Abstracts COBRAE Conference Stuttgart

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SUBMITTED PAPERS

Thin thermoplastic CFRP tapes support wooden structures
Prof. Dr. Urs Meier (Chairman of COBRAE)
EMPA, Dübendorf, Switzerland

This paper will present two case histories where thin CFRP tapes and wood have been combined.

Case (i): The town church of Homberg-Efze was built in the first half of the 14th century. The assignment was the stabilisation of the roof truss against high wind loads. To meet this challenge it was decided to apply in the cross section of the truss girder diagonal pin-loaded thermoplastic CFRP ties. The application of the transverse bracing happened in October 2005. Since then there is a continuous on-line remote monitoring of the wind velocity and the loads on the CFRP cross-ties.
Case (ii): The bowstring arch bridge concept is a new idea applying CFRP tapes for the bowstring and glulam for the arch shaped bridge deck. This deck is stress-laminated. The bowstring arch concept allows an extremely slender and therefore very elegant bridge design. The first bridge of this kind was built end of 2006 and will be presented.

Design of an emergency truck GFRP truss bridge
M. Dolores G. Pulido
PEDELTA, Barcelona, Spain

A truck truss bridge in Colombia, 30 m span, 3.6 m wide, composed of GFRP pultruded profiles, is being designed.
One of the main requirements of this structure is a rapid installation, due to emergency situations. That is why as longitudinal as truss girders have to be made of FRP profiles, as well as deck, using bolted joints. The demand for simpler assembly and reduced service time has led to an enhanced interest in alternative technologies. Due to its low self weight, FRP structures offer new possibilities in this field.
However, there is no approved code or guide for the design of pultruded structures, and therefore, the design basis for pultruded structural design needs to be defined by the designer.
In this paper, a design approach used in the design of this structure is presented, which takes into account the composite laminate, mixing and multi-layer Kirchhoff-Love thin plate theories, specific failure criteria as well as guidance for bolted joints.

Experiencing more Composite-Deck Bridges and Developing Innovative Profile of Snap-Fit Connections
Prof. Sung Woo Lee, Kee Jeung Hong
Kookmin University, Seoul, Korea

Due to the merit of lightweight, high durability and speedy construction, increasing number of bridges of various girder types are recently being built with fiber-reinforced composite deck in Korea. This paper describes background of development of the current composite-deck profile of a hollow trapezoidal section. It also presents design and construction perspectives of built bridges of many types of girder including plate girder, concrete girder, steel box girder, pier-type girder. Especially, the pier-type bridge is 300m long and 35m wide, which is currently the largest composite-deck installation in the world for a single bridge, and has set another milestone for the earnest use of composites to the civil infrastructure. Some details for design, assembly, transportation and construction of this bridge will be included in the paper. Also performance of a constructed bridge of plate-girder type, which has composite decks with non-composite action, is verified through static and dynamic field load tests. It demonstrates that the bridge possesses safety margin for strength and serviceability well over the requirements of the Korean Highway Code. This paper also introduces newly developed innovative composite-deck profile of vertical snap-fit connection which significantly improves the constructability and costs compared with conventional composite decks of tongue-and-groove type. Analytical and experimental results for the snap-fit connected decks are presented. It also presents applications of the snap-fit connection to not only traffic bridges but also pedestrian bridges. Furthermore, applications of the deck having snap-fit connections to the road mat show another great potential.

Experimental and FEM Study of the Flexural Behavior of Carbon Fiber Reinforced Polymers Strengthened Concrete Structures
Dr. Saud Aldajah, Dr. Ashraf Biddah, Ammar Al-omari, Dr. Adel Hammami
United Arab Emirates University, Al-Ain, United Arab Emirates

This paper studies the experimental flexural behavior of concrete beams and slabs and asses the impact of carbon fiber reinforced polymers (CFRP) on their behavior. Results showed that CFRP sheets increased the load carrying capacity for the beam by 20% and for the slab by 17% whereas the CFRP strips increased the load carrying capacity for the beams by 40% and for the slabs by 77%. Finite element modeling, using Abaqus software with the smeared crack assumption, was carried on for the control beam and the strengthened beam assuming perfect bonding between the CFRP and the concrete. The model results were in good agreement with the experimental data.

Partial Connection of Beams made of High Performance Materials
Mr. Jakub Dolejs
CTU Prague, Prague, Czech Republic

Composite beams are mostly designed according to plastic theory. Specific material properties with respect to ordinary design processes bring many questions. One of them is a behaviour of partially connected composite beams made of higher strength steel and high performance concrete. A research project to study behaviour of such beams is in a progress at CTU Prague nowadays. Results of experimental research with composite beams made of steel S460 and concrete C70/85 are presented. Special attention is focused on shear connection and normal stress distribution. Possibility of a partial connection has been studied.

Experiments and Numerical Investigation of Perfobond Connector
Mr. Peter Chromiak
CTU Prague, Prague, Czech Republic

Two types of perforated shear connector for composite connection transfer used in building and bridge structures were investigated at CTU Prague till today. Many experimental tests under static loading with both connectors were executed to determine its static shear load capacity. The experiments have been done as specified in EC4 for standard push-out test. Numerical models of push-out specimen with both connectors were prepared in software ANSYS and ABAQUS. Now, the small modification of basic connector was successfully investigated. The results of 3 new test specimens and their comparisons with primary results are presented in the paper. The following paper is focused on description of a numerical model creation of the last tested type of perforated connector under static loading as well.

Keywords: Composite structure; perforated shear connector; push-out test; modified basic connector, numerical model.

CFRP in Germany - Development of Strengthening of Engineering Structures
Dr. Horst Peters
SIKA Deutschland GmbH, Stuttgart, Germany

Based on first experiences at the EMPA (Switzerland) in the 80th and works at Universities in Germany (e.g. TU-Braunschweig) in November 1997 the first technical Approval was given for the strengthening of RC-structures with CFRP tendons in Germany (Z-36.12-29).
In the meantime the adventures of material and applications are "State of the Art" in building constructions and civil engineering. Sika is cooperating with different Universities (e.g. TU-Berlin, TU-München, Uni Karlsruhe, Uni Leipzig, Uni Stuttgart,…) to improve the implementation of CFRP in structures. Beside the approval different CFPP-types like L-shaped shearbrackets or highmodulus lamellas or CFRP-Wraps find their practice with a "ZiE".
A special attention deserves the strengthening of structures with pre-stressed CFRP-tendons. The requirements of the "ETAG 013" of the steel-tendons were translated to the CFRP-tendons. Since the worldwide first pre-stressing application in 1998 at the "Gomadingen Bridge" the third generation is developed and successful applied in big bridge-strengthenings.
According to the theme "Benefits of Composites…" exemplify projects of strengthened structures should be introduced:

* Strengthening of Parking garages / Industry buildings / historical buildings
* Strengthening of a Cooling tower (Wraps)
* Untensioned strengthening of Bridges
* Pre-stressed strengthening of Bridges (survey)

Advances in Underwater Pile Repair using FRP
Prof. Rajan Sen
USF Tampa, Department of Civil & Environmental Engineering, Tampa, USA

The availability of resins that can cure in water has made it possible to explore the use of FRP for the corrosion repair of piles. Over the past three years, USF has completed four such demonstration projects. Three of these were conducted in the tidal waters of Tampa Bay, Florida’s largest estuary connecting Tampa Bay to the Gulf of Mexico. In each case selected piles were instrumented to allow long term monitoring of FRP’s performance in mitigating corrosion. This paper presents an overview on the lessons learnt and future developments planned with particular reference to the completed field demonstration projects.

Aerospace Grade Composite Technology for Infrastructure
Dr. Laurence Walker
Wave Engineering, Perth, AUS

The use of secondary bonded and onsite wet layup composite systems for the repair and strengthening of infrastructure has been increasing gradually over the last 5-10 years. There is little doubt that engineers are enthusiastic about their possibilities however issues such as environmental concerns, void levels and limited system versatility have all contributed to their limited acceptance. While infrastructure is using decades old ambient cure technologies, aerospace and automotive projects use pre-impregnated fibres or prepregs. Prepreg materials are supplied with the resin already impregnated into the fibre and provide a far more robust and reliable composite product. This paper examines the applicability of pre preg technologies to the infrastructure rehabilitation industry and the requirements for processing them on site.

Availability of Antiseismic Inverted Suspension Bridge
Dr. Robert Azoyan, Dr. Grigor Sargsyan
Yerevan State University of Architecture and Construction, Yerevan, Republic of Armenia

The structure of antiseismic inverted suspension bridge was described in our work. Main point of the offer is to use suspension system without pylons where cable can be fixed in span approach zone as well as in bridge approach zone.
Using similar systems are practical in mountain areas. The structure of inverted suspension bridge let us covered up to three hundred meter spans with advantages of material expanses.
In lecture was adduced short reduction of structure decisions and bridge conduct analyses under earthquake action. Was shown that span satisfy use requirements. The steel expanses are appreciably less in comparison with other antiseismic bridges.

Development of Calculation Resistance Definition Model for Bridge Designs Elements from Composite Materials
Prof. Andrey Ye. Ushakov, Yury G. Klenin, Dr. Andrey V. Pankov, Sergey N. Ozerov
ApATeCh Co., Zhukovsky, Russia

Experience of application and perspective projects of bridge designs from FRP in Russia. Creation of normative base for FRP application in bridge building. Experimental definition of parameters of static, fatigue and long-term durability, crack resistance parameters of pultrusion profiles in view of climatic factors, and also static and fatigue resistance of bolted joints. Dependence for definition of calculation resistance in view of influence of climatic factors, crack resistance parameters of material and dispersion of characteristics.

Carbon fibre stress-ribbon bridge
Prof.Dr. Mike Schlaich, Dipl.-Ing. Achim Bleicher
Institute of Conceptual and Structural Design, Technical University of Berlin, Germany

Up to now,carbon fibre is used in structural engineering only to enforce existing old concrete beamsor columns.Instead,the big economic and structural potential for new structures is still unused.
To show this potential,the first stress-ribbon bridge with carbon fibre reinforced plastics for the primary structure was built in the laboratory hall of the institute of civil engineering at the TechnicalUniversity of Berlin.
Stress-ribbon bridges are one of the lightest and smartest bridges.The ribbons are anchored in the abutments on both sides.Pedestrians walk directly on the ribbons that have been covered and weight down wit open-jointed concrete planks.Usually the ribbons are steel plates,ropes or lacings. But using carbon fibre reinforced plastics instead of normal steel plates creates an opportunity for an innovative development of stress-ribbon bridges.Compared with normal structural steel,the tensile strength of carbon fibre is ten times higher and the dead load is five times lower.This higher efficiency allows longer spans and smaller cross sections. However,for the load transfer between the fibre material and the abutment,a special solution is necessary.Using a very thin cross section that is wrapped around the anchorage bolts at the two abutments several times,a multilayered ribbon is created.This reduces bending stress at the anchorage or at points of deviating.Such a multilayered ribbon was provided for this prototype from Carbo-Link and it was for the first time used as a primary structural element for bridges.

Bond Behavior of Glass Fiber Reinforced Polymer Bars with various Deformations
J. S. Park, Y. C. You, Y. H. Park , Y. J. You, K. H. Kim
Korea Institute of Construction Technology, Republic of Korea

In this paper, an analytical and experimental study is presented to examine the bonding behaviour of ribbed glass fiber reinforced polymer (GFRP) rebar in concrete. Many different types of rebar shape have been proposed to improve the bond between the rebar and concrete. In order to design a viable shape of FRP rebar, the deformation shape and face angle were considered as design parameters. Based on the equilibrium and compatibility equations, an analytical equation was proposed to determine the deformation shape of rebar. Using the resin transfer molding, filament winding and pultrusion method of fabrication, a number of rebar samples having the proposed rebar’s shape were fabricated. The bond strength of rebar is obtained by using a direct pull-out testing method. The test results are compared with those of commercial available FRP rebars. Overall, the test results indicated that the bond strength of rebar with the proposed shape is greater than those of commercial available FRP rebars. In this paper, the effects of rebar’s shape in concrete members are also summarized.

Reinforcing Details of a FRP-Concrete Composite Deck on a Girder
Keunhee CHO, Sung Yong PARK, Jeong-Rae CHO, Sung Tae KIM, Byung-Suk KIM
Korea Institute of Construction Technology, Republic of Korea

This study investigated the behaviors of FRP-concrete composite deck in negative moment region, typically on a girder, for the several reinforcing methods. FRP-concrete composite deck considered in this study uses FRP panel as permanent formwork and main tensile member and concrete as main compressive member. In the study, several reinforcing details were deviced and tested: (1) continuation/discontinuation of FRP panel on a girder, (2) reinforcement ratio of FRP rebar, and (3) with/without shear stirrup used for the deck-to-deck joint. The experimental results show that load resisting capacity increases as reinforcement ratio increases. Continuation of FRP panel gives more load resisting capacity than the discontinued case. Shear stirrup does not affect load resisting capacity, but prevents the separation of concrete blocks on the girder.

Newly Developed GFRP Rebar for Concrete Structures
Y. J. You, Y. H. Park, J. S. Park, K. H. Kim
Korea Institute of Construction Technology, Republic of Korea

An innovative FRP reinforcing bar (rebar) for concrete structures has been developed at the Korea Institute of Construction Technology in Korea. This paper presents the development and current accomplishments of this research project, with emphasis on newly proposed fabrication method, specific constitution of deformation and the strength of developed FRP rebar. Various FRP rebar samples having different shapes of deformation have been designed and fabricated. Based on the test results for the samples, a FRP rebar profile having braided deformations was finally selected considering productivity, initial costs, and strength. The characteristics of fabricating method in this study are braiding with tension and self-impregnating of deformations and outer skin. A bundle of fibers progresses through resin pool and then two types of fiber with thick and thin diameters are braided successively with tension around the impregnated bundle of fibers to form deformations and outer skin. Those are impregnated by themselves in this step with the extruded resin from the uncured core in contrast with general fabricating method which needs secondary process to form deformation on cured core. The induced tension in fiber for deformations forms indentation on the surface of uncured core. Tensioned fibers for outer skin make them fixed and protect rebar from alkali-attack. This constitution of deformation improves the tensile and bond strength of the FRP rebar. The developed FRP rebar composed of a GFRP core (E-glass fiber/vinylester) of 12.7 mm in diameter, helically wound deformations, and braided outer skin on the external surface. PVA fibers were used for the deformations and outer skin. The minimum tensile strength, elastic modulus, and bond strength of the developed GFRP rebar were identified as 1,000 MPa, 45 GPa, and 24 MPa, respectively. This paper also presents the results of some test conducted on concrete beams reinforced with the proposed GFRP rebars.

Experimental study on the perfobond shear connector for FRP-concrete composite decks
S. Y. Park, J. R. Cho, K. Cho, B. S. Kim
Korea Institute of Construction Technology, Republic of Korea

Korea Institute of Construction Technology has been developing an innovative bridge deck system, FRP-concrete composite deck. It is composed of lower glass fiber-reinforced polymer (FRP) panels and upper concrete slab. One of main issues of this new system is shear connection between FRP panel and concrete. To solve this problem, perfobond rib FRP shear connector, which is pultruded with FRP panel as a unique module, is introduced for the mechanical shear connection in the deck system. In this paper, experimental study was carried out on the perfobond shear connectors in order to develop the effective details of them. Lots of pull-out test specimens were manufactured and tested. Main parameters of them diameter of holes, spacing between the centres of holes, thickness of FRP plates. Based on test results, an empirical expression for predicting the shear strength of perfobond FRP rib shear connectors is proposed.

Experimental Studies on Coarse Sand Coating Between FRP and Concrete
Jeong Rae Cho, Sung Yong Park, Kunhee Cho, Sung Tae Kim, and Byung Suk Kim
Korea Institute of Construction Technology, Republic of Korea

In FRP-concrete composite deck systems, coarse sand coating is usually applied to secure composite behaviour of the two materials. In this study, the performance of coarse sand coating between FRP and concrete according to aggregate sizes and its degrees of distribution is evaluated experimentally. Five test parameters were selected according to 3 aggregate sizes (4~7mm, 1.67~4.5mm, and 6.75~9mm) and 3 degrees of distribution (4kgf/m2, 3kgf/m2, and 2kgf/m2) in the coarse sand coating. Three specimens were manufactured for each parameter for a total of 15 specimens and double lap pull-pull joint tests were performed for the evaluation of shear performance. In addition, pull-out tests were also performed for that of normal performance using a total of 15 specimens. Regard to the tests, it has been seen that the shear bond performance increases with smaller aggregate size and larger distribution of coarse sand. However, similar shear performances have been observed for the given 5 types of test parameters at the exception of the case of G47-D4 (4~7mm and 4kgf/m2). Besides, in the pull-out test, G47-D2 (4~7mm and 4kgf/m2) and G15-D4 (1.67~4.5mm and 4kgf/m2) exhibited relatively poor normal bond strength compared to the other specimens, while the three other sets of specimens developed similar normal bond strengths. Consequently, regard to the selected test variables, the grades and densities of the sand for G47-D3 (4~7mm and 3kgf/m2), G47-D4 (4~7mm and 4kgf/m2) and G79-D4 (6.75~9mm and 4kgf/m2) are developing comparable shear and normal bond performances.

Evolution of a Hybrid-Composite Beam System
John R. Hillman
TENG, Chicago, USA

A new concept for a hybrid-composite beam includes a fiber reinforced plastic beam shell with compression and tension reinforcement. The compression reinforcement consists of cement grout, which is pumped into a profiled conduit within the beam shell. The tension reinforcement consists of carbon or steel fibers along the bottom flange and anchored at the ends of the compression reinforcement. Minimizing and optimizing the use of high strength/high modulus materials within the hybrid beam configuration, results in an economical use of FRP for a bridge girder. The composite beams can be used in the construction of bridges using conventional erection techniques.

Experiments on deviated CFRP Strips for external prestressing
Mohamed Hwash*, Jan Knippers*, Fathy Saad**
*: Institute of Building and Structural Design (ITKE), University of Stuttgart, Germany
**: Ain Shams University, Cairo, Egypt

In the last decade, the use of CFRP-Strips for reinforcement of concrete members has emerged as a very promising technology. The aim of this research is to develop a conceptual design for bridges, particularly externally prestressed Concrete Bridges and Extradosed Bridges, by which CFRP-Strips are integrated with the optimum efficiency. The most important construction details for this applications are the anchorage of the CFRP-strips at the deviation saddle and at the deck structure. This paper will highlight the problematic of the construction details of this application, namely the deviation of prestressed CFRP-Strips at bearing saddles. The impact of the contact surface, the deviation saddle geometry and acting load are to be investigated experimentally. Therefore, several groups of experimental tests for deviated CFRP-Strips are under investigation. The results of this work show, that the ultimate strength of the deviated CFRP-Strips is highly affected by the bending radius/thickness ratio, the deviation angle and the nature of the contact surface between the saddle and the Strips. An analytical model for the calculation of the bearing capacity of the CFRP-Strips at deviation saddle will be accordingly developed. Finally, the results of this study will be summarized with other available information to present design recommendations for externally prestressed concrete bridges with freestanding CFRP-Strips.

Hybrid FRP Bridges: Design, Analysis and Material Tests
Dipl.Ing. Markus Gabler, Prof Dr. Ing. Jan Knippers
Institute of Building and Structural Design (ITKE), University of Stuttgart, Germany

Fibre reinforced polymers (FRP) offer new options for bridge design. Especially hybrid structures, i.e. steel girders combined with a bridge deck made of pultruded FRP sections are competitive. Based on this technology a highway fly-over was designed, which will be erected in 2007. The entire deck is prefabricated, the FRP sections are adhesively bonded to the steel girders, so the assembly time and the traffic interference during construction is reduced to a minimum.
In contrast to other FRP bridges in the US or UK, the composite action of the bridge deck and the steel girders is considered. This leads to a loading of the FRP sections perpendicular to the pultrusion direction and so to local instability effects, i.e. inter-laminar failure due to compression perpendicular to the fibres. The absence of general accepted structural analysis methods, design codes and building regulations necessitate extensive testing programmes.
The design of the bridge as well as its structural analysis and the results of the bridge deck tests are highlighted in the presentation.

Influence of Internal Percentage Steel Rebar Variation on Load-Deformation Characteristics of FRP Strengthened Concrete Beams
DB Tann, R Delpak, P Davies
Division of Civil and Mechanical Engineering, University of Glamorgan, United Kingdom

This article examines the load-deformation behaviour (including ductility and deformability) of FRP strengthened concrete beams with internal steel rebars. The parameters considered include (1) the section performance to failure, due to different amounts of FRP bonded to the tension surface, and (2) sensitivity to the percentage of steel reinforcement used in the initial cast. The paper aims to demonstrate a possible connection between (i) the total equivalent reinforcement content, (ii) the influence on ductility/deformability and (iii) the failure mode.

In addition to direct tests at the University of Glamorgan laboratories, data from other published sources have been analysed. To date, the study shows:

* With some exceptions, there is an influence on element behaviour up to failure due to the combined action of steel reinforcement and externally-bonded FRP.
* There were identifiable differences in failure modes as a result of total tensile equivalent steel reinforcement (TESR) present.
* The above modes consisted of (a) de-bonding of the FRP, (b) tearing-off of concrete cover and (c) compressive concrete failure; all of which were primarily attributable to various TESR percentages, together with concrete strength.
* It was possible to "group" different numerical values of Ductility/Deformability against TESR levels.

The study is ultimately expected to lead to criteria for safe design of FRP strengthened RC beam elements, where the ductility/deformability considerations are taken into account in addition to strength/stress limiting criterion.

Composite action in GFRP-Composite bridges
Dr. Herbert W. Guertler
Dr. Deuring + Oehninger AG, Winterthur, Switzerland
(starting on January 15th at: Krebs und Kiefer, Karlsruhe, Germany)

The paper describes the behaviour of hybrid girders consisting of FRP bridge decks adhesively connected to steel main girders. Presented are the experimental investigations carried out to determine the system properties of pultruded GFRP bridge decks as well as the results of tests on large-scale girders which were tested at the serviceability, the ultimate limit state and at failure. The girder experiments showed that, although shear was fully transferred through the adhesive connection between the steel girders and the decks, deformations in the webs of the decks reduced the participation of the upper face panels. Based on the test results, a conceptual design method for bonded FRP/steel girders with partially composite action in the bridge deck was developed and is explained.

Development of New Hybrid Composite Girders Consisting of Carbon and Glass Fibers
1)Prof. Hiroshi Mutsuyoshi, 2)A/Prof. Thiru Aravinthan, 3)Dr. Shingo Asamoto, 4)Kenji Suzukawa

1) Professor, Saitama University, Japan
2) Saitama University (Associate Professor, University of Southern Queensland, Australia)
3) Assistant Professor, Saitama University, Japan
4) Toray Industries, Inc., Japan

An innovative hybrid composite girder is being developed in Japan consisting of carbon and glass fibers. The innovative feature of this girder is the optimum use of CFRP and GFRP in flanges to maximize structural performance while reducing the overall cost by using glass fibers in the web section. A series of I-shaped girders were tested with varying amount of GFRP and CFRP. Another factor that was investigated was the effect of flange width on the failure mode. Preliminary experimental investigations revealed that the failure was induced by the delamination of the interface of glass and carbon fibers in the compressive flange. The experimental results are discussed in this paper with the emphasis on the appropriate composition of GFRP and CFRP for the optimum design of such I-shaped girders. In addition, the economical aspects such as initial cost and life cycle cost will be discussed including potential application in full scale highway bridges.

Structural Health Monitoring and Nondestructive Evaluation of Composites in Construction applications
Maria Q. Feng, Masanobu Shinozuka and Ayman Mosallam
University of California, Irvine, CA, USA

Civil infrastructures are exposed to various external loads such as traffic, earthquakes, gusts, and wave loads during their lifetime. Composites structures may get deteriorated and degraded with time in unexpected ways, which may lead to structural failures causing costly repair and/or heavy loss of human lives. Consequently, structural health monitoring has become an important research topic in conjunction with damage assessment and safety evaluation of the structures. This paper presents innovative technologies for structural health monitoring and nondestructive evaluation developed by the authors at University of California, Irvine, including a novel optical fiber accelerometer system, a dynamic displacement measurement system using digital image processing technique, and a microwave nondestructive evaluation system for fiber reinforced polymer (FRP) wrapped concrete structures. The innovations of each technology were briefly introduced, and some experimental results using the developed systems demonstrated their high performance and effectiveness as well.

Composites for Highway Bridges Applications: A State-of-Art Review
Ayman S. Mosallam, M. Shinozuka and M. Feng
University of California, Irvine, CA, USA

This paper provides an overview on some of the latest advances in bridge rehabilitation and safety.
In the rehabilitation side, innovative polymer composite systems were developed, evaluated and applied on a portion of the Sauvie Island highway steel bridge in Portland, Oregon. A description of the field application of the composite systems is presented. The use of hybrid composite decks for providing an efficient solution for the chronic fatigue problem of the lift span of the Schuyler Heim highway bridge in Long Beach, California is also presented. In addition to weight saving, the composite deck has a superior fatigue properties and high strength-to-weight and stiffness-to-weight ratios as compared to the existing welded steel gratings. In this program, a pilot project in developing field emergency repair procedure was conducted and the repaired deck exceeded the strength of the undamaged deck by over 25%. Rapid and emergency repair of reinforced concrete bridge columns is another successful application of FRP composites. The results and details of a pilot project was conducted at the University of California of Irvine aiming at evaluating repaired shear-deficient columns damaged by a simulated gravity and cyclic forces is reported. The results of the large-scale testing indicated that the use of polymeric composites as external jackets can be performed rapidly in the field with minimum workmanship requirements in addition of being a cost-effective solution capable of not only restoring the original capacity of the damaged column, but also increases its shear strength and ductility. In addition, details of an innovative functionally-degraded sandwich system for enhancing the high-energy impact resistance of reinforced concrete highway bridge girders are discussed. This innovative system will increase the safety of both the over-height trucks as well as the impacted girder. The efficiency of this innovative system was validated via large-scale horizontal impact tests as well as numerical simulation using Dyna-LS software.

FRP Structural Formwork for Rapid Renewal of Bridge Decks Without Steel
Vistasp M. Karbhari, Joanne Mitchell and Anna Pridmore
Department of Structural Engineering, University of California, San Diego, USA

Charles Sikorsky
Engineering Services Division, California Department of Transportation, Sacramento, USA

Among bridge components, decks undergo substantial degradation resulting from factors ranging from steel corrosion to deterioration of concrete. While the use of all FRP bridge decks has been successfully demonstrated both through laboratory testing and field implementation, cost considerations currently cause these to often be non-competitive. This paper describes the use of a unique FRP structural formwork consisting of tailored stiffened plates which act as both formwork and as reinforcement enabling concrete to be merely poured on top. In regions of continuity thin carbon fiber grids are placed as reinforcement. The FRP panels are light-weight and easily attached to existing girders of even deck sections enabling both rapid construction of new structures and rehabilitation of deteriorated structures in local areas. Test results from T-girder and box-girder bridges are discussed including the extremely goof fatigue response.

Deterioration Science Based Consideration of Durability in Design of FRP Rehabilitation
V. Karbhari, P. Wilcox, R. Walker, Q. Yang and G. Xian
Department of Structural Engineering, University of California, San Diego, USA

Current design of FRP used in rehabilitation is based on simplistic factors that provide "guesses" for reduction factors to be used for durability irrespective of intended service-life. In reality FRP materials deterioration can be assessed based on time periods using methods of reliability and deterioration science. This paper provides examples of FRP durability as applied to seismic retrofit and strengthening, explaining the approach from a materials level to the structural level. Reliability theory is used to provide realistic estimates of durability and service-life thereby enabling the designer to choose risk and level of service-life depending on the type of structure under consideration for rehabilitation. Examples using both glass and carbon fiber are provided.

Delamination of FRP reinforced steel girders and their fiber Bragg grating sensing
Prof. Seishi Yamada*, Dr. Satoshi Yamada**, Dr. Iwao Komiya***
* Toyohashi University of Technology, Toyohashi, Japan
** Topy Industries, Ltd., Toyohashi, Japan
*** Fukui Fibrtech Co., Toyohashi, Japan

A FRP plate was bonded to a steel girder and the delamination behaviour of the bonded layer has been studied in this paper. An innovative fiber optic sensing using fiber Bragg grating (FBG) sensors were installed to the bonded layer. The bending tests and the tension tests were carried out and the precise variations of optical power spectra as well as optical wavelength associated with the stain quantities of the steel and FRP in the bonded layer have been discussed.

Integrative Design Approach for Using Advanced Composite Materials in Bridge Deck Applications
Hwai-Chung Wu
Department of Civil and Environmental Engineering, Wayne State University, Detroit, USA

Fiber Reinforced Polymer (FRP) composites, especially lightweight sandwich structures, are rapidly finding their ways into civil infrastructure application. As in any paradigm design using FRPs, the composite must be optimized to deliver maximum benefits for its intended use. For civil engineering application, a suitable composite deck design must consider the sub- and super-bridge components all together. Analytical treatment of the deck as a simply supported panel is often oversimplified. Another important consideration is to be able to determine the durability performance of FRP materials under weathering conditions, especially freeze-thaw and low temperature exposure. Therefore an integrative design approach has been adopted at the Wayne State University, and has being used to develop mechanics model capable of performing both tasks.

Glass Fibres reinforced polymer for mitre gates used for lock EU class 1 as experiment
Brahim Benaissa Dr. Ingenieur
Head assistant of department : Ports Maritimes et Voies Navigables (Centre d’Etudes Techniques Maritimes Et Fluviales) 2,Bd Gambetta 60321 Compiègne (France)

From stress analysis to environmental integration and selection of materials, all aspects of the problem were studied in order to make the new generation of lock gate an innovative, reliable product, both from the design point of view and from that of the materials used. Fibre reinforced polymer (FRP) have greater strength capabilities and are less susceptible to environmental deterioration than steel. Additionally, FRP has a weight to strength ratio 18 times that of steel.
The introduction of new material as FRP presents the opportunity of economic benefit and facility, enabling cost saving when upgrading or maintaining existing infrastructures as lock gates. For testing the new material VNF (French Waterways office) was involved in an experiment on real site, consisting of a lock with two mitre gates.
A lock gate consists of two leaves, each consisting of :
* A curved coloured single skin composite structure, strengthened by horizontal stiffeners. This structure has stainless steel fitting designed to receive the bearing surface, sealing and securing components;
* Stainless steel frames fitted to the masonry structure;
* A standard stainless steel valve fitted into each leaf;
* A continuous bearing surface consisting of polymer seals along the leaves vertical edges;
* A bridge, in two sections, consisting of a stainless steel handrail and a composite grating.
Within its dimensional limits (length, width sluice surface for water filling and emptying), the design adopted can be adapted to all FREYCINET (European class I)– sized lock sites.The search for standardization led to the following choices being made :
* a single gate width (5.2 m);
* identical design up to a lift of 8 m;
* right-left interchangeability of leaves with a single mitre angle of 20°;
* use of standard valves and accessories;
* standard stainless-steel frames and fittings with 0,8 m2 for sluice surface.
The new doors benefit of a number of technical innovations and improvements designed to improve reliability and reduce maintenance cost by absence of corrosion and considerable lightening of leaves (weight reduced by a factor of 2.5)The purpose of the project was to test the use of compound material (glass fibres reinforced polymer) as construction material for lock gates. The test site (Golbey, near Épinal) was chosen because a quick upgrade of the existing gates was needed, as other gates of EU class I (Freycinet : ships 38,5 x 5 m) locks.
The design (width, number of layers for composite materials…) was standardized for locks with a lift of maximum 8 m and draft 2,5 m. The valves are sluice gates made of stainless-steel. A flap gate is added behind the sluice gate to break the flow. Both valves and gates were first manoeuvred manually, then equipped with hydraulic jacks.
The gate is composed of a skin plate in FRP, the surface layer being coloured (the skin plate is not painted). Reinforcements are made of U-shaped FRP beams filled with PU foam (density <1).

Elastic Systems for Dynamic Retrofitting (ESDR) of Structures
Paolo Casadei, Emo Agneloni
TEC.INN. S.R.L., , Milano, Italy & San Mariano-Perugia, Italy

Recent world events have showed that performance of buildings to blast loads is an ever increasing issue. Many older buildings contain un-reinforced masonry (URM) infill walls. Due to their low flexural capacity and their brittle mode of failure, these walls have a low resistance to out-of-plane loads, including a blast load. As a result, an effort has been undertaken to examine retrofit methods that are feasible to enhance their out-of-plane resistance. The use of externally bonded Fiber Reinforced Polymer (FRP) laminates has been proven, by several research studies around the world, to increase the out-of-plane load capacity and improve both in static and dynamic tests the performance of URM infill walls. One draw back of FRP is their lack of ductility at ultimate state. It is for this reason that new strengthening solutions are investigated in order to provide the necessary strength coupled with sufficient ductility. The present study has investigated the performance of a package that couples together the high strength of FRP systems with the ductility of a polyurea resin that can elongate up to 400%. The new strengthening system allows different layers of FRP and polyurea to: 1) provide the necessary strength to the infill wall subjected to out-of-plane forces, 2) provide a ballistic layer to catch flying debris, 3) guarantee sufficient deformations of the strengthened walls (as a car-airbag), dissipating energy without completely collapsing. Results from both static and field blast tests on 8 2x2 meter brick walls, will show the effect of different strengthening solutions to out-of-plane loads.

Fifteen years of FRP Applications in Italy: Case Studies
Paolo Casadei, Emo Agneloni
TEC.INN. S.R.L., , Milano, Italy & San Mariano-Perugia, Italy

Due to their light weight, high stiffness-to-weight and strength-to-weight ratios, and potentially high resistance to environmental degradation, resulting in lower life-cycle costs, advanced composites materials, commonly known with the acronym FRP, are increasingly being considered for use in civil engineering applications, ranging from the retrofit and rehabilitation of buildings and bridges to the restoration and strengthening of historical-monumental masonry structures. Thanks to the recently published Italian FRP guidelines, CNR-DT 200/2004, by the Italian National Research Council, there has been an increasingly demand of their implementation for general strengthening and retrofitting applications as well as seismic mitigation, being the latter pushed by the new organization of the national territory into a large seismic area with different magnitudes depending on the geographical location. This paper aims to provide a general overview of the Italian state of the art implementation of FRP materials in the last 10 years, through different case studies, ranging from reinforced concrete to masonry and timber structures, on recent and historic buildings and infrastructures, such as the Royal Palace in Milan, Kock’s Palace of the Italian Bank in Rome, the arch viaduct on the Flaminia road, the Monterchi’s Bridge and many others.

Wedge Anchorage for FRP
Dr. Stefan L. Burtscher
Institute for Structural Engineering (Institut für Tragkonstruktionen – Betonbau)
Vienna University of Technology, Austria

Wedge anchorages are used with great success for prestressed steel strands. These anchorages are economic and considerable experience exists in the structural design of such structures, wedge anchorages and necessary equipment. In this paper numerical and experimental studies for a wedge anchorage are shown.

The high axial and the low lateral strength make it difficult to anchor FRPs with high efficiency. To end up with an efficient, economic and easily applicable anchoring system special wedges were developed. These wedges are made of two components with different modulus of elasticity and varying thickness. This special design provides an evenly distributed lateral pressure and shear stresses along the wedge – CFRP strip interface. Therefore, anchoring of high loads is possible.

An Innovative Hybrid Concrete-FRP System for Short- and Medium-Span Bridges
Mamdouh El-Badry, Mohamed Sorour, and Kyle Schonknecht*
Department of Civil Engineering, The University of Calgary, Calgary, Alberta, Canada

An innovative corrosion-free system for short- and medium-span bridges has been developed at the University of Calgary. The system consists of precast prestressed concrete truss girders and cast-in-situ concrete deck. The girders consist of top and bottom concrete flanges connected by vertical and diagonal members made of fibre reinforced polymer (FRP) tubes filled with concrete. The vertical members, subjected to compression, are connected to the flanges by Glass FRP dowels protruding from the ends. The diagonal members, subjected to tension, are connected to the flanges by headed studs. The FRP tubes serve as stay-in-place formwork, confine the concrete core in the compression members, provide tensile reinforcement in the tension members, and protect the concrete from the environment. The truss flanges are pretentioned with carbon FRP tendons. The deck slab reinforcement consists of corrosion-resistant steel bars in the bottom transverse layers and glass FRP bars in the bottom longitudinal and the top layers. The girders are post-tensioned with external carbon FRP tendons to balance the slab weight and to provide continuity in multi-span bridges. Advantages of the new system are reduced self-weight and enhanced durability. The light weight reduces the initial cost and allows for longer spans; the improved durability reduces the maintenance cost and can extend the life span to 100 years, instead of the 50 years for which many existing bridges were designed but failed to achieve. This paper describes the general details of the new system and presents experimental evaluation its most important aspects, including the effects of different types of FRP tubes on confining concrete in the compression members, and the performance of different types of connection between the tension members and the flanges. Three types of FRP tube are examined and four types of connection are investigated. The results of testing twelve connection specimens under static or fatigue loading are presented. Girders built from the best type of FRP tube and the best performing connection are tested for strength and service load behaviour under static and fatigue loading. The tests have shown excellent performance of the proposed new system.

Using Prestressed CFRP Laminates for Strengthening of Steel Beams
1)Reza Haghani, 2)Mohammad Al-Emrani, 3)Robert Kliger
1) Graduate student, Department of Civil and Environmental Engineering, Chalmers University of Technology, Sweden.
2) Assistant Prof., Department of Civil and Environmental Engineering, Chalmers University of Technology, Sweden.
3) Professor, Department of Civil and Environmental Engineering, Chalmers University of Technology, Sweden.

Outstanding mechanical properties of Carbon Fiber Reinforced Polymers (CFRP) such as very high strength to weight ratio, high modulus of elasticity (eg. up to 600 GPa), high corrosion resistance and durability have made them suitable candidates for strengthening purposes. Lately, it has been proven that the benefits of CFRP material could even be increased by inducing prestressing in the laminate before bonding it to the structural element. Where, this technique is beneficial in concrete structures for improving serviceability limit state by reducing the deflections as well as compensating the lost in prestress in prestressed concrete structures, it is also very favourable in the case of steel structures where prestressing could be used to enhance the fatigue strength and to prevent or stop fatigue cracking in structural element. A major problem with using bonded prestressed CFRP laminates for strengthening of structures is the high shear stresses at the ends of the laminate caused by the prestressing force. These stresses are normally several times higher than the strength of conventional adhesives used in strengthening systems. In this paper an analytical solution for shear stress distribution along the bond line for prestressed scheme is presented. The factors affecting the magnitude of the shear stress are investigated. Finally, several solutions that can be applied to reduce the value of maximum shear stress at the end of the laminate are presented and discussed. FE analysis is used to evaluate these methods.
Keywords: Prestress, CFRP, Laminate, Shear stress.

In search of Optimal Shapes for Composite Bridges
Ryszard A. Daniel
Ministry of Transport, Public Works & Water Management, Civil Engineering Division, Utrecht, the Netherlands

So far, composite bridge designs basically follow the forms acquired from the engineering practice in other materials, like steel. This was indeed a proper approach in the introduction stage of composite bridges. The best way to win customer’s confidence was to copy the shapes and sections well-tested in other materials. Therefore we usually see composite I-beams, channels, box girders, deck grids etc. that resemble the conventional steel components. Now the customer’s confidence is growing, it is time to review this strategy and to ask which shapes are the most appropriate for the best performance of composites in bridge structures.

This paper presents some considerations concerning composite shape selection for bridges. Attention has been paid to the shapes of entire bridges as well as their components, such as decks, girders, crossbeams etc. In particular, the anisotropic nature of composite materials and their relatively flexible technology offer the possibility to apply shapes of double curvature, smooth transitions, less fatigue sensitivity, high strength properties in the areas of stress peaks etc. Some new shape ideas for composite bridges have globally been sketched and discussed. The author is primarily a bridge construction engineer, not a composite technologist. The presented suggestions have, however, been discussed with some representatives of the composite branch. The intention is to continue this discussion, because the combination of both disciplines’ know-how can, obviously, be seen as a condition for successful composite bridge applications.