Field Demonstration Projects
British Columbia

John Hart Bridge

It is one of the largest strengthening projects of its kind. Carbon fibre reinforced polymer (CFRP) 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.

The bridge 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 FRP sheets covering a four-m 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 CFRP sheets. Dave Scouten, a principal of Scouten and Associates Ltd., located in Prince George, British Columbia, consulted with ISIS Canada on the design. Replark 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 of the project involves a monitoring program to collect data on the long-term performance of CFRP 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 are conducted to assess the bridge's long term performance. In the future, a twin bridge will be constructed and, 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, and the use of CFRP reinforcing bars has been proposed.

Back

Portage Creek Bridge

This disaster-route bridge in Victoria, British Columbia was built prior to current seismic design codes and construction practices and would not resist potential earthquake forces as required by today’s standards. ISIS Canada is assisting with a retrofit involving FRP wraps to strengthen the short columns and a system for structural health monitoring. The project calls for a retrofit to strengthen the Pier No. 2 columns of the Portage Creek Bridge, which could potentially fail in catastrophic shear during a large earthquake.

The Portage Creek Bridge was designed in 1982 by the Department of Highways Bridge Engineering Branch and crosses Interurban Road and Colquitz River at McKenzie Avenue. It is a 125-m (410-ft) long three-span steel structure with a reinforced concrete deck supported on two reinforced concrete piers and abutments on steel H piles. The deck has a roadway width of 16 m (52 ft) with 2-1.5 m (5-ft) sidewalks and aluminum railings.

Most of the bridge is being retrofitted by conventional materials and methods. The dynamic analysis of the bridge predicts the two tall columns of Pier No. 1 will form plastic hinges under an earthquake. Once these hinges form, additional shear will be attracted by the short columns of Pier No. 2. A nonlinear static pushover analysis indicates that the short columns will not be able to form plastic hinges prior to failure in shear. Therefore, it was decided that FRP wraps should be used to strengthen the short columns for shear without increasing the moment capacity.

Back

Safe Bridge, Cowichan Lake

In cooperation with the Ministry of Transportation and Highways of British Columbia, ISIS researchers repaired the Safe Bridge in the Cowichan Lake area on Vancouver Island using the spray composite technique. The concrete on the girders was severely spalled and the girder sections needed to be reformed before the FRP spray could be applied. Several girders were instrumented before and after placement of the spray. For instrumentation before the spray, traditional sensors were placed on the rebars, and after spraying, fibre optic sensors were installed. Measurements from these sensors are carried out remotely.

Back

Trout River Bridge

The Trout River Bridge is located in British Columbia’s Muncho Lake Provincial Park. As part of the Alaska Highways Program, Public Works and Government Services Canada (PWGSC) will replace this three-span bridge with a new structure that will provide 75 years of service life, meet all code requirements and have the capacity to carry all provincial and territorial regulation loads.

PWGSC has allocated over $120,000 for a structural health monitoring (SHM) plan for the bridge to assess the in-service performance of the innovative bridge design and provide a decision-making program that will optimize long-term maintenance costs. Elongation of the box girders due to temperature and forces induced in the integral abutments will be measured, as well as strains in GFRP reinforcement in the deck. A data logger and a resident computer will be installed, as well as a Thermal Energy Generator (TEG) for this remote site. Communication between the bridge and the monitoring engineer will be accomplished via satellite using Internet. ISIS Canada will assist in the interpretation of the monitoring and confirm the practicality of remote monitoring by FOS sensors in an environment where power supply is not readily available.

Back

Waterloo Creek Bridge

The Waterloo Creek Bridge is part of a series of bridges constructed by the British Columbia Ministry of Transportation and Highways as part of the Vancouver Island highway, in the northern part of the island. The bridge consists of two separate single-span decks, one for the north-bound lanes and one for the south-bound lanes, with common abutments. Each deck is about 25-m long and 12-m wide. Each deck is supported by five precast concrete girders, with the deck slab and girders monolithically connected to the abutments.

The abutments are supported by steel pipe piles. The north-bound structure has a steel-free deck, while the south has a conventional, reinforced concrete deck. Fifty-three sensors were installed at various locations of the north-bound structure and eleven sensors were installed in the south-bound structure.

Back

University of BC Aquatic Center - Resurfacing of Outdoor Plaza Deck

Part of the outdoor plaza deck at the University of British Columbia’s Aquatic Center was resurfaced using a high performance fibre reinforced concrete (HPFRC) mixture with shrinkage compensating admixtures. Previous resurfacing efforts had produced unsatisfactory results with overlays exhibiting excessive cracking, premature delamination and unwarranted saturation.

Two adjoining overlays were placed, one with plain concrete and the other with HPFRC. The overlays each contain 16 embedded sensors to monitor strains, temperature variations and the chemical environment in the overlay to better understand the reasons for debonding. Two types of embedded sensors were used. One is a newly developed ceramic sensor from Japan, and the other is the ECFRC (electrically conducting fibre reinforced concrete) sensor being developed at UBC under the auspices of ISIS. Data will be collected for a period of three years following placement of the concrete, using the WebDAQ/100 data acquisition system, which is capable of transmitting signals over the Internet.

This project will endeavour to increase understanding of the behaviour of bonded cement-based overlays and explain the mechanisms causing debonding and lack of adequate durability. It will also contribute to the development of embedded sensors and novel sensors based on ECFRC.

Back

Instrumented Loading Dock at ChemBioE Building (UBC) with Three Types of Embedded Sensors

Long-term structural health monitoring of the loading dock at the newly built ChemBioE Building at the University of British Columbia is being undertaken. The outdoor dock is heavily leaded and will witness a chloride-rich environment. Three types of sensors will be installed in the dock for long term remote monitoring. These will include traditional electrical resistance gauges, fibre optic sensors and the newly developed ECFRC (cement-based) sensors. The latter are capable of monitoring the chemical environment in concrete and detect onset of rebar corrosion. Data from the above sensors will be further supported by non-destructive tests (NDT) including Ultrasonic Pulse Velocity (UPV) measurements (using Raleigh Waves) and Electrical Impedance (EM) measurements (using Wenner Probe Protocol). In addition, the corrosion activity will be monitored at select locations in the loading dock by using a sitemounted Potentiostat/ Galvanostat/ EIS System. Along with sensing, the dock will be divided into five parts to investigate the following novel concepts in concrete technology: joint-free floor technology; fibre reinforced concrete; high volume fly-ash concrete; and concrete with shrinkage reducing admixture (SRA).

Back