"Innovator" Newsletter
February 2000CONTENTS
Feature Stories
Fibre for Health - Strengthening the Maryland Street Bridge
Demonstration Projects and Innovative Products
Focus on Research
International Collaboration
Fibre for Health - Strengthening the Maryland Street Bridge
The City of Winnipeg has implemented a trial application of carbon fibre reinforced polymer (FRP) sheets as a first step in upgrading the shear capacity of the Maryland Street bridge in Winnipeg. The twin five-span continuous precast prestressed concrete structures were designed and constructed in 1969. However, analysis using current codes indicates that the shear strength of the I-shaped girders is not sufficient to withstand today's increased truck loads. An experimental study was conducted by ISIS Canada at the University of Manitoba to examine the use of carbon FRP sheets on this particular girder shape. Four girders have since been strengthened using the sheets which were placed vertically with a horizontal layer placed across the top and bottom of the web.
Patching the four girders is actually phase two of this multi-phased project. Phase one consisted of testing the strength of FRPs on scale beams in the University of Manitoba's McQuade Structures Laboratory. The $160,000 laboratory tests were financed jointly by the University of Manitoba, ISIS Canada, and the City of Winnipeg.
The tests began in 1996 with seven 10-metre long beams. They were strengthened using various types of carbon FRP sheets in ten different configurations. They were then tested to shear failure at each end to determine the most efficient shear strengthening scheme for the Maryland bridge's I-shaped girders.
During the testing phase, contractors participated in the process of wrapping (strengthening) the beams. Work crews from Concrete Restoration Services Ltd. and Vector Construction Group took part in applying the composite material and its epoxy-resin base in preparation of the field application.
Two girders were strengthened by Vector Construction Ltd. using the MBraceTM system manufactured by Master Builders Inc., and two girders were strengthened by Concrete Restoration Services Ltd. using the ReplarkTM system manufactured by Mitsubishi Chemical Corporation.
Phase Two has been completed with four of the Maryland bridge girders strengthened. Horizontal and vertical strain gauges were applied so that the structure can be monitored over a two- year period. ISIS Canada engineers will determine how the technique stands up to Winnipeg's extreme climates.
There are numerous concrete structures throughout Winnipeg which are currently restricted to carrying weights well below the legal limits. The preliminary research conducted for the Maryland bridge will result in substantial savings amounting to millions of dollars because it can be applied to numerous other bridges (see John Hart bridge story).
Plug and Play Sensors for Structural Health Monitoring
Results of ISIS Canada's research project located at the University of Alberta show that wireless technology achieves continuous monitoring of structures while reducing the volume of data collected and power consumed, and increasing the lifespan of instruments.
The University of Alberta and Optimum Instruments Inc. have introduced a second generation wireless datalogger and radio modem that connects a monitoring site to an office. The DRM-1200 Wireless Datalogger eliminates the need for permanent site installations, phone hook-ups, power, and site heating. When combined with new Internet management technologies, it also allows management of monitoring networks with minimal overhead costs for data collection and scheduled site maintenance.
The Datalogger connects directly to the Internet or a secure private network. It can instantly monitor sensors and evaluate the structure's current conditions. By using the menu-driven WIMComm Software, also developed by Optimum Instruments and the University of Alberta, the data can be viewed immediately.
The DRM-1200 is self-monitoring and issues alarm warnings to the central computer. It also reports low battery or solar power. Tampering or vandalism can be monitored by the analog/digital inputs. As well, if a radio is connected to the Internet, problems are reported to multiple e-mail locations including digital cell phones. At this point the technology is being used with conventional strain gauges. A wireless remote monitoring system for fibre optic sensors is currently being designed and constructed by Gerald Manuelpillai at the University of Toronto Institute for Aerospace Studies.
Sensing a Trend
The future for sensors is heading toward wireless communication. This is due to the cost of installing, terminating, testing, maintaining, troubleshooting and upgrading the wiring. ISIS Canada is exploring networks of wireless sensors that can operate under severe climatic conditions and still provide measurable advantages in cost, power, flexibility and distributed intelligence.
Demonstration Projects and Innovative Products
John Hart Bridge Strengthened for Shear
It is one of the largest strengthening projects of its kind. Carbon FRP sheets have been used to upgrade the shear capacity of the John Hart Bridge in Prince George, British Columbia. The bridge, owned by B.C.'s Ministry of Transportation Central Northeast Region, required shear strengthening in order to support heavier truck loads. It consists of seven simply supported spans with six prestressed concrete girders per span. The 42 girders are 1500 mm deep with a typical I-shaped AASHTO cross-section. They were strengthened with carbon fibre-reinforced polymer (FRP) sheets covering a four-metre length at each end of the girder. By strengthening 64 girder ends, shear capacity was increased by 15 to 20 percent.
Similar to the Maryland Street bridge in Winnipeg, Manitoba, the John Hart bridge was strengthened by applying diagonal carbon (FRP) sheets. Dave Scouten, a principal of Scouten and Associates Ltd., located in Prince George, British Columbia, consulted with ISIS Canada on the design. ReplarkTM sheets manufactured by Mitsubishi Chemical Corporation were chosen and then installed by specialty contractor Retro, of Vancouver. The project was completed in six weeks with the assistance of the general contractor, SureSpan, also of Vancouver. During this time the bridge remained completely accessible to traffic.
Phase II - The next phase of the project involves a monitoring program to collect data on the long-term performance of carbon FRP sheets for shear strengthening this particular type of cross-section. The bridge was instrumented to monitor its behaviour under dynamic vertical and service load conditions. Periodic site visits and visual inspections will also be conducted to assess the bridge's long term performance.
In a future phase of the project, a twin bridge will be constructed. Upon opening of the new lanes, the existing bridge will undergo further rehabilitation. The existing high-density overlay will be replaced with a reinforced concrete deck topping. The use of carbon FRP reinforcing bars has been proposed.
Hall's Harbour Wharf Near Completion
Deterioration in marine infrastructure can be more rapid and severe than in land-based structures. The Hall's Harbour Wharf on the Bay of Fundy shore in Nova Scotia suffered a 40-metre collapse in 1998. The 96-year-old combination wharf/breakwater has been rehabilitated using glass fibre reinforced polymer (FRP) bars and design criteria from draft versions of both the Canadian Highway Bridge Design Code and the American Concrete Institute Code.
The new structure consists of pile support concrete beam and deck elements above an armour stone and timber crib breakwater. The concrete beams are designed with a hybrid reinforcement scheme of steel and glass FRP rods. The outer durable layer of glass FRP protects the inner core of steel reinforcement. The deck consists of precast steel-free concrete bridge deck panels modified to meet the durability needs of this structure.
As the wharf represents a new application for glass FRP and is based on current draft codes, there is a strong requirement to monitor and assess its in situ performance. A system of fibre optic strain sensors and conventional foil strain gauges have been embedded in the structure. The wharf will be monitored under various environmental conditions and physical loads.
Strengthening Timber Bridges is Cost Effective
The Tourond Creek Bridge south of Winnipeg on Highway 59 has been selected as the first of its kind to undergo an innovative strengthening technique developed by ISIS Canada. Upon completion, this 39-year-old structure will be at least 30 percent stronger. Manitoba Highways and Government Services has committed $110,000 to test the new technology, anticipating it will be suitable for extending the service life of similar bridges.
The Province has 575 timber bridges all of which were built prior to 1980 and require strengthening in order to accommodate the increased traffic loads permitted by the Transportation Association of Canada (TAC Loads). Manitoba Highways and Government Services has estimated that replacing the Province's aging structures would require an investment of approximately $260 million. It estimates it will cost $90 million to replace the 170 treated timber bridges on the Provincial Trunk Highway system and $170 million to replace the remaining 405 treated timber bridges with new bridges. However, by using the simple, innovative strengthening technique whereby glass fibre reinforced polymer (FRP) bars are embedded longitudinally in the stringers and adhered to the wood beam grooves with an epoxy resin, bridges like the Tourand Creek bridge can achieve the same strength as a new structure for less than 15 percent of the $800,000 estimated to completely replace the bridge.
The cost to strengthen each stringer with glass FRP bars is $1,500. The benefits of using glass FRP bars are that they do not add significant weight to the structure and do not corrode when exposed to road salt.
For contractors like Joe Solomon, C.E.T. - President of Concrete Restoration Services Ltd., who is working on the Tourand Creek bridge project, FRPs provide a convenient alternative to conventional strengthening techniques. "The material is easy to work with, offering such benefits as being non-corrosive. In addition, no heavy equipment is required to install the FRP reinforcement because it is lightweight. It can be installed with virtually no obstructions, disturbances or inconvenience to the travelling public," Solomon said.
Dr. Sami Rizkalla, President of ISIS Canada and professor of civil engineering at the University of Manitoba explains that the Tourand Creek bridge is an unprecedented strengthening project. However, it is by no means an experimental exercise. "The experimental program was completed much earlier in the McQuade Structures Laboratory at the University of Manitoba. Tests proved that glass FRP bars are a feasible solution for strengthening timber bridges. Ductility is dramatically improved and the flexural strength can be increased by 20 to 50 percent," Rizkalla said.
Twenty-two beams were tested to determine the predictable behaviour of full-scale and half-scale creosote treated beams strengthened using glass FRPs. In applying the test results to the field application, the three-span 23.3-m-long Tourand Creek bridge is a particularly useful example of how FRPs can be used to strengthen wood bridges. Its design incorporates two standard stringer sizes used in most timber bridges (two 6.4-m approach spans and one 10.06-m centre span). ISIS Canada will monitor the bridge's behaviour to confirm its research.
Focus on Research
Canadian Research at 4th International Symposium on FRP for Reinforced Concrete Structures
ISIS Canada researchers were well represented in the content at a recent international symposium attended by over 1,000 delegates. The Fourth International Symposium on Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures (FRPRCS-4) was co-chaired by ISIS Canada President Dr. Sami Rizkalla and hosted in conjunction with the American Concrete Institute (ACI) fall convention, October 31 to November 5, 1999 in Baltimore, Maryland, USA.
PRESENTATIONSBrahim Benmokrane, Radhouane Masmoudi, Mohamed Chekired, Habib Rahman (Université de Sherbrooke)
Gamil Tadros (SPECO Engineering)
Design, Construction and Monitoring of FRP Reinforced Concrete Bridge Deck
Mark Green (Queen's University)
Raafat El Hacha, Gordon Wright (University of Waterloo)
Strengthening Concrete Beams with Prestressed FRP Sheets Behaviour at Room and Low Temperatures
Tarek Hassan, Sami Rizkalla (University of Manitoba)
Amr Abdelrahman (University of Ain-Shams)
Gamil Tadros (SPECO Engineering)
Design Recommendations for Bridge Deck Slabs Reinforced by FRPs
Robin Hutchinson, Sami Rizkalla (University of Manitoba)
Shear Strengthening of AASHTO Bridge Girders Using FRP Sheets
Emile Shehata, Ryan Morphy, Sami Rizkalla (University of Manitoba)
FRP Shear Reinforcement for Concrete Structures
Ted Sherwood, Khaled Soudki (University of Waterloo)
Confinement of Corrosion Cracking in Reinforced Concrete Beams with Carbon Fibre Reinforced Polymer LaminatesDagmar Svecova (University of Manitoba)
Ghani Razaqpur (Carleton University)
Prestressed Tension Elements as Reinforcement for Concrete
Khaled Soudki (University of Waterloo)
Timothy White, Marie Anne Erki (Royal Military College)
Analytical Model of RC Beams Strengthened with CFRP Laminates Subjected to High Strain Rates
Gamil Tadros (SPECO Engineering)
Ken McWhinnie, Jadwiga Kroman (City of Calgary)
Deck Strengthening for Country Hills Bridge in Canada
MODERATORSBrahim Benmokrane (Université de Sherbrooke)
Bond Characteristics of FRP Reinforcement for Concrete
Mark Green (Queen's University)
Properties of FRP Reinforcement for Concrete
Kenneth Neale (Université de Sherbrooke)
Case Studies of FRP Reinforced Concrete Structures
Khaled Soudki (University of Waterloo)
FRP Applications in Bridges, Masonry and Pavement
Solution for Reinforced Concrete Beams Affected by Alkali-Aggregate Reactions
Many corrective techniques exist to inhibit alkali-aggregate reactions in concrete structures. However, most of the existing techniques do not allow the structures to recover their initial mechanical properties. An established technique for strengthening structures is to bond steel plates onto the elements for which an increase in strength is required. These plates are usually difficult to handle because of their heavy weight and lack of flexibility which adds to the attractiveness of fibre reinforced polymer (FRP) sheets as an alternative to steel plates.
At the Université de Sherbrooke in Quebec, Christine Lacasse is investigating the effectiveness of FRPs as external reinforcement for reinforced concrete beams affected by alkali-aggregrate reactions (AARs). Ms. Lacasse is evaluating the contribution of FRP technology in reducing the expansion in the beams, and also assessing the increases in their flexural strength. This investigation will focus on measuring the gains or losses in strength as well as measuring expansion over time. The research forms her Masters thesis under the direction of Drs. Pierre Labossière and Kenneth Neale.
International Collaboration
USA Infrastructure Delegation Explores Network Concept
ISIS Canada hosted an American delegation representing civil engineering and infrastructure interests October 4, 1999 in Winnipeg to discuss how Canada is using innovative technologies to deal with the ongoing problem of deteriorating infrastructure.The objective of the one-day meeting was to provide information that will assist the American delegation in establishing a technology transfer network similar to ISIS Canada, and to seek new opportunities for cross border collaboration.
Professor Farhad Ansari of the University of Illinois at Chicago expressed his warm appreciation for ISIS Canada's hospitality and stated, "The U.S. delegation was very impressed with the breadth and the quality of your activities. We enjoyed the wide range of research activities, especially the implementation of the research products by the Provincial Government for repair and monitoring of bridges."
The two parties confirmed their intention to promote contact between the two countries with a view to enhancing the availability of resources and sharing knowledge. They underscored the importance of this relationship given that by 2005 American traffic delays due to inadequate roads may cost $50 billion per year (US funds) in lost wages and wasted fuel (Civil Engineering Research Foundation).
American participants included:
Shuaib Ahmad, Chief Engineer, American Concrete Institute International; Farhad Ansari, Professor, University of Illinois at Chicago; Richard Belle, Senior Research Advisor, Civil Engineering Research Foundation; Vijaya Gopu, Program Director, National Science Foundation; and Nicholas Vitillo, Project Engineer, Research, State of New Jersey, Department of Transportation.
ISIS Canada participants included:
Sami Rizkalla, University of Manitoba; Aftab Mufti, Dalhousie University; Rod Tennyson, University of Toronto; Kenneth Neale, Université de Sherbrooke; Lloyd McGinnis, ISIS Canada; Gamil Tadros, SPECO Engineering; Walter Saltzberg, Consultant; Joanne Keselman, Vice President Research, University of Manitoba; Ray Hoemsen, Director, Industry Liaison Office, University of Manitoba; and Andrew Horosko, Deputy Minister, Manitoba Highways and Transportation.
Collaboration with Université Claude-Bernard, Lyon, France
Within the framework of the Quebec-France research exchange agreements, an international collaboration has recently been established involving the ISIS Sherbrooke research team of Professors Kenneth W. Neale and Pierre Labossière, with that led by Professor Patrice Hamelin of the Université Claude-Bernard of Lyon, France. This program funds the exchange of researchers for periods varying from one week to two months. Funding has initially been approved for a two-year period.As part of this program, in the fall of 1999, ISIS Sherbrooke hosted Professor Hamelin, Assistant Professor Dr. David Bigaud and Ph.D. candidate Emmanuel Ferrier from France, while Professor Neale and ISIS Ph.D. candidate Pierre Rochette of Sherbrooke were received by Professor Hamelin's group. The topics of research collaboration include the use of FRPs for the repair and strengthening of concrete structures, the durability of FRP-repaired concrete structures, and the integration of fibre optic sensors for the monitoring of FRP-rehabilitated structures.
ISIS Hosts Meeting with EU Counterpart
On November 18, 1999 ISIS headquarters hosted three members of the Confibrecrete Training and Mobility of Researchers (TMR) EU-based network. Dr. Kypros Pilakoutas, Network Coordinator and Professor of Civil and Structural Engineering, University of Sheffield, UK, was accompanied by Maurizio Guadagnini, Assistant Coordinator, and Abdel Wahab El-Ghandour, a Ph.D. candidate. ConFibreCrete is co-ordinating European research efforts in fibre reinforced polymers (FRP) and developing guidelines for design, as identified by the Comité Européen du Béton. It is similar to ISIS Canada in that its research program is complemented by efforts to increase industrial collaboration. The Network includes 11 teams from nine European countries and has a total budget of 1,325,000 ECU over a period of four years beginning December 1997. The meeting served as an information session for the two networks. Website: www.shef.ac.uk/~tmrnet
