Monitoring and Control of Structural Vibrations

Monitoring and control of structural vibrations are crucial to ensure structural safety and vibration comfort of civil engineering structures, such as buildings, bridges, tunnels, antennas, stadia etc. [1,2]. Structures may vibrate due to earthquakes [3], wind [4], traffic [5], and pedestrians [6]. The associated loading models are needed to accurately describe the impacts of the different excitation mechanisms on the dynamics of civil structures. The resulting structural vibrations are often measured using accelerometers, as these sensors do not require a reference point, unlike, for example, displacement transducers. However, modern monitoring systems are enriched by displacement transducers, velocity sensors (geophones), strain gauges, etc., to directly measure the states of interest [7]. The classical approach is to wire the sensors with the data recorder and to activate the acquisition of the raw or slightly lowpass filtered data based on trigger levels. Another approach is to use the sensors as so-called nodes, where some of the post-processing is conducted, and the states of interest, rather than the raw data, are wirelessly sent from node to node and eventually to the data recorder to avoid wiring [8]. These sensor networks may be preferable when wiring is difficult and the states of interest are clear. The wiring of sensors should occur when the full information of the sensor signals is of interest. In a subsequent step, the analysis of the measurement data in terms of amplitudes and frequencies or model updating techniques to identify structural parameters may be used for the model-based design of structural dampers, isolators, and vibration compensators, as well as for structural health monitoring [9,10]. This complements the further development of hydraulic and steel hysteretic dampers, curved surface sliders and lead rubber bearings, and tuned mass dampers [11,12]. These vibration dampers, isolators, and compensators can be passive, semi-active, or active, of which, the semi-active solutions combine the advantages of enhancing the resulting vibration reduction and requiring less power [13]. In the fields of measurement data analysis and structural health monitoring, the goal is to derive a digital twin of the structure to predict or estimate fatigue and damage [14].

This Special Issue presents current research in these fields. Structural vibration monitoring is addressed by Gadiraju et al., who describe a holistic modular structural health monitoring system for bridges. Amarantidou et al. investigate the strengthening of existing masonry structures against seismic excitation, considering soil–structure interaction, which is a realistic situation for many existing buildings. The research of Kodakkal et al. focuses on the question of how the modelling approach of tall buildings under wind excitation influences the prediction of the resulting storey accelerations, which is crucial for deciding whether a tuned mass damper is needed. In the contribution of Hogsberg, the tuning and efficacy of a tuned mass damper with an inerter is discussed, to better understand the impact of the inerter on the dynamics of the damper. Wang et al. analyse the loading of long-span bridges due to congested traffic using a probabilistic modelling approach, to take into consideration the random nature of this type of excitation. The semi-active tuned mass damper based on a real-time controlled semi-active damper, presented by Maslanka, is a further development of the semi-active tuned mass dampers of the Volgograd Bridge and represents the optimum solution of this semi-active control approach.

This Special Issue is enriched by two review articles. Dharmajan and Al Hamaydeh review the behaviour of steel–concrete composite structures under seismic loading conditions, and Katsimpini et al. provide a general overview of the state of art of structural control systems and identify gaps for future research.

After approximately two years, the Special Issue on “Vibration Monitoring and Control of the Built Environment” is now closed. It contributes to the documentation of recent advances in the fields of vibration monitoring and control and may motivate further research and development.