High-performance control systems (HPCSs) are sophisticated vibration mitigation strategies that include active, semi-active and hybrid systems. They generally outperform passive supplemental damping systems by relying on a feedback mechanism enabling adaptability, resulting in better control reachability over a wide excitation frequency bandwidth. HPCSs are therefore ideal for multi-hazard mitigation. However, the performance of these systems is highly dependent on the controller design, which requires appropriate tuning based on assumptions or on knowledge of dynamic parameters, long-term performance of sensors, excitations, etc. The quantification of performance based on possible uncertainties on such assumptions and/or knowledge could be a powerful tool in financially or technically justifying the use of an HPCS, or simply to benchmark the long-term performance of a given control algorithm. This paper investigates a methodology to assess the performance of control algorithms under various sources of uncertainties. To reduce the computational demand of the uncertainty quantification process, surrogate models are employed to map the nonlinear relationship between structural response and controller configurations. Long-term performance is quantified using life-cycle cost analysis. The investigation is conducted on a 39-story building, located in Boston (MA), and equipped with a set of semi-active friction devices. Results demonstrate that the proposed framework can be used to assess the performance of a given control algorithm considering various sources of uncertainties.
A novel semi-active damping device termed Variable Friction Cladding Connection (VFCC) has been previously proposed to leverage cladding systems for the mitigation of natural and man-made hazards. The VFCC is a semi-active friction damper that connects cladding elements to the structural system. The friction force is generated by sliding plates and varied using an actuator through a system of adjustable toggles. The dynamics of the device has been previously characterized in a laboratory environment. In this paper, the performance of the VFCC at mitigating non-simultaneous multi-hazard excitations that includes wind and seismic loads is investigated on a simulated benchmark building. Simulations consider the robustness with respect to some uncertainties, including the wear of the friction surfaces and sensor failure. The performance of the VFCC is compared against other connection strategies including traditional stiffness, passive viscous, and passive friction elements. Results show that the VFCC is robust and capable of outperforming passive systems for the mitigation of multiple hazards.
Stochastic subspace identification (SSID) is a first-order linear system identification technique enabling modal analysis through the time domain. Research in the field of structural health monitoring has demonstrated that SSID can be used to successfully retrieve modal properties, including modal damping ratios, using output-only measurements. In this paper, the utilization of SSID for indirectly retrieving structures’ stiffness matrix was investigated, through the study of a simply supported reinforced concrete beam subjected to dynamic loads. Hence, by introducing a physical model of the structure, a second-order identification method is achieved. The reconstruction is based on system condensation methods, which enables calculation of reduced order stiffness, damping, and mass matrices for the structural system. The methods compute the reduced order matrices directly from the modal properties, obtained through the use of SSID. Lastly, the reduced properties of the system are used to reconstruct the stiffness matrix of the beam. The proposed approach is first verified through numerical simulations and then validated using experimental data obtained from a full-scale reinforced concrete beam that experienced progressive damage. Results show that the SSID technique can be used to diagnose, locate, and quantify damage through the reconstruction of the stiffness matrix.
KEYWORDS: Control systems, Probability theory, Numerical simulations, Buildings, Systems modeling, Magnesium, Hazard analysis, Magnetic resonance imaging, Computer simulations, Seaborgium, Turbulence
High performance control systems (HPCS) are advanced damping systems capable of high damping performance over a
wide frequency bandwidth, ideal for mitigation of multi-hazards. They include active, semi-active, and hybrid damping
systems. However, HPCS are more expensive than typical passive mitigation systems, rely on power and hardware (e.g.,
sensors, actuators) to operate, and require maintenance. In this paper, a life cycle cost analysis (LCA) approach is proposed
to estimate the economic benefit these systems over the entire life of the structure. The novelty resides in the life cycle
cost analysis in the performance based design (PBD) tailored to multi-level wind hazards. This yields a probabilistic
performance-based design approach for HPCS. Numerical simulations are conducted on a building located in Boston,
MA. LCA are conducted for passive control systems and HPCS, and the concept of controller robustness is demonstrated.
Results highlight the promise of the proposed performance-based design procedure.
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