Deterioration of J-Bar Reinforcement in Abutments and Piers
Author: Harries, Kent | Size: 4.56 MB | Format:PDF | Quality:Original preprint | Publisher: University of Pittsburgh | Year: 2011 | pages: 73
Deterioration and necking of J-bars has been reportedly observed at the interface of the footing and stem wall during the demolition of older retaining walls and bridge abutments. Similar deterioration has been reportedly observed between the pier column and footing. Any decrease in the area of steel at these interfaces may result in foundation instability, and hamper efforts to rehabilitate or preserve existing foundations. The objective of this project was to determine the extent and nature of deterioration and/or necking of J-bars in existing bridge structures. This must be understood in order to identify existing structures having the potential for or existence of deteriorated J-bars. Once at-risk structures were identified, methods to identify and validate deterioration and remedial measures, details, and methodologies were developed to address affected structures.
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Posted by: mahyarov - 10-29-2012, 06:46 AM - Forum: Concrete
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Manual for Design, Construction, and Maintenance of Orthotropic Steel Deck Bridges
Author: Anderson, Darryl DiBrito, Bill | Size: 2.77 MB | Format:PDF | Quality:Original preprint | Publisher: Anderson Engineering and Surveying, Incorporated | Year: 2012 | pages: 60
The Oregon Department of Transportation (ODOT) has experienced early age cracking of newly placed high performance concrete (HPC) bridge decks. The silica fume contained in the HPC requires immediate and proper curing application after placement to avoid early age cracks. Many construction contractors do not consistently apply adequate curing procedures, and project sites may not have easy access to water. This problem led ODOT to investigate a self-curing admixture (SCA) for bridge deck concrete mixes. The SCA reduces wet curing requirements by counteracting to some degree water loss due to evaporation. An admixture in place of wet curing that allows HPC bridge deck concrete to cure properly without early age cracking and without decreasing other performance requirements would provide another option for contractors. The study showed that concrete with the SCA after a 3-day wet cure can produce similar results to standard HPC concrete with a 14-day wet cure. However, the concrete additives in the concrete must be compatible with the SCA.
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Manual for Design, Construction, and Maintenance of Orthotropic Steel Deck Bridges
Author: Connor, Robert Fisher, John Gatti, Walter Gopalaratnam, Vellore Kozy, Brian Leshko, Brian McQuaid, David L Medlock, Ronald Mertz, Dennis Murphy, Thomas Paterson, Duncan Sorensen, Ove Yadlosky, John | Size: 9.92 MB | Format:PDF | Quality:Original preprint | Publisher: HDR Engineering, Incorporated | Year: 2012 | pages: 291
Precast concrete bridge rail systems offer several advantages over traditional cast-in-place rail designs, including reduced construction time and costs, installation in a wide range of environmental conditions, easier maintenance and repair, improved railing quality, and greater flexibility for aesthetic treatments. The objective of this project was to develop a precast concrete bridge rail system that met the Test Level 4 impact safety standards provided in the American Association for State Highway and Transportation Officials (AASHTO) document entitled Manual for Assessing Safety Hardware (MASH). The design criteria for the new bridge rail system included criteria for barrier geometry, provisions for open and closed rail options, constructability, weight limitations, segment length, design impact loads, connection of barrier segments, and connection to the bridge deck among other factors. The research effort proceeded in several phases. First, the research focused on determining the overall concept for the new bridge rail system in terms of the rail configuration and geometry as well as the required barrier reinforcement. Next, design concepts for the joints connecting adjacent rail segments were designed and subjected to dynamic component testing in order to select a design capable of meeting design criteria for the precast bridge rail system. After selection of an appropriate rail joint, the researchers developed connection details for the attachment of the rail to the bridge deck. Once the design of the various precast bridge rail components was completed, a complete set of computer-aided design (CAD) details for the prototype precast concrete bridge rail system were completed. Following the design effort, recommendations were made regarding the full-scale testing required to implement the new, precast concrete bridge rail system.
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Phase 1 Development of An Aesthetic Precast Concrete Bridge Rail
Author: Rosenbaugh, Scott K Faller, Ronald K Bielenberg, Robert W Sicking, Dean L Reid, John D | Size: 41.66 MB | Format:PDF | Quality:Original preprint | Publisher: University of Nebraska, Lincoln | Year: 2012 | pages: 360
Precast concrete bridge rail systems offer several advantages over traditional cast-in-place rail designs, including reduced construction time and costs, installation in a wide range of environmental conditions, easier maintenance and repair, improved railing quality, and greater flexibility for aesthetic treatments. The objective of this project was to develop a precast concrete bridge rail system that met the Test Level 4 impact safety standards provided in the American Association for State Highway and Transportation Officials (AASHTO) document entitled Manual for Assessing Safety Hardware (MASH). The design criteria for the new bridge rail system included criteria for barrier geometry, provisions for open and closed rail options, constructability, weight limitations, segment length, design impact loads, connection of barrier segments, and connection to the bridge deck among other factors. The research effort proceeded in several phases. First, the research focused on determining the overall concept for the new bridge rail system in terms of the rail configuration and geometry as well as the required barrier reinforcement. Next, design concepts for the joints connecting adjacent rail segments were designed and subjected to dynamic component testing in order to select a design capable of meeting design criteria for the precast bridge rail system. After selection of an appropriate rail joint, the researchers developed connection details for the attachment of the rail to the bridge deck. Once the design of the various precast bridge rail components was completed, a complete set of computer-aided design (CAD) details for the prototype precast concrete bridge rail system were completed. Following the design effort, recommendations were made regarding the full-scale testing required to implement the new, precast concrete bridge rail system.
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This document contains the Appendices A through D for the report Strength and Durability of Near-Surface Mounted CFRP Bars for Shear Strengthening Reinforced Concrete Bridge Girders published in a separate 123-page document.
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Health Monitoring of Precast Bridge Deck Panels Reinforced with Glass Fiber Reinforced Polymer Bars
Author: Pantelides, Chris P Holden, Korin M Ries, James | Size: 3.88 MB | Format:PDF | Quality:Original preprint | Publisher: University of Utah, Salt Lake City | Year: 2012 | pages: 105
The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, long term health monitoring is important to record the performance and limit states of the GFRP decks and bridge as a whole. In this research, data is collected on concrete strains, bridge deflections, vertical girder accelerations, as well as initial truck load testing and lifting strains.
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Author: Arneson, L A Zevenbergen, L W Lagasse, P F Clopper, P E | Size: 6.55 MB | Format:PDF | Quality:Original preprint | Publisher: Ayres Associates, Incorporated | Year: 2012 | pages: 340
This document is the fifth edition of HEC-18. It presents the state of knowledge and practice for the design, evaluation and inspection of bridges for scour. There are two companion documents, HEC-20 entitled "Stream Stability at Highway Structures," and HEC-23 entitled "Bridge Scour and Stream Instability Countermeasures." These three documents contain updated material from previous editions and continued research by NCHRP, FHWA, State DOTs, and universities. This fifth edition of HEC-18 also contains revisions obtained from further scour-related developments and the use of the 2001 edition by the highway community. The major changes in the fifth edition of HEC-18 are: expanded discussion on the policy and regulatory basis for the FHWA Scour Program, including risk-based approaches for evaluations, developing Plans of Action (POAs) for scour critical bridges, and expanded discussion on countermeasure design philosophy (new vs. existing bridges). This fifth edition includes: a new section on contraction scour in cohesive materials, an updated abutment scour section, alternative abutment design approaches, alternative procedures for estimating pier scour, and new guidance on pier scour with debris loading. There is a new chapter on soils, rock and geotechnical considerations related to scour. Additional changes include: a new approach for pier scour in coarse material, new sections on pier scour in cohesive materials and pier scour in erodible rock, revised guidance for vertical contraction scour (pressure flow) conditions, guidance for predicting scour at bottomless culverts, deletion of the "General Scour" term, and revised discussion on scour at tidal bridges to reflect material now covered in HEC-25 (2nd Edition).
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Settlement and heave related movements of bridge approach slabs relative to bridge decks create a bump in the roadway. Several problems arise from these bumps, which include poor riding conditions, potential vehicle damage, loss of vehicle control causing injuries or even casualities, lowered perception of the department’s road works, increased maintenance works, and constant delays to rehabilitate the distressed lanes. All these make this bump problem a major maintenance problem in Texas. Several mitigation methods have been employed, and the results are not always satisfactory. In the present research, two treatment methods were investigated for controlling settlements of approach slabs of new bridge construction. Researchers from the University of Texas at Arlington and the University of Texas at El Paso performed two phases to accomplish these studies. During the first phase, the documented information that covers various methods used so far for approach slab settlement mitigation technologies was compiled and presented. The second and final phase focused on field evaluation studies of deep soil mixing and lightweight embankment fill treatment methods in reducing settlements. A few other technologies were also evaluated for reducing settlements of existing bridge approach slabs. Both design and construction specifications of the new methods that provided effective treatments in field conditions are presented.
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This Primer is intended to be a practical supplement to NCHRP Report 534, "Guidelines for Inspection and Strength Evaluation of Suspension Bridge Parallel Wire Cables," and FHWA Report No. FHWA-PD-96-001, titled "Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges." This Primer will serve as an initial resource for those involved in the inspection, metallurgical testing, and strength evaluation of suspension bridge cables in addition to providing necessary documentation for recording performed inspections, testing, and strength evaluations. Furthermore, this document is intended to provide field inspectors, technicians, and/or engineers with the necessary forms and information they need to perform an inspection.
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Posted by: mahyarov - 10-29-2012, 06:27 AM - Forum: Concrete
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Validation of Prestressed Concrete I-Beam Deflection and Camber Estimates
Author: O’Neill, Cullen R French, Catherine E | Size: 3.34 MB | Format:PDF | Quality:Original preprint | Publisher: University of Minnesota, Twin Cities | Year: 2012 | pages: 205
The camber at the time of bridge erection of prestressed concrete bridge girders predicted by the Minnesota Department of Transportation (MnDOT) was observed to often overestimate the measured cambers of girders erected at bridge sites in Minnesota, which, in some cases, was causing significant problems related to the formation of the bridge deck profile, the composite behavior of the girders and bridge deck, delays in construction and increased costs. Extensive historical data was collected from two precasting plants and MN counties and it was found that, on average, the measured cambers at release and erection were only 74% and 83.5%, respectively, of the design values. Through data collection, analysis, and material testing, it was found that the primary causes of the low camber at release were concrete release strengths that exceeded the design values, the use of an equation for concrete elastic modulus that greatly under-predicted the measured values, and thermal prestress losses not accounted for in design. Fourteen girders were instrumented and their camber measured and the program PBEAM was used to evaluate the influence of various time-dependent effects (i.e., solar radiation, relative humidity, concrete creep and shrinkage, length of cure and bunking/storage conditions) on long-term camber. Once investigated, these effects were included in long-term camber predictions that were used to create sets of both time-dependent and singlevalue camber multipliers. The use of these multipliers, along with modifications made to the elastic release camber calculations, greatly reduced the observed discrepancy between measured and design release and erection cambers.
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