decks. Instruments were placed in the decks to monitor strains. From the data, it appears that cracking is caused by several factors. High heat of hydration caused the plastic concrete to expand. When the concrete sets and cools, tensile stressed develop. Further tensile stresses develop through drying shrinkage. Restraining the deck against normal thermal movement contributes to additional tensile stress. Autogeneous shrinkage, where high heats of hydration cause water evaporation during hydration, and plastic shrinkage may cause more tensile stress. Recommendations for mitigating cracking include using lower cement contents, adding pozzolans and retarders, using slightly higher water/cement ratios, using larger aggregates, taking steps to limit shrinkage and eliminating restraints.
Cause And Control Of Transverse Cracking In Concrete Bridge Decks
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Author : M. Ala Saadeghvaziri
language : en
Publisher:
Release Date : 2002
Cause And Control Of Transverse Cracking In Concrete Bridge Decks written by M. Ala Saadeghvaziri and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Concrete bridges categories.
Many concrete bridge decks develop transverse cracking and most of these cracks develop at early ages, some right after construction and some after the bridge has been opened to traffic for a period of time. Structural design factors have not been the subject of much research in the past and they were the main thrust of this research study. Using 2-D and 3-D linear and nonlinear finite element models many design factors such as girder stiffness, deck thickness, girder spacing, relative stiffness of deck to girder, amount of reinforcements, etc., were studied. The research study also included a comprehensive review of the existing literature as well as survey of 24 bridges in the state of New Jersey. Results of each research task are presented and discussed in detail. Furthermore, based on analytical results and literature review, the effect of various factors are quantified and specific recommendations for possible consideration in design are made.
Identification Of Causes And Solution Strategies For Deck Cracking In Jointless Bridges
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Author : David J. Stringer
language : en
Publisher:
Release Date : 2012
Identification Of Causes And Solution Strategies For Deck Cracking In Jointless Bridges written by David J. Stringer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Bridges categories.
Bridges have traditionally relied on a system of expansion joints and flexible bearings to accommodate movements due to temperature, creep, and shrinkage loading. Joints and elements in their vicinity experience a high amount of degradation; thus modern design approaches are advocating their removal, with movement accommodated through flexible piles and abutment walls. While jointless bridges have been performing well, many of them suffer from widespread early-age transverse deck cracking. Restrained concrete shrinkage was identified as the most dominant source for the noted damage based on a literature review and a field investigation. Deck cracking is caused by the build-up of tensile forces resulting from the increased rigidity in jointless bridges. Experimentally calibrated finite-element models were used to predict deck cracking in two bridge systems under shrinkage-induced loading and a parametric study was conducted to investigate the influence of design parameters on restrained shrinkage cracking. Simulation results confirmed that the increase of system restraint increases the tendency for cracking. Models for steel and concrete beam bridges showed that both systems were equally susceptible to deck cracking due to restrained concrete shrinkage. The lowest amount of cracking was predicted for bridges with non-integral abutments, higher shear connector spacing, and a low-shrinkage concrete mix. Changing the deck reinforcement configuration had little effect on the predicted damage patterns. Use of a low-shrinkage concrete mix had the greatest impact on minimizing deck cracking. Overall, the computational simulations indicated that restrained shrinkage cracking in the decks of jointless bridges is unavoidable, but that modifying design details and improving concrete mixture designs can help reduce its extent.
Phase 1 Report On The Development Of Predictive Model For Bridge Deck Cracking And Strength Development
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Author :
language : en
Publisher:
Release Date : 2009
Phase 1 Report On The Development Of Predictive Model For Bridge Deck Cracking And Strength Development written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Bridges categories.
Early-age cracking, typically caused by drying shrinkage (and often coupled with autogenous and thermal shrinkage), can have several detrimental effects on long-term behavior and durability. Cracking can also provide ingress of water that can drive chemical reactions, such as alkali-silica reaction (ASR) and sulfate attack. Because of the problems associated with cracking observed in bridge decks, and the impact of early-age cracking on long-term performance and durability, it is imperative that bridge decks be constructed with minimal early-age cracking and that exhibit satisfactory long-term performance and durability. To achieve these goals for bridges in the state of Texas, a research team has been assembled that possesses significant expertise and background in cement chemistry, concrete materials and durability, structural performance, computational mechanics (finite difference/element), bridge deck construction and maintenance, monitoring of in-site behavior of field structures, and the development of test methods and specifications aimed at practical implementation by state highway departments. This proposal describes a laboratory- and field-based research program aimed at developing a bridge deck cracking model that will ultimately be integrated into ConcreteWorks, a suite of software programs developed for TxDOT by this same research team.
Design Methods For The Control Of Restrained Shrinkage Cracking
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Author : Robert J. Frosch
language : en
Publisher:
Release Date : 2006-09-15
Design Methods For The Control Of Restrained Shrinkage Cracking written by Robert J. Frosch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-09-15 with categories.
Transverse Cracking In Newly Constructed Bridge Decks
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Author : Paul D. Krauss
language : en
Publisher:
Release Date : 1996
Transverse Cracking In Newly Constructed Bridge Decks written by Paul D. Krauss and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Bridges, Concrete categories.
Controlling Early Age Transverse Cracking In High Performance Concrete Bridge Decks
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Author : Eric Ying Xian Liu
language : en
Publisher:
Release Date : 2013
Controlling Early Age Transverse Cracking In High Performance Concrete Bridge Decks written by Eric Ying Xian Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Transverse Cracking Of High Performance Concrete Bridge Decks
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Author : Prakash Ganesh
language : en
Publisher:
Release Date : 2006
Transverse Cracking Of High Performance Concrete Bridge Decks written by Prakash Ganesh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Cracking is a major problem with newly placed concrete decks. These decks tend to develop full depth, transverse cracks and partial depth longitudinal cracks within a few months of the concrete being placed. A literature review showed that several other states had experienced similar problems. A review of data from Ohio bridge decks showed weak correlations between deck cracking and slump, time of year when the deck was placed, shrinkage, chloride permeability and compressive strength, but there was no clear relationship between cracking and any of these properties. Data also suggested that using a coarse aggregate with an absorption> 1% may help mitigate deck cracking but will not always stop it. As part of this study, three bridge decks were instrumented. One was a standard class S concrete deck and the other two were high performance concrete. The class S deck showed only hairline cracking after 1 year, but transverse cracking occurred in the HPC decks. Instruments were placed in the decks to monitor strains. From the data, it appears that cracking is caused by several factors. High heat of hydration caused the plastic concrete to expand. When the concrete sets and cools, tensile stresses develop. Additional tensile stresses develop through drying shrinkage. Restraining the deck against normal thermal movement contributes to additional tensile stress. Autogeneous shrinkage, where high heats of hydration cause water evaporation during hydration, and plastic shrinkage may cause more tensile stress. Recommendations for mitigating cracking include using lower cement contents, adding pozzolans and retarders, using slightly higher water/cement ratios, using larger aggregates, taking steps to limit shrinkage and eliminating restraints.
Field Monitoring Of Shrinkage Cracking Potential In A High Performance Bridge Deck
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Author : Timothy Walkowich
language : en
Publisher:
Release Date : 2011
Field Monitoring Of Shrinkage Cracking Potential In A High Performance Bridge Deck written by Timothy Walkowich and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Bridges categories.
Over the past decade many state engineers throughout New Jersey have reported cracking on High Performance Concrete (HPC) bridge decks at early ages. The presence of cracking early in the life of a high performance deck offsets the benefits gained in using the material as the potential for corrosion begins at the onset of cracking. While many factors apply to bridge deck cracking, the shrinkage of the concrete's mass is a primary concern. Because of shear studs and boundary conditions, among other causes that act in restraining the deck itself, it is important to understand the mechanics of concrete under restraint. The AASHTO Passive Ring Test (PP 34-06) is seeing an increase in use in studies analyzing restrained shrinkage. The test simulates a concrete member of infinite length and allows researchers to study the effects of various parameters on restrained shrinkage. This thesis presents the results of a study that analyzed the ring test's ability to simulate restrained shrinkage on HPC bridge decks. The investigation incorporated an instrumented, simply supported composite bridge deck with laboratory samples taken on the day of the pour as well as a finite element analysis. The results suggest the AASHTO Passive Ring Test simulates the restrained shrinkage of simply supported HPC decks reasonably well. Fewer than 1% of all cracking present on the ring specimens saw complete penetration through the sample with 80-90% of all cracking considered to be micro cracking. While the presence of several cracks along the bridge deck itself showed no correlation with the shrinkage ring specimens, finite element analysis suggests these cracks are a result of adjacent live load. Also, the findings of this study highlight the importance of following design in the field as well as the effect of live load on staged construction of HPC bridge decks.