The bridge in question is an auxiliary structure designed to support construction and maintenance operations associated with the main bridge; it is therefore only used by maintenance vehicles. This auxiliary structure is designed to withstand the hydraulic forces, climatic conditions, and geotechnical stresses of the site. Given the age of the structure, the concrete in the footing of this bridge now shows cracks. It should be noted that these cracks do not compromise the safety of the structure or its users.
Figure 1 : Typical crack on the footing
A pilot project was set up to monitor certain cracks over a period of several years. The RTF crackmeter was chosen because of its robustness.
Figure 2 : RTF Crackmeter
As the footings are located underwater at a depth of several meters, the RTF vibrating wire crackmeter was installed by a team of divers. A total of 16 sensors were installed on four footings. A template was developed to enable divers to install the sensors accurately and easily.
Figure 3 : Drilling template
Each sensor is protected by a cover due to the possibility of ice forming in winter.
Figure 4 : Protecting cover
The sensors are connected to an automated data acquisition system that transmits readings on a daily basis.
Figure 5 : Data acquisition system
For reference on the RTF crackmeter, see https://roctest.com/en/product/rtf-surface-jointmeter/
