Use of the Promising Composite Delta Deck for Various Composite-deck Bridges

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1 Fourth International Conference on FRP Composites in Civil Engineering (CICE2008) 22-24July 2008, Zurich, Switzerland Use of the Promising Composite Delta Deck for Various Composite-deck Bridges S.W. Lee 1, K.J. Hong 2 & J.I. Kim 3 1 Professor, School of Civil & Environmental Engineering, Kookmin University, Seoul, Korea 2 Assistant Professor, School of Civil & Environmental Engineering, Kookmin University, Seoul, Korea 3 Vice President, Kookmin Composite Infrastructure Inc., Anyang, Korea ABSTRACT: Recently, the composite deck has emerged as a promising alternative to a concrete deck for bridge structures. This type of deck has many advantages. It utilizes a lightweight and high-strength material, has good resistance against corrosion, and is highly durable. This paper gives a brief description of the development of two types of composite decks. The first of these uses a tongue-and-groove connection and the second a snap-fit connection. The snap-fit connection significantly lowers the cost and improves the quality of construction compared to conventional construction techniques that use composite decks with tongue-and-groove connections. Recent applications of these types of composite decks are also discussed. 1 INTRODUCTION To cope with the problems of deterioration and corrosion in conventional steel and concrete materials, highly durable and lightweight fiber-reinforced composites are considered to be one of the most promising alternative materials for civil infrastructure projects. Among the many applications of these materials, composite decks for bridges are highly notable. Composite decks for bridges have significant advantages compared to conventional concrete decks as they are highly durable and corrosion-free. Much longer service life and lower maintenance costs are expected for bridges with composite decks, which will result in a much lower life-cycle cost (LCC). Due to the light weight of a composite deck, it can offer a reduction of the dead load by as much as 80% compared to that of a conventional concrete deck. Much slimmer substructures are possible for bridges on account of the use of lightweight composite decks. When a composite deck is used for re-decking of a bridge, the capacity of the live load on the bridge is upgraded automatically without the need to strengthen its girders or substructures. Furthermore, composite decks can be installed quickly, significantly reducing the duration of construction and lessening the amount of time when traffic is blocked. This allows considerable savings to be achieved. Due to these notable advantages of a composite deck, numerous studies have been carried out and an increasing number of field applications have been reported (DARPA 2000, Keller 2003). Moreover, many profiles of composite decks have been developed and put into practice since the 1990 s (Keller 2003). The United States is leading the research on composite decks, and more than 200 bridges with composite decks, including pedestrian bridges, are already in use there. In Korea, more than 10 composite-deck bridges, including the world s largest in the Busan Newport area, are in use, with more scheduled to be constructed. By the year 2007, the total area of composite decks installed in Korea was 13,000m 2, which exceeds the total installed area in the United States of 8,000m 2. 2 COMPOSITE DECK WITH TONGUE-AND-GROOVE CONNECTION: DELTA DECK Through extensive studies, a composite deck profile that uses a tongue-and-groove connection - 1 -

2 was developed. It is known as a Delta Deck (Lee 2004). As shown in Fig. 1, it has three trapezoidal cells that are 200mm in height. It is fabricated via pultrusion, as shown in Fig. 2. The deck is designed for typical girders with spacings ranging from 2.5 to 3.0m under the DB24 Korean Highway truck load (with a rear axle load of 94.1kN). As shown in Fig. 3, pultruded deck tubes are assembled by bonding them together with epoxy to create a deck panel that is used as part of the bridge. As laminates for the deck, 8800 Tex E-glass roving is used in the longitudinal direction in conjunction with multi-axial stitched fabrics (90, ±45 ). Unsaturated polyester is used as a resin base. Figure 1. Profile of a Delta Deck Figure 2. Pultrusion Figure 3 Assemblage 2.1 The world s largest composite deck bridge A wharf-type girder bridge at the Busan Newport terminal in Korea measuring 300m long and 35m wide was constructed in It is known as the Noolcha Bridge. This bridge is currently the largest composite-deck bridge in the world. Figure 4. Profile of the Noolcha Bridge Figure 5. Cross-section of the Noolcha Bridge Figure 6. Foundation and girders Figure 7. Decks stored in the yard Figure 8. Installation of decks The composite deck was selected for this bridge for the benefits of cost savings in construction and maintenance. The lightweight property of the composite deck significantly reduces the required number of marine foundation piles, which lowers the initial construction cost considerably. In addition, the high durability of the composite deck reduces the life-cycle cost remarkably. Figs. 4 and 5 show the profile and a cross-section, respectively, of the Noolcha Bridge. Fig. 6 shows the marine foundation piles on the left side and completed girders on marine foundation piles of the Noolcha Bridge on the right. The composite decks are stored in a yard before installation, as shown in Fig. 7. They are then moved from the yard onto bridge girders for installation, as shown in Fig. 8. This installation process is considerably faster than that in conventional concrete deck construction. Fig. 9 shows installed composite decks that are connected to each other by epoxy bonding. These composite decks then are fixed to girders by installing shear studs through pre-opened holes, as shown in Fig. 10, and non-shrink concrete is then poured, as shown in Fig. 11, into these holes to fix the composite decks onto the girders. After constructing - 2 -

3 part of the bridge, lifting equipment moves onto the constructed part and assists with the installation of composite decks for other parts of the bridge, as illustrated in Fig. 12. Fig. 13 shows the completely installed decks on girders and Fig. 14 shows the completed bridge after placing pavement and sidewalks. Figure 9. Assembling decks Figure 10. Shear studs Figure 11. Pouring concrete Figure 12. Equipment on decks Figure 13. Installed decks Figure 14. Completed bridge 2.2 Steel plate girder bridge at Gangnung, Korea A composite deck was used in the construction of a 36m long and 7m wide bridge at Gangnung in Korea. Fig. 15 shows the profile and a cross-section of this bridge. The composite decks are easily moved onto plate girders by lightweight lifting equipment, as shown in Fig. 16. By utilizing the lifting equipment that sits on the installed parts of the deck, the composite decks are assembled one by one with epoxy bonding, as shown in Fig. 17. Fig. 18 shows the pouring of the concrete to fix steel reinforcement to the composite decks for guardrails. After completing the installation of the composite decks, urethane resin is sprayed onto the top surface of the composite deck for protection purposes, as shown in Fig. 19. 교량시점 교량종 하상정리선 EL.= Figure 15. Profile and cross-section Figure 16. Moving composite decks on girders - 3 -

4 Figure 17. Installation of decks Figure 18. Installation of guardrail Figure 19. Surface treatment 3 COMPOSITE DECK OF A VERTICAL SNAP-FIT CONNECTION Thus far, the aforementioned tongue-and-groove connection method is prevailing in the assembly of composite decks. In conventional means of steel or concrete deck construction, shear connectors are provided on top of the girder prior to the placement of decks. However, when composite decks are installed by connecting them to each other via tongue-and-groove connections, shear connectors cannot be used until the composite decks are completely assembled. The deck should be assembled side by side horizontally on top of the girder without barriers such as shear studs that vertically stand on the girders. Welding shear studs to steel girders through predrilled small confined holes of the deck causes poor workability and leads to poor welding quality, requiring additional funding and time. If a girder is made of concrete, the installation process of the shear connector is far more difficult. In addition, accumulated horizontal gaps between bonded composite decks become larger for a longer bridge, which can create a mismatch between the locations of the shear studs and the pre-drilled holes. To avoid this problem, an innovative composite-deck profile of a multi-cell polygonal shape with a vertical snap-fit connection was developed (Lee 2006, Lee & Hong 2007a,b,c). Figure 20. Section of a composite deck with a snap-fit connection Figure 21. Deck assembly by snap-fitting Figure 22. Deck assembly for curved pathway Fig. 20 shows the developed profiles of a snap-fit deck for pedestrian bridges. Fig. 21 shows an illustration of a deck assembly by snap-fitting. Developed snap-fit decks significantly improve construction workability and quality, provide snap-fit mechanical connections with or without adhesive bonding, and reduce the necessary installation time and associated costs. Fur

5 thermore, the snap-fit deck is easily applicable to curved bridges as shown in Fig. 22, whereas this is not the case for tongue-and-groove type of deck. The skewed decks in Fig. 22 can be assembled by rivet connection or epoxy binding with channels installed between the decks. Vertical snap-fit connections provide easy assembly and disassembly if decks are connected without adhesive bonding. This advantage enables the application of snap-fit decks not only to temporary bridges but also to road-mats for use with oil and gas development, disaster relief, and military operations, as well as mining, logging and construction activities. It is hoped that the development of the vertical snap-fit connection will pave the way for far wider applications of composite decks. 3.1 Steel plate girder bridge at Geeheung, Korea A 776m long and 3.5m wide curved pedestrian bridge is currently under construction at Geeheung, Korea. The profile of this bridge is shown in Fig. 23. The snap-fit decks are easily moved onto steel plate girders by lightweight lifting equipment, as shown in Fig. 24. Fig. 25 shows workers assembling the composite decks by snap-fitting, and Fig. 26 shows the completely installed curved decks before the placement of pavement. Figure 23. Profile of a steel plate girder bridge at Geeheung Figure 24. Moving decks Figure 25. Assembling Figure 26. Installed decks 3.2 Walkway expansion at Hangang Bridge, Seoul Given that a composite deck is lightweight, an existing pedestrian bridge can be upgraded by replacing a concrete deck with composite decks. For this reason, the existing walkway of Hangang Bridge in Seoul is scheduled to be upgraded by replacing the existing concrete decks with the snap-fit composite decks. Fig. 27 shows the Hangang Bridge, and Fig. 28 shows the existing walkway of this bridge. The width of this walkway is currently 2.45m but will be nearly doubled to 4.95m after the upgrade, as shown in Fig. 29. The design of this expansion of a sidewalk has been completed and the construction will start in Figure 27. Hangang Bridge in Seoul, Korea - 5 -

6 Figure 28. Existing walkway Figure 29. Expanded walkway 4 CONCLUSION This paper presented a brief description of two different types of composite deck developed in our study. The first utilizes tongue-and-groove connections while the second uses vertical snapfit connections. The tongue-and-groove composite decks have been applied to many bridges in Korea, including the world s largest composite-deck bridge located at the Busan Newport area in Korea and a plate-girder bridge at Gangnung in Korea. The snap-fit composite decks were applied to a steel plate-girder pedestrian bridge at Geeheung in Korea, and in 2008, the snap-fit composite decks will be applied to the walkway expansion project of Hangang Bridge in Seoul. Construction of additional pedestrian bridges is planned with the snap-fit composite decks in the near future. Due to the many advantages of a composite deck with snap-fit connections, additional applications of these types of decks are anticipated. ACKNOWLEDGEMENT The study presented in this paper has received support from the Korea Science and Engineering Foundation (Grant no: R ) and the Ministry of Construction and Transportation (Construction Core Technology R&D 06-C04 and 01-Mokjeok A01). The authors gratefully acknowledge the support from these institutions. REFERENCES DARPA Advanced Composites for Bridge Infrastructure Renewal-Phase II Tasks 16- Modular Composite Bridge. Defense Advanced Research Projects Agency. Technical Report Vol. IV. USA. Keller, Thomas Use of Fiber Reinforced Polymers in Bridge Construction. Structural Engineering Documents 7. IABSE (International Association for Bridge and Structural Engineering). Switzerland. Lee, S.W Development of High Durable, Light Weight and Fast Installable Composite Deck. MOCT R&D Report. Ministry of Construction and Transportation. Korea. Lee, S.W Fiber Reinforced Polymer Composite Bridge Deck of Tubular Profile Having Vertical Snap-Fit Connection, US Patent No. US 7, 131, 161 B2, USA Lee, S.W. & Hong, K.J. 2007a. Development of Composite Deck Connection for Pedestrian Bridge Using Korean Traditional Wooden Joint Method. KOSEF Research Report. Korean Science and Engineering Foundation. Korea. Lee, S.W. & Hong, K.J. 2007b. Development of Light-Weight Composite Deck with Snap-Fit Connection for Rigmat and Bridge Deck. MOCT R&D Report. Ministry of Construction and Transportation. Korea. Lee, S.W. and Hong, K.J. 2007c. Experiencing More Composite-Deck Bridge and Developing Innovative Profile of Snap-Fit Connections, Proceedings of COBRAE Conference. March Stuttgart, Germany