TABLE OF CONTENTS

EXECUTIVE SUMMARY 1

1.0 SCANNING TOUR OBJECTIVES 3

1.1 Mission Statement 3
1.2 Goals 3

2.0 SCOPE OF STUDY AND PARTICIPANTS 5

2.1 Scope of the Study 5
2.2 Projects, Locations, and Schedules 6
2.3 Scanning Team Members and Foreign Contacts 10

3.0 TOPICAL SUMMARIES 13

3.1 New Bridge Structures (Topic 1) 14
3.2 Strengthening of Existing Bridges (Topic 2) 18
3.3 Seismic Retrofit (Topic 3) 21
3.4 Design (Topic 4) 23
3.5 Connections and Detailing (Topic 5) 25
3.6 Instrumentation and Monitoring (Topic 6) 28
3.7 Durability (Topic 7) 30
3.8 Research (Topic 8) 32
3.9 Construction (Topic 9) 34
3.10 Management (Topic 10) 36

4.0 ADVANCED COMPOSITES IN BRIDGES IN EUROPE 37

4.1 Cambridge Workshop (Project E1) 38
4.2 Aberfeldy Footbridge (Project E2) 42
4.3 Bonds Mill Bridge (Project E3) 46
4.4 Second Severn Approach Enclosures (Project E4) 49
4.5 Düsseldorf Workshop (Project E5) 52
4.6 Ulenbergstrasse Bridge (ProjectE6) 55
4.7 Schiessbergstrasse Bridge (Project E7) 58
4.8 EMPA Workshop (Project E8) 62
4.9 Storchenbrücke (Stork Bridge) (Project E9) 65
4.10 Co-op City Department Store (Project E10) 69
4.11 Oberriet Rhein Bridge (Project E11) 72
4.12 Fürstenland Bridge (Project E12) 76
4.13 Koblenz/Waldshut Bridge (Project E13) 80
4.14 Advanced Composites Manufacturing (Project E14) 82
4.15 Haltingen Bridges (Project E15) 85
4.16 Giezenen Bridge (Project E16) 88
4.17 Ibach Bridge (Project E17) 92
4.18 Sins Wooden Bridge (Project E18) 95

5.0 ADVANCED COMPOSITES IN BRIDGES IN JAPAN 99

5.1 Tsukuba City Workshop (Project J1) 100
5.2 Osaka Workshop (Project J2) 103
5.3 PWRI Composite Cable Stayed Bridge (Project J3) 106
5.4 Sumitomo Bridges (Project J4) 109
5.5 Aramid Rod Anchor Block Reinforcement (Project J5) 113
5.6 Seismic Column Retrofitting (Project J6) 115
5.7 Akashi-Kaikyo Bridge (Project J7) 119
5.8 Bridge Deck Strengthening (Project J8) 121
5.9 Rolling Traffic Load Simulator (Project J9) 123
5.10 Hiyoshigura Viaduct (Project J10) 127
5.11 Tokyo Rainbow Bridge (Project J11) 131

6.0 TRANSFERABILITY OF TECHNOLOGY TO THE UNITED STATES 135

6.1 U.S. Technology Perspective 135
6.2 Transferable Technology 135

ACRONYMS AND ABBREVIATIONS 139

REFERENCES 141

Tables

1. Study Tour Topic Areas 5
2. Scanning Tour Workshops and Projects 7
3. Scanning Team Members and Affiliations 10
4. Foreign Contacts and Experts 11
5. Quantitative Rating of Fiber Types 31
6. Akashi-Kaikyo Bridge Pilot Rope Comparison 120

Figures

1. Map of England and Scotland 8
2. Map of Germany 8
3. Map of Switzerland 9
4. Map of Japan 9
5. Aberfeldy Footbridge 14
6. Bonds Mill Bridge 14
7. PWRI Demonstration Bridge 15
8. Maunsell's Bridge Enclosure System 15
9. Beadington Trail Bridge, Calgary, Alberta 17
10. CFRP Laminate Strengthening 18
11. CFRP Sheet Strengthening 19
12. Seismic Retrofit of Bridge Columns With CFRP Sheets 21
13. Toggle Connection for Pultruded GFRP Panels 25
14. GFRP Bolted Connection 25
15. Carbon Rod Anchorage Model 26
16. GFRP Rods Instrumented With Fiber Optics and Copper Wire 28
17. Professor Burgoyne at the Cambridge Workshop 38
18. Demonstration of Parafil Anchor Technique 39
19. Adjustable Parafil Anchorage 40
20. Crack Patterns and Failure Modes in Prestressed Concrete Beams 40
21. Shear Specimens Reinforced With Aramid Stirrups 41
22. Aberfeldy Footbridge, Overview 42
23. Geometry and Details of Aberfeldy Footbridge 44
24. Toggle-Connected Crossbeam and Stay Cable Anchorage Connection 44
25. Prefab GFP Handrail System and Conveyor Belt Wear Surface 45
26. A-Frame Pylon and Cable Stay Anchorages 45
27. Bonds Mill Bridge, Overview 46
28. Cross-Section Geometry and Dimensions 47
29. Connection Details 48
30. Bascule Bridge in Open Position 48
31. Bridge Structure Crossing One of the Second Severn Approaches, Overview 49
32. Hanger System 50
33. Enclosure System and GRP Flares 51
34. Model of Bridge Enclosure System 51
35. Mechanical Characteristics of Polystal⁷ 52
36. Polystal⁷ Repair to Paris Metro 54
37. Ulenbergstrasse Bridge, Overview 55
38. Geometric Dimensions 57
39. Two-Lane Road Bridge With Large Pedestrian Cantilever Overhangs 57
40. Schiessbergstrasse Bridge, Overview 58
41. Technical Bridge Data 59
42. Soffit Groove for Optical Fiber Sensors 60
43. Tendon Anchorage in Abutment Control Room 60
44. Arrangement of the Optical Fiber Sensors and Chemical Sensors 61
45. External CFRP Laminate Strengthening on T-Girder Web 62
46. Cyclic Load Testing of CFRP Beams 64
47. Long-Term Creep Test on GFRP Beam 64
48. Storchenbrücke, Overview 65
49. Bridge and Geometry Dimensions 66
50. Sealing (Waterproofing) of Bridge 67
51. Waterproofing and Wear Surface Application 67
52. Top Cable-Stay-Stressing Anchorages 68
53. Bottom (Fixed) Anchorage of Carbon Cable and Instrumentation 68
54. New Escalator Opening in Existing Reinforced Concrete Floor Slab 69
55. Strip Bonding Layout Around Escalator Opening 70
56. Crossing of CFRP Laminates 71
57. Installed CFRP Laminates and Steel Strip 71
58. Oberriet Bridge, Overview 72
59. Cross-Section and Dimensions 73
60. Application of Epoxy Adhesive to Carbon Laminate 74
61. Application of Carbon Laminate to Bridge Soffit 74
62. Tensile Bond Testing on Cored Carbon Laminates and Glued Steel Disks 75
63. Demec Points for Absolute and Relative Strain Measurements 75
64. Fürstenland Bridge, Overview 76
65. Three-Cell Box Girder Superstructure 77
66. Cross-Section and Strengthening Locations 78
67. Application of CFRP Strips 78
68. Deteriorated Bottom Soffit Panel 79
69. Temporary Construction Strengthening with CFRP Strips
During Bottom Soffit Repair 79
70. The Historic Koblenz/Waldshut Wrought Iron Bridge, ca. 1859 80
71. The Historic Koblenz/Waldshut Wrought Iron Bridge, 1996 81
72. CFRP Laminate Pultrusion Setup at Stesalit AG 82
73. Creel Rack 83
74. Alignment Screen for Carbon Tools 84
75. Tractor To Pull Pultruded Member 84
76. One of the Steel-Plate-Strengthened Bridges in Haltingen 85
77. Transverse Steel Plate Strengthening of Continuous Road Slab Bridge 86
78. Steel Plate Bonding and Exhaust/Temperature Protection Over Railway Line 86
79. Giezenen Bridge, Overview 88
80. Giezenen Arch Bridge 89
81. Dual-Tied, Reinforced-Concrete Arch Bridge 89
82. Dual-Tied Arch Bridge 90
83. Steel Plate Strengthening of Orthotropic Concrete Deck Beams 91
84. Corrosion Damage and Calcium Stalactites on Steel Plate Strengthening 91
85. Ibach Bridge, Overview 92
86. CFRP Laminate Strengthening of Ibach Bridge 93
87. Ibach Bridge Strengthened With Three Strips of CFRP Laminate 94
88. Sins Wooden Bridge, Overview 95
89. Covered Wooden Arch Bridge, Exterior 96
90. Covered Wooden Arch Bridge, Interior 97
91. Crossbeams Strengthened with CFRP Laminates 98
92. Strain Gauge and Demec Point Instrumentation on CFRP-Strengthened Crossbeams 98
93. Example of Arch Bridge Post-Tensioned With Carbon Laminates 101
94. External Carbon Tendons in Post-Tensioned Arch Bridge 101
95. Cumulative Quantity of FRP Bars and Tendons Used in Japan (Since 1987) 102
96. Carbon Sheet Column Retrofitting 103
97. Bridge Deck Strengthening 103
98. Seismic Retrofit of Tsushi Viaduct Column With Carbon Sheets 104
99. Retrofitting of Tsushi Viaduct Column With Carbon Sheets 104
100. Carbon Sheet Strengthening Against Punching Shear in Deck Cantilever 105
101. Carbon Sheet Strengthening of Tunnel Section 105
102. PWRI Composite Cable-Stayed Bridge 106
103. Pylon and Cable Stays 107
104. Carbon Fiber Cable Stay Anchorage Assembly 108
105. Durability and Creep Test Stand 108
106. Bridge Geometry and Dimensions 110
107. Technora⁷ Deformed Bar Tendons With Composite Anchorages 111
108. Internal Post-Tensioning 111
109. Pretensioned Multicell Box Girder Bridge 112
110. Post-Tensioned Single-Cell Box Girder Bridge 112
111. External Anchor Block Stressed to the Girder With Six Technora⁷ Tendons 113
112. Technora⁷ 9-Bar Tendon and Anchorage 114
113. Seismic Column Retrofitting Tests 115
114. Aramid Sheet Retrofitting 116
115. Carbon Sheet Retrofitting 117
116. Column Retrofitting on the Hanshin Expressway 117
117. Application of Vertical Carbon Sheet at the Hanshin Expressway 118
118. Akashi-Kaikyo Bridge, October 1996 119
119. Geometry and Dimensions 120
120. Carbon Sheet Slab Strengthening 121
121. Wheel Running Machine for Fatigue Test of Highway Bridge Slabs 123
122. Deterioration Process of Slabs 124
123a. Comparison of Cracking PatternsCTest Slab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
123b. Comparison of Cracking PatternsCActual Slab 124
124. New Type of Fatigue Machines 125
125. Rolling Traffic Simulator Prototype 126
126. Test of Carbon Sheet Strengthening and Running Wheel Load 126
127. Hiyoshigura Viaduct 127
128. Damage to Existing Bridge Deck 128
129. Strain and Deformation Measurements of Strengthened Deck 129
130. Closeup of CFRP-Sheet-Strengthened Deck 129
131. CFRP Strengthening of Hiyoshigura Viaduct 130
132. Tokyo Rainbow Bridge 131
133. Geometry and Dimensions of Precast Concrete Deck Panels 132
134. Geometry and Dimensions 132
135. Precast Concrete Walkway at Southeast Cable Anchorage 133
136. Port of Tokyo and Rainbow Bridge 133

EXECUTIVE SUMMARY

Under the Federal Highway Administration's (FHWA) International Technology Scanning Program, a team of 13 U.S. bridge engineers and advanced composite experts from Federal and State transportation agencies, academia, and industry conducted a 2-week scanning tour of Europe and Japan. The purpose of the tour was to assess the state of technology in the use of advanced composite materials, known as fiber-rein-forced polymers (FRPs) or polymer matrix composites (PMCs), in bridge design and construction.

The scanning team visited the United King-dom, Germany, Switzerland, and Japan from 14 to 28 October 1996. The tour included 23 project sites, 1 manufacturing site, and 5 workshops that provided an overview of the developments and applications of PMCs in bridge engineering.

The study had five primary objectives, which were to:

1. Evaluate the performance of PMCs in the civil engineering environment for new bridges and for the rehabilitation of existing structures

2. Gain an understanding of all issues involved in selecting and applying PMCs to bridges, ranging from technical specification to proof testing and performance monitoring

3. Learn about project implementations in the areas of design, construction, and project management

4. Summarize the findings in a compre-hensive report for the benefit of the U.S. bridge engineering community

5. Assist in accelerating the acceptance and implementation of PMCs in the U.S. bridge industry.

The results of the first four objectives are documented in this report in the form of ten topical review summaries on issues related to PMCs in bridges. These summaries are organized as follows:

• New Bridge Structures
• Strengthening of Existing Bridges
• Seismic Retrofit
• Design
• Connection and Detailing
• Instrumentation and Monitoring
• Durability
• Research
• Construction
• Management.

The fifth objective was achieved by all scanning team members through an in-creased awareness and understanding of the state of PMC bridge technology outside the United States. This objective will continue to be met with the dissemination of this report.

The technical findings of the scanning tour can be summarized under three categories: new construction, strengthening of existing structures, and seismic retrofit. Although all the countries visited had built new structures using PMCs, the structures were all in one-of-a-kind demonstration projects to show-case the technology and were supported by significant subsidies from the public and private sectors. The most promise for the use of PMCs in bridge design and construction was found in structural rehabilitation, both for strengthening of existing deficient bridge structures and for seismic retrofit. In both areas, several commercial systems have been developed in the countries visited, including materials, design and application specifica-tions, application methods, and quality assurance procedures. The technologies encountered are of potential interest for the rehabilitation of U.S. bridges, concurrent developments in the United States have resulted in equivalent technologies. The technologies observed by the scanning team can, however, provide additional rehabilita-tion tools and concepts for broader appli-cations of PMCs in the United States, as long as the fairly high costs quoted for these technologies abroad can be made competi-tive for the U.S. market.

The scanning team encountered some devel-opments related to connections and detailing of PMCs in bridge engineering, but the general lack of innovative and simple con-nection concepts seems to slow the imple-mentation of advanced composite structural systems worldwide. All countries visited had similar concerns about durability and long-term performance. Aside from reports on a few accelerated material test programs and long-term exposure tests, however, no sys-tematic and permanent monitoring programs and procedures are in place to assist in developing verified long-term performance and life-cycle cost data.

The focus of research differs from country to country and, in most cases, is product or industry driven. In the United States, the focus of research is more generic, which is partially the result of the funding sources and mechanisms used in this country. Most research in the United States is funded by the Government and conducted at academic institutions. In Europe and Japan, industry in general and the construction industry in particular play more significant roles in PMC research and development for civil engineering applications.

Probably the most significant finding of the scanning team was the close collaboration among the construction industry, the composite materials and manufacturing industry, the civil engineering design community, the academic community, and government agencies. This collaboration has allowed the countries visited to effectively coordinate product development and implementation in a large number of high-visibility demonstration projects to showcase the technology. These demonstration projects are paralleled by comprehensive education and training programs for design professionals and the construction industry. Although similar efforts have been attempted in the United States, they must be characterized as sporadic and isolated.

This report on the use of advanced composite materials in bridges in Europe and Japan provides information on the scanning tour objectives, scope, format, and participants. This is followed by summaries of the findings in the topic areas outlined above. Project descriptions for each of the sites visited and the workshops are included for both Europe (projects E1 to E18) and Japan (projects J1 to J11). The project descriptions are followed by brief assessments of the technologies and their potential uses for bridge applications in the United States. Pertinent published references are listed at the end of this report.

SCANNING TOUR OBJECTIVES

In recent years, problems with the aging and rapidly deteriorating bridge infrastructure have prompted a resurgence in research and development of new and more durable materials for bridge infrastructure renewal. New materials may have applications in rehabilitation of existing bridges and complete structural replacement or new construction. Fiber-reinforced polymer matrix composite (PMC) materials were developed and used primarily in the aerospace and defense industries. In addition to outstanding strength/weight ratios, these materials also have a high degree of chemical inertness to most civil engineering or bridge environments, which strongly suggests their consideration for bridge infrastructure renewal. Over the past decade, numerous research projects into the characterization and development of PMCs in bridge design and construction have been ongoing in the United States. Even so, the United States seems to be falling behind countries in Europe and Japan, where there are a number of high-visibility demonstration projects and field applications.

To gauge the state of U.S. technology in this area, the FHWA organized a technology scanning tour to assess advanced composite bridge construction technology in selected European countries and Japan. In addition, the panel was to identify and recommend areas in which foreign technologies should be further investigated for possible transfer to the United States and pinpoint mechanisms and procedures through which U.S. advanced composite bridge technology could be enhanced and accelerated. The mission statement and goals in the following paragraphs guided the scanning team's investigation.

1.1 Mission Statement

In fulfilling the mandate of Section 6005 of the Intermodal Surface Transportation Efficiency Act (ISTEA), a scanning team was formed to observe, investigate, and document the application of fiber-reinforced polymer composite materials in highway bridge structures and the experiences of transportation agencies in Japan and selected European countries (the United Kingdom, Switzerland, and Germany) in using such applications.

1.2 Goals

The goals of the scanning team were to:

• Evaluate the performance and durability of bridges built with composite materials as they relate to the manufacturing process of the composite materials and the fabrication process of structural members for new construction, as well as for rehabilitation and/or strengthening of existing members

• Interview owners, designers, fabricators, and contractors of composite material bridges about technical issues involving selection, specification, design, manu-facturing, fabrication, construction, in-spection, proof testing, and performance monitoring, as well as research and development of bridge applications for composite materials

• Gather and review details and documentation on all aspects of the projects, including design methodology, specifications, standards, production processes, contracting methods, costs, and performance records

• Publish a comprehensive report summarizing the findings of the scanning team to share with engineers and researchers and to make presentations to the U.S. bridge engineering community on practical structural applications.

• Assist in accelerating the implementation of fiber-reinforced polymer composite materials in U.S. bridge engineering.

2.0

SCOPE OF STUDY AND PARTICIPANTS

2.1 Scope of the Study

This study of the state of advanced composites in bridge structures in Europe and Japan consisted of a review of published materials on advanced composite bridge projects; four organizational meetings before and during the scanning tour; the scanning tour itself, including visits to the United Kingdom, Germany, Switzerland, and Japan; a review of literature obtained during the scanning tour; and this assessment report. During the tour, the scanning team visited 23 projects and 1 manufacturing facility. Team members also participated in 5 work-shops on advanced composite bridge technology, emphasizing development and applications in the particular country or region.

The study focused on the 10 topic areas listed in Table 1. The issues of the development and application of advanced composites in bridges for the topic areas are presented in Section 3.0 of this report. This section includes a summary of the scanning team's findings and their relevance to U.S. practice, an assessment of transferable technologies, and a discussion of research and development needs in the United States. Of particular interest were the applications of fiber-reinforced PMCs in the construction and rehabilitation of new and existing bridge structures.

For new bridge structures, technological advantages of these materials were investigated, together with their impact on construction, maintenance, durability, and cost. For structural rehabilitation of existing bridges, the application of PMCs was broken down into strengthening and seismic retrofit because of differences in design and performance objectives. Strengthening typically addressed issues of structural repair and increased live load. Seismic retrofit also requires consideration of structural ductility, in addition to strength and stiffness considerations.

Table 1. Study Tour Topic Areas

Topic Number	Topic Area
1	New Bridge Structures
2	Strengthening of Existing Bridges
3	Seismic Retrofitting
4	Design
5	Connections and Detailing
6	Instrumentation and Monitoring
7	Durability
8	Research
9	Construction
10	Management

In examining design, the scanning team explored the differences in design philosophies and approaches, as well as the availability of comprehensive design guidelines, criteria, and standards. Particular emphasis was placed on connections and detailing, because simplification in construction and long-term performance of connections are critical for broad application of advanced composites in civil engineering. The health and service life monitoring of bridge systems becomes increasingly important; this issue is addressed under the topic of instrumentation and monitoring.

The most important obstacles to the general acceptance of PMCs in civil engineering and construction are the uncertainties, claims, and speculations regarding the durability of these materials in the civil engineering environment. To overcome these obstacles, significant research is required into the long-term behavior of these materials, accelerated test methods and procedures, new shapes and forms, and design concepts, in conjunction with conventional structural materials and design standards. Finally, the impact of these new materials on actual construction, in terms of weight and handling, and on the management of projects involving PMCs was investigated.

2.2 Projects, Locations, and Schedules

A list of workshops and project sites visited is in Table 2, which is divided into sections on Europe (projects E1 to E18) and Japan (projects J1 to J11). Workshops in each country are listed first, followed by the projects and site visits.

Locations of the sites visited are indicated by project numbers on the maps of the United Kingdom, Germany, Switzerland, and Japan (Figures 1 through 4). Summaries of the individual projects in Europe are in Section 4.0, and the projects in Japan are summarized in Section 5.0.

Table 2. Scanning Tour Workshops and Projects

Country	Project	Project Description
United Kingdom	E1	Cambridge Workshop: development of aramid cables, Prof. C. Burgoyne
	E2	Aberfeldy Footbridge: all advanced-composite cable-stayed bridge, pultruded glass-reinforced polymer (GRP) box sections and aramid cable stays
	E3	Bonds Mill Bridge: bascule bridge made with pultruded GRP box sections
	E4	Second Severn Approach Enclosures: pultruded GRP enclosures for bridge approaches
Germany	E5	Düsseldorf Workshop: overview on post-tensioning of bridges with composite cables, Prof. F. Rostasy
	E6	Ulenbergstrasse Bridge, City of Düsseldorf: glass fiber prestressing tendons in two-span concrete slab bridge
	E7	Schiessbergstrasse Bridge: Bayer AG, Leverkusen, glass fiber prestressing tendons in three-span slab bridge with fiber optic sensors for crack detection and chemical sensors for corrosion monitoring
Switzerland	E8	EMPA Workshop, Dübendorf: presentation and lab visit, Prof. U. Meier
	E9	Storchenbrücke, Winterthur: cable-stayed bridge with two carbon-fiber-reinforced plastic (CFRP) cables
	E10	Co-op City, Winterthur: department store with carbon laminate strengthening of floor slabs around escalator cutouts
	E11	Oberriet Rhein Bridge: recently strengthened with 1 km of carbon laminates
	E12	Fürstenland Bridge: strengthening of box girder bridge with 8 km of carbon laminates applied to insides of webs
	E13	Koblenz/Waldshut Railway Bridge: strengthening of steel cross-girders with carbon laminates
	E14	Advanced Composite Manufacturing: manufacturing of carbon laminate sheets and filament winding
	E15	Haltingen Bridges: steel plate bonding project
	E16	Giezenen Bridge: ca.1912 arch bridge with corrosion damage to steel plate strengthening
	E17	Ibach Bridge: first carbon laminate strengthening of a prestressed concrete bridge
	E18	Sins Wooden Bridge: strengthening of cross-girders with carbon laminates
Japan	J1	Tsukuba City Workshop: Japanese perspective on FRP reinforcement and tendons, Public Works Research Institute (PWRI)
	J2	Osaka Worskhop: carbon fiber sheet strengthening
	J3	PWRI Composite Cable-Stayed Bridge: entirely composite cable-stayed pedestrian bridge, demonstration project, 20 m long
	J4	Sumitomo Bridges: external aramid cable prestressing tendons
	J5	Aramid Rod Anchor Blocks
	J6	Seismic Column Retrofitting
	J7	Akashi-Kaikyo Bridge: aramid pilot rope for world's longest span bridge (1,992-m mainspan)
	J8	Hanshin Expressway Bridge: deck strengthening, CFRP sheet strengthening
	J9	Rolling Traffic Load Test Simulator: reinforced-concrete slab strengthened with carbon fiber sheets, Prof. S. Matsui
	J10	Hiyoshigura Viaduct: CFRP sheeting, Tonen Corporation
	J11	Tokyo Rainbow Bridge: precast aramid tendon, prestressed walkway panels

2.3 Scanning Team Members and Foreign Contacts

The scanning team included a broad representation of professionals from the bridge design and composite manufacturing areas. The team consisted of four representatives from FHWA, four representatives from State Departments of Transportation (DOTs), two representatives from academia, and three from the advanced composite industry (see Table 3). The team members' diverse backgrounds and expertise in bridge design, re-search, project management, administration, composite manufacturing, and composite application provided balance and depth to the study and workshop discussions and to this report.

In each of the countries visited, the scanning team was privileged to meet some of the leading experts in the fields of advanced composite bridge research and development. A partial list of the principal contributors to the information exchange during this technology scanning tour is in Table 4.

In addition to the key people listed in Table 4, who helped greatly in organizing the study in their respective countries, other participants and experts in individual projects and workshops are listed with each project report. Their contributions to the discussions and assistance with providing project information are greatly appreciated.

Table 3. Scanning Team Members and Affiliations

Name	Affiliation
John Hooks	FHWA, Washington, DC (Co-Chair)
James Siebels	Colorado DOT, Denver, CO (Co-Chair)
Frieder Seible	University of California, San Diego, CA
John Busel	Composites Institute, New York, NY
Milo Cress	FHWA, Lincoln, NB
Chao H. Hu	Delaware DOT, Dover, DE
Fred Isley	Hexcel, Pleasanton, CA
Gloria Ma	Xxsys Technologies, San Diego, CA
Eric Munley	FHWA, McLean, VA
Jerry Potter	Florida DOT, Tallahassee, FL
James Roberts	California DOT, Sacramento, CA
Benjamin Tang	FHWA, Washington, DC
Abdul-Hamid Zureick	Georgia Institute of Technology, Atlanta, GA

Table 4. Foreign Contacts and Experts

Country	Name	Title	Affiliation
United Kingdom	Mr. A.E. Churchman	Managing Director	Maunsell Structural Plastics, Ltd.
	Dr. Chris J. Burgoyne	Lecturer	University of Cambridge
Germany	Dr.-Ing. Ferdinand Rostasy	Professor	Technical University, Braunschweig
	Dr.-Ing. Rainer Voigt	Technnical Program Director	Federal Department of Transportation
Switzerland	Prof. Urs Meier	Director	Federal Laboratory for Materials Testing and Research (EMPA)
	Dr. Marie Anne Erki	Professor and Head	Dept. of Civil Engineering, Royal Military College of Canada
Japan	Mr. K. Nishikawa	Head, Bridge Division	PWRI, Ministry of Construction
	Mr. M. Kanda	Chief Research Engineer, Bridge Div.	PWRI, Ministry of Construction
	Mr. M. Uemara	General Manager	Tonen Corporation

3.0

TOPICAL SUMMARIES

To assess the state of advanced composite technology in selected European countries and Japan and to put this state of technology in perspective with developments in the United States, findings from the review are discussed in the contexts of the topics shown in Table 1. Each topical review summarizes the findings relevant to the topic with direct

reference to projects E1 through E18 and J1 through J11. Following the summary of findings, the relevance to U.S. practice is established, and transferable technologies are identified. Finally, research and development activities necessary to advance the use of PMCs in U.S. bridge engineering and construction are discussed for each of the topic areas.

3.1

NEW BRIDGE STRUCTURES (TOPIC 1) Summary of Findings

Advanced composite materials have been used on a wide variety of new bridge projects both in Europe and Japan. The observed application of advanced composite materials in new bridge construction can be classified into three categories: bridge structures made entirely of advanced composite materials (Figures 5, 6, and 7); concrete bridges with nonmetallic reinforcement, prestressing components, or external cable stays; and protective or secondary structural systems (Figure 8).

The scanning team visited three bridges made entirely of advanced composite materials: the Aberfeldy Footbridge (E2), the Bonds Mill Bridge (E3), and the Public Works Research Institute (PWRI) Composite Cable Stayed Demonstration Bridge (J3). These projects clearly show the feasibility and potential for advanced composite bridges and constitute the pioneering work in this field. All three bridges, however, are "one-of-a-kind" or demonstration projects; broad-based acceptance in the civil engineering community and commercialization have not yet occurred. Although significant advantages for construction can be derived from the lightweight and high strength/weight ratio of these new bridge materials, durability and long-term performance issues still require further research and data development. Initial cost also seems to be a major obstacle when material and labor donations to the projects are discounted. Long-term life-cycle cost models do not yet exist, but need to be developed before broader applications can be implemented.

For advanced composite bridge systems to be successful, components should be modular, and assembly should be simple and have reliable connections. The Aberfeldy and Bonds Mill Bridges rely on chemical bonding with an epoxy adhesive and a mechanical toggle system. The PWRI demonstration bridge uses only mechanical fasteners in the form of glass-fiber-rein-forced plastic (GFRP) bolts with assembly and connection concepts derived from steel structures. The long-term performance of these connection details must be monitored.

Currently, complete FRP bridge systems are limited primarily to pedestrian bridges. For all-advanced-composite vehicular bridges, developments in guard or barrier rails and their connections to the decks are still needed.

Significant developments and advances were observed both in Europe and Japan in the use of fiber-reinforced plastic reinforcing and prestressing elements and stay cables for structural concrete. Tendon and rebar systems based on carbon (CFRP), aramid (AFRP), and GFRP exist. Cable/tendon types of all fiber materials have been developed in Europe. Examples of these developments include:

• In the United Kingdom, the dry parallel aramid fiber Parafil⁷ system developed by Linear Composites
• In Germany, the GFRP Polystal⁷ system developed by Bayer AG and Strabag AG
• In Switzerland, the CFRP carbon fiber cables and anchorages developed by BBR and the Federal Laboratory for Materials Testing and Research (EMPA).

All three systems have been used as internal or external post-tensioning systems or as cable stays in numerous demonstration projects (E2, E6, E7, and E9).

Again, however, cost differences in using these developments compared with continuously improving conventional steel tendon technology limit commercial applications. The least expensive tendon system of those mentioned, the German GFRP (E5) post-tensioning system Polystal,⁷ was discontinued for economic reasons after the system development and demonstration projects. Problems with durability of conventional steel tendon systems were at one time the driving force behind FRP tendon development. Now, improved corrosion protection systems for steel tendons lessen the need for new nonmetallic materials, except for applications in very corrosive environments. Thus, applications of FRP tendons are expected to be limited. The best opportunities are in ground anchors, external tendons, and guy systems. Some special applications can benefit from the lower modulus in FRP tendons, which results in reduced prestress losses in case of tendon shortening.

In Japan, in addition to aramid and carbon prestressing tendon systems, unstressed FRP reinforcing bars and grids have been developed (J1). The most common brand names of aramid reinforcement are Technora,⁷ Arapree,⁷ and Fibra,⁷ and of carbon elements, Leadline,⁷ CFCC,⁷ and NACC.⁷ Glass fibers are used in the reinforcement grid system known as Nefmac.⁷ Actual usage of FRP reinforcement or prestressing of concrete bridges has declined in Japan since the early 1990's for simple economic reasons. However, close to 100 demonstration projects of new concrete structures with FRP reinforcement have been executed in Japan (J15) and elsewhere (Figure 9).

Finally, the use of FRPs in the form of enclosure systems for new steel girder bridges was demonstrated in England by Maunsell (E4). Such systems provide a protective enclosure that reduces corrosion by 95 percent, provides access and a plat-form during construction of the bridge concrete deck, and allows continued inspection and maintenance without traffic interruptions. Maunsell developed this bridge enclosure system from the pultruded glass-fiber-composite (GFC) modules of its advanced composite construction system (ACCS), with the addition of special connectors, seals, and edge members. Although the concept is very attractive from a technical point of view, the high cost associated with the enclosure system (about US$44/ft² of enclosure area) may make commercialization outside the United Kingdom difficult.

Relevance to U.S. Practice

The FRP tendon systems developed in Europe and Japan are of interest, because only limited U.S. developments are in progress in this area. In particular, the applications as ground anchors and external tendons should be investigated. Also, short prestressing units, where anchor set, creep, and relaxation can greatly diminish actual prestressing force levels, should be reevaluated for use of FRP tendon technology.

Transferable Technologies

In addition to the acquisition of complete tendon systems for specific applications, the Swiss anchorage technology for carbon tendons seems very promising. This technology includes gradated stiffness in the anchorage housing filler material by means of aluminum oxide pellet additions to the epoxy matrix (E8, E9).

Research and Development

For further research and development of FRPs in new bridge systems, primary emphasis must be placed on low-cost manufacturing, simple and reliable connection details, and complete characterization of issues related to durability. Furthermore, design guidelines and standards should be developed, and training of engineering and design professionals in these new technologies should be facilitated.

3.2

STRENGTHENING OF EXISTING BRIDGES (TOPIC 2)

Strengthening of existing bridge systems with FRPs has been widely observed both in Switzerland and Japan. In all strengthening projects, the composite material was carbon-fiber based, because carbon fibers offer the best strength, stiffness, and durability characteristics. The strengthening philosophies and approaches in Switzerland and Japan vary, however, based on differences in the perceived problems and rehabilitation philosophies.

The primary area of application of CFRP bridge-strengthening measures is in deck strengthening, mainly for conventional-composite reinforced- concrete decks on steel girders. In Switzerland, the main objective in deck strengthening is the transverse positive moment capacity between longitudinal girders. In Japan, the deficiency is primarily the deck punching shear capacity. In both cases, increased live-load capacities (increased legal truckloads) are the main reasons for strengthening the deck soffit.

The Swiss concept of additional live- load capacity in the transverse direction between steel girders (E11) relies on discretely spaced and epoxy-bonded pultruded carbon laminates that are 1 to 2.5 mm (0.04 to 0.1 in) thick and 25 to 120 mm (1 to 5 in) wide. These act as concentrated strips of additional soffit reinforcement, spaced as much as 0.75 m (2.5 ft) apart (see Figure 10). This spacing clearly does not affect or improve the potential deck punching shear problems under traveling wheel loads, but is used to increase the factor of safety in terms of flexural deck capacity. CFRP laminate strengthening is not used where the factor of safety is less than 1 or where the concrete quality of the deck soffit is deteriorated. The pultruded carbon laminates are manufactured by Stesalit AG, and the strengthening system is marketed by Sika Corporation as Sika Carbodur.⁷

The Japanese concept for strengthening the deck slab soffit is driven by two design considerations: supplementation of very little, nominally provided longitudinal deck reinforcement and the wheel load punching shear failure mode for higher legal loads and illegal overloads. Thus, both the soffit area between longitudinal girders and the bridge deck cantilever soffit regions are strengthened (J8). Because punching shear failure under wheel loads can occur anywhere in the bridge deck, distributed strengthening in the form of carbon sheet wet layup strips covering the entire soffit area are used (J2, J9, J10) (see Figure 11). Three main manufacturers and products exist on the Japanese market: Replark⁷ from Mitsubishi, Towsheet⁷ from Tonen, and Torayca Cloth⁷ from Toray.

In addition to differences in design philosophies, the Swiss and Japanese systems also differ in ease of application and quality control. The Swiss system requires minimal surface preparations (only grinding in the strip area) and provides a high degree of quality control as a result of due to the use of premanufactured and certified laminates. Japanese systems require onsite field mixing of the epoxy matrix, as well as sandblasting and priming of the entire bridge deck soffit area. Both systems use direct tension pullout tests of cored discs to validate tensile bond characteristics between the carbon overlay and the concrete substrate. During these tests, the failure surface has to be located in the concrete substrate for a successful application.

In addition to deck slab strengthening, both systems have been applied to concrete column and girder strengthening (E9, J17, J18). Tests and applications in Switzerland (E8, E12) have also demonstrated CFRP laminate strengthening on the sides of beam or girder webs for temporary or permanent strengthening measures.

The costs for the various strengthening techniques vary from project to project. For current U.S. market conditions, costs were estimated to be approximately US$30/ft of installed CFRP strip and approximately US$15 to $25/ft² per layer of wet layup carbon sheet. Note that these estimates can change considerably, based on material costs and production volumes.

Relevance to U.S. Practices

Bridge-strengthening systems do have considerable relevance to the U.S. market because of the large number of deficient bridges in the U.S. inventory. However, deck punching failures under wheel loads, encountered in Japan, do not seem to be a problem in most U.S. bridges. Furthermore, carbon sheet strengthening has also been developed and applied in the United States. No additional relevance exists, other than the need to apply this technology consistently.

Transferable Technologies

The Sika Carbodur⁷ system is currently being evaluated in the United States as part of the Civil Engineering Research Foundation Hitec Program. This system, together with two of the Japanese systems, could have numerous applications in U.S. bridge strengthening where flexural deck deficiencies exist.

Research and Development Needs

Research and further developments should focus on a philosophy that is consistent with

U.S. design practice. Research and development should also focus on design guidelines and criteria that will allow general applications, not just in regions where safety factors need to be slightly increased. In particular, anchorage and CFRP termination guidelines should be established, as well as design criteria that would ensure full participation of the concrete substrate, through strain limits and quantifiable crack width control.

3.3

SEISMIC RETROFIT (TOPIC 3)

Summary of Findings

Rehabilitation for seismic strength and/or ductility enhancement of bridge structures with FRP was observed only in Japan. The study tour did not visit regions of high seismicity in Europe. Seismic retrofit with FRPs in Japan was limited to square and rectangular bridge columns, using either aramid or carbon sheet overlays in a manual wet layup process (J2, J6) (Figure 12).

In Japan, the seismic retrofit philosophy for bridge columns is somewhat different from the U.S. approach. The primary emphasis is on rehabilitation in the form of strength enhancement, not in increased deformation capacity or ductility. Most single-bent bridge columns in Japan have cutoffs (dropoffs) of the main column reinforcement at one or more locations along the column height. These are strictly based on linear elastic demands of first mode or cantilever response, without tension shift considerations for flexurally cracked zones. Past earthquakes in Japan, in particular the Kobe earthquake of 1995, have shown the vulnerability of these single column bents with the formation of flexural hinges at the bar cutoff location, when elastic design levels are exceeded. Seismic retrofit in Japan addresses this longitudinal flexural strength deficiency by addition of longitudinal column reinforcement in the form of FRP sheet overlays of predominantly vertical fibers. Even small amounts of FRP sheets with horizontal fiber orientation can also significantly increase column shear strength, which was another deficiency encountered in large rectangular single column bents during the 1995 Kobe earthquake. Both aramid and carbon sheet (or tape) retrofit applications have been developed and applied in Japan. To date, an estimated 200 bridge columns have been retrofitted with CFRP sheet overlays, and another 800 or more retrofits are in the planning and construction phases (J2, J6).

The three primary manufacturers for CFRP sheets are Mitsubishi with the Replark⁷ system, Tonen with the Towsheet,⁷ and Toray with the Torayca Cloth.⁷ All systems are applied using similar processes: sand-blasting of the column surface, sealing or priming with epoxy primer, application of the CFRP sheets in vertical and horizontal layers, and epoxy saturation of each layer. Various application processes that ensure proper field mixing of multicomponent epoxies by distinct color schemes for the

components and the mixed adhesive, such as the Sho-bond system, are used to provide a high level of quality assurance. The dimensions of the single column bents currently retrofitted with CFRP sheets do not allow significant ductility enhancement in the potential plastic hinge region at the column base with the CFRP sheets applied directly onto the rectangular column geometry. Significant transverse or out-of-plane stiffness would be required from the jacket retrofits to stabilize the longitudinal column bars against buckling. However, the same is true for thin steel plating of rectangular columns. Although some tests on small-scale rectangular or square columns at Sumitomo Construction Company (J6) showed ductility enhancements by a factor of about 2, the same enhancement cannot be expected in full-scale columns with side dimensions of up to 2 to 3 m (6.6 to 9.8 ft).

In addition to the FRP sheet bridge column retrofit, Mitsubishi and Obayashi have also developed an automated carbon tow, wet-winding system that has been used primarily for chimney retrofits, not bridge columns.

Relevance to U.S. Practice

The seismic column retrofit technology with FRP sheet overlays is clearly relevant to general U.S. seismic retrofit practices, but it is not unique. It is already practiced widely in the United States, although with different design philosophies, guidelines, and criteria.

Transferable Technologies

The Japanese CFRP sheet systems should be considered for application to seismic column retrofit in the United States. Application should, however, be subsequent to full validation testing to meet U.S. design criteria.

Research and Development Needs

Significant strength enhancement both for flexure and shear can be expected with CFRP sheet overlays, even on large rectangular concrete columns. Considerable research is required, however, both in the United States and Japan, to establish design and behavior models for large concrete sections in which only the perimeter is reinforced and the core is made up of effectively unreinforced concrete.

3.4

DESIGN (TOPIC 4)

Summary of Findings

The lack of comprehensive design guide-lines for the use and application of FRP materials in bridge design and construction seems to be one of the key reasons that FRPs have so far been applied only in one-of-a-kind demonstration projects. Clearly, each of the projects observed was guided by specific design requirements and criteria, but few attempts have been made to formulate comprehensive national and international standards. Design guidelines range from proprietary-limit state design packages, such as the one developed for new structures by Maunsell for the ACCS (E1 to E4) to system-specific guidelines developed in Switzerland by EMPA and Sika for CFRP laminate strengthening. Only in Japan do efforts seem to be underway to develop more generic design guidelines for groups of applications, such as cable systems and CFRP sheet strengthening.

With the possible exception of the Maunsell system, which was described in very general terms as a complete-limit state design package independently and specifically developed for the ACCS, all other applications were developed in conjunction with conventional concrete technology. These applications require direct reference of the design to conventional national design procedures and codes. It is difficult to assess all the aspects and implications of the specific design approaches encountered, but the following list highlights some general impressions of the state of design using advanced composite materials in civil engineering and bridge applications.

• The high strength and relatively low modulus of affordable advanced composites often result in designs that are stiffness driven and do not use the strength capacities.

• Thin FRP laminates, overlays, or members need to be checked and designed for local stability (e.g., GFRP webs in the Bonds Mill Bridge [E3]) and may require stabilization with structural foam cores or stiffeners.

• To provide effective interaction with existing concrete members, the crack widths in the concrete need to be limited to levels that still ensure full aggregate interlock. Strain limits in the existing reinforcement (E10 to E12) and strain limits in the existing FRP overlay should play a greater role in design criteria and guidelines.

• Design of FRP strengthening measures for existing concrete structures must address FRP reinforcement termination and spacing requirements to provide safety and serviceability performance levels consistent with conventional concrete design practice.

• Loss of strength or aging of certain FRPs under sustained loads, referred to as "stress corrosion," seems to be a potential problem (E5, E8) with GFRP, in particular, and should be addressed as part of the design process.

• Cyclic load and fatigue characteristics of FRPs seem to exceed those of other materials, as long as the stress range and the mean stress do not facilitate stress corrosion.

• High temperature and fire response characteristics can be controlled by resin additives and coatings and can be comparable to or better than those for conventional materials, such as steel.

• Durability of advanced composite materials under the typical civil engineering environments still requires a broader data base, both from accelerated tests and long-term exposure tests, before durability can be used as a dominant design parameter.

• Because of the multitude of fibers and fiber architecture, resins and resin formulations, and manufacturing processes for advanced composite materials, strict performance specifications--not material or process specifications--are needed to ensure safety and serviceability.

• In the design process, more emphasis should be placed on the light weight of FRPs and simplifications that can be derived from this characteristic in the construction process.

• Detailed cost/benefit models, including maintenance and life-cycle data, should be developed, both for advanced composite materials and conventional materials to provide rational bases for choices of materials.

Relevance to U.S. Practice

Although some of the design criteria and guidelines developed in other countries deal with similar performance issues, they have indirect relevance to U.S. design practices. Some behavior characteristics that were observed and documented could, however, form the basis for research and development in the United States.

Transferable Technologies

Because design philosophies, procedures, criteria, and codes need to be accepted by the U.S. civil engineering community, direct transfer of design technologies is only applicable in a limited form. Direct correlation to U.S. design practice must be established.

Research and Development Needs

Design guidelines for the United States need to be developed and based on well-defined performance criteria, rather than on material or process specifications. These guidelines must address the impact of uncertainties in short- and long-term mechanical characteristics in the form of partial safety factors.

3.5

CONNECTIONS AND DETAILING (TOPIC 5)