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The lack of aerodynamic damping of wind turbine blades in the edgewise direction causes larger dynamic responses and lowers the reliability. As blades become longer, edgewise fatigue loading increases rapidly. To mitigate the blade edgewise vibration, structural control techniques using a tuned mass damper (TMD) are applied in this paper. The “TMD” module in FASTv8 was upgraded to enable the high-fidelity simulation of structural control of the blade response. With the developed tool, the optimal parameters and generalized design formulas were established through a parametric study. Also, the control effect of the optimal blade-TMD on reducing fatigue and extreme loads of two different multi-megawatts turbine blades is investigated. Fully-coupled non-linear time marching simulations were conducted by running key design load cases (DLCs) with site-specific meteorological conditions. The results provide insight into the potential benefits and impacts of passive structural control to reduce the fatigue and extreme loads of turbine blades.

The structural concept of the dome dates back to the Pantheon in Rome. It is used as the cover of many churches and mosques all around the world. Light solutions, with a well-visible dome-shaped truss skeleton, are often preferred in modern architecture. Base isolation techniques can be adopted to mitigate the seismic effects. This paper aims to investigate the efficiency of different designs for the truss skeleton. To solve the problem, one has to assign the constraints, the materials and the geometry of the dome, its supporting structure and the isolation devices (number, locations, and type). The screening of the effects of different scheme assumptions on structural behaviour provides a better insight into the problem.

A multi-objective tuning framework for optimizing Tuned Mass Damper (TMD) systems is presented. This framework optimizes the controlling parameters of TMDs while considering building resilience. The employed optimizer is the multi-objective HBA. Since TMDs are used in tall structures to mitigate seismic-induced structural responses, the proposed framework must be applicable to real-world scenarios; therefore, it determines both the placement and parameters of TMDs by accounting for the effects of various soil types and multiple earthquake records. Based on the obtained results, the optimal TMDs achieved an average roof-displacement reduction of 17% in soft soil, 7% in fixed-base conditions, and only 4% in dense soil, highlighting the decisive influence of soil–structure interaction on system efficiency. Moreover, there was considerable outcome variability across different earthquake records—ranging from 0.8% to 26% reduction—along with the observed negative effect (response amplification of up to 13.9% in certain fixed-base cases), which occurs when the TMD becomes detuned relative to the dominant frequency of the specific ground motion. This confirms the necessity for a robust design approach that simultaneously considers an ensemble of ground motions rather than optimizing for a single record.

Summary Structures today may be equipped with passive structural control devices to achieve some performance criteria. The optimal design of these passive control devices, whether via a formal optimization algorithm or a response surface parameter study, requires multiple solutions of the dynamic response of that structure, incurring a significant computational cost for complex structures. These passive control elements are typically point‐located, introducing a local change (possibly nonlinear, possibly uncertain) that affects the global behavior of the rest of the structure. When the structure, other than these localized devices, is linear and deterministic, conventional solvers (e.g., Runge–Kutta, MATLAB's ode45, etc.) ignore the localized nature of the passive control elements. The methodology applied in this paper exploits the locality of the uncertain and/or nonlinear passive control element(s) by exactly converting the form of the dynamics of the high‐order structural model to a low‐dimensional Volterra integral equation. Design optimization for parameters and placement of linear and nonlinear passive dampers, tuned mass dampers, and their combination, as well as their design‐under‐uncertainty for a benchmark cable‐stayed bridge, is performed using this approach. For the examples considered herein, the proposed method achieves a two‐orders‐of‐magnitude gain in computational efficiency compared with a conventional method of comparable accuracy. Copyright © 2016 John Wiley & Sons, Ltd.

SUMMARY Seismic isolation is an appreciable control strategy that reduces the vibrations of structural and nonstructural systems induced by strong ground motions. However, under near‐fault (NF) ground motion, the seismic isolation devices might perform poorly because of large isolator displacements caused by long‐period large velocity and displacement pulses associated with such strong motion. The objective of this paper is to assess the effectiveness of a new seismic isolation device, referred to as roll‐in‐cage (RNC) isolator, in protecting against NF ground motions. The device is intended to achieve a balance in controlling isolator displacement demands and structural accelerations. The RNC isolator provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability, and energy dissipation characteristics. Moreover, it is distinguished from other isolation devices by two unique features: (i) it has a built‐in energy‐absorbing buffer to limit the design displacement under strong excitation, and (ii) it has a built‐in linear recentering mechanism that prevents residual displacement after earthquakes. The seismic response of multistory buildings isolated by the RNC isolator is investigated under three recorded NF earthquakes and three synthetic ground motions. The results show that the RNC isolator is a convenient isolation system in protecting against NF earthquakes. Copyright © 2013 John Wiley & Sons, Ltd.

Stay cables exhibit both great slenderness and low damping, which make them sensitive to resonant phenomena induced by the dynamic character of external actions. Furthermore, for these same reasons, their modal properties may vary significantly while in service due to the modification of the operational and environmental conditions. In order to cope with these two limitations, passive damping devices are usually installed at these structural systems. Robust design methods are thus mandatory in order to ensure the adequate behavior of the stay cables without compromising the budget of the passive control systems. To this end, a motion-based design method under uncertainty conditions is proposed and further implemented in this paper. In particular, the proposal focuses on the robust design of different passive damping devices when they are employed to control the response of stay cables under wind-induced vibrations. The proposed method transforms the design problem into a constrained multi-objective optimization problem, where the objective function is defined in terms of the characteristic parameters of the passive damping device, together with an inequality constraint aimed at guaranteeing the serviceability limit state of the structure. The performance of the proposed method was validated via its application to a benchmark structure with vibratory problems: The longest stay cable of the Alamillo bridge (Seville, Spain) was adopted for this purpose. Three different passive damping devices are considered herein, namely: (i) viscous; (ii) elastomeric; and (iii) frictions dampers. The results obtained by the proposed approach are analyzed and further compared with those provided by a conventional method adopted in the Standards. This comparison illustrates how the newly proposed method allows reduction of the cost of the three types of passive damping devices considered in this study without compromising the performance of the structure.

Background Eddy current damper (ECD) pledges better control over damping coefficient, provides contactless damping, requires little or no maintenance, has simpler construction, no performance degradation over time, and is cost-effective as compared to mechanical dampers. Its challenge includes the development of a system which provides comparable damping density to other mechanical systems for structural applications. Purpose ECD has the potential to protect common structures in seismically active areas at low cost and with better vibration control. Further, the application of such dampers may protect industrial assembly structures against undesirable fatigue and increase the lifespan of structures that are constantly prone to vibrations. Methods This paper produces a review of existing literature in vibration control of structures equipped with ECDs, types of ECDs developed for structural applications, SDOF (single degree of freedom) benchmark structure equipped with ECD, challenges, and opportunities in the development of ECD therein.

SUMMARYA methodology is developed for the design of optimum viscous fluid passive energy dissipation systems using pole assignment active control algorithm. In this method, the procedure to assign the new structural poles is slightly modified such that the resulting structural properties (i.e., the optimum locations of system poles) can be achieved merely by modification of structural stiffness and addition of a passive control system. A combination of stiffness reduction and increase of damping is utilized to reduce both acceleration and displacement response. It is shown that the control systems designed using this method provide structural performances slightly better than or close to those of ordinarily designed optimum passive systems. Furthermore, by an educated selection of the locations of the structural poles, the proposed method provides more versatility in the design of passive control systems. Copyright © 2013 John Wiley & Sons, Ltd.

Glazing facades are widely used in building structures, due to a series of aesthetic, thermal, lightening aspects. From a structural point of view, under the action of exceptional loads as impacts, explosions, seismic events or hazards in general, the glazing envelopes often represent the critical component for multi-storey buildings, due to the typically brittle behaviour and limited tensile resistance of the glass panes, hence requiring specific, fail-safe design concepts. In this paper, the feasibility and potential of special mechanical connectors interposed at the interface between a given multi-storey primary building structure and the glazing facade are investigated via accurate finite-element numerical models, under various impact scenarios. As shown, the final result is an assembled structural system in which the facade can work as passive control system for the primary structure, in the form of a distributed tuned-mass damper (TMD).

Multi-level Pipe Damper (MPD) recently proposed by the authors is a passive control device to reduce the seismic vibration. In this research, seismic response of steel structures equipped with MPD is studied. To evaluate the effects of the proposed damper, typical 5, 10 and 15-story steel buildings are modeled and their seismic responses under seven earthquake excitations are investigated using dynamic nonlinear time-history analyses by SAP2000 program. Results show the effectiveness of MPD to altering the seismic response of the structures such that maximum displacement reduced by average of 54, 52, and 19% and maximum roof acceleration decreased by average of 16, 14, and 11% compared to those of the bare frames for the 5, 10 and 15-story buildings respectively. Moreover, using MPD decreases the structural and nonstructural damages noticeably by limiting the inter story drifts because of the secondary hardening branch of force-displacement by average of 53, 54, and 11% for the 5, 10 and 15-story buildings respectively proving the effectiveness of the proposed damper as a retrofitting technique for structures at high seismic risk areas.