Response Control Of Structures Research Articles

Experimental investigation of the effective parameters on the lead extrusion damper performance

Lead extrusion dampers (LED) are employed for seismic response control of various structures due to their advantages over other energy-dissipative devices. However, a reliable design algorithm and an optimization process are essential to ensure optimal performance within the host structural system. Thus, the influence of device parameters on the damper behavior must be clearly understood. In the first part of this comprehensive study, the effect of different parameters on the LED performance was experimentally investigated. To this end, 23 specimens with different prestressing levels, bulge-to-shaft diameter ratios, shaft-to-bulge transition zone geometries, and device length ratios were cyclically tested under varying displacement amplitudes, i.e., 5 mm, 10 mm, and 20 mm, and loading rates, 0.5 mm/s, 1.0 mm/s, and 2.0 mm/s. Subsequently, they were exposed to a ramp-type loading up to the amplified design displacement. After satisfactorily completing the experimental tests, the behavior of the LEDs was compared in terms of their hysteretic behavior, energy dissipation capacities, temperature change, and stable behavior. It was concluded that the most influential parameters on the LED behavior were the bulge-to-shaft diameter ratio and the prestressing level on the lead. In addition to its effects on improving the hysteretic behavior, having a smooth shaft-to-bulge transition zone geometry was essential to guarantee a stable damper behavior.

Performance Evaluation and Comparative Analyses of Tuned Inerter Damper for Stochastic Base Excited Structures Based on Hybrid H2/H∞ Optimization

Compared with tuned mass damper, tuned inerter damper (TID) has higher damping efficiency and lightweight characteristic if appropriate optimal methods are selected. Generally, [Formula: see text] or [Formula: see text] optimal methods are adopted to determine the optimal parameters of TID individually. But the vibration mitigation performance of the TID under near resonance frequency band based on [Formula: see text] optimization is less than [Formula: see text] optimization, but the peak frequency response based on [Formula: see text] optimization will be greater than [Formula: see text] optimization at the same time. Dual-characteristic-based vibration control may not be achievable based on [Formula: see text] or [Formula: see text] criteria, respectively. For this reason, hybrid [Formula: see text] optimization can be adopted. In this work, closed-form expressions are derived for the control of structural displacement responses based on hybrid [Formula: see text] optimal method. The vibration mitigation performance of the different optimized TIDs is evaluated considering the single-degree-of-freedom and multi-degrees-of-freedom systems are subjected to typical ground motions excitation. Results illustrate that because of the use of the optimal stiffness ratio of [Formula: see text] optimization and very close value of [Formula: see text] optimizations’ nominal damping ratio in [Formula: see text] optimization, [Formula: see text] optimization shows ‘dual characteristics’ in different excitation situations. Specifically, the peak response and structural fundamental frequencies’ response in displacement frequency response function using hybrid [Formula: see text] optimal methods are between [Formula: see text] and [Formula: see text] optimization, which indicates an excellent and balanced control performance combining the advantages of [Formula: see text] and [Formula: see text] optimal solutions. Hence, this hybrid method is more suitable for more complex ground motions excitation to control critical structural responses instead of single characteristic excitation. And the comprehensive vibration control in dynamic time histories analyses can be achieved by this dual characteristic-based optimal strategy. When designing the specific TID, hybrid [Formula: see text] optimization can be considered as the best choice for its compatibility and high adaptability for complex practical engineering scenarios with random and diverse excitations.

Investigating Large-Scale Tuned Liquid Dampers through Real-Time Hybrid Simulations

As buildings become taller and slenderer, managing their vibrational response and mitigating it pose significant challenges in design. Tuned liquid dampers (TLDs) are liquid (usually water)-filled tanks that can mitigate structural vibrations by leveraging the sloshing motion of the contained fluid. However, the dynamic behavior of TLDs and their interaction with structures is complex. While most research on TLDs has focused on mitigating wind-induced vibrations, less attention has been paid to their seismic control of structural responses. Moreover, existing literature on the experimental research involving TLDs mostly pertains to small-scale models. This study aims to experimentally explore the effectiveness of large-scale TLDs in mitigating vibrations in both linear and nonlinear structures under seismic loads. A real-time hybrid simulation is employed as the experimental method, where only the TLD is physically constructed and tested, while the rest of the system is simulated numerically in a coupled manner, allowing for obtaining the dynamic response of the structure equipped with the TLD in real time. This approach offers the flexibility to significantly scale up the TLD size for physical testing while exploring various TLD-structure scenarios by numerically adjusting the structural properties within the simulation.

Seismic response control of large-span suspend-dome structures using multidimensional isolation systems

Three isolation strategies have been developed for seismic response control of suspend-domes: bidirectional isolation, bidirectional isolation with additional restrainers, and three-dimensional (3D) isolation. The first and second control strategies use pendulum sliding isolation bearings (PSIBs) and shape memory alloy (SMA)-restrained PSIBs (SPSIBs), respectively, as high-position bearings to support the roof of a structure. The third strategy uses of prepressed spring bearings with additional dampers and SPSIBs with slack SMA strands to form a vertical isolation layer at the roof support and a horizontal isolation layer at the base of the substructure. This paper describes the configurations, working mechanisms, and numerical simulations of these isolation systems in detail and presents their parameter design based on the related design objectives of a prototype suspend-dome structure. In this study, an extensive numerical modeling investigation was performed on isolated and non-isolated suspend-domes to examine the feasibility and effectiveness of the seismic control systems. The results showed that the segmental 3D isolation system provides superior seismic protection performance for the target suspend-dome compared with the bidirectional isolation systems, although the former involves a complex design, modeling, and construction.

Deep reinforcement learning‐based active mass driver decoupled control framework considering control–structure interaction effects

AbstractControl–structure interaction (CSI) plays a significant role in active control systems. Popular methods incorporate actuator dynamics into an integrated control system to account for CSI, leading to a situation where existing structural control algorithms that ignore CSI cannot be applied directly. To address this issue, this study proposes a deep reinforcement learning (DRL) based active mass driver (AMD) decoupled control framework, in which a structural control algorithm is employed to generate the control force command without consideration of CSI, while a DRL agent is utilized to attenuate the CSI effects of AMD systems and achieve a desired control force. The DRL‐based AMD control framework is verified through a series of numerical experiments. Furthermore, the applicability of the control framework is confirmed in a wind‐excited 76‐story benchmark building. Comprehensive analysis indicates that the proposed control framework can effectively eliminate the CSI effects and apply accurate control force to the structure in various scenarios, which allows for an ideal structural response control.

Experimental and numerical investigations of a novel parallel double-stage crawler-track-shaped shear damper

In this study, a novel parallel double-stage crawler-track-shaped shear damper (PDCSD) was developed, which is fabricated using thin-walled steel plates. An asynchronized double-stage working mechanism was achieved based on the parallel energy dissipation (inner and outer crawler-track-shaped steel plates), restraining (upper and lower restraining plates), and load transfer (outer and inner blockers with initial clearance) systems. Accordingly, theoretical equations for the skeleton curve of the PDCSD and the design load for the load transfer system were proposed. The double-stage working mechanism and performance of the PDCSD were verified based on full-scale seismic and fatigue performance tests. Subsequently, based on refined finite element analyze, the working mechanism of the PDCSD was revealed and the theoretical equations were validated. A simplified model of the PDCSD with an emphasize on the hysteretic behavior was conclusively recommended and validated against the test and simulation results obtained from the refined numerical models, providing an accurate and efficient approach for the seismic response control of structures equipped with PDCSDs.

Experimental study on open core hybrid buckling restrained braces with different debonding layer geometries

AbstractThis study evaluates performances of newly developed open core hybrid buckling restrained braces (OC‐HyBRB) with debonding layers of two geometries. OC‐HyBRB has an axial load‐carrying steel core, two steel restrainers and two 3‐mm‐thick highly deformable rubber debonding layers. Debonding layer is continuous in first specimen and discontinuous in second specimen. OC‐HyBRB is designed to dissipate energy at lower strain levels through shear deformation of debonding layers. However, restrained local buckling of core first about weak axis and then about strong axis after threshold axial strain (∼2%) contributes to energy dissipation at higher strain levels. Thus, OC‐HyBRB is capable of dissipating energy in a wide range of core strain levels. Both types of OC‐HyBRBs are investigated using a specially designed test setup under a cyclic loading protocol, applied using a servo‐hydraulic actuator. Experimental force‐displacement hysteretic behaviour are found to be stable for both the specimens with enhanced stiffness at higher axial strain. This would reduce the residual deformation of the OC‐HyBRB. Thus, newly developed OC‐HyBRB would provide a simple yet efficient energy‐dissipation device for seismic response control of structures.

Bi-directional semi-active tuned mass damper for torsional asymmetric structural seismic response control

Tuned mass damper (TMD) is a popular vibration absorber. To improve the seismic protection performance of a bi-directional passive TMD, a bi-directional semi-active TMD (BSTMD) with adaptive stiffness, variable mass and semi-active damping is proposed in this study. The BSTMD can adapt to structural X- and Y-directional instantaneous frequencies at the same time under bi-directional ground motions, which are identified through wavelet transform (WT), and the instantaneous angle of a diamond spring device is adjusted according to the instantaneous frequency ratio of two directions, which means that the stiffness ratio of two directions is retuned first. Then, the mass is retuned to match the exact instantaneous frequency. At last, the semi-active damping is realized according to an extended output signals-based control algorithm. A two-directional asymmetric torsional benchmark model is proposed as a case study. For comparison, two optimal passive TMDs implemented in X and Y directions separately and two unidirectional STMDs with variable stiffness and damping implemented in X and Y directions separately are investigated as well. Numerical results show that under bi-directional earthquake excitations in the benchmark problem, the two optimal passive TMDs have a good control effect. Two unidirectional STMDs have the best aseismic mitigation effect generally, in both lateral and torsional dynamic responses; while the BSTMD has a comparable control effect with less electromechanical devices, and can reduce the stroke of unidirectional STMD to a great degree. Though the BSTMD is aimed at X- and Y- directional dynamic responses, it can control torsional responses effectively as well, and when the eccentricity is enlarged to double, it remains effective for seismic mitigation.

Seismic response control of core wall structures using tuned viscous mass damper (TVMD) outriggers

This paper presents research on the seismic response control of core wall structures through the installation of innovative damped outriggers known as tuned viscous mass damper (TVMD) outriggers. In this novel system, the TVMDs are arranged vertically between the outrigger trusses/beams and perimeter columns. A simplified model based on the distributed-parameter system was developed to represent a core wall structure equipped with TVMD outriggers. The dynamic properties and seismic responses of high-rise buildings were calculated through a dynamic analysis of the simplified model in MATLAB. The results indicate that TVMD outriggers designed by using fixed-point theory not only suppress the dynamic responses for the target tuning mode, but also supplement additional damping to lower-order modes. When tuned to the second mode, TVMD outriggers with a mass ratio of 0.1 reduce the maximum inter-story drift and floor acceleration responses by 23.48% and 35.80%, respectively. In addition, the control advantages of TVMD outriggers were demonstrated through energy dissipation analysis and damper force decomposition. The vibration control performance of multiple TVMD outriggers was also investigated and was found to achieve superior seismic control with a significantly reduced demand on the TVMD parameters.

Active Global Vibration Control of Helicopter Fuselage

Active control of structural response (ACSR) has been widely used to suppress helicopter fuselage vibration due to its advantages. However, ACSR, by taking the vibration responses at target measurement points as the active control objective, is a local vibration control method for the fuselage. In this paper, an active global vibration control (AGVC) method for the fuselage by taking the vibratory loads transmitting to the fuselage through gearbox struts as the active control objective is proposed. By installing piezoelectric stack actuators on a gearbox strut, the active strut is formed and its electromechanical coupling equation of motion is derived. The AGVC model, algorithm, convergence, and system for a dynamically similar frame structure of a helicopter fuselage are presented. The simulation results indicate that AGVC can suppress the global vibration of the fuselage under the excitation of the rotor vibratory loads more effectively with faster convergence speed than ACSR. The vibration at the target measurement points in ACSR can be effectively reduced, but the control effect at other positions is not satisfied, and even the vibration at some positions is larger than that in control off.

A Novel Active Vibration Control Method for Helicopter Fuselages Based on Diffusion Cooperation

Against the background of low-frequency vibration control for a helicopter fuselage in flight, active control of structural response (ACSR) has been employed for vibration control design. With the increase in control positions in the fuselage, more actuators and error sensors are needed to meet the vibration reduction requirements, forming a large-scale multichannel system. This leads to a rapid increase in the computation amount, causing the control performance of the conventional centralized algorithm main processor to become poor under overload operation. To this end, a novel distributed active vibration control algorithm based on the diffusion cooperative strategy was proposed and explored in this research. The diffusion cooperative strategy is widely used in complex wireless sensor network (WSN) systems to efficiently reduce the computation amount during data aggregation. This distributed algorithm utilizes the advantages of the diffusion-cooperative strategy to reduce the computation amount and coupling relationship of the secondary path in a large-scale multichannel system. First, a novel control law was established by introducing the network topology of the diffusion cooperation strategy into the classical filtered-x least mean square (FxLMS) algorithm, forming the diffusion FxLMS (DFxLMS) algorithm. Then, a secondary path trade-off quantization standard based on the complex undirected network connectivity condition was developed. It determined whether a secondary path was discarded or not and formed the topology of a large-scale multichannel system control network. To examine the effectiveness and superiority of the proposed DFxLMS algorithm, a comparative simulation with a scale of 1 × 10 × 10 was carried out for a simplified helicopter fuselage. Numerical results in realistic scenarios showed the ability of the DFxLMS algorithms to achieve good control performance when proper values of these parameters are chosen.

A novel bi-directional rail variable friction pendulum-tuned mass damper (BRVFP-TMD)

The shape of hysteretic loops for a friction pendulum system transforms when excited by bi-directional motion, which exhibits unexpected dynamic behavior compared with unidirectional motion. Therefore, a novel bidirectional rail variable friction pendulum-tuned mass damper (BRVFP-TMD) with two independent rails that satisfied the purpose of bidirectional structural response control and provided a full bidirectional friction force was proposed. The variable friction arrangement was applied to the rails so that the BRVFP-TMD could be accomplished with a linear hysteretic damping property that is contributed by the displacement-dependent variable friction force. Using unidirectional harmonic excitations with attack angle as bi-directional loading, illustrations were created to investigate the control effect of traditional pendulum friction TMDs with a spherical sliding surface. This demonstrated the collapse of hysteretic loops of traditional pendulum friction TMDs and superiority of BRVFP-TMD in terms of mechanism. For the BRVFP-TMD with a lightly damped structure, the optimizations of the fixed-point theory were accessed to obtain the closed-form solutions of the optimal parameters of the BRVFP-TMD. Numerical verifications based on bidirectional motions were conducted to evaluate the performance of the BRVFP-TMD. The bidirectional earthquake results indicated stable and excellent performance of the BRVFP-TMD in terms of either frequency response reduction or friction energy dissipation efficiency. Meanwhile, bidirectional wind-induced vibrations confirmed the correctness of the optimization and the stable robustness of the optimized BRVFP-TMD.

Development of a double-stage-yield dissipative beam-to-column joint: Experimental study and application for structural response control

Energy-dissipative beam-to-column joints are an effective method for improving the seismic performance of precast concrete (PC) frame structures. The development of double-stage-yield dampers is a new trend for realizing the comprehensive response control of structures under different levels of earthquakes. However, dissipative beam-to-column joints with double-stage-yield behaviors have rarely been investigated. In this study, a novel double-stage-yield dry-connected beam-to-column joint (DDBJ) is developed by combining a rotational friction damper and buckling-restrained slitted steel plates. First, experimental investigations were conducted, and the working mechanism and theoretical equations of the DDBJ were verified. Subsequently, a numerical simulation method for DDBJ was proposed based on OpenSees, which was proven to be capable of efficiently capturing the double-stage-yield behavior of DDBJ and was suitable for the response assessment of PC frames with DDBJ. Based on this method, the control effect of the DDBJ on the seismic responses of the PC frame was conclusively identified through a numerical comparison between a six-story reinforced concrete frame, a PC frame using single-stage-yield dissipative beam-to-column joints, and a PC frame using DDBJs, emphasizing the effects under four levels of earthquakes. The research outcomes of this study could provide new strategies for the seismic response control of PC frame structures.

Performance and efficiency oriented optimal design of tuned inerter damper for seismic response control of building structures

Characterized by mass and damping enhancement effects, inerter-based dampers (IBDs) have recently been applied in structural vibration control as efficient vibration control devices. Prior studies have demonstrated the applicability of IBDs in various control objects, where two typical IBDs, the tuned viscous mass damper, and tuned inerter damper (TID), are considered. Research has proposed optimization procedures to determine the design parameters of IBDs, and most of the optimization objects are indices related to the magnitude or mitigation ratio of the structural response. This study investigates the damping enhancement and optimal design from the equivalent damping ratio supplied by the TID because the supplemental equivalent damping ratio (SEDR) is commonly utilized in the design of energy dissipation devices. Based on the indices related to the SEDR and the installation position of the TID, the control performance and damping enhancement effect are investigated. Two closed-form solutions for the optimal parameters are developed to achieve the best control performance and highest damping enhancement effect. The proposed optimization methods are verified by a time history analysis of single- and multi-degree-of-freedom structures. In addition, the proposed methods are compared with conventional optimization approaches based on a fixed-point strategy. When the mass ratio was less than 20%, the TID optimized by the proposed method achieved a similar control performance but a better damping enhancement effect compared with those by the conventional optimization approaches. Installing the TID in the story with the largest interstory drift improved the deformation uniformity of the primary structure and achieved a better damping enhancement effect.

Improved Three-Variable Control for Electromagnetic Mass Damper System Considering Control–Structure Interaction

Current methods account for control–structure interaction (CSI) in structural control design, which may be unavailable in the preliminary design phase of actively controlled structures due to the unknown dynamic characteristic of an actuator. Therefore, it may result in significant difference in the design and evaluation of an active structural control system when ignoring or considering CSI at different phases. To eliminate the CSI effects of electromagnetic mass damper (EMD) system and thus decouple the tracking control of EMD from the control design of structure, in this paper, an improved three-variable control (ITVC) combining a signal convertor, a typical three-variable controller, and a voltage compensator is developed. The voltage compensator counteracts the influence of lower-order CSI including viscous damping force and Coulomb friction. The three-variable controller reduces the higher-order CSI effects, while the signal convertor converts all command and feedback signals to the relative coordinate system and eliminates the additional CSI effects. Performance tests and frequency response tests of the EMD system show that the CSI effects are basically eliminated by ITVC. In addition, shake table tests are performed on a one-story actively controlled structure to further verify ITVC. Experimental results suggest that ITVC can apply accurate control force on the structure and achieve ideal structural response control.

Seismic performance of an assembled self-centering buckling-restrained brace with controllable initial stiffness

An innovative assembled self-centering buckling-restrained brace (ASC-BRB) with controllable initial stiffness is introduced. The brace consists of a self-centering system and an energy dissipation system. Unlike existing post-tensioned self-centering energy dissipation braces, whose initial stiffness has high uncertainty and is sensitive to machining errors, the proposed ASC-BRB can obtain highly controllable initial stiffness because of its unique working mechanism. Therefore, structural seismic response uncertainties can be reduced significantly. The configuration, working mechanism, and theoretical restoring force model of the ASC-BRB are first presented. Quasi-static tests are then conducted to examine the feasibility of the brace, and typical flag-shaped hysteretic behavior and stable energy dissipation capability are observed. The main components of the ASC-BRB keep intact after repeated loadings, except for the core plates, which are damaged; however, the core plates can be easily replaced. This observation highlights the superiority of the ASC-BRB in terms of damage concentration and high recoverability. The proposed theoretical restoring force model can accurately predict the hysteretic response of the brace, especially for the initial stiffness, with the predicted value being within 5 % of the experimental value. A simplified numerical model is developed and used in a parametric study conducted to examine the effects of two key design parameters on the brace behavior. Furthermore, the effect of machining errors on the initial stiffness of the ASC-BRB is studied. An analysis of steel frames with ASC-BRBs indicates that the ASC-BRB can effectively reduce the residual inter-story drift and help achieve a peak floor acceleration response comparable to that of the frame with BRBs. However, the peak inter-story drift is amplified owing to the lower initial stiffness of the proposed brace. On the basis of a system-level parametric analysis, recommended optimized design parameters of the ASC-BRB are presented to facilitate efficient control of structural seismic responses.

Nonlinear gas-spring DVA for seismic response control: Experiment and numerical simulation

A gas-spring with adjustable nonlinear capacity is introduced into a conventional linear dynamic vibration absorber (DVA), thus forming a nonlinear gas-spring dynamic vibration absorber for structural seismic response control, which is a nonlinear energy sink with a fundamental tuning function. The mechanical properties of the symmetrical combined gas-spring system are studied first by theoretical analysis and model tests. A series of shaking table tests are designed and conducted to systematically investigate the control effect and nonlinear damping mechanism of the gas-spring DVA for a 5-story structure. A numerical model of the nonlinear gas-spring DVA attached to the structure is established and validated by the experimental results. The experimental results show that the proposed nonlinear gas-spring DVA can effectively mitigate the structural dynamic responses and has a wide damping bandwidth with good stability. The presented system has amplitude-frequency characteristics, and the sensitivity of its control performance to amplitude is significantly reduced by introducing a fundamental tuning mechanism. The nonlinear DVA vibrates in a broadband mode and is capable of resonating with the structure at multiple frequencies so that the nonlinear restoring force of the gas-spring DVA redistributes the structure’s vibration energy from its low-order modes to high-order modes. Compared with the optimum tuning DVA, the reasonably designed nonlinear gas-spring DVA has a similar control effect and shorter working stroke, possessing the advantage of flexible parameter configuration capabilities. Moreover, the experimental and numerical simulation results are in good agreement, indicating that the proposed numerical model is accurate in predicting the behaviors of the nonlinear gas-spring DVA.

A composite control scheme for electromagnetic active mass damper against control-structure-interaction effects

Existing methods account for control-structure-interaction (CSI) in structural control design. However, their implementations may be challenging since the dynamic characteristics of actuator are unavailable in the preliminary design phase of actively controlled structures. In this study, a composite control scheme (CCS) is proposed to eliminate the CSI effects of electromagnetic active mass damper (AMD), and thus decouple the tracking control of AMD from the control design of structure. In the CCS, force compensation is performed to counteract the influence of lower-order CSI including the damping force and friction, while hierarchical control comprised of low-level feed-forward/feedback control and high-level sliding mode control is designed to reduce the higher-order CSI effect and achieve a high-performance force control. Performance tests and frequency response tests of the electromagnetic AMD system indicate that the CSI effects are significantly reduced by the proposed CCS. Furthermore, shake table tests are conducted on a two-story actively controlled structure to verify the effectiveness of CCS. Experimental results show that the proposed CCS can apply accurate control force to the structure, which contributes to an ideal structural response control.

Effective damping ratio enhancement effect of tuned inerter dampers for seismic response control of civil structures

Tuned inerter dampers (TIDs) are widely recognized as promising inerter-based devices for controlling the seismic response of civil structures. However, the effective damping ratio enhancement (EDRE) effect of a TID has not been investigated thoroughly. In this study, the TID control effectiveness is considered as the effective damping ratio (EDR) applied to the main structure, and the analytical expression of the EDR is derived based on the white-noise seismic excitation hypothesis. The theory of the EDRE effect is introduced to explain the superior control effectiveness of a TID to that of a bare dashpot. Theoretical formulas of TID optimum parameters are proposed based on the EDRE effect for both damped and undamped main structures. These formulas ensure that the optimum control effectiveness and EDRE effect of a TID are achieved simultaneously. For this purpose, the TID is supposed to provide the highest EDR with the lowest damping ratio cost for the optimum EDRE effect. Compared to another well-known inerter-based device, i.e., a tuned viscous mass damper, a TID is particularly recommended when the damping ratio is restricted to less than 0.03. Moreover, the TID control effectiveness and EDRE effect are verified numerically under real seismic ground motions recommended by ATC-40. The numerical analysis results show that the TID is effective in controlling the structural seismic response, primarily because of its good performance in suppressing the system input energy.

Seismic response control of base-isolated structures with fluid inerter damper

Seismic response control of base-isolated structures with fluid inerter damper