Download or read book Phase 1 Report on the Development of Predictive Model for Bridge Deck Cracking and Strength Development written by and published by . This book was released on 2009 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Development of Predictive Model for Bridge Deck Cracking written by Philip Pesek and published by . This book was released on 2017 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Temperature Stress and Strength Development of Early age Bridge Deck Concrete written by Phillip Wayne Pesek and published by . This book was released on 2011 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: In bridge deck concrete, early-age cracking can lead to substantial serviceability and structural integrity issues over the lifespan of the bridge. An understanding of the temperature, stress, and strength development of concrete can aid determining the early-age cracking susceptibility. This project, funded by the Texas Department of Transportation, evaluated these properties for various bridge deck materials and mixture proportions. The research presented in this thesis involved a laboratory testing program that used a combination of semi-adiabatic calorimetry, rigid cracking frame, free shrinkage frame, and match cured cylinder testing program that allowed the research team to simulate the performance of common bridge deck mixture designs under hot and cold weather conditions. In this program, the semi-adiabatic calorimetry was used, with previously generated models, to generate the temperature profile of the mixture. The rigid cracking frame and free shrinkage frame were used to evaluate the restrained stress development and the unrestrained volume changes, respectively, under the simulated temperatures. The match-cure cylinder testing program allowed the research team to generate a strength development profile for the concrete mixtures under the various simulated temperature profiles. Results from the laboratory program revealed that in hot weather simulations, ground granulated blast furnace slag mixtures developed the lowest stress / strength ratios, and in cold weather simulations, Class F fly ash mixtures developed the lowest stress / strength ratios. In general, use of SCMs and limestone coarse aggregate results in mixtures that generate less heat and lower stress / strength ratios. Isothermal testing showed that shrinkage reducing admixtures were effective in reducing early-age strains from chemical shrinkage. In addition to the laboratory testing program, a field testing program was completed to measure the temperature development of four bridge decks during the winter and summer months. The recorded concrete temperatures and the effects of the environmental conditions at the time of the pour will aid in the calibration and validation of the temperature prediction component of ConcreteWorks for bridge deck construction. In addition, experience gained through these field pours resulted in an optimized instrumentation procedure that will aid in the successful collection of data in future projects.

Download or read book Development and Validation of Deterioration Models for Concrete Bridge Decks written by Emily K. Winn and published by . This book was released on 2013 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research documents the development and evaluation of artificial neural network (ANN) models to predict the condition ratings of concrete highway bridge decks in Michigan. Historical condition assessments chronicled in the national bridge inventory (NBI) database were used to develop the ANN models. Two types of artificial neural networks, multi-layer perceptrons and ensembles of neural networks (ENNs), were developed and their performance was evaluated by comparing them against recorded field inspections and using statistical methods. The MLP and ENN models had an average predictive capability across all ratings of 83% and 85%,respectively, when allowed a variance equal to bridge inspectors. A method to extract the influence of parameters from the ANN models was implemented and the results are consistent with the expectations from engineering judgment. An approach for generalizing the neural networks for a population of bridges was developed and compared with Markov chain methods. Thus, the developed ANN models allow modeling of bridge deck deterioration at the project (i.e., a specific existing or new bridge) and system/network levels. Further, the generalized ANN degradation curves provided a more detailed degradation profile than what can be generated using Markov models. A bridge management system (BMS) that optimizes the allocation of repair and maintenance funds for a network of bridges is proposed. The BMS uses a genetic algorithm and the trained ENN models to predict bridge deck degradation. Employing the proposed BMS leads to the selection of optimal bridge repair strategies to protect valuable infrastructure assets while satisfying budgetary constraints. A program for deck degradation modeling based on trained ENN models was developed as part of this project.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1982 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Numerically Modeling Steel Continuous Bridges for Early Age Concrete Deck Cracking written by Abdul Aziz Salah and published by . This book was released on 2020 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early age bridge deck cracking is a common problem throughout the United States. Early age cracking develops shortly after the deck is poured. It reduces the serviceability and lifespan of bridges. Early age cracking can be typically attributed to either of two factors, 1) construction practices, and 2) shrinkage. The Arkansas Department of Transportation (ARDOT) has experienced early age bridge deck cracking. ARDOT currently specifies a sequence deck pour on most of their bridges; however, contractors prefer continuous deck pours because of ease and construction time. During the period of this TRC1903 research project, ARDOT has only approved a few continuous pours for relatively short bridges, 180 to 190 ft. long. Concrete cracking occurs when concrete tensile stresses exceed the concrete's tensile strength. Therefore, early age bridge deck cracking is evaluated in this thesis be monitoring induced concrete tensile stresses and comparing these values with the concrete's concurrent tensile strength. Bridge site visits at bridges constructed using a continuous deck pour process were conducted to study deck cracking patterns in newly constructed bridges and identify deck sections that were experiencing cracking. In addition to a visual approach for identifying sections experiencing cracking, a numerical method was used. Finite element bridge models were created using ABAQUS to compare numerical modeling results to field recorded results attained from a bridge instrumented with strain gauges cast inside the concrete deck. Additional numerical models were made to verify the modeling techniques used by the author by validating calculated stresses with numerical models in the literature. The Finite element models were specifically developed to model the bridge deck construction process. Therefore, time dependent loads and material properties were considered in the numerical model. Concrete material time dependency was estimated using the Eurocode specifications (CEN., 1992). In addition, concrete stresses were calculated in this thesis using the Eurocode modular ratio approach.

Download or read book Public Roads written by and published by . This book was released on 1971 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Methods for the Control of Restrained Shrinkage Cracking written by Robert J. Frosch and published by . This book was released on 2006-09-15 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Validation of Deterioration Models for Concrete Bridge Decks written by Nan Hu and published by . This book was released on 2013 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes a research project aimed at developing degradation models for bridge decks in the state of Michigan based on durability mechanics. A probabilistic framework to implement local-level mechanistic-based models for predicting the chloride-induced corrosion of the RC deck was developed. The methodology is a two-level strategy: a three-phase corrosion process was modeled at a local (unit cell) level to predict the time of surface cracking while a Monte Carlo simulation (MCS) approach was implemented on a representative number of cells to predict global (bridge deck) level degradation by estimating cumulative damage of a complete deck. The predicted damage severity and extent over the deck domain was mapped to the structural condition rating scale prescribed by the National Bridge Inventory (NBI). The influence of multiple effects was investigated by implementing a carbonation induced corrosion deterministic model. By utilizing realistic and site-specific model inputs, the statistics-based framework is capable of estimating the service states of RC decks for comparison with field data at the project level. Predicted results showed that different surface cracking time can be identified by the local deterministic model due to the variation of material and environmental properties based on probability distributions. Bridges from different regions in Michigan were used to validate the prediction model and the results show a good match between observed and predicted bridge condition ratings. A parametric study was carried out to calibrate the influence of key material properties and environmental parameters on service life prediction and facilitate use of the model. A computer program with a user-friendly interface was developed for degradation modeling due to chloride induced corrosion.

Download or read book Developing Predictive Tools and Guidance to Increase the Durability of Concrete Infrastructure by Reducing Alkali Silica Reaction ASR and Early Age Cracking written by Jared Robert Wright and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete degradation modes that reduce concrete durability are typically summarized as the following: cracking, physical attack, and chemical attack. Examples of cracking that reduces concrete durability are those that are caused by restrained volume reduction of concrete and those due to service loads exceeding the tensile strength of concrete. An example of physical attack is stresses induced by freezing and thawing cycles. Examples of chemical attack are alkali-silica reaction (ASR) and corrosion of embedded reinforcing steel. This dissertation develops predictive statistical tools and guidance to reduce concrete degradation and increase the durability of concrete infrastructure by reducing 1) cracking (specifically at early-ages) and 2) alkali-silica reaction (ASR). Therefore, this dissertation is separated into two (2) paths. Research Path 1: Identify potential causes of early-age cracking and provide best practices guidance to mitigate future cracking. The main objective of this research path is to identify the causes of longitudinal early-age cracking in concrete deck segments placed adjacent to newly replaced bridge deck expansion joints in Pennsylvania. The work consists of: 1) a literature review of the causes of early-age cracking on bridge decks; 2) a review of past and active bridge deck rehabilitation projects; and 3) an experimental evaluation of the most commonly used PennDOT bridge deck concrete mixtures to revise/update PennDOT specifications. Overall, an integrated approach to ensure proper selection and design of concrete materials, proper structural design of the deck (including the repair section), and proper construction and curing methods is needed to minimize early-age cracking of the concrete deck and repair sections. Main conclusions are material properties and construction practices play a greater role in determining the early-age concrete cracking characteristics for traditionally designed bridge decks. Results may be used as a best practices outline for reducing early-age concrete cracking. Research Path 2: Develop predictive statistical tools and guidance to reduce ASR in concrete infrastructure. It is important to limit the unnecessary waste of high quality pulverized coal fly ash because it is estimated that the supply of ASTM C 618 compliant fly ash (or 'concrete grade' fly ash) in the U.S. in 2030 will be approximately 14 million tons while the demand by the concrete industry will exceed 35 million tons. Accordingly, it is clear that all existing 'concrete grade' fly ash must be used efficiently and that the future and present needs of concrete producers include the availability of new supplemental cementitious materials (SCMs) and/or chemical admixtures effective at mitigating ASR. Therefore, this dissertation develops predictive statistical models to efficiently utilize the existing supply of 'concrete grade' fly ash and determines the effectiveness of novel SCMs and/or chemical admixtures effective at mitigating ASR for use in concrete as fly ash use sunsets. Task 1: Develop predictive statistical models to assist in mix proportioning of concrete to mitigate ASR. Three predictive statistical models are developed as part of this dissertation. The 1st statistical model modifies and evaluates an existing model to determine fly ash dosages necessary to mitigate ASR in concrete mixtures containing highly reactive recycled glass sand according to the accelerated ASTM C 1567 test. For the first time, this statistical model provides a blueprint for material producers to attain the proper fly ash dosage necessary to mitigate ASR when using very highly reactive recycled glass sand aggregates. The 2nd statistical model modifies and evaluates an existing model to determine fly ash dosages necessary to mitigate ASR in concrete mixtures according to ASTM C 1293. Finally, a 3rd statistical model is summarized, which is a novel statistical model which also determines fly ash dosages necessary to mitigate ASR in concrete mixtures according to ASTM C 1293. Task 2: Develop guidance for deploying next generation supplemental cementitious materials (SCMs) and chemical admixtures effective at mitigating ASR This dissertation provides a summary of the performance of recycled soda-lime glass powder (SLGP) and Al(OH)3 as supplemental cementitious materials (SCMs) at mitigating ASR. It is determined that both admixtures undergo the pozzolanic reaction and reduce ASR. However, results indicate SLGP is a net contributor to the total alkalis of the cementitious pore solution, thus exacerbating ASR over time. With respect to Al(OH)3, for the first time, it is proven that Portland cement admixed with Al(OH)3 will mitigate ASR according to long-term ASTM C 1293 testing. The three (3) main ASR reducing mechanisms are described within.

Download or read book Government Reports Annual Index written by and published by . This book was released on 1991 with total page 1646 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

Download or read book Deterioration Prediction Models for Condition Assessment of Concrete Bridge Decks Using Machine Learning Techniques written by Nour Hider Almarahlleh and published by . This book was released on 2021 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges play a significant role in the U.S. economy. The number of the bridges in the U.S. exceeds six hundred thousand. Almost one third of them are considered structurally deficient and will require more than $164 billion to repair or replace. Identifying the factors that affect the performance of concrete bridge decks during its service life is critical to the development of an accurate condition assessment and deterioration prediction model. Accurate bridge deck deterioration models can provide vital information for predicting short- and long-term behavior of concrete bridge decks and minimizing costly routine inspection and maintenance activities. Therefore, the main goal of this dissertation is to develop a deterioration prediction model for concrete bridge decks that is based on the National Bridge Inventory (NBI) database. To achieve the goal, five deterioration prediction models for concrete bridge decks were developed using Multinomial Logistic Regression, Decision Tree, Artificial Neural Network, k-Nearest Neighbors and Naive Bayesian machine learning techniques. Michigan bridge deck data from NBI between the years 1992 to 2015 were used for training the various prediction models. The results show that the performance of all five developed models were acceptable. However, the artificial neural network achieved the highest accuracy in the validation process. Additionally, bridge decks age, area, average daily traffic, and skew angle are found to be significant factors in the deterioration of concrete bridge decks. Furthermore, it was observed that bridge decks could stay in their condition rating more than the typical 2-year inspection interval, suggesting that inspection schedules could be extended for certain bridges that had slower deterioration rates. The contributions of this work include 1) the development of an optimized deterioration prediction model that can be used in the condition assessment process for concrete bridge decks, 2)the identification of the factors that have the most impact on concrete bridge deck deterioration,and 3) demonstrating that the inspection schedule can be longer than 2 years for bridges that do not deteriorate fast which can lead to cost and time savings. Future work can include the following: (1)developing deterioration prediction models for concrete bridge decks using deep learning techniques; (2) developing deterioration prediction models for other bridge specific elements (i.e., superstructure and substructure) using multivariant analysis; (3) developing deterioration prediction models for other (or all) U.S. states using the framework developed in this research; and (4) investigating the prospect of revising the mandated inspection interval beyond the 2-year period.

Download or read book Study of Internal Strains Developed in Concrete Decks at Early Ages in Steel Continuous Bridges written by Fernando Rafael Benitez Ortiz and published by . This book was released on 2019 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arkansas Department of Transportation (ARDOT) has identified bridge deck cracking shortly after concrete decks are placed and prior to applying traffic loads. Previous researchers have confirmed improper construction practices and design methods can lead to deck cracking. Currently, many contractors throughout Arkansas are using continuous deck pours. This construction approach may restrict the concrete slab from movement during early age shrinkage, causing tensile stresses to develop. The final stresses at the end of construction must be lower than the concrete tensile strength, if not cracking issues will develop. Eventually, these cracks may enlarge due to service load stresses and environmental damage. A nation-wide Department of Transportation (US DOTs) survey was performed to investigate the early age cracking extensiveness level in other state's bridges and what corrections, if any, they have made to address this problem. Additionally, Arkansas bridges with early age cracking were visited to examine any trends and inform instrumentation for bridge testing. A bridge deck was instrumented with 32 vibrating wire strain gauges prior to concrete placement to investigate strain and temperature changes in the first 14 days. Eurocode and ACI approximations for concrete mechanical properties were compared to field measured data for improving the understanding of an early age concrete deck behavior in a continuous steel bridge. Stress analysis study through the span length of bridge 030428 detected some locations prone to concrete cracking due to the variability of concrete mechanical properties and stress developed in the concrete deck. This thesis describes the results of this monitoring and anything that can be learned about formation of concrete stresses in continuous concrete bridge deck pours.

Download or read book Deterioration Prediction Modeling for the Condition Assessment of Concrete Bridge Decks written by Aqeed Mohsin Chyad and published by . This book was released on 2018 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges are key elements in the US transportation system. There are more than six hundred thousand bridges on the highway system in the United States. Approximately one third of these bridges are in need of maintenance and will cost more than $120 billion to rehabilitate or repair. Several factors affect the performance of bridges over their life spans. Identifying these factors and accurately assessing the condition of bridges are critical in the development of an effective maintenance program. While there are several methods available for condition assessment, selecting the best technique remains a challenge. Therefore, developing an accurate and reliable model for concrete bridge deck deterioration is a key step towards improving the overall bridge condition assessment process. Consequently, the main goal of this dissertation is to develop an improved bridge deck deterioration prediction model that is based on the National Bridge Inventory (NBI) database. To achieve the goal, deterministic and stochastic approaches have been investigated to model the condition of bridge decks. While the literatures have typically proposed the Markov chain method as the best technique for the condition assessment of bridges, this dissertation reveals that some probability distribution functions, such as Lognormal and Weibull, could be better prediction models for concrete bridge decks under certain condition ratings. A new universal framework for optimizing the performance of prediction of concrete bridge deck condition was developed for this study. The framework is based on a nonlinear regression model that combines the Markov chain method with a state-specific probability distribution function. In this dissertation, it was observed that on average, bridge decks could stay much longer in their condition ratings than the typical 2-year inspection interval, suggesting that inspection schedules might be extended beyond 2 years for bridges in certain condition rating ranges. The results also showed that the best statistical model varied from one state to another and there was no universal statistical prediction model that can be developed for all states. The new framework was implemented on Michigan data and demonstrated that the prediction error in the combined model was less than each of the two models (i.e. Markov and Lognormal). The results also showed that average daily traffic, age, deck area, structure type, skew angle, and environmental factors have significant impact on the deterioration of concrete bridge decks. The contributions of the work presented in this dissertation include: 1) the identification of the significant factors that impact concrete bridge deck deterioration; 2) the development of a universal deterioration prediction framework that can be uniquely tailored for each state’s data; and 3) supporting the possibility of extending inspection schedules beyond the typical 2-year cycles. Future work may involve: 1) evaluating each of the factors that impact the deterioration rates in more depth by refining the investigation ranges; 2) investigating the possibility of revising the regular bridge deck inspection intervals beyond the 2-year cycles; and 3) developing deterioration prediction models for other bridge elements (i.e. superstructure and substructure) using the framework developed in this dissertation.

Download or read book Cause and Control of Transverse Cracking in Concrete Bridge Decks written by M. Ala Saadeghvaziri and published by . This book was released on 2002 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Highway Research Abstracts written by and published by . This book was released on 1992 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: