Completed Research 1995 to 2006

Theme 2 Projects (2002-2006):
Materials Science and Innovative Structures

Director: Dr. Nemkumar Banthia, University of British Columbia

Focus Area 2.1:  Materials Science

Integrated Durability and Fundamental Materials Assessments (2.1.1)
Project Leader: Dr. Nemkumar Banthia, University of British Columbia

This project is investigating the combined influence of applied stress and a deleterious environment on the long-term durability of systems having FRP bonded internally/externally to concrete/steel/wood surfaces. Equal emphasis is placed on material science of the resin systems, bonding agents, fibre types and their longevity and morphological degradation of the interface. Long-term and durability performances are being quantified by non-linear fracture mechanics-based parameters such as KC and GF and interfacial R-curves. Among the deleterious environments, prolonged water exposure, UV exposure, exposure to freezing and thawing and mildly aggressive chemicals is being investigated. From a structural health monitoring perspective, some specimens have been instrumented with sensors such that durability problems in the field can be rapidly identified. Results so far indicate that an integrated approach of this type is essential for developing long lasting reinforcement systems.

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Durability of Polymer Interfaces (2.1.2)
Project Leader: Dr. Suong Van Hoa, Concordia University

The objective of this project is to examine the durability of polymer interfaces in civil engineering structures.  This can be the adhesive between the composite sheets used to reinforce concrete, the adhesive used to bond optical fibres to civil structures, or the polymer interface between the fibres and the resin in composite materials.  Specifically, the durability of the resin used at these interfaces is being investigated.  The approach taken is not only to characterize the durability behaviour at these interfaces, but also to find ways to improve their performance.  Two particular aspects are under investigation:

Improvement of water absorption: Absorption of water into the resin can degrade the performance of the resin.  Nanoclay particles are incorporated into these resins to improve their resistance against water absorption.  Preliminary results have show significant improvement.

Improvement of flammability resistance: Flammability is of great concern for those who use polymeric resins in their applications.  Incorporation of nanoclay particles has shown great improvement of the flammability resistance of epoxy resins.  The epoxy nanocomposites were shown to be self extinguishing after being burned with a fire source.  This improvement in flammability resistance can greatly enhance the confidence of users.

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Monograph on Durability of FRPs in Civil Infrastructure (2.1.3)
Project Leader: Dr. Nemkumar Banthia, University of British Columbia

In this project, a monograph entitled “Durability of Fiber Reinforced Polymers in Civil Infrastructure” is being produced based on an extensive search of the literature, consultation with experts and visit to ISIS demonstration projects. The purpose is twofold: first to produce a detailed account of our current state-of-the-art in the area of FRP durability in aggressive environments, and second, to identify areas of potential durability concerns. The document will first introduce the current practice and describe the various fibres and matrices commercially available for new construction and repair. A detailed description of the mechanical and physical properties of these composites will be provided and available test methods will be discussed. Next, the durability of various fibre and matrix combinations when subjected to aggressive environments will be elaborated upon. The following deleterious environments will be included: wet/dry cycling, sustained exposure to moisture, sustained low/high temperature, freezing, thawing and scaling, acids, alkalis, ultraviolet (UV) exposure, carbonation, other chemicals, and combination of an environmental exposure and stress. Finally, case studies will be chosen from the many ISIS demonstration projects to draw further lessons with respect to field performance of FRPs.

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Mechanics and Durability of FRP/Concrete Interfaces (2.1.4)
Project Leader: Dr. Kenneth Neale, Université de Sherbrooke

This project was initiated in 2002 in response to a research gap identified by the Expert Panel that reviewed the ISIS Canada research program for the 2nd cycle of funding.  The Expert Panel felt that the basic research component of the ISIS program was weak; consequently, this project was formulated to address that particular concern.  The project focuses on the implementation of rigorous principles of mechanics, materials science, and computational techniques to model interfacial phenomena when FRPs are externally bonded to concrete.  These numerical models are to be validated through appropriate experimental investigations.  The results are of great practical importance as failures in FRP-strengthened structures often occur by de-bonding.  These failure phenomena are not well understood; furthermore, reliable numerical and analytical predictive models are lacking.  The first phase of the research will focus on mechanical aspects, while the latter work will address durability issues.  The thrust of this basic research is closely linked to research being conducted in Dr. Neale’s Canada Research Chair on Advanced Engineered Material Systems.

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Fire Resistance of FRP Systems (2.1.5)
Project Leader: Dr. Mark Green, Queen’s University

The objectives of this project are: (i) To conduct fire resistance tests on full-scale FRP reinforced concrete columns and beams. (ii) To develop a computer model for predicting fire performance of FRP reinforced concrete structures. (iii) To develop fire resistance design guidelines for FRP reinforced concrete structures suitable for incorporation into the National Building Code of Canada (NBCC) and other relevant North American standards. This comprehensive study will be undertaken as a three-party effort by the NRC/IRC, ISIS and industry to develop computer models for predicting the fire resistance of FRP reinforced concrete elements, and related design equations suitable for incorporation in building codes.  The project will consider the fire resistance of columns and beams with FRP as internal or external reinforcement.

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Service Life Prediction of RC Structures (2.1.6)
Project Leader: Dr. Moh Boulfiza, University of Saskatchewan

The use of fibre reinforced polymer in new construction is not widespread, despite the numerous advantages over traditional material such as steel. Economic and technical barriers hinder industry’s aggressive adoption of this new technology. The primary economic barrier preventing the use of FRPs is often the high initial cost, whereas the primary technical hurdle remains the relative uncertainty about the long-term performance of FRP reinforced structures in their service environment. Current practice is that up-front costs control the choice of materials and design alternatives without consideration of how cost effective a material might be over the life cycle of the structure. Clearly, this practice has failed to provide reliable long term performance of structures exposed to aggressive environments at low costs.

To overcome this cost-based barrier to the adoption of ISIS technologies, the construction industry needs practical economic methods, such as life cycle cost analysis, for evaluating alternative construction materials in a comprehensive and consistent manner. To conduct a credible life cycle cost analysis, one needs rational tools to predict the performance of the alternative designs (structures and materials) in their natural environment (field conditions). The purpose of this project is to develop reliable tools for service life prediction of concrete structures. This will be achieved through:

1. Prediction of service performance of reinforced concrete structures in their natural environment and monitoring of degradation over time
2. Estimating the service life of concrete structures and determining time to repair
3. Developing innovative and reliable accelerated tests for calibration of predictive models
4. Developing two model versions: a simplified version that requires relatively simple calculations to arrive at an estimate for service life; and a more sophisticated, scientifically sound model that can be used for detailed analyses, taking into account as many as possible of the real mechanisms controlling the structure’s performance
5. Evaluating advantages and disadvantages of FRP reinforcement compared with steel reinforcement
6. Using decision analysis and sensitivity analysis to identify key elements in the prediction models affecting the life cycle cost of a structure.

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Focus Area 2.2: Evaluation of FRP Materials for Infrastructure

Durability of FRPs for New Construction (2.2.1)
Project Leader: Dr. Brahim Benmokrane, Université de Sherbrooke

The main objective of this research program is to evaluate long-term durability and to optimize the mechanical and structural characteristics of FRPs for new construction. Fundamental material parameters of FRP specimens exposed to various environmental and loading conditions are being identified. In parallel with fundamental studies on FRPs, this research program will develop guidelines for durability in terms of assessment and use for design of FRPs for construction. This is being achieved by evaluating critical long-term performance characteristics that can serve as degradation indicators, identifying the expected types and range of degradation factors, and developing service life prediction models. The outcome of this research will assist Canadian industrial companies in improving the characteristics of their FRP products (types of resins and fibres, manufacturing processes, surface coating, sizing chemistry, etc.), to enhance the properties regarding long-term durability, to optimize the mechanical and structural properties, and to help engineers and users to utilize this innovative technology with enhanced confidence.

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Durability of FRPs for Rehabilitation (2.2.2)
Project Leader: Dr. Pierre Labossière, Université de Sherbrooke

This project addresses two significant issues related to the life-span of existing reinforced concrete structures: (i) the evaluation of adverse climatic conditions on FRPs and on structural elements externally reinforced with FRPs, and (ii) the use of FRPs in preventive or remedial situations to limit the extent of damage due to alkali-aggregate reactions in existing reinforced concrete structures. For the two issues, most of the research activities in this project are experimental in nature. In both cases, specimens are being fabricated, exposed to the adverse exposure condition under consideration, and laboratory-tested to evaluate how the natural aging process has affected mechanical properties. The experimental results are being analyzed using advanced statistical methods. A significant number of specimens are located on existing exposure facilities at Sherbrooke and in collaboration with the Public Works Research Institute of Japan, and thus are subjected to actual extreme climatic conditions.

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Focus Area 2.3:  Innovative Structures

Hybrid FRP/Concrete Structural Systems (2.3.1)
Project Leader: Dr. Aftab Mufti, University of Manitoba

The focus of this project is on the development of innovative, economical, corrosion-free structural systems for new construction and the replacement of old reinforced concrete structures. The research consists of integrating the steel-free concrete deck slab and FRP cellular deck with FRP/concrete hybrid beams and columns to develop a total corrosion-free structural system. Experimental tests are being conducted to test the inter-connection of various components of the structural system under dead and live loads. The objective is to show that the corrosion-free system proposed is economically justifiable.

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FRP Reinforced Concrete Structures (2.3.2)
Project Leader: Dr. Bruno Massicotte, École Polytechnique de Montréal

This research project comprises two distinct research topics linked together: (i) the modelling of FRP reinforced concrete structures, and (ii) the development of innovative precast components for bridges. The first topic deals with two families of model: sophisticated 3D FE software that can simulate all failure mechanisms of concrete for modelling complex structural components and or phenomenon, and design oriented software that enables modelling various stages of damages and strengthening with FRPs of concrete girders. The second topic deals with the analysis of innovative strengthening techniques for rectangular bridge piers and precast structural elements developed in collaboration with industrial partners. Precast girders containing innovative FRP stirrups are considered. Numerical and experimental activities are being carried out through that topic, following the development occurring in the industrial sector.

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Prestressed Girders with FRP Webs (2.3.3)
Project Leader: Dr. John Newhook, Dalhousie University

Based on a steel-concrete composite girder concept originally researched in France, a new type of girder is being developed. The new girder will be a composite construction using prestressed concrete flanges and a corrugated FRP web. The configuration of the web results in an optimum distribution of forces into the beam components such that the flanges will only carry flexural tension and compression and the web will carry only shear. As well, the corrugated profile eliminates the need for web stiffeners for resistance against global and local buckling creating a light-weight web even for deep girders. The potential advantages of this type of construction are the reduced total weight of the girder leading to easier construction and longer spans, and the increased durability of FRP over the corrugated steel web alternative.

The initial experimental program has demonstrated the feasibility of using a corrugated quasi-isotropic glass FRP web in a prestressed I-girder configuration. On-going activities include the development of appropriate numerical and analytical models for predicting the shear buckling capacity of corrugated anisotropic plates, optimization of the fibre orientation for the web design and development of details for the FRP web to concrete flange connection.

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FRP Products for Masonry Structures (2.3.4)
Project Leader: Dr. Nigel Shrive, University of Calgary

This research is aimed at creating and testing FRP products that will be utilized in the masonry industry. There are three areas of opportunity in masonry where FRP products could be the solution. The primary issue for connectors is corrosion. The second area is a bed joint reinforcement that is ineffective in increasing strength in its current form, partly because of its shape and partly because of the way masonry cracks. The research approach is one of connector/reinforcement design, given the requirements identified for the product. Prototypes are being manufactured by a local firm and tested in Calgary. A third area is to develop techniques for spraying concrete masonry walls with carbon fibre reinforced polymer (CFRP) to improve flexural behaviour. The major use of the technique is expected to be in the construction of basement walls. Research is also required into optimum fibre lengths and layer thickness.

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FRPs for Glulam Structural Members (2.3.5)
Project Leader: Dr. Farid Taheri, Dalhousie University

In early 80’s a patent was launched for glue laminated beams reinforced with FRP sheets (FRP/Glam), thereafter called FiRP©.  In 2001, another novel FRP-reinforced Glulam product, under the name of TENLAM©, was developed by Hi Tech Wood Products of Nova Scotia, using proprietary methodology. TENLAM was promised to offer superior mechanical properties to that of the FiRP Glulam. However, no design guidelines are available for this new product, nor have there been any studies conducted to explore the impact and vibration characteristics of these structural products. Moreover, other structural applications of FRP/Glam have not been explored.  It is therefore the aim of this project to: (a) gain a better understanding of the static and dynamic mechanical behaviour of FRP/Glam beams, produce robust and accurate solutions for their characterization, and (b) with the gained knowledge, to explore new applications of FRP/Glam with the aim of producing cost-effective FRP/Glam columns and arches.

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Hog Waste Storage Facilities Using FRPs (2.3.6)
Project Leader: Dr. Aftab Mufti, University of Manitoba

Hog waste storage constitutes a major concern for confined animal production systems. Expanding levels of production are making the conditions even more severe. In some cases, environmental concerns relating to earthen lagoons have led to a requirement for structures more impervious to the elements. In many cases, reinforced concrete has been used for these structures, but the hostile service environment associated with hog waste storage has led to a relatively short useful life, due to the corrosion of the reinforcing steel, which leads to concrete deterioration. This, in turn, releases waste into the soil to the detriment of ground water supplies.

The use of FRPs can eliminate problems related to corrosion and, therefore, enable these structures to withstand such harsh service conditions. This research investigated the use of FRPs when installed in conditions similar to hog waste storage tanks. The results found that FRPs provide improved performance relative to steel, giving industry the knowledge and opportunity to design and build safer and more economical hog waste storage facilities. The research included developing innovative design procedures for concrete storage tanks reinforced with FRP. The advantage of composite materials as a group is that they are non-corrosive. This research determined the type of FRPs that are most economical and capable of withstanding a severe storage environment.

In addition to the use of FRP reinforcements in storage tanks, this concept could also be applicable for other markets in animal production systems, in particular, reinforcement for slats, floors, and waste handling systems within production buildings.

See Field Demo

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Innovative FRP-Reinforced Precast Concrete Deck Panels (2.3.7)
Project Leader: Dr. Kenneth Neale, Université de Sherbrooke

Numerous bridge decks in Canada are in urgent need of repair or replacement.  Many of these bridges cannot be completely closed to traffic during construction.  The most viable solution, therefore, is to fabricate precast concrete deck panel components that can be rapidly installed during short temporary closings of the bridges.

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Innovative Corrosion-Free Bridge System (2.3.8)
Project Leader: Dr. Mamdouh El-Badry, University of Calgary

This objective of this project is to develop an innovative corrosion-free system for short- and medium-span bridges. In the proposed system, the superstructure consists of precast truss girders covered with cast-in place or precast concrete deck. The superstructure is built entirely from materials that are durable and not vulnerable to corrosion. An additional advantage is the reduced self-weight of the structure. The light weight reduces the load on the supports and allows for longer spans, resulting in reduction in the size of substructure and in the number of supporting piers in multi-span bridges and, hence, reduction in the initial cost. 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. The research plan is divided into three phases: optimum design of the truss girder and the concrete deck, testing connections and small scale girders, and full scale testing. The project is being carried out in collaboration with several national and international industrial partners.

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Reinforced and Prestressed Concrete-Filled FRP Tubes (2.3.9)
Project Leader: Dr. Amir Fam, Queen’s University

In this research program, the structural performance of prestressed and reinforced concrete-filled FRP tubes (CFFT) is investigated. This innovative system provides a more durable alternative for conventional piles and mono-poles. The research program includes two experimental sub-projects I and II. In sub-project I, the flexural behavior of prestressed CFFT is investigated. The study is focused on the effects of prestressing level, prestressed reinforcement ratio, pre-tensioned versus unbonded post-tensioned strands, and GFRP tubes of different laminate structures versus conventional steel spiral reinforcement. In sub-project II, the behavior of CFFT with internal rebar reinforcement is investigated under pure bending as well as in shear. Steel, GFRP and CFRP rebar of different reinforcement ratios will be used in the experimental investigation. The research program will also include the development of a comprehensive analytical model to predict the behavior of CFFT with internal reinforcement or prestressing under a general loading condition including flexural, axial compression loads and shear. The model accounts for the variable confinement of concrete imposed by the FRP tubes, the progressive laminate failure of the FRP tubes and cracked section analysis.

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Durability of FRP Pins and Reinforcement in Heritage Concrete Structures (2.3.10)
Project Leader: Dr. Aftab Mufti, University of Manitoba

In the fall of 2001, Veterans Affairs Canada (VAC) and Heritage Conservation Services Canada (HCS) initiated a study on marker mountings that are rapidly deteriorating at Brookside Cemetery in Winnipeg, Manitoba. This research project addresses two conditions believed to be deleterious to the anchor assembly for the marker: mechanical (i.e. service load) and environmental (i.e. frost action and exposure to moisture) conditions. The investigation focuses on the mechanism of degradation of the anchor assembly system and GFRP reinforcement concrete support beams under synergetic effect of chemical and mechanical processes and harsh environmental conditions. Five variables are being considered in the laboratory investigation: marker mounting methods; concrete type used for the supporting beams; reinforcement/rod type; adhesive type; and method of support beam emplacement. The testing program focuses on three structural anchor assembly types: pinning, pocket and bumper. The anchor marker assembly is subjected to an accelerated aging regime that represents the long-term exposure to the actual environment. The bond degradation is quantified with a direct pull-out test, and deterioration of the reinforced concrete supporting beams is quantified by monitoring the changes in the mechanical properties with lateral loading, shear and bending tests.

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Innovative Designs for Piles, Columns, Concrete Filled FRP Tubes (2.3.11)
Project Leader: Dr. Aftab Mufti, University of Manitoba

With the growing infrastructure crisis in the world, the search for innovative solutions is growing as well. One of these innovative solutions is the concrete filled FRP tube hybrid system. This system is becoming an attractive alternative for use in marine structures and for column piers due to its ease of fabrication. It eliminates formworks and reinforcement cage assembly as well, it is resistant to corrosion and attack by marine organisms. In addition, laboratory tests to date on the strength of the system have showed positive results. However, due to the novelty of this new system, concerns have been raised regarding its performance. This study is an attempt to address one of these concerns, which is the effect of driving forces on the static and cyclic behavior of the system.

In order achieve this goal, five piles, 356 mm in diameter, two of which were spliced, were driven into the ground and then extracted, cut into 0.3 m and 6.0 m portions and tested. The tests were compared to that of control specimens that were not subjected to such forces. Testing for the static behavior included beam tests on the 6.0 m portions to study the effect of the driving forces on the overall flexural behavior and the performance of the splices. In addition several tests were conducted on the 0.3 m portions to study the effect of driving forces on the different components of the system. These tests included, push-out tests to test the bond between the FRP tube and the concrete, tension coupon tests to test the tube and concrete core tests to test the concrete.

Preliminary test results indicate that the driving forces had very little effect on the strength of the piles. Further studies are being conducted to study the effect of the driving forces on cyclic behavior as well.

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FRP Wraps for Eccentrically-Loaded and/or Slender Reinforced Concrete Columns (2.3.12)
Project Leader: Dr. Luke Bisby, Queen’s University

Externally-applied circumferential FRP wraps have proven to be an efficient and effective technique to repair and strengthen reinforced concrete columns. Guidelines for the design of FRP-wrapped concrete members are currently available and field applications of this technique have been implemented around the world. However, the effects of column slenderness and load eccentricity on the effectiveness of FRP wraps remain incompletely understood and require immediate research attention to enable widespread application of FRP wraps in industry. The vast majority of tests conducted to date on FRP-confined concrete have been performed on short concrete cylinders tested under concentric axial load. In practice, however, most concrete columns are subjected to eccentric loads and have height-to-diameter ratios significantly greater than 3. Furthermore, the potential for increased susceptibility of wrapped columns to slenderness effects has received little research attention to date and requires further investigation, both for columns that become slender as a consequence of wrapping, and for structural strengthening of pre-existing slender members. ISIS Project 2.3.12 is thus targeted to fill specific knowledge gaps in the ISIS mandate, and seeks to experimentally and theoretically investigate the effects of eccentric loading and member slenderness on FRP-wrapped concrete members.

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Focus Area 2.4:  Integrated Fibre Optic FRP Products

FRP Structural Towers (2.4.1)
Project Leader: Dr. Dimos Polyzois, University of Manitoba

Typically, wind turbines are supported by conical, tubular steel towers manufactured in two to three sections of 20 to 30 meters and bolted together on site. Because of their size and weight, transportation and erection require heavy equipment, making the use of such towers prohibitive in remote areas. To develop towers that can be easy to transport and construct in remote areas is an important strategy. In recent years, Fibre Reinforced Polymers (FRPs) have received much attention as an alternative material to steel in the construction industry. FRP materials have the potential to decrease the weight of the wind turbine towers, leading to substantial savings in transportation and construction as well as allowing the erection of such towers in remote communities.

The objective of this strategic research project, currently underway, is to capitalize on the filament winding technologies developed at the University of Manitoba to produce composite tubular towers to support wind turbines. More specifically, the objectives of this research program are:

a) Conduct a review of the load requirements for towers taking into account climatic conditions in the North, weights of nacelle, rotors, etc.;
b) Conduct a preliminary analysis and design of various types of towers, such as single cell, multiple-cell, single tower and frame tower;
c) Carry out experimental work to determine the material properties of various GFRP layouts. Parameters to be investigated will include: type of resin, type of fibre, fibre angle, method of fabrication (wet and dry winding) and method of curing;
d) Fabricate and test scaled and full-sized specimens;
e) Select site for the construction of prototype wind turbine; design and fabricate full scale wind turbine tower;
f) Erect tower and construct the wind turbine; monitor tower performance using fibre optic sensors.

The research program is being carried out in phases. During the first phase, an analytical investigation on various shapes of GFRP towers was carried out using the ANSYS finite element program. The concept of a composite multi-cell tower was examined in great detail and the finite element results showed that such a tower could result in almost 35 percent reduction in weight.

In the second phase of this research program, a filament winding machine was designed and constructed at the University of Manitoba. Individual scaled cell segments and scaled multi-cell towers are being fabricated using this winder and are being tested as cantilevers under static loading.

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Smart FRP Tendons (2.4.2)
Project Leader: Dr. Alex Kalamkarov, Dalhousie University

The goal of this project was to develop smart FRP tendons and reinforcements with integrated sensors and actuators. The major objective was to develop, test and apply the innovative smart FRP tendons with enhanced functionality to be used in innovative bridges and structures. The FRP reinforcements were developed with integrated actuators (piezoelectrical, shape memory alloy wires or other appropriate types of actuators) and sensors (FOSs, piezoelectrical or other adequate types of sensors). These smart FRP tendons and reinforcements have the ability to monitor the health and deformation of critical civil engineering structures, adjust their stiffness, strengthen other physical and mechanical properties, dampen vibrations, and report excessive deformation or damage. The final product design specification and manufacturing guidelines to facilitate technology transfer for commercial use were produced as a result of this project.

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Design Manual Update (2.4.3)
Project Leader: Dr. Aftab Mufti, University of Manitoba

One of the major accomplishments and tangible results of Phase I of the ISIS mandate was the publication of four design manuals in 2001.  These manuals were developed over a two-year period by Network participants under the leadership of the ISIS Theme Directors.  These manuals were prepared for two reasons.  The first is to provide practicing engineers with detailed guidelines regarding the use of FRPs and FOSs in the design and construction of civil engineering structures.  The second is to provide a credible reference for the Code Committees to facilitate and accelerate changes to existing codes which did not envisage the use of advanced composite materials such as FRPs. 

New chapters are being added and the manuals are in the process of being updated with additional case studies.

More information on Design Manuals

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Completed Research 1995 to 2006