Empa - un établissement de recherche du Domaine des EPF
Ingénierie des structures  
Static and Dynamics of Structures
Structural Monitoring and Adaptive Structures
Advanced Materials for Construction
Cable Systems
Strengthening and Seismic Retrofitting
Timber Engineering

Structural Monitoring and adaptive Structures
Research and Development
Structural monitoring with wireless sensor networks
In the past decade, wireless sensor networks (WSNs) have emerged as an innovative structural monitoring technology. Their advantages such as rapid deployment, ease of scalability, and self-configuration allow to reduce the costs, to increase the flexibility, and to simplify the operability of monitoring. These advantages are weakened by the power limitations that impose energy saving mechanisms such as low power hardware, duty-cycle operation, and multi-hop communication with low power protocols for achieving long term running periods of the sensor nodes. For data intensive applications (vibrations, fatigue), however, these energy saving mechanisms are insufficient. In-node data processing, which is much more energy efficient than data communication, has the beneficial effect to significantly extend the running periods and to increase the system reliability by dramatically reducing the data communication.
Link to article reference (RefShare)
Contact: Dr. Glauco Feltrin, Dr. Kallirroi Flouri

Controlled magnetorheological dampers for stay cable bridges
Empa and the industrial partner Maurer Söhne from Munich developed real-time controlled magnetorheological dampers that mitigate stay cable vibrations independent of frequency and amplitude with the same efficiency. The system is installed on the Franjo Tudjman Bridge near Dubrovnik and the Alamillo Bridge in Sevilla as retrofit measures after these bridges underwent large cable vibrations. In case of the Sutong Bridge in China and the Russky Bridge near Vladivostok in Russia, the system was installed on the 6 and 5, respectively, longest cables from the very beginning due to the very long cables, i.e. up to 540 m and 580 m, respectively.
Link Publication list
Partner: Maurer Söhne
Contact: Dr. Felix Weber

Real-time controlled tuned mass damper based on MR technology
In collaboration with the industrial partner Maurer Söhne from Munich, Empa developed in 2011 an adaptive tuned mass damper with controlled magnetorheological damper that enables to adjust the frequency and energy dissipation of the device in real-time to the actual frequency of the main structure. The system is experimentally validated for +/-20% frequency shifts and installed on the Volgograd Bridge in Russia since October 2011.
Link Publication list
Partner: Maurer Söhne
Contact: Dr. Felix Weber

Material development for friction based vibration control
An electrostatic tunable friction damper consists of two electrodes and a dielectric material which is placed on a structure which should be damped.
To optimise the damping effect this project is primarily concerned with the material development of a new dielectric material.
Contact: Rebekka Ginés
Distributed mitigation of wind-induced vibrations in long-span bridges
The past two decades has seen significant construction of long-span, cable supported bridges in many parts of Asia and Europe. The increase in the span length of the bridges has resulted in a remarkable decrease in their stiffness and natural frequencies. Due to low structural damping and relatively low mass, long-span bridges become very susceptible to vibrations caused by strong winds.
Contact: Dr. Glauco Feltrin
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