Field Demonstration Projects
Saskatchewan

Hudson Bay Bridge

The Hudson Bay bridge in Saskatchewan supports an important timber haul connecting local mills to forested areas. Currently, however, concerns regarding the strength of the bridge have limited permitted truck loads. Efforts that successfully support higher truck loads will therefore lower the trucking costs incurred by industry - leading to a more cost-competitive forestry sector in the province.

To strengthen the bridge, Saskatchewan Department of Highways and Transportation SDHT) has opted for CFRP wraps installed under centre span beams. To ensure the added strength obtained is sufficient to support higher truck loads and to ameliorate concerns regarding long-term durability, SDHT and Weyerhauser agreed to participate in a structural health monitoring (SHM) research program designed to monitor and analyze the behaviour of the bridge under live load before, during and after the installation of the CFRP wraps. The results of this research will help determine whether or not bridge engineers within SDHT permit higher loads over the bridge.

From the standpoint of life cycle costing (LCC), any haul weight decisions reached should balance the cost-savings enjoyed by industry and the infrastructure-related costs incurred by SDHT. While higher haul weights certainly suit industry, concomitant implications for bridge- and road-related efforts and costs must be taken into account to ensure total life cycle costs are indeed minimized. Broadly speaking, the purpose of project 1.3.16 is to establish a haul weight policy that is likely to minimize the total life cycle costs of infrastructure use and management in this regards.

Employing the life cycle engineering and costing (LCE&C) method developed under project 4.1.1, participants in this research program will iteratively model and analyze the life cycle costs associated with the use and management of Hudson Bay bridge to help determine an optimal haul weight policy. Ultimately, the insights reached through this investigation will be embodied in a computer-based LCE&C model linking condition assessment (supported by SHM) to life cycle performance prediction and, finally, to life cycle costs.

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Saskatoon Overpass

The Attridge Drive Overpass in the City of Saskatoon is a newly constructed two-span continuous slab-on-girder structure with integral abutments. Data from 53 permanently installed strain gauges and six accelerometers, temporarily installed at 21 locations, are being used to measure the dynamic properties of the structure (i.e. its natural frequencies and mode shapes). Changes to these properties over time are being investigated as possible indicators of progressive damage due to deterioration of structural components.

In addition to generating a baseline dynamic signature, additional objectives include evaluating the effectiveness of ambient traffic to excite vibrations; investigating the effectiveness of strain gauges and accelerometers for dynamic measurements in the field; and identifying important issues that must be addressed for the successful implementation of dynamic measurement techniques in field applications.

A finite element model of the structure is being used to simulate the dynamic response at various stages of progressive damage. This information will be used to develop reliable vibration-based structural health monitoring techniques.

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