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ABSTRACTS OF ALL PAPERS

1.
Opening presentation:
Innovative design concepts for composite bridges in Germany - Technology and aesthetics
Jan Knippers,
University of Stuttgart, Stuttgart, Germany

The introduction of a new material in building technology requires not only new technological solutions but also an adequate architectural approach. The famous pioneers in steel and concrete bridge building were successful, because they built technical as well as esthetically convincing bridges. This is necessary to achieve public acceptance and without the latter the propagation of new technologies is not possible.
In terms of composite bridges the situation is not very satisfying. Despite many technical advantages and a high level of experience only very few composite bridges were built in Europe. One reason might be, that emphasis was laid on solving the technical challenges while esthetical items were not discussed yet.
In our lecture we want to show some design approaches for German authorities, which try to improve this situation. Our aim is, to develop structural systems and details, which make the special features of the composite bridges visible, understandable and help to propagate the technology of composite bridges.

Session 1: COMPOSITE REINFORCEMENTS OF CONCRETE

2.
Effectiveness of near surface mounted CFRP reinforcement for strengthening of reinforced concrete structures
Renata Kotynia
Technical University of Lodz, Lodz, Poland

Effective technology for increasing flexural capacity of reinforced concrete structures with Near Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) reinforcement is presented in the paper. Flexural behaviour of the strengthend beams and modes of failure are presented and discussed. RC beams were tested under four point monotonic loading. Parameters investigated include the thickness of a concrete cover and density of CFRP reinforcement. The test results indicated that application of NSM CFRP strips significantly increased load bearing capacity and improved the stiffness of the beams. Failure of all members was caused by increasing of deflections, crack widths and gradual loosing of adhesion of the CFRP strip to the concrete cover. This technique is more effective than externally bonded CFRP reinforcement, provided higher strength capacity and higher utilisation of the strip. A non-linear model of reinforced concrete members was used for analysis. The calculated results correspond to the test results over the entire range of loading. Effectiveness of the strengthening with NSM CFRP strips in comparison of externally bonded CFRP strips is discussed.

3.
Debonding problems in beams strengthened using externally bonded FRP reinforcement
Oguz Gunes
University of Massachusetts Lowell, USA

concrete beams is a design issue with important performance and safety implications. This paper provides the highlights of an experimental and analytical research aimed at understanding and modelling of debonding failures in FRP strengthened beams. An evolutionary experimental program investigated debonding failure mechanisms and modes in beams strengthened in shear and/or flexure in various configurations and tested under monotonic and cyclic loading. A newly developed fracture-based model considers the global energy balance of the system and predicts the debonding failure load by characterizing the dominant mechanisms of energy dissipation during debonding. Validation of the model is performed using experimental data from various independent research studies and the results are compared with the current code provisions for debonding failure prevention.

4.
Strengthening of a large-scale prestressed RC bridge girder
Christoph Czaderski and Masoud Motavalli
EMPA, Dübendorf, Switzerland

The replacement of the superstructure of the highway bridges "Viadotto delle Cantine a Capolago" in the south part of Switzerland gave EMPA the possibility to get five large scale beams for several investigations. The beams are 17 m long and are prestressed with two internal tendons.
The paper presents results of a large-scale experiment on a beam which was strengthened for flexural by using CFRP plates. The failure load, the strains and the deformations of this strengthened beam are compared with an unstrengthened reference
beam. Furthermore, the results are compared with the design regulations of the Swiss code focusing on the debonding failure modes ‘anchorage’ and ‘shear’ of CFRP plates.

Demonstrations in the "Structural Engineering Research Laboratory":
CFRP-post-strengthening of large bridge girders
Masoud Motavalli, and Christoph Czaderski, EMPA, Switzerland

Session 2: TECHNOLOGY AND RESEARCH

5.
Application of bolted connection system for proposed GFRP bridge decks
Ki-Tae Park, Yoon-Koog Hwang, Young-Hu Lee, Sun-Myung Kim
Korea Institute of Construction Technology, Republic of Korea

This paper presents the level of composite action behavior for the bolt connection system of the proposed GFRP bridge decks. To verify the level of composite action of the bolted connection system, the prototype of proposed GFRP bridge decks are manufactured by pultruded method. And static tests on three specimens which are composed of FRP bridge decks and H-beam are performed. From this test results, the useful FEM models and analysis method for bolted deck-to-girder connection systems are selected. Using this FEM models, the level of composite action variations are analyzed as bolt spacings variation.

6.
Development of glass fiber reinforced polymer bridge deck system
Emile Shehata1; Doug Stewart1; Rick Haldane-Wilsone1; and Aftab Mufti2
1 Wardrop Engineering Inc, Winnipeg, Canada
2 ISIS Canada, University of Manitoba, Winnipeg, Canada

Development of efficient and durable bridge deck system is a priority for most of the highway authorities worldwide. This paper summarizes the results of experimental programs designed to study the behavior of an innovative glass fiber reinforced polymer (GFRP) bridge deck modules and its transverse connection. The deck consisted of a number of triangular filament wound tubes bonded with epoxy resin. Pultruded GFRP laminates were adhered to the top and bottom of the tubes to create one modular unit.
The experimental program, described in this paper, discusses the evolution of last two generations of the bridge deck. Full-scale prototype specimen was subjected to two million cycles at 135 % of the service load level and was tested to failure afterward. Another generation of bridge deck system was fabricated by optimizing the weight of the deck section and tested to failure. The performance was evaluated based on load capacity, mode of failure, deflection at service load level and stiffness degradation under cyclic loading. The next phase of the work was to establish a means of connecting adjacent deck panels. A GFRP shear key was designed, manufactured, and installed in a full-scale deck module to address this need. Assessment of the structural adequacy in both resisting repeated loading and in transmitting loads between adjacent deck modules is presented. The GFRP deck system with and without the shear key was capable of resisting two million cycles of an equivalent AASHTO HS-30 design truck wheel load including dynamic load allowance (DLA).

7.
Basaltocomposites as perspective materials for bridge structures
A.A. Dalinkevich, K.Z. Gumargalieva, A.V. Sukhanov, A.V. Asseev
Armoproject Company Ltd, Moscow, Russia

Continuous basalt fiber materials (CBFM), i.e. filaments, rovings and fabrics are perspective materials for producing composites with organic and inorganic matrices and deriving from these composites reinforcement elements for building constructions.
At present, mechanical and chemical properties of these materials, especially their resistance to various media, are studied intensively.
The main objectives of the present paper are determination of aging regularities for basalt rovings and reeled epoxy composites in various aggressive media (alkali, acids, overheated steam) and creation of corresponded kinetic aging models of the materials.
It is intimated that CBFM resistance to aggressive media (acids and alkali) depends on chemical composition of basalt and the surface condition (i.e. defectiveness) of the fibers. The surface condition can vary with respect to production conditions (stretching) of the fibers.
Comparative study shows that the resistance (i.e. strength preservation degree) of the majority of basalt rovings pre-exposed to hydrochloric acid (20%) highly (by tens of times) exceeds the resistance of E-type glass rovings. It is also found that resistance of the majority of basalt rovings pre-exposed to alkali (5% NaOH) and saturated cement tract exceeds resistance to alkali of the widespread alkali-free E-glass rovings. The latter fact indicates the possibility and prospect of basalt composite application as reinforcement of concrete in low-weight building constructions. Comparative studies of heat-humidity (overheated steam) aging of epoxy basaltoplastics and fiberglass show much higher wet strength of basaltoplastics. This makes the composite attractive for application in bridge structures exposed to long-term operation under high moisture conditions. Kinetic equations describing roving and composite properties reduction during aging and allowing forecasting of the properties conservation level are derived for these materials.

Session 2: TECHNOLOGY AND RESEARCH

8.
Newly developed GFRP–rebar as internal reinforcement
André Weber
Schöck Bauteile GmbH, Baden-Baden, Germany

Corrosion of reinforcement is an essential factor that limits lifetime of reinforced concrete structures. The parts of bridges, tunnels and parking decks that are frequently exposed to deicing salts are especially vulnerable.
The installation of GFRP-rebars is a possible solution to this problem. Due to high strength and stiffness and excellent durability a new GFRP-reinforcement system allows high design strength and high moment capacity of the structure. The bond behavior matches that of conventional steel reinforcement.
Applications in civil engineering and building construction are reviewed. The focus lies on the installation in areas of diaphragm walls that are to be cut by tunnel boring machines.

9.
Investigation of bond strength on steel-polymer-steel sandwich composite system
J. Y. Richard Liew, T. Y. Wang
National University of Singapore, Singapore

Series of experiments are being performed on steel-polymer-steel sandwich decking panels. The bonding strength between face plates and sandwich core is investigated. Novel mechanical shear connectors are introduced to improve the performance of the composite sandwich panels. Compared with specimens relying on adhesive bonding strength, it is shown that the proposed shear connectors can enhance the composite action between face plates and lightweight core materials. The experimental results in terms of static strength and impact resistance are compared with those obtained from finite element analysis. Finally, feasibility study will be performed to demonstrate the application of composite polymer steel sandwich system for use in offshore and marine environment.

10.
Development of a modular bridge system made in polymer composites
Josef Kurath
University of Applied Science, Winterthur, Switzerland

Faserverstärkte Kunststoffprofile (FVK-Profile) werden bereits heute sehr oft als Biegeträger für tragende Konstruktionen eingesetzt. Diese Konstruktionen sind meist wesentlich teurer als Tragstrukturen in Stahl, Beton oder Holz. Aus diesem Grund werden FVK-Konstruktionen meist nur an Orten eingesetzt, wo die Vorzüge des Materials stark zum Tragen kommen. Dies sind beispielsweise Konstruktionen in korrosiver Umgebung wie Kläranlagen und Oelplattformen oder Stege in Werkstätten mit aggressiven Oelen. Obwohl hauptsächlich die relativ günstigen Glasfasern als Verstärkungsmaterialien eingesetzt werden, sind die hohen Material- und Fertigungskosten ein Hauptgrund für den hohen Preis der Profile. Weiter orientieren sich die meisten herkömmlichen FVK-Profile stark an den im Stahlbau verwendeten Profilformen. Diese Formen werden den teilweise sehr guten Materialeigenschaften des glasfaserverstärkten Kunststoffes (GFK) nicht gerecht. Da die Steifigkeit, hauptsächlich von GFK-Profilen, relativ klein ist, kann in den meisten Fällen die hohe Festigkeit des FVK nicht genutzt werden.
Anhand eines Forschungsprojektes wurden an der Zürcher Hochschule Winterthur Biegeträgerformen gesucht, die die Qualitäten von Faserverbundkunststoffen (FVK) besser nutzen. Die Arbeiten wurden von der Kommission für Technologie und Innovation (KTI) und verschiedenen Industriepartnern stark unterstützt.
Ziel des Forschungsprojektes war es, einen Biegeträger in FVK zu entwickeln, der für kleine Lasten und mittlere bis grosse Spannweiten eingesetzt werden kann. Die Produktionskosten sollten wesentlich tiefer liegen als jene der heute für diesen Zweck eingesetzten FVK (hauptsächlich GFK)-Profile.

11.
Swissfiber bridge VC02: A modular pedestrian bridge system in FRP
Thomas Roth
Swissfiber AG, Zürich, Switzerland

To date we could not find a FRP-bridge system using the maximum potential of fiber reinforced plastic materials. The goal of the research project was to develop a lightweight modular bridge system for pedestrian loads that can compete with other construction materials

System
The main part of the system consists of an oval shaped 1m long beam element. The beam elements will connected to each other using pretensioned rods. Depending on the width required 1, 2 or more beams will be used. In between the beams transversal girders supporting the walking platform as well as the handrail are being used. For permanent use the pretensioning rods on the tension side of the main beam will be replaced by carbon fiber laminates made e.g. by Sika AG.
The Kempt bridge near the town of Winterthur is serving for more than 3 years by now with very good success.

12.
An Introduction to the CFRP stays of the Stork Bridge in Winterthur
Urs Meier
EMPA, Dübendorf, Switzerland

Site visits:
KEMPT / SWISSFIBER FRP BRIDGE AND CABLE STAYED STORK BRIDGE NEAR WINTERTHUR

Session 2: TECHNOLOGY AND RESEARCH

13.
Development and field applications of fiber reinforced composite bridge deck
Sung Woo Lee, Je In Kim, Nam Hoon Cho, Gyu Sang Jeong
Kookmin University, Seoul, Korea

Recent days composite bridge deck is considered one of the promising alternative to concrete bridge deck due to many advantages. In this paper, results of flexural tests for composite model decks of 3 different profile types fabricated with vacuum bag process were presented. Utilizing above results, full-scale pilot composite deck was fabricated with filament winding and flexural tests and finite element analysis were carried out. Based on the study for the model and pilot decks, pultruded deck of 3-cell trapezoidal profile, called ‘Delta Deck’, for real application was developed. Extensive experiments including flexural tests, fatigue tests, tests for girder connection and deck-barrier connections, and field load tests for the pultruded deck were conducted. Finite element analysis also performed and the results were compared with experiments. Serviceabilty and strength criteria were evaluated for Korean highway truck load. It also proposes the next generation deck profile for vertical snap-fit connections.

14.
Characterisation of mechanical properties of adhesive joints with mineral surfaces
Cornelia Bieker, Michael Schlimmer
University of Kassel, Kassel, Germany

For the lay-out of post- strengthening of buildings and bridges several aspects have to be considered. Besides the question of the service life time of a bonded structure under temperature and moisture or other media, the maximum carrying load of the post-strengthened structural member and the behaviour of the adhesive joints at dynamic loading conditions are of particular importance. Since post-strengthening often has to be carried out on components whose properties are not exactly known it is necessary to accomplish the investigations directly on these components, which are still in service. Therefore, it is necessary to have a testing method which causes little destruction.
At present, adhesive shear strength data to be used for analysis is determined in special tensile tests. In the presentation, a new testing method is presented. With this method it is possible not only to determine the uniaxial und multi-axial strength of adhesive joints with mineral surfaces but also to investigate their long-term behaviour, e.g. under static and dynamic loading when exposed to hygrothermal temperature and media. The advantage is that the real surfaces in questions are involved in the test. Exemplarily, results for bonded Ultra High Performance Concrete are presented demonstrating that the method is flexible, thus applicable to other materials such as concrete and bricks.

Session 3: MONITORING OF STRUCTURES

15.
Fatigue and reliability analysis of fiber glass bridges
Alexander Tesar
Slovak Academy of Sciences, Bratislava, Slovak Republic

Reliability analysis of fatigue behaviour of fiber glass composites adopted in bridge engineering. In reliability analysis of engineering systems it is conventional to represent the limit state function as a precise surface. Uncertainty in the limit state function may be represented by introducing one or more additional random variables. Fuzzy label methods for constructing of imprecise limit state functions are adopted in this paper. Simulation model adopting the running wave approach together with parallel processing technique and back-propagation neural network is used for numerical analysis of the problem. The numerical treatment of the non-linear problems appearing is made using the updated Lagrange formulation of motion. Specified are the non-linear pseudo-forces, with updated back propagation control of the solution strategy in iteration steps. Numerical and experimental verifications are submitted in order to demonstrate the efficiency of the techniques suggested.

16.
On the vibration mitigation of light-weight bridges
Daniel Gsell, Glauco Feltrin and Masoud Motavalli
EMPA, Dübendorf, Switzerland

Light-weighted structures show a high live load - dead load ratio. Thus, their resonance frequencies are dependent on the current loading state and may vary in a quite broad range. This behavior is a real challenge in vibration mitigation of such structures, since common damping devices are designed to fit one particular frequency. Adaptive vibration mitigation systems are necessary.
Tuned mass dampers are reliable and efficient devices to mitigate vibrations of bridge girders. This paper discusses strategies to realize a tuned mass damper, which is able to adapt the current resonance frequency of the structure.

Demonstrations in the "Structural Engineering Research Laboratory":
On the vibration mitigation on a FRP bridge
Masoud Motavalli and Daniel Gsell, EMPA, Switzerland

Session 4: STANDARDS AND CODES FOR COMPOSITE MATERIALS AND DESIGN CRITERIA

17.
External FRP reinforcement and uncertainties in standards
Ane de Boer1, Ernst Klamer2
1 Ministry of Transport, Public Works and Water Management, Utrecht, the Netherlands
2 Technical University of Eindhoven, Eindhoven, the Netherlands

Concrete structures can become in an unacceptable structural condition by the decreasing material behavior or the increasing loading conditions of the structure. Today, by strengthening the concrete structure with external FRP reinforcements, the structural lifetime will be extended again to an acceptable redesign level.
However, code checking the redesign calculations of the structure is still based to some national recommendations or technical reports. Recommendations like the British report 55, 2e edition, and the Dutch recommendation CUR 91, as well as the fib technical report 14 must be mentioned in this field. Acceptation of these recommendations into a new Eurocode or Model Code for concrete structures takes a long period of time. During this period also new lab tests and engineering practise enlarge the knowledge of the external reinforcement of concrete structures.
The common checking codes are based on stresses, strains and deformations. Today the checking code can be extended to a reliability index of the structure, which doesn’t take a lot of computational process time anymore. The uncertainties of standards can be encapsulated into a full probabilistic nonlinear analyses of the structure, which opens the acceptation of using incomplete proven materials.
Recent research of the Bayesian believe method of Denmark and the Netherlands, can be useful to couple the overall standardization acceptation process with instantaneous new results during a new standardization process. So, within the Bayesian believe method, the existing recommendation articles can be extended at any time in a proper way with lab tests and results of monitoring structures and inspection methods of strengthened structures. This should be very useful for accepting new materials like FRP reinforcement into new codes.

18.
In-service performance of an advanced composite materials bridge superstructure
Hyo-Seon Ji1, B.J. Son2, Y.H. Cho3
1 Deawon Science College, Chungpuk-Do, South Korea
2 Korea Research Institute of Standards and Sciences, Chungnam-Do, South Korea
3 Seongwon Construction Co., Ltd., Gangwon-Do, South Korea

The first all advanced composite materials short - span bridge superstructure in South Korea on a public highway system was installed in May, 2002. These composite materials are new to bridge application, so no sufficient data exists on their in-service performance. This paper describes in-service performance of all advanced composite materials bridge superstructure. To investigate its in-service performance, field load testing and visual inspections was conducted under controlled conditions. The test data indicate that the bridge superstructure is structurally performing well. The results from the field load test serve as a baseline data for future field durability assessments as part of a long-term performance of advanced composite materials bridge superstructure.

19.
Use of CFRP in precast prestressed high performance concrete for innovative bridge deck systems
Derek Tardif1, Kenneth W. Neale1, Marc Demers1, Adel R. Zaki2, Gamil Tadros3,
1 University of Sherbrooke, Sherbrooke, Canada
2 SNC-Lavalin Inc., Montreal, Canada
3 ISIS Canada, Calgary, Canada

This research project focuses on an innovative design concept for precast prestressed concrete bridge deck systems, with the objectives of increasing the service life of new bridge decks and understanding their structural behaviour. The project was initiated after a major bridge deck reconstruction on Jacques-Cartier Bridge in Montreal. Precast concrete bridge elements with carbon fiber reinforced polymer (CFRP) draped prestressing strands as longitudinal reinforcement and glass fiber reinforced polymer (GFRP) as stirrups and slab reinforcement will be compared to conventional reinforced and prestressed steel concrete elements. Based on the testing of full-scale elements, the paper will present comparison on the serviceability, ultimate strength and failure modes.

Session 5: DESIGN AND CASES

20.
Project highlight: A landmark application of FRP bridge decks on the Broadway Bridge in Portland, Oregon, USA.
Matt Sams
Martin Marietta Composites, Raleigh, USA

Broadway Bridge was originally constructed in 1912. Located in the heart of the Portland harbor, Broadway sees 30,000 vehicles per day & several bascule span openings per month.
According to its owner, Broadway is the 7th longest bascule bridge in the world.
Currently undergoing largest renovation project in its history.
In August, 2004 the bascule span's steel grating was replaced with an FRP deck.
Likely one of the largest and most frequently traveled FRP decks in the world.
Prefabrication allowed all FRP panels to be installed in two shifts (with misc FRP tasks completed in 3rd shift).

We see this installation as a significant event in not only the application of FRP, but in the use of prefabricated bridge components.

21.
Design and testing of an inventive GFRP-truss-bridge for 40 ton trucks and 30 meter span
Heiko Trumpf, G. Sedlacek
Institute of Steel Constructions, RWTH Aachen, Aachen, Germany

Presented are the design and test programme of a truss-bridge including the development of new deck elements made of pultruded glass-fibre-reinforced polymer profiles for 40 t trucks and 30 m span. Several experimental investigations have been performed to increase the resistance of the bolted connections of the bridge by local strengthening with inductive-bonded collar jackets and reinforcing with bonded adaptive cold-formed fittings. Based on these test results the favourite connection techniques have been improved and applied to the final bridge construction. The geometry and laminate composition of the developed deck elements have been determined by using micro- and macro-mechanics as well as sophisticated strength hypotheses on the bases of small-scaled tests and microscopic analyses. All investigations have been accompanied by numerical simulations using finite element models with composite-layered-shell elements and simplified engineer-shell elements. Finally all connections of the final bridge and new manufactured pultruded deck elements were tested in large-scaled static and dynamic tests to verify the calculations and finite-element-analyses as well as to enable a determination of the safety factors by statistical evaluations.

22.
Reinforcement of bridges and the use of multidirectional carbon fibre laminates
Roan Van Boeckel
Tradecc NV, Wilrijk, Belgium

The technique of gluing carbon fibre reinforced laminates for strengthening of concrete structures has been known for about 10 years now. These laminates are very light, easy and fast in application, they do not corrode and have a high tensile strength.
The weakness of this system however is what we call "concrete rip-off"/ The cause of this brittle failure mode will be explained during the presentation. Due to this phenomenon the carbon fibres can no be exploited in their full capacity.
For the reinforcement of the bridges in Zwolle reference was made to the CUR prescriptions. The CUR prescribes for instance that the concrete tensile strength has to be at least 1,5 Mpa in order to use externally bonded laminates to reinforce the structure. However, tests have shown that this was not the case for the concrete of the bridges.
To overcome this problem TRADECC nv developed an innovative production process to fabricate the PC CarboComp Plus. These are multidirectional carbon fibre reinforced laminates, with not only fibres in the longitudinal direction but also in the directions +/- 45 degrees. Hereby the laminates can be anchored with bolts to prevent concrete rip-off. With this technique the bearing capacity of a beam or plate can be uplifted considerably. In addition the failure mode becomes ductile. This means that in case of overloading of the reinforced element, a great deflection will appear before collapse, which leaves enough time to evacuate the building safely and to do what is necessary to overcome this collapse.
PC CarboComp Plus is tested in laboratories. Some of the experiments will be used to make a comparison between the failure mechanism of a traditional T-beam, the same beam with a glued carbon laminate and finally the same beam reinforced with a bolted PC CarboComp Plus laminate.
Thanks to the technique of bolted carbon fibre laminates 5 bridges in Zwolle have been reinforced to fulfil all safety demands. During the application of the laminates traffic on.

23.
Experience in calculation and experimental researches for pedestrian bridge constructions
A.E. Ushakov, Yu.G. Klenin, A.V. Pankov, S.N. Ozerov
ApATeCh, Moscow, Russia

ApATeCh Co. activities. Experimental determination of parameters of static, fatigue, long-term strength and fracture toughness of pultrusion profiles taking into account climatic factors and static and fatigue strength of bolt joints in bridge construction in Chertanovo (Moscow). Calculation of construction of Chertanovo Bridge. Estimation of damage tolerant value and development of schedule of maintenance. Results of bridge section static and dynamics tests and bridge section actual test. Expansion of Standardization and Codes base for wide implementation of pultrusion materials in bridge construction industry in Russia.

Visit to the "Carbo-Link Company", a young Spin-Off Company of EMPA.
Carbo-Link is producing CFRP tensile elements for civil and mechanical engineering. They were and still are developing CFRP stays and other elements for the winner of the Americas Cup: ‘Alinghi’.

24.
Prodeck bridge systems: the road to the future
Thomas S. Wright
Bedford Reinforced Plastics, Bedford, USA

This presentation will demonstrate the Prodeck 4 and Prodeck 8 deck systems manufactured by Bedford Reinforced Plastics, Inc. The Prodeck systems will be shown being manufactured in the pultrusion process, assembled into bridge deck modules and the installation of several bridges. Included in the installation process will be the glass overlay on the field joints, the deck connection to the bridge super structure, the application of polymer and asphalt overlay material forming the road surface, as well as different types of guardrail systems.

25.
Static and dynamic load tests of 20 meter long span of composite truss footbridge
Henryk Zobel1, Krysztof Zoltowski2, Wojciech Karwowski1, Andrzej Kozakiewicz2
1 Warsaw University of Technology, Warsaw, Poland
2 Gdansk University of Technology, Gdansk, Poland

The GFRP footbridge was made for the waste-water treatment plant in Lodz in 1999. It was designed by Ramboll, Hannemann & Hojlund GmbH from Berlin and built by Fiberline A/S from Kolding (Denmark). This footbridge is the first and only one composite object in Poland up to now. The authors decided on making some research to check the condition of the object after the five years of exploitation. It was decided on carrying out tests with static loading and what was even more important – with dynamic loading. The results were used for verification of FEM model (deflection and eigenfrequency). Dynamic research was made also to check the dynamic model of the pedestrian load. This is part of the experiment on the dynamic behaviour of footbridges which is taking place in Gdansk University of Technology. The paper presents the results of the static and dynamic experiments.

26.
Carbon fibre composites for a new generation of prestressing tendons
Markus Maier, Hans-Peter Andrae
Leonhardt, Andrae & Partner, Stuttgart, Germany

Carbon fibre plates are generally used for repair and strengthening of structures to replace missing or corroded reinforcement. The benefits of this material increase dramatically however when used as prestressing tendons.
According to the European Technical Approvals Guideline (ETAG), Anchorages of post-tensioning kits traditionally need to be designed such that the full strength of the tendon can be developed and that failure of the tendon at breaking load occurs outside the anchorage. For steel tendons the effectiveness of anchor systems depends on the isotropy and plasticity of steel.
The lack of plasticity and the totally anisotropic material texture of FRP’s however are less favourable conditions to meet the above mentioned ETAG requirement. New anchorage design approaches are necessary.
This paper will report the research and development work of a new Carbon fibre posttensioning- and anchoring kit, based on CFRP plates, finishing up with a multi-layer CFRP tendon with possible prestressing forces up to 1.5MN. Case studies of practical applications will be presented and illustrated.

CLOSING PRESENTATION:
How to bridge the credibility gap
Urs Meier
EMPA, Dübendorf, Switzerland