Field Inspection of In-Service FRP Bridge Decks (2006) / Chapter Skim
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Pages 124-164
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From page 125... ...
SUMMARY: REPORT After the Cold War, the technology transfer initiatives taken by the federal government to use the unused manufacturing capacities of composite manufacturers in the military and space industries resulted in the proliferation of fiber reinforced polymers (FRP) usage in the bridge industry.
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CHAPTER 1 INTRODUCTION AND RESEARCH APPROACH The objective of NCHRP Project 10-64, "Field Inspection of In-Service FRP Bridge Decks" (initiated by the project research team on April 24, 2003) was to develop a recommended manual and an inspector's training course for field inspection of in-service FRP bridges.
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The number of FRP-decked bridges is continuously growing as bridge engineers become more comfortable with the material and its performance. The lack of standardization, however, has been a challenge to bridge engineers, who traditionally are accustomed to standard shapes, sizes, and material properties.
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127 Field Inspection of In-Service FRP Bridge Decks: Report inspection, to experimental NDE techniques. The criteria for field inspection should be based on identification of critical components of FRP decks and determination of critical accumulated damage thresholds in those components.
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detection, select procedures from those identified in Task 2 based on technical, operational, and economic criteria. Document and justify the reasons for these selections.
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129 Field Inspection of In-Service FRP Bridge Decks: Report The research team conducted a complete technological review to identify the variety of FRP bridge deck problems and their causes. Emphasis was given to identifying the types and composition of FRP bridge decks, common detailing practices, problems associated with each type of bridge deck, and the likely causes responsible for the various problems.
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Inspection and assessment of FRP components. Because limited published literature was available from civil engineering applications, the literature in this area was collected from sources and industries such as the military, aerospace, shipbuilding/naval engineering, pipeline, and industrial applications.
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131 Field Inspection of In-Service FRP Bridge Decks: Report for the Tech-21 Bridge from Butler County, Ohio. Design and inspection reports on the Hanover Street Bridge were obtained from West Virginia.
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• Task 3: Determine suitable inspection procedures for each critical detail, damage type, and deck type identified in Task 1. – A list of potential inspection methods used for inspection of FRP components was created.
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133 Field Inspection of In-Service FRP Bridge Decks: Report to use the inspection and testing instruments and methods on samples of FRP deck sections brought to the classroom. During the training course, the participants had the opportunity to inspect samples of FRP decks using the various field instruments and assessment and condition evaluation methods described in the training manual.
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• Chapter 3: Interpretation and Applications. This section presents interpretation of the findings, key issues, applicability of the interpretations to practice, practical considerations, and selection of ideal inspection methods.
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135 Field Inspection of In-Service FRP Bridge Decks: Report CHAPTER 2 FINDINGS This chapter presents a summary of the research team findings. The findings are based primarily on a survey of the bridge and FRP community, the literature search, the personal experiences of the research team members, and feedback from bridge inspector trainees attending the pilot FRP deck inspector training session.
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Field Inspection of In-Service FRP Bridge Decks: Report 136 Manufacturer Deck Description Number of Bridges Deck Cross Section Kansas Structural Composites, Inc.
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In addition, three other manufacturers or fabricators have provided FRP decks: Fiber Reinforced Systems; Bedford Reinforced Plastics; and Diversified Plastics/Hughes Brothers, Inc. However, for most practical purposes, the six major manufacturers have greater than 95% of the installed base of FRP bridge decks and appear to have established themselves as the suppliers of choice for future installations.
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From page 139... ...
overlays were used instead of conventional bituminous overlays as the wearing surface on the decks. • Haunch supports: There was a concern that the FRP deck may not "sit" solidly on the haunch, creating a gap between the bottom surface of the FRP deck and the top surface of haunch, thereby causing impact between the deck and the haunch due to the passage of vehicles.
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139 Field Inspection of In-Service FRP Bridge Decks: Report 2.1.3 CURRENT INSPECTION PRACTICE Key observations based on the survey and interview and inspection reports on the current inspection practice are summarized and presented below: • No special inspection guidelines currently exist for inspecting FRP decks. Only New York State DOT has guidelines (i.e., advisory circulars)
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University of Delaware)
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141 Field Inspection of In-Service FRP Bridge Decks: Report Although the defense and aerospace industries readily adopted composite materials early on, it took another 20 years before the bridge industry started considering FRP as a viable alternative to traditional materials. The first civil engineering application of FRP material was a dome constructed in Benghazi in 1968 (22)
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1990s, and the number of such bridges continues to grow as bridge engineers become comfortable with the material and its performance. However, most of these bridge decks have been built using proprietary experimental systems and details.
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143 Field Inspection of In-Service FRP Bridge Decks: Report most bridge owners did not have such memos or guidance documents, two publications by New York State DOT were found to be valuable in this study (28, 29)
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well as by higher temperatures. These research studies are limited in their scope, however, and do not provide in-depth insights into the post-damage strength and behavior of FRP decks, nor the effect of damage on the serviceability criteria and useful life of these components.
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145 Field Inspection of In-Service FRP Bridge Decks: Report 2.3 KEY PUBLICATIONS The following publications from the Department of Defense, the U.S. Army Corps of Engineers (USACE)
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• Laboratory and Field Testing of FRP Composite Bridge Decks and FRPReinforced Concrete Bridge for the City of St. James, Phelps County, MO, a report published by Missouri DOT (12)
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147 Field Inspection of In-Service FRP Bridge Decks: Report CHAPTER 3 INTERPRETATION AND APPLICATIONS This section presents interpretation of the findings, key issues, applicability of the interpretations to practice, practical considerations, and selection of ideal inspection methods. 3.1 ISSUES WITH DESIGN VARIANTS The large variability in types of FRP decks and the lack of standardization in deck shapes, material composition, manufacturing processes, design methods, and details are important issues that affect the inspection, maintenance, and management of the FRP deck inventory in the United States.
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core–to–face sheet connections while in pultruded sections, the critical locations could be at joints between each pultruded subcomponent. In addition, the corrugated core in some sandwich-panel decks is bonded to the face sheets along thin edges, creating potentially weak areas that can easily separate due to poor adhesion or load-deflection effects.
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149 Field Inspection of In-Service FRP Bridge Decks: Report maintenance issues regarding such decks; however, personnel not involved in the design and those responsible only for deck inspection or maintenance seemed to consider these decks similar to conventional concrete decks in their inspection and repair needs. Very few of the survey participants seemed to employ FRP deck–specific inspection methods while inspecting their FRP deck inventories.
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details in this category are not necessarily associated with a specific type of deck, but are more globally applicable. Various commonly observed damage types associated with these significant details have been identified (see Appendixes 4–6)
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151 Field Inspection of In-Service FRP Bridge Decks: Report The visual method is by far the most important and simplest technique for inspection of FRP decks. Even in the aerospace and defense industries, inspectors rely on the visual technique for detecting in-service problems.
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3.5 DETAILS AND DESIGNS THAT WILL BE DIFFICULT TO INSPECT As discussed in the previous section, numerous methods are available to inspect critical details and detect defects or damage in FRP bridge decks. The research team feels that visual and tap-test methods can provide satisfactory results in detecting defects and damages at most locations on FRP decks.
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153 Field Inspection of In-Service FRP Bridge Decks: Report would lead to other signs such as larger deflections, discolorations, dimpling, stretch marks, and so forth that would alert the inspector to the existence of problems. (Further discussion on significant details, inspection methods, and difficult-to-inspect areas of each of the major deck types is presented in Appendixes 4 and 7.)
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The research team developed a semi-empirical method that would assist an inspector in evaluating and assessing the damage and deterioration based on some uniform or standard scale. This correlation of damage or deterioration to remaining life either could be set arbitrarily or could be devised using some of the test data from aerospace applications.
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155 Field Inspection of In-Service FRP Bridge Decks: Report CHAPTER 4 CONCLUSIONS The research conducted under NCHRP Project 10-64 has developed recommended uniform guidelines for inspection and condition evaluation of in-service FRP bridge decks and developed and implemented the pilot session of a course to train bridge inspectors on the methods of inspecting these bridge decks. The study is based on current state-of-the-art knowledge on FRP material and decks; ongoing research; experiences of bridge owners, maintainers, fabricators, and designers; knowledge from the defense and aerospace industries; and the state of current practice in the use and assessment of this material in the United States and in other countries.
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• In addition to the inspection manual, future development of analytical rating and maintenance guidelines for FRP decks and components is warranted. • The many commercial variants of FRP bridge deck types in service today make it more challenging to design, build and maintain FRP deck types.
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157 Field Inspection of In-Service FRP Bridge Decks: Report aerospace industries, the studies have not yet been extended to civil engineering applications. – Composite action or the effect of composite action on FRP decks.
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REFERENCES FOR REPORT 1. Dumlao.
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159 Field Inspection of In-Service FRP Bridge Decks: Report of St. James, Phelps County, MO, Missouri DOT Report RDT02-012, Missouri DOT, 2002.
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24. Hooks, J., et al.
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161 Field Inspection of In-Service FRP Bridge Decks: Report 38. Sadka, B
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50. McGowan, D.M., and Ambur, D.R.
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163 Field Inspection of In-Service FRP Bridge Decks: Report APPENDIXES FOR REPORT The following appendixes are not published herein but are available online at trb.org/news/blurb_detail.asp? id=5905: • Appendix 1: List of Reviewed Literature • Appendix 2: Survey Questionnaire • Appendix 3: Survey Results • Appendix 4: Summary of Installed FRP Decks and Their Damage Inspection • Appendix 5: Connection Details and Critical Inspection Points • Appendix 6: Damage Types • Appendix 7: Inspection Methods • Appendix 8: Manual for Inspection of In-Service FRP Bridge Decks • Appendix 9: Assessment of Likelihood of Damage Progression • Appendix 10: Training Guide and Presentation for Manual for Inspection of InService FRP Bridge Decks
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