Monitoring the Prestressed Rods in the Basel Border Bridge Maintenance Project: Data Analysis during the Passage of Trucks

Abstract

More than 40 years ago, the expansion joints on the Basel border bridge were constructed using corbels and dapped ends. The consoles had to be reinforced as part of the renovation measures due to damage caused by chloride entry and due to the increased loads. Diagonal rods, which were prestressed, were used. Fiber-optic sensors were additionally installed to these highly stressed rods in order to measure the strains and temperatures. This now makes it possible to measure the actual strains in the strengthening of the corbel, estimate fatigue loads, and set up a warning system in case of overstressing. This article presents the design of the measurement system and the analysis of the data. Furthermore, the reference measurements that can establish the relationship between the measured strains and the loads passed over are presented.

Fatigue Measurements in an Existing Highway Concrete Bridge

“…In [8], reference measurements were made to obtain a correlation between the passing truck loads and the measured strains. Due to the special position of the sensors, it is possible to analyze the traffic on each of the two lanes of the bridge separately.…”

“…The peaks are characterized by 4 points, the start of the peak, the maximal value and the time position of that value and finally the end of the peak. The asymmetrical triangular shape of the peaks is explained in detail in [8].…”

“…Despite the tight conditions, more than two thirds of the sensors could be installed without damage and measure reasonable values. For more specific information about the fiber-optical sensors see [8]. The data is collected on site and then transmitted via mobile phone network to the server at the research institute, where it can be further processed and analyzed.…”

“…The data is collected on site and then transmitted via mobile phone network to the server at the research institute, where it can be further processed and analyzed. In [8], a new measurement setup for monitoring the corbels of the Basel border bridge was presented. As part of this project, it was determined that it was not possible to accurately calculate the stress peaks in the reinforcing rods due to passing trucks.…”

“…As part of this project, it was determined that it was not possible to accurately calculate the stress peaks in the reinforcing rods due to passing trucks. Therefore, reference measurements were carried out and are described in detail in [8]. This article is about counting truck passages under regular operation to determine fatigue loads.…”