Frédéric Bossens

Active Tendon Control of Large Trusses

The use of tension cables to stiffen and control precision trusses as needed for future interferometric missions is investigated. A strategy for damping cable structures with active tendons is presented. Each tendon consists of a displacement actuator (piezoelectric in this case) collocated with a force sensor; the local control law consists of an integral force feedback, which has guaranteed stability if we assume perfect actuator and sensor dynamics. Then an approximate linear theory that allows one to predict the closed-loop poles of a cable structure with a root locus technique is developed; the methodology is applied numerically to a model of the Jet Propulsion Laboratory Micro-Precision Interferometer. Finally, a laboratory experiment on a guyed truss with three active tendons is described, and the experimental results are compared with the numerical predictions.

Active damping and flutter control of cable-stayed bridges

Abstract This paper presents a strategy for active damping of structures with guyed cables connected to active tendons; the control algorithm has guaranteed stability, including at the parametric resonance. The theoretical results are confirmed by experiments. The strategy is applied to the flutter control of cable-stayed bridges.

Active Tendon Control of Vibration of Truss Structures: Theory and Experiments

This paper proposes a strategy for the active damping of cable structures, using active tendons. The first part of the paper summarizes the theoretical background: the control law is first briefly presented and the main results of an approximate linear theory which allows to predict the closed-loop poles with a root-locus technique are mentioned. The second part of the paper reports on experimental results obtained with two truss structures representative of future space applications. Finally, the behaviour of the control system for microvibrations is investigated.

Active tendon control of cable-stayed bridges

This paper presents a strategy for active damping of cable structures, using active tendons. The first part of the paper summarizes the theoretical background: the control law is briefly presented together with the main results of an approximate linear theory which allows to predict the closed- loop poles with a root locus technique. The second part of the paper reports on experimental results obtained with two test structures: the first one is a small size mock-up representative of a cable-stayed bridge during the construction phase. The control of the parametric vibration of passive cables due to deck vibration is demonstrated. The second one is a 30 m long mock-up built on the reaction wall of the ELSA test facility at the JRC Ispra (Italy); this test structure is used to demonstrate the practical implementation of the control strategy with hydraulic actuators.

Active Control of Cable-Stayed Bridges: Large-Scale Experiments

Abstract After a brief review of the strategy for damping cable-structures with active tendons, the paper presents a large-scale experiment installed at the EL SA Laboratory of the JRC-Ispra. The test-bed is a model of cable-stayed bridge during its construction phase, equipped with hydraulic actuators on the two longest stay-cables. The design of the actuator is briefly outlined. The results of several active damping experiments are presented; they demonstrate clearly the efficiency of the active damping system.

Application of Active Tendons to the Damping of Aerospace and Civil Engineering Structures

In recent years, cable structures have had spectacular applications in large cable-stayed bridges. However, cable and deck vibrations have become a major design issue, because the ever increasing span of the bridges makes them more sensitive to flutter instability as well as to wind and traffic induced vibrations. This justifies the development of active damping devices for future large bridges.