The current trend toward lighter and slender pedestrian structures, with new aesthetic requirements and high-performance materials, has resulted in structures with increased susceptibility to vibration. Notable vibrations under human-induced excitations might appear, and the vibration serviceability requirements might not be accomplished. The Valladolid Science Museum Footbridge (Spain) is an example of a lively structure that might achieve excessive vertical acceleration under walking or running excitation. The control of excessive footbridge vibrations via passive and active devices is dealt with in this work. More specifically, this paper is concerned with the design and experimental implementation of a passive tuned mass damper (TMD) and an active mass damper (AMD) to mitigate human-induced vibrations on this in-service footbridge. The TMD, with a mass ratio of 1%, is designed by a numerical method based on H_∞ controllers. The AMD consists of a proof-mass actuator, with a mass ratio of approximately 0.2%, controlled by a strategy based on acceleration feedback with a phase-lag network. The performance of both devices has been assessed. Copyright © 2011 John Wiley & Sons, Ltd.

This paper presents the design, development and testing of a low-cost Structural Health Monitoring (SHM) system based on MEMS (Micro Electro-Mechanical Systems) triaxial accelerometers. A new control system composed by a myRIO platform, managed by specific LabVIEW software, has been developed. The LabVIEW software also computes the frequency response functions for the subsequent modal analysis. The proposed SHM system was validated by comparing the data measured by this set-up with a conventional SHM system based on piezoelectric accelerometers. After carrying out some validation tests, a high correlation can be appreciated in the behavior of both systems, being possible to conclude that the proposed system is sufficiently accurate and sensitive for operative purposes, apart from being significantly more affordable than the traditional one.