Mass Dampers For Buildings Research Articles

Multi-objective optimization of inerter-based building mass dampers

The building mass damper (BMD) is a design concept in which a structure is substructured in such a way that the upper substructure behaves as a large-mass tuned mass damper for the lower one. Its correct tuning usually requires softening (partial isolating) the upper substructure, which limits its application for retrofitting. The recently proposed inerter-based building mass damper (IBMD) solves, reasonably, the softening dynamically through the use of an inerter. This implies an in parallel intervention, which drastically simplifies the practicability of the BMD for retrofitting. The present paper involves comprehensive numerical simulations for multi-objective optimization of an IBMD, accounting for inherent structural damping. In particular, the deformation of the upper substructure is an additional objective function, besides the deformation of the lower substructure as considered in a previous work. Results demonstrate that the IBMD outperforms various benchmark interventions, including dampers, stiffeners, softening devices, and inerters without dampers. Additionally, it was found that the inherent structural damping partially replaces the need for additional damping. Finally, it was also shown that emphasizing the optimization of the lower substructure deformation enhances the overall structural safety in most cases. Nevertheless, the multi-objective optimization increases the versatility of the design concept in the case of substructures with different allowable deformations.

Real-Time Integration of Identification and Semiactive Optimization Control for Mass Damper-Building Combined Systems under Known/Unknown Seismic Excitations

The integration of structural identification and vibration optimal control has been studied. Since the semiactive optimization vibrational control of civil structures needs to be implemented by massive control devices such as mass dampers, it is necessary to investigate the real-time integration of identification and semiactive optimization vibration control for mass damper-building combined systems. However, there is a lack of such studies in the literature. In this paper, a methodology is presented for real-time integration of identification and semiactive optimization vibration control of the mass damper-building combined system under known/unknown seismic excitations. For the combined system under known seismic excitations, the identification is implemented by the extended Kalman filter (EKF) using only partial structural acceleration responses. The identified structural state and parameters of mass damper-building systems are integrated in real time for the optimal control of systems by the linear-quadratic regulator (LQR) control algorithm and the Hrovat semiactive optimization control strategy via semiactive optimization mass dampers (SAMD). Then, it is extended to the scenario of unknown seismic excitations. The partially measured structural acceleration responses are absolute ones in this case, so the generalized extended Kalman filter with unknown input (GEKF-UI) developed by the authors is used to identify the structural input-state parameters of the mass dampers-building combined systems. The identification results are also integrated in real time for the semiactive optimization control of the combined system via SAMD. Two numerical simulation examples are used to test the proposed integration methods. It is shown that the proposed integration methods can reach almost the same optimal control effects as the conventional semiactive optimization control with known parameters of the mass damper-building combined systems under known/unknown seismic excitations.

Inerter-based Building Mass Damper: Optimization and experimental study

The Building Mass Damper is a design concept for vibration control of structures where the upper substructure effectively behaves as a Tuned Mass Damper (TMD) for the lower one. Unfortunately, its tuning usually requires softening or partial isolation of the upper substructure; limiting its applicability for retrofitting. The recently proposed Inerter-based Building Mass Damper (IBMD) is an in-parallel intervention on the upper substructure with an inerter and a damper. Thus, the inerter allows correct Tuning, the upper substructure provides the Mass, and the damper adds the Damping. Therefore, a very large mass-ratio TMD is obtained with marginal additional weight and minimal practical impact. In the present work, experimental tests supported by numerical simulations on a small two-story structure model quantitatively confirm the effectiveness of the IBMD. Besides, an innovative compliant mechanism design is introduced for the implementation of the translation-rotational converter that drives the inerter; which has minimal backlash and friction, still allowing large strokes. The experiments involved a frictional damper, which performed comparable to a linear viscous damper considered in the simulations.

On the vibration control through mode coupling in a near-uniform chain-like structure using an inerter

The tuned mass damper (TMD) is a classical device interesting for reducing deformations between DOFs without physically connecting them. However, it has a practical limit due to the increase in mass required for improving its performance. A building mass damper (BMD) uses mode coupling to make the upper substructure of a chain-like structure behave as a TMD for the lower substructure, which avoids adding mass to the structure. Unfortunately, near-uniform chain-like structures require isolation of the upper substructure for tuning the BMD, making it impractical for retrofitting existing structures since it is an in-series intervention. This paper proposes and evaluates using an inerter, instead of isolating the upper substructure, to control vibrations through mode coupling in a chain-like structure. From an analytical and numerical study, it was found a significant reduction of lower substructure deformations by implementing solely an inerter and a damper in the upper substructure. The inerter-based approach showed similar performance to the classical BMD with the advantage of being an in-parallel intervention. Therefore, this approach constitutes a practical retrofit to improve the dynamic behavior of existing structures with excessive deformations in a lower substructure whose functionality or esthetics would be compromised if control devices were installed in it.

Model reference predictive control for building mass damper

Model reference predictive control for building mass damper

Stability Analysis and Verification of Real-Time Hybrid Simulation Using a Shake Table for Building Mass Damper Systems

The building mass damper (BMD) system, which incorporates the concept of a tuned mass damper into a mid-story isolation system, has been demonstrated as an effective system for suppressing structural vibration due to earthquakes. The BMD system separates a building into a substructure, a control layer and a superstructure. By applying well-design parameters, the seismic responses of the superstructure and substructure of a building can be mitigated simultaneously. However, merely limited design parameters have been verified by shaking table testing because it is difficult to construct several sets of specimens with limited research funding. Therefore, real-time hybrid simulation (RTHS) may become an alternative to conduct parametric studies of the BMD system efficiently and economically. In this study, the BMD system is separated into a numerical substructure and an experimental substructure. The experimental substructure includes the control layer and the superstructure of the BMD system installed on a seismic shake table while the substructure is numerically simulated. Then, substructuring method of the BMD system is derived and the stability analysis considering the dynamics of the shake table is performed to realize the potential feasibility of RTHS for BMD systems. The stability margin is represented as an allowable mass ratio of the experimental substructure to the entire BMD system. Finally, RTHS of a simplified BMD system has been conducted to verify the stability margin in the laboratory. Phase-lead compensation and force correction are applied to RTHS in order to improve the accuracy of RTHS for the simplified BMD system.

Building mass damper design based on optimum dynamic response control approach

The building mass damper (BMD) design features the use of partial structural mass, instead of additional tuned mass, as an energy absorber. Therefore, it becomes more effective in dynamic response reduction compared to the conventional tuned mass damper (TMD) design with very limited added tuned mass. In this study, an optimum building mass damper (OBMD) design approach, namely optimum dynamic response control approach, based on a simplified 3-lumped-mass structure model is proposed to enhance the seismic performances of both the superstructure (or tuned mass) and substructure (or primary structure) respectively above and below the control layer. A series of shaking table tests on one bare and two OBMD specimens were conducted to experimentally verify the efficacy of the proposed OBMD design approach. To further demonstrate the advantage of the OBMD design conditionally over other passive control approaches, the seismic responses of the same structure model but respectively designed with a mid-story seismic isolation (MSI) system and additional energy dissipation devices are also numerically analyzed and compared. It is found that the OBMD design can reveal a better seismic performance than the energy dissipation design. More importantly, it can have a comparable and even superior seismic performance to the MSI design especially when the structure model has a medium or long period of vibration.

Analytical and experimental studies on building mass damper system with semi-active control device

A concept of improving an optimum building mass damper (OBMD) system through a semi-active control method for enhancing the efficiency of controlling structural responses is proposed. The proposed concept entails replacing the passive fluid viscous dampers used in an OBMD system with semi-active magnetorheological dampers, thus transforming the system into a novel semi-active OBMD (SOBMD) system for better seismic performance. A numerical model based on the Bouc–Wen model with the interpolation technique was established to represent the behavior of the semi-active magnetorheological dampers. The SOBMD system was then developed on the basis of linear-quadratic regulator method and a continuous-optimal control concept. The damping force in the SOBMD system can be manipulated according to the structural response; therefore, the SOBMD system affords the possibility of improving the displacement or acceleration response compared with the original OBMD system. Both of the numerical analysis and the experimental verification demonstrated the superior seismic mitigation ability of the SOBMD system. Several earthquake events with different characteristics were simulated in a series of numerical analysis to further verify the performance of the proposed SOBMD system. In short, the benefits of both the active and passive control system are successfully combined in the proposed SOBMD system.

Optimum dynamic characteristic control approach for building mass damper design

SummaryA new seismic design manner, namely building mass damper (BMD), which is inspired from a combination of mid‐story isolation and tuned mass damper design concepts, recently attracts immense attention. It is mainly because that the use of partial structural mass of the building as an energy absorber in the BMD design can overcome the drawback of limited response reduction due to insufficient added tuned mass in the conventional tuned mass damper design. In this study, an optimum BMD (OBMD) design approach, namely optimum dynamic characteristic control approach, based on a simplified 3‐lumped‐mass structure model is proposed to seismically protect both the superstructure (or tuned mass) and the substructure (or primary structure), respectively, above and below the control layer. A series of sensitivity analyses and experimental studies on different parameters, including mass, frequency, and damping ratios, of a building model designed with a BMD system were conducted. The test results verify the practical feasibility of the BMD concept as well as the effectiveness of the proposed OBMD design. Furthermore, by comparing with the numerical results of a mid‐story isolated counterpart, it is demonstrated that the proposed OBMD design can have a comparable and even better control performance.

The Application of Resettable Device to Semi-Active Tuned Mass Damper Building Systems for Multi-level Seismic Hazard Mitigation

An innovative multi-story Semi-Active Tuned Mass Damper (SATMD) building system is proposed to control seismic response of existing structures. The application of adding new stories as large tuned mass and semi-active (SA) resettable actuators as central features of the control scheme is derived. For the effective control of the structures, the optimal tuning parameters are considered for the large mass ratio, for which a previously proposed equation is used and the practical optimal stiffness is allocated to the actuator stiffness and rubber bearing stiffness. A two-degree-of freedom (2-DOF) model is adopted to verify the principal efficiency of the suggested structural control concept. The simulations for this study utilizes the three ground motions, from SAC project, having probability of exceedance of 50% in 50 years, 10% in 50 years, and 2% in 50 years for the Los Angeles region. 12-story moment resisting frames, which are modified as '12+2' and '12+4' story structures, are investigated to assess the viability and effectiveness of the system that aims to reduce the response of the buildings to earthquakes. The control ability of the SATMD scheme is compared to that of an uncontrolled and an ideal Passive Tuned Mass Damper (PTMD) building system. From the performance results of suggested '12+2' and '12+4' story retrofitting case studies, SATMD systems shows significant promise for application of structural control where extra stories might be added.

A novel robust disturbance rejection anti-windup framework

In this article, we propose a novel anti-windup (AW) framework for coping with input saturation in the disturbance rejection problem of stable plant systems. This framework is based on the one developed by Weston and Postlethwaite (W&P) (Weston, P.F., and Postlethwaite, I. (2000), ‘Linear Conditioning for Systems Containing Saturating Actuators’, Automatica, 36, 1347–1354). The new AW-design improves the disturbance rejection performance over the design framework usually suggested for the coprime-factorisation based W&P-approach. Performance improvement is achieved by explicitly incorporating a transfer function, which represents the effect of the disturbance on the nonlinear loop, into the AW compensator synthesis. An extra degree of freedom is exploited for the coprime factorisation, resulting in an implicitly computed multivariable algebraic loop for the AW-implementation. Suggestions are made to overcome the algebraic loop problem via explicit computation. Furthermore, paralleling the results of former work (Turner, M.C., Herrmann, G., and Postlethwaite, I. (2007), ‘Incorporating Robustness Requirements into Antiwindup Design’, IEEE Transactions on Automatic Control, 52, 1842–1855), the additive plant uncertainty is incorporated into the AW compensator synthesis, by using a novel augmentation for the disturbance rejection problem. In this new framework, it is shown that the internal model control (IMC) scheme is optimally robust, as was the case in Turner, Herrmann, and Postlethwaite (2007) and Zheng and Morari (Zheng, A., and Morari, M. (1994), ‘Anti-windup using Internal Model Control’, International Journal of Control, 60, 1015–1024). The new AW approach is applied to the control of dynamically substructured systems (DSS) subject to external excitation signals and actuator limits. The benefit of this approach is demonstrated in the simulations for a small-scale building mass damper DSS and a quasi-motorcycle DSS.

Using upper storeys as semi-active tuned mass damper building systems

This paper presents an exploratory case study based analysis of the seismic performance of multi-storey passive and semi-active tuned mass damper (PTMD and SATMD) building systems are investigated for 12-storey moment resisting frames modelled as ‘10+2’ storey and ‘8+4’ storey. Segmented upper stories of the structure are isolated as a tuned mass, and a passive viscous damper or semi-active resetable device is adopted for energy dissipation. Optimum TMD control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two degree of freedom (2-DOF) system. Log-normal statistical performance results are presented for 30 probabilistically scaled earthquake records. The time history analysis and normalised reduction factor results show the response reductions for all seismic hazards. Thus, large SATMD systems can effectively manage seismic response for multi degree of freedom (MDOF) systems across a broad range of ground motions in comparison to passive solutions. This research demonstrates the validity of the TMD building systems for consideration in future design and construction. It also provides a template for the design and analysis of passive or semi-active TMD buildings utilising large masses, or more efficiently, added storys, for improving seismic response performance.

Semi‐active tuned mass damper building systems: Application

AbstractSeismic performance attributes of multi‐story passive and semi‐active tuned mass damper (PTMD and SATMD) building systems are investigated for 12‐story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper portion of the stories are isolated as a tuned mass, and a passive viscous damper or semi‐active resetable device is adopted as energy dissipation strategy. The semi‐active approach uses feedback control to alter or manipulate the reaction forces, effectively re‐tuning the system depending on the structural response. Optimum tuned mass damper control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two‐degree‐of‐freedom system. Statistical performance metrics are presented for 30 probabilistically scaled earthquake records from the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that large SATMD systems can effectively manage seismic response for multi‐degree‐of freedom systems across a broad range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Additionally, variability is seen to be tighter for the SATMD systems across the suites of ground motions used, indicating a more robust control system. While the overall efficacy of the concept is shown the major issues, such as isolation layer displacement, are discussed in detail not available in simplified spectral analyses, providing further insight into the dynamics of these issues for these systems. Copyright © 2009 John Wiley & Sons, Ltd.

Semi‐active tuned mass damper building systems: Design

AbstractPassive and semi‐active tuned mass damper (PTMD and SATMD) building systems are proposed to mitigate structural response due to seismic loads. The structure's upper portion self plays a role either as a tuned mass passive damper or a semi‐active resetable device is adopted as a control feature for the PTMD, creating a SATMD system. Two‐degree‐of‐freedom analytical studies are employed to design the prototype structural system, specify its element characteristics and effectiveness for seismic responses, including defining the resetable device dynamics. The optimal parameters are derived for the large mass ratio by numerical analysis. For the SATMD building system the stiffness of the resetable device design is combined with rubber bearing stiffness. From parametric studies, effective practical control schemes can be derived for the SATMD system. To verify the principal efficacy of the conceptual system, the controlled system response is compared with the response spectrum of the earthquake suites used. The control ability of the SATMD scheme is compared with that of an uncontrolled (No TMD) and an ideal PTMD building systems for multi‐level seismic intensity. Copyright © 2009 John Wiley & Sons, Ltd.

Directional mass dampers for buildings under wind or seismic loads

Three passive damper configurations are studied for buildings: unidirectional dampers oriented to the story principal axes and dampers with a single mass attached to spring-dashpot elements laid out at 90°/120° to each other. A simple damper design procedure to minimize a weighted combination of RMS building responses, using the concept of structure-constrained feedback control, is presented. Examples of six tall buildings with roof dampers and various plan geometries are considered. Performance of the simple dampers under along/across wind loads and seismic excitation are studied. With varying loading direction, unidirectional dampers show differing levels of control performance; however, performance of the latter types of dampers appears independent of excitation direction. For multi-winged buildings a good damper seems to be a single mass connected to one set of spring-dashpot elements for each wing; for wings exactly or nearly aligned with each other, a single spring-dashpot unit in one of them appears sufficient. Numerical results for performance and effectiveness of the dampers are presented and discussed.

Fundamental Study of Structural Response Control by Friction Controllable Active Brace Using Piezoelectric Actuator.

Active/passive mass dampers for buildings are mainly used to improve habitability or human comfort in the buildings in the event of strong winds, and energy dissipation devices are mainly used to enhance the safety of the buildings in the event of strong earthquakes. However very few systems are useful for both of these purposes. As a system which can serve both purposes, an active brace system was proposed, which is installed in stories of a building and can vary the friction force acting between the upper and lower floors of the story using piezoelectric actuators. Thus the active brace works as a friction controllable damper or a variable stiffness system for semiactive response control of the building. Excitation tests were carried out for a single-story building model with a mass of 1 150 kg supported by 4 columns. The active brace model equipped with two piezoelectric actuators produced a friction force of up to 2.5 kN. Through the test, it was shown that the response control by the active brace exhibited good performance throughout a wide range of excitation intensity.

Semianalytical Method for Parametric Study of Tuned Mass Dampers

Based on wind-tunnel measurements of wind-induced response of tall buildings, a semianalytical method of performing parametric study of tuned mass dampers for tall buildings is proposed. This method was verified through a series of aeroelastic model tests of buildings with and without mass dampers, and a close agreement between semianalytical and experimental results was found. The method can be used to provide an accurate estimate of motion reduction of a building without having to conduct aeroelastic model tests of mass damper–building systems. Both the analytical and experimental results show that the effectiveness of tuned mass dampers depends to some extent on the type of wind excitation. The conventional parametric study method, which is based on a white-noise excitation model, usually overestimates the performance of tuned mass dampers. The practical application of the proposed method and the selection of the optimal mass damper parameters are demonstrated. The limitation of the present study and the required further research are pointed out.

Optimal Tuned Mass Dampers for Buildings

This note has presented approximate formulas for the design of a TMD system. For most buildings, the accuracy obtained from the closed form expressions is adequate for preliminary design. This note has also shown, using results of the feasibility study of the Citicorp Center TMD, that the effective damping of a building with a TMD is smaller than predicted by a model that represents the building by its first mode only.

Tuned Mass Dampers for Buildings

Tuned mass dampers attached to single degree-of-freedom systems representing tall buildings are studied. System equations are formulated and solved for various input forcing functions. Design parameters of the damper are varied to study the response reduction. Experimental wind tunnel results are presented, and a practical application of a large-scale damper is illustrated.