Pierre Labossière

Recent Bridge Applications of FRPs in Canada

It is estimated that the rehabilitation of Canada’s deteriorating infrastructure will cost at least CAND 49 billion. This simple fact illustrates the urgent need to take advantage of emerging technologies showing potential for increasing the life of civil engineering structures and reducing their maintenance costs. The ISIS Canada Network of Centres of Excellence is planning to expend its resources over the next eight years to advance the widespread use of new technologies in infrastructure projects mainly by judicious and innovative use of fibre reinforced polymers (FRPs) and fibre optic sensing (FOS) devices. It will build upon the expertise gained over the previous six years in a number of practical applications of these technologies, such as the ones reported in this paper.

Fiber Optic Sensors for Strain Measurement of CFRP-strengthened RC Beams

There is a growing need for built-in monitoring systems for new and aging civil engineering structures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fiber optic sensors FOS), capable of reading strains, loads, deflections, and temperature are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This article reports on the performance of strain extrinsic FOS attached to carbon fiber-reinforced polymer CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete RC) beams with an additional external CFRP reinforcement. The strain data obtained from the FOS were compared with data obtained from collocated electrical strain gauges. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then they were tested monotonically for failure under four-point-bending. The test results provide an insight on the fatigue and postfatigue behavior of FOS used for strain measurement in reinforced concrete structures.

ON FIBER-REINFORCED POLYMER REHABILITATION OF ALKALI-AGGREGATE REACTION-DAMAGED BEAMS

This paper describes an experimental research program conducted to study the potential application of fiber-reinforced polymer (FRP) materials as external reinforcement for reinforced concrete beams damaged by alkali-aggregate reactions (AAR). 38 small-scale specimens were constructed using 2 concrete mixture proportions and exposed to conditions selected to generate a rapid increase of AAR. The specimens were externally reinforced with FRPs at different stages of the AAR progression. It was found that the parameters having the greatest effect on beam expansion were the type of concrete and the presence of the FRPs. Concrete expansion due to AARs was not similar in all directions; it depended on the orientation and ratio of reinforcement. Although FRPs produced a significant increase of flexural strength for the beams, this increase depended on the extent of AAR-induced damage and on the duration of AAR-inducing exposure conditions.

Lessons Learned from a Design Competition for Structural Engineering Students: The Case of a Pedestrian Walkway at the Université de Sherbrooke

Competence in design is an engineering skill that can only be achieved with appropriate training and through accumulation of relevant experience. While in some fields of engineering there are numerous industry-oriented problems that can be investigated reasonably thoroughly, and for which the pinnacle of formation is attained when a team of university students builds a working prototype, there are unfortunately few genuinely realistic conceive-design-build-test (operate) opportunities in which structural engineering students can participate actively during their formative years. This stems from the very nature of structural engineering itself which, as in the case of most civil engineering designs, usually calls for a unique solution to a problem of relatively large scale. One way to provide a realistic and significant structural engineering design opportunity is through student design competitions. However, the conditions of success for such a competition depend on the appropriate coincidence of interest...

FRP Protection And Rehabilitation Of Corrosion-Damaged Reinforced Concrete Columns

The results of two complementary experimental investigations on the use of fibre reinforced polymer (FRP) wraps for the protection and rehabilitation of reinforced concrete columns are presented. The first study consists of reinforced concrete cylinders with axial steel reinforcement subjected to accelerated corrosion, and an assessment of the FRP protection that can be provided by three types of FRP wrap (glass, carbon and aramid). This study also includes a comparison with results for two conventional protective systems (siloxane and polymer concrete). In the second study, on concrete columns with both axial and spiral reinforcement, an accelerated corrosion process is developed and applied to induce overall corroded conditions similar to those encountered in the field. The effects of FRP wrapping on restoring strength losses due to steel corrosion, and on arresting further corrosion damage, are investigated.

Durability of CFRP Sheet Reinforcement through Exposure Tests

Synopsis: Over the last few years, the use of composite materials has become an increasingly popular method of repairing and strengthening ageing civil engineering structures. However, despite the efficiency and attractiveness of this technique, its market progression has been impaired by the relative lack of knowledge on the longterm behavior of the FRP materials themselves and, by extension, on the behavior of the structures strengthened with such products. The authors are conducting a 10-year exposure test program on FRP products, and this paper provides midway results from the first 5 years of exposure data. There was no significant change in the tensile strength of the CFRP laminates after a 5-year exposure, however in-plane shear strength showed a slight decrease. Bending strength of matrix resin also decreased in the early exposure stage. The results suggest a reduction of the bonding properties between carbon fibers and resin.

Impact resonance method for damage detection in RC beams strengthened with composites

There are numerous successful applications of fibre-reinforced composites for strengthening the civil engineering infrastructure. Most of these repairs are being continuously or intermittently monitored for assessing their effectiveness and safety. The impact resonance method (IRM), a non-destructive technique, utilized in civil engineering exclusively for determining the dynamic concrete properties, could be a valuable and viable damage detection tool for structural elements. The IRM gives useful information about the dynamic characteristics of rectangular and circular concrete members such as beams and columns. In this experimental program, a 1.2-m-long reinforced concrete beam strengthened with a carbon fibre-reinforced polymer (CFRP) plate has been employed. The CFRP-strengthened beam has been loaded in fatigue for two million cycles at 3 Hz. The load amplitude was from 15 to 35% of the anticipated yielding load of the beam. Throughout fatigue testing the cycling was stopped for IRM measurements to be taken. The obtained data provided information about changes in modal properties such as natural frequencies of vibration. These results have shown the successful use of the IRM for detecting fatigue damage in concrete members strengthened with composites.

Effect of geometric parameters on the behavior of bolted GFRP pultruded plates

This paper presents the effect of geometric parameters on the behavior of bolted glass fibre reinforced polymer (GFRP) pultruded plates for civil engineering applications. After a literature review, results of an experimental analysis investigating the behavior of GFRP-to-steel single-lap bolted connections are presented. Then, a finite element analysis validated by experimental data is used to evaluate the effects of the end-distance, side-distance, pitch, and plate properties on the strength and failure mode of the connection. A critical examination of geometric recommendations proposed in design references is presented. Bearing failure caused by contact of the bolt on the GFRP plate is usually defined as the preferred failure mode. With highly orthotropic plate, this type of failure was found to be less likely to occur when loading is applied in the pultruded direction. The investigation showed that the minimum end-distance and pitch-distance recommended by design references usually produce a connection with the maximum capacity. However, it was found that the minimum side-distance recommended by these references does not necessarily lead to the maximum capacity for one bolt and for two bolt in a column connections.

FRP-strengthened Structures: Monitoring Issues from Québec Applications

Since 1996, our research group has been involved in the installation of fibre optic sensors in a number of structural rehabilitation projects with FRPs in Quebec. Each project brought its share of technical problems, tested our capacity for innovation, and attained a different level of success. Fibre Bragg Gratings (FBG), Fabry-Perot sensors, or a combination of both, were used in each case. Following our first field tests on a multi-storey parkade and a highway overpass, which allowed us to gain familiarity with the installation of sensors in actual construction conditions, our first significant project making use of fibre optic sensors (FOS) was the rehabilitation of the Sainte-Emelie-del’Energie Bridge. For this short-span bridge that was strengthened with FRPs in 1998, conventional instruments were also incorporated to the repairwork to corroborate the FOS measurements. The behaviour of the bridge has since been measured frequently. After more than six years of service following the installation of the FRP reinforcement and initiation of the monitoring procedure, it was submitted to a full series of load tests. Other FRP-reinforced structures that incorporated FOS include repairs to a nuclear reactor secondary containment structure and a new pedestrian bridge on the campus of the Universite de Sherbrooke.

Fatigue and post-fatigue performance of Fabry-Perot FOS installed on CFRP-strengthened RC-beams

There is a growing need for built-in monitoring systems for civil engineering infrastructures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fibre optic sensors (FOS), capable of reading various parameters are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This paper reports on the performance of strain extrinsic FOS attached to carbon fibre reinforced polymer (CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete (RC) beams with an additional external CFRP reinforcement. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then, they were tested monotonically to failure under four-point-bending. The test results provide an insight on the fatigue and post-fatigue behaviour of FOS used for monitoring reinforced concrete structures.