THEME 3 PROJECTS

Structural Strengthening and Rehabilitation
With FRPs

Director: Dr. Kenneth W. Neale, Université de Sherbrooke

THEME 3 OVERVIEW

Assessment of FRP Repairs in Canadian Environments

This project is an investigation of the post repair structural and bond performance of FRP repaired members under sustained and cyclical loads in a corrosive environment. Following an exposure to corrosion, the concrete members will be wrapped with external FRP sheets and then subjected to further corrosion while the performance of the FRP repair is monitored. Service life prediction models will be developed for FRP repair of corroded structural members.

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This project builds on the results of current ISIS research and has the objective of developing innovative and durable FRP retrofitting techniques for concrete structures to enhance their performance under extreme physical and environmental loads. Laboratory and analytical research will be tested in the field through monitoring of FRP retrofitting applications. The output will be the development of rational design procedures and guidelines for civil engineers.

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The objective is to provide engineers the knowledge to design seismic strengthening with wrapped FRPs on non-ductile bridge piers for Canadian climatic conditions. This project will demonstrate full scale test performance of FRP strengthening at high strain rate and low temperature. Upon conclusion, design guidelines will be provided for applying this new technology.

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Concrete Structures

Performance of Retrofitted Bridge Piers and Columns (F3.2.1)
Project Leader: Dr. Patrick Paultre, Université de Sherbrooke

The objectives of this project are to evaluate the seismic risk for existing deficient structures and carry out full scale seismic testing of rehabilitated structures to evaluate the performance of the retrofitted structures. The goal is to develop analytical tools to detect deficiencies and to predict behaviour of rehabilitated structures. It is planned to integrate the effects of high strain rate and low temperature on the stress-strain behaviour of FRP concrete and FRP reinforced concrete columns, using the results obtained from Dr. Massicotte’s research at École Polytechnique.

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The goal of the research is to develop a system for prestressing concrete beams and slabs with near surface mounted FRP rebars and strips that can be used in the field. Static and fatigue tests will be conducted as part of the research. The project includes the development of a durable anchorage system and a non-linear analytical model to predict behaviour of the concrete components. Design guidelines will also be a deliverable of this project.

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The goal is to develop a new, corrosion free, FRP system for punching, strengthening and retrofit of existing flat reinforced concrete slabs supported on columns. The project includes an investigation of the performance of FRP composite shear bolts and design of FRP-stainless steel composite bolts for construction application. Design guidelines and construction procedures will be developed upon completion of the research.

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The purpose of this project is to experimentally evaluate the durability and performance of near surface mounted FRP reinforcement for strengthening concrete structures. This will include freeze-thaw and wet-dry cycling, cold climate and fire temperatures and long term sustained (creep) loading. Examining durability of fibre optic sensors, anchorage and bond considerations will also be included. The research results will be included in an updated version of ISIS Design Manual No. 4.

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The objective is to examine the use of FRP material to strengthen structures against blast load by mitigation of progressive collapse. Repair of structures damaged by blast loading will also be examined. The project includes development of a progressive collapse model and estimation of residual capacity post blast. Development of techniques for using FRPs for strengthening structures to mitigate collapse and to repair structures damaged by blast forms part of the research. Design guidelines will be provided upon completion of the research.

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Thousands of unbonded post-tensioned buildings in North America are suffering from corrosion of the steel wire strands that form part of their strengthening system and are in need of repair. The objective of the project is to determine the feasibility of replacing steel strands with carbon fibre reinforced polymer (CFRP) strands in a draped duct, which is a common building component. Development of a suitable anchorage system and field demonstration form part of the project. Design guidelines will be prepared for the replacement of steel strands with CFRP strands.

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The objective is to examine the use of CFRP tendons (or strips) in the external prestressing of concrete structures utilizing anchor and deviator systems. Research details include the development of anchor and deviator systems for different types of CFRP tendons, conduct numerical simulations and laboratory evaluations of various combinations of tendon anchorage, and investigate the monotonic and fatigue behaviour of the concrete beams using different tendon profiles. The deliverable consists of establishing a design approach for CFRP tendon/anchorage/deviator systems and transfer the technology for field implementation.

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Timber, Steel and Masonry Structures

FRP Repair and Strengthening Systems for Steel Structures (F3.3.1)
Project Leader: Dr. Roger Cheng, University of Alberta

The main objective is to develop strengthening and rehabilitation technologies using FRPs for aging/ damaged/deficient steel structures. There is need to better understand the bond behaviour between steel and FRPs, interaction between the two, fatigue and corrosion resistance of FRP on steel, toughness and durability of the repair, and optimum design of FRP patches and wraps on steel. Field research applications will include steel pipelines, fibre reinforced pipelines, railway and highway steel bridges and steel structures in cold regions.

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The project consists of developing strengthening schemes that will lead to improved performance of lower grade timber and promote reuse of old timber stringers for structural purposes. This will include increasing the flexural and shear capacity and assessing the durability of strengthening systems under varying climatic conditions. The feasibility of using innovative FRP sheet prestressing techniques for stress-laminated wood decks will also be investigated.

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The Province of British Columbia plans to strengthen its public schools located in high-risk earthquake zones.  Many of these schools are unreinforced masonry (brick) buildings, and are good candidates for FRP rehabilitation.  This project will establish a theoretical basis to estimate the strengthening requirements for the structure, substructure, exterior enclosures and partitions.  An FRP system will be designed accordingly, tested in the structural lab and applied to a demonstration project.  The structure will be monitored to validate the theoretical and lab results and the FRP system can then be used to strengthen masonry (brick) schools.

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There are three objectives for this project. One is to develop an effective and flexible monitoring system for heritage structures. Another is to develop a technique for providing strength and toughness to cracked masonry structures without detracting from the visual appearance of the structure. Finally, to develop a simple numerical methodology that can be utilized in the design office to assess the long term effects of an intervention in terms of load redistribution due to creep.

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