Bridge beauty under observation

Madrid. How do the loads really develop during the construction phase of a bridge? The planners in Madrid wanted to know exactly and asked MAURER. The bearing experts from Munich developed special spherical bearings with pressure sensors. In addition, five bearings were convertible and equipped with lateral guides only for the construction phase.

The "Puente de la Concordia de Valdebebas" is an arch bridge that connects Terminal 4 of Barajas Airport Madrid with the Valdebebas district in a wide sweep. With a main span of 162 m and a total length of 207 m, it has the largest span in the region. Valdebebas is a completely new district of Madrid and is expected to have 40,000 inhabitants in the future.

Spherical bearings with monitoring system MAURER supplied a total of 22 MSM®/MSA® spherical bearings. Spherical bearings allow very large rotations around all axes with low friction at the same time.

All sliding surfaces are equipped with the high-performance material MSM® (MAURER Sliding Material), which among other things can support particularly high loads. In the case of the Valdebebas Bridge, 10 of the bearings are designed for loads up to 39,000 kN. For this, MAURER guarantees a lifetime of 50 years without wear.

In order to achieve low coefficients of friction, the MSM® discs are equipped with lubrication pockets that ensure constant and permanent lubrication of the sliding surfaces.

The spherical caps at the heart of the bearings are made of MSA® (MAURER Sliding Alloy), an extremely corrosion-free material. Compared to a chromium-plated calotte, the sliding alloy reduces tolerances and increases service life. For this purpose, the sliding surfaces are polished to the lowest possible surface roughness.

With the high loads, however, the planners did not want to rely on calculated values as usual. "This is a tendency we observe in bridge construction," explains project manager Luca Paroli from MAURER. "Planners want to see exactly what happens during the construction phase and what the structure actually does."

MAURER installed a monitoring system in six of the large spherical bearings. "What's special about it is that we can measure the pressure continuously and read it at any time via an Internet connection," Paroli says.

The sensor system measures the pressure in the bearing in real time, from which the surcharge load is calculated. The sensors are installed centrally in the bearing under the calotte.

The monitored bearings are located at key points with highly fluctuating load input during construction.

Convertible bearings In addition, the planners wanted to convert one of the piers into a fixed axis during the construction phase. For this reason, the bearings of the P2 axis were designed to be convertible, i.e. they were provided with lateral locks that were removed after the construction phase.

The Valdebebas Bridge was inaugurated in March 2022. Ferrovial was the construction company, IDEAM, S.A. was responsible for the structural design and was in charge of construction management.