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  • Reflective Crack Mitigation Guide for Flexible Pavements
    Flexible Pavements 4 79 mb pdf October 2015 Tech transfer summary Reflective Crack Mitigation Guide for Flexible Pavements 206 92 kb pdf Oct 2015 Sponsor s partner s Sponsor s Iowa Department of Transportation Iowa Highway Research Board About the research Abstract Reflective cracks form in pavements when hot mix asphalt HMA overlays are placed over jointed and or severely cracked rigid and flexible pavements In the first part of the research survival analysis was conducted to identify the most appropriate rehabilitation method for composite pavements and to evaluate the influence of different factors on reflective crack development Four rehabilitation methods including mill and fill overlay heater scarification SCR and rubblization were analyzed using three performance indicators reflective cracking international roughness index IRI and pavement condition index PCI It was found that rubblization can significantly retard reflective cracking development compared to the other three methods No significant difference for PCI was seen among the four rehabilitation methods Heater scarification showed the lowest survival probability for both reflective cracking and IRI while overlay resulted in the poorest overall pavement condition based on PCI In addition traffic level was found not to be a significant factor for reflective cracking development An increase in overlay thickness can significantly delay the propagation of reflective cracking for all four treatments Soil types in rubblization pavement sites were assessed and no close relationship was found between rubblized pavement performance and subgrade soil condition In the second part of the research the study objective was to evaluate the modulus and performance of four reflective cracking treatments full rubblization modified rubblization crack and seat and rock interlayer A total of 16 pavement sites were tested by the surface wave method SWM and in the first four sites both falling weight deflectometer FWD and SWM were conducted for a

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=-1513285634 (2015-11-09)
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  • Evaluation of the Need for Longitudinal Median Joints in Bridge Decks on Dual Structures
    Joints in Bridge Decks on Dual Structures Longitudinal median joints under bridge deck Diagonal cracks at the corner of a bridge deck Researcher s Principal investigators Brent Phares 515 294 5879 bphares iastate edu Iowa State University Project status Completed Start date 05 01 13 End date 09 30 15 Publications Report Evaluation of the Need for Longitudinal Median Joints in Bridge Decks on Dual Structures 10 26 mb pdf September 2015 Tech transfer summary Evaluation of the Need for Longitudinal Median Joints in Bridge Decks on Dual Structures 290 97 kb pdf Sep 2015 Sponsor s partner s Sponsor s Iowa Department of Transportation Iowa Highway Research Board About the research Abstract The primary objective of this project was to determine the effect of bridge width on deck cracking in bridges Other parameters such as bridge skew girder spacing and type abutment type pier type and number of bridge spans were also studied To achieve the above objectives one bridge was selected for live load and long term testing The data obtained from both field tests were used to calibrate a three dimensional 3D finite element model FEM Three different types of loading live loading thermal loading and shrinkage loading were applied The predicted crack pattern from the FEM was compared to the crack pattern from bridge inspection results A parametric study was conducted using the calibrated FEM The general conclusions recommendations areas follows Longitudinal and diagonal cracking in the deck near the abutment on an integral abutment bridge is due to the temperature differences between the abutment and the deck Although not likely to induce cracking shrinkage of the deck concrete may further exacerbate cracks developed from thermal effects Based upon a limited review of bridges in the Iowa DOT inventory it appears that regardless of bridge width

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=1398606246 (2015-11-09)
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  • Improving the Accuracy of Camber Predictions for Precast Prestensioned Concrete Beams
    the Accuracy of Camber Predictions for Precast Prestensioned Concrete Beams Image from camber predictions field study Use of laser level system in the field Researcher s Principal investigators Sri Sritharan 515 294 5238 sri iastate edu Iowa State University Co principal investigators Terry Wipf 515 294 6979 tjwipf iastate edu Matt Rouse 515 201 6686 jmr19 iastate edu Project status Completed Start date 01 01 11 End date 09 30 15 Publications Reports Improving the Accuracy of Camber Predictions for Precast Prestensioned Concrete Beams 4 72 mb pdf September 2015 Improving the Accuracy of Camber Predictions for Precast Prestensioned Concrete Beams Appendices 6 16 mb pdf September 2015 Related publications Improving Accuracy of the Camber Predictions for Precast Prestressed Concrete Bridge Girders website off site Sep 2015 Improving the Accuracy of Camber Predictions for Precast Prestensioned Concrete Beams 599 16 kb pdf Tech transfer summary Sep 2015 Sponsor s partner s Sponsor s Iowa Department of Transportation Iowa Highway Research Board About the research Abstract The discrepancies between the designed and measured camber of precast pretensioned concrete beams PPCBs observed by the Iowa DOT have created challenges in the field during bridge construction causing construction delays and additional costs This study was undertaken to systematically identify the potential sources of discrepancies between the designed and measured camber from release to time of erection and improve the accuracy of camber estimations in order to minimize the associated problems in the field To successfully accomplish the project objectives engineering properties including creep and shrinkage of three normal concrete and four high performance concrete mix designs were characterized In parallel another task focused on identifying the instantaneous camber and the variables affecting the instantaneous camber and evaluated the corresponding impact of this factor using more than 100 PPCBs Using a combination of finite

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=-1685116323 (2015-11-09)
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  • Investigation of Negative Moment Reinforcing in Bridge Decks
    Phares 515 294 5879 bphares iastate edu Iowa State University Co principal investigators Travis Hosteng 515 294 7197 kickhos iastate edu Yaohua Deng 515 294 2882 jimdeng iastate edu Project status Completed Start date 05 01 13 End date 09 30 15 Publications Report Investigation of Negative Moment Reinforcing in Bridge Decks 6 62 mb pdf September 2015 Tech transfer summary Investigation of Negative Moment Reinforcing in Bridge Decks 780 28 kb pdf Sep 2015 Sponsor s partner s Sponsor s Iowa Department of Transportation Iowa Highway Research Board About the research Abstract Multi span pre tensioned pre stressed concrete beam PPCB bridges made continuous usually experience a negative live load moment region over the intermediate supports Conventional thinking dictates that sufficient reinforcement must be provided in this region to satisfy the strength and serviceability requirements associated with the tensile stresses in the deck The American Association of State Highway and Transportation Officials AASHTO Load and Resistance Factor Design LRFD Bridge Design Specifications recommend the negative moment reinforcement b2 reinforcement be extended beyond the inflection point However based upon satisfactory previous performance and judgment the Iowa Department of Transportation DOT Office of Bridges and Structures OBS currently terminates b2 reinforcement at 1 8 of the span length Although the Iowa DOT policy results in approximately 50 shorter b2 reinforcement than the AASHTO LRFD specifications the Iowa DOT has not experienced any significant deck cracking over the intermediate supports The primary objective of this project was to investigate the Iowa DOT OBS policy regarding the required amount of b2 reinforcement to provide the continuity over bridge decks Other parameters such as termination length termination pattern and effects of the secondary moments were also studied Live load tests were carried out on five bridges The data were used to calibrate three dimensional

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=-1258966231 (2015-11-09)
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  • Asset Management Program Enhancement Plan: Baseline Assessment Phases I and II
    crumbling fascia and steel girders in satisfactory condition Image Bridge Engineering Center Researcher s Principal investigators Doug Gransberg 515 294 2140 dgran iastate edu Project status Completed Start date 03 15 12 End date 09 22 15 Publications Report Asset Management Program Enhancement Plan Baseline Assessment Phases I and II 7 05 mb pdf September 2015 Related publications Asset Management Program Enhancement Plan Baseline Assessment Phases I and II 323 25 kb pdf Tech transfer summary Sep 2015 Transportation Asset Management from Plans to Practice A Workshop for State Practitioners off site May 2015 Sponsor s partner s Sponsor s Federal Highway Administration State Planning and Research Funding Iowa Department of Transportation About the research Abstract This project resulted in the development of a framework for making asset management decisions on low volume bridges The research focused on low volume bridges located in the agricultural counties of Iowa because recent research has shown that these counties have the greatest percentage of structurally deficient bridges in the nation Many of the same counties also have the highest crop yields in the state creating a situation where detours caused by deficient bridges on farm to market roads increase the cost to transport

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=-1646980532 (2015-11-09)
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  • Designing and Applying a Decision Support System for DOT Fleet Assignment and Operation
    for Transportation Address 2711 S Loop Drive Suite 4700 Ames IA 50010 8664 Phone 515 294 8103 FAX 515 294 0467 Website www ctre iastate edu Copyright 1996 2009 Iowa State University All rights reserved Designing and Applying a Decision Support System for DOT Fleet Assignment and Operation Researcher s Principal investigator Ron McGarvey University of Missouri Columbia Co principal investigator Charles Nemmers University of Missouri Columbia Project status Completed Start date 06 23 14 End date 08 31 15 Publications Report Improving Striping Operations through System Optimization 3 07 mb pdf October 2015 Sponsor s partner s Sponsor s Midwest Transportation Center Missouri Department of Transportation USDOT OST R About the research Abstract Striping operations generate a significant workload for Missouri Department of Transportation MoDOT maintenance operations The requirement for each striping crew to replenish its stock of paint and other consumable items from a bulk storage facility along with the necessity to make several passes on most of the routes to stripe all the lines on that road introduce the potential for inefficiencies in the form of deadhead miles that striping crew vehicles must travel while not actively applying pavement markings These inefficiencies generate unnecessary travel wasted time

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=2139436905 (2015-11-09)
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  • Evaluating Roadway Subsurface Drainage Practices - Phase II
    Iowa State University center administered by the Institute for Transportation Address 2711 S Loop Drive Suite 4700 Ames IA 50010 8664 Phone 515 294 8103 FAX 515 294 0467 Website www ctre iastate edu Copyright 1996 2009 Iowa State University All rights reserved Evaluating Roadway Subsurface Drainage Practices Phase II Researcher s Principal investigators Halil Ceylan 515 294 8051 hceylan iastate edu Iowa State University Co principal investigators Bob Steffes 515 294 7323 steffesr iastate edu Iowa State University Kasthurira Gopalakrishnan 515 294 3044 rangan iastate edu Iowa State University Sunghwan Kim sunghwan iastate edu Project status Completed Start date 06 10 13 End date 08 31 15 Publications Report Evaluating Roadway Subsurface Drainage Practices Phase II 10 23 mb pdf May 2015 Tech transfer summary Evaluating Roadway Subsurface Drainage Practices Phase II 1 24 mb pdf May 2015 Sponsor s partner s Sponsor s Iowa Department of Transportation Iowa Highway Research Board About the research Abstract The primary objectives of this Phase II research are as follows Evaluate seasonal variation effects dry Fall 2012 versus wet Spring Summer 2013 etc on subdrain outlet condition and performance Investigate the characteristics of tufa formation in Iowa subdrain outlets i e identify

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=-1099886015 (2015-11-09)
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  • Laboratory Investigation of Grouted Coupler Connection Details for ABC Bridge Projects
    2009 Iowa State University All rights reserved Laboratory Investigation of Grouted Coupler Connection Details for ABC Bridge Projects Typical width of cracks with UHPC bedding grout during loading of specimen Typical width of cracks with standard bedding grout during loading of specimen UHPC grout bed Static four point bending test with applied axial load specimen in the test frame setup with axial load applied with post tension rods Researcher s Principal investigators Brent Phares 515 294 5879 bphares iastate edu Iowa State University Co principal investigators Travis Hosteng 515 294 7197 kickhos iastate edu Project status Completed Start date 11 01 12 End date 08 31 15 Publications Report Laboratory Investigation of Grouted Coupler Connection Details for ABC Bridge Projects 5 36 mb pdf August 2015 Tech transfer summary Laboratory Investigation of Grouted Coupler Connection Details for ABC Bridge Projects 1 88 mb pdf Aug 2015 Sponsor s partner s Sponsor s Federal Highway Administration State Planning and Research Funding Iowa Department of Transportation About the research Abstract With an ever increasing desire to utilize accelerated bridge construction ABC techniques it is becoming critical that bridge designers and contractors have confidence in typical details The Keg Creek Bridge on US 6 in Iowa was a recent ABC example that utilized a number of connection details that had been utilized elsewhere The connection details used between the drilled shaft and pier column and between the pier column and the pier cap were details needing evaluation These connection details utilized grouted couplers that have been tested by others with mixed results some indicating quality performance and some indicating questionable performance There was a need to test these couplers to gain an understanding of their performance in likely Iowa details and to understand how their performance might be impacted by different construction processes

    Original URL path: http://www.ctre.iastate.edu/research/detail.cfm?projectID=1939251825 (2015-11-09)
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