Earthquake-induced Vibrations Research Articles

Smart structural control and analysis for earthquake excited building with evolutionary design

In recent years, with the maximization of control design and efficiency, and the improvement of economy and energy efficiency, building technology and control in the theory have attracted the attention of lots researchers. By trying various control theorems, many numerical methods have been investigated in the literature to achieve this target, but all these numerical methods are difficult to work out the problem correctly. This paper puts forward a potentially feasible evolutionary bat algorithm (EB) method for active control of earthquake-induced vibration in building structures. Based disturbance observer based control and S surface combined with the robust adaptive control scheme for solving optimization problems proposed, an important contribution in the control law is what the configuration control in the present study should not require known uncertainty limits and the disturbance is eliminated. A simulation case study was proposed to illustrate the possibility of implementing an apparent learning method in ANN to effectively control structural vibration under the influence of systematic motion under earthquake citations. The proposed learning numerical methods does not need to develop a mathematical model of structural dynamics or train another neural network to approximate the actual structural response to be performed.

Seismic Vibration Mitigation of Wind Turbine Tower Using Bi-Directional Tuned Mass Dampers

Wind turbines have been increasingly erected in earthquake regions to harvest abundant wind energy. However, the wind turbine tower is slender and lightly damping, which exhibits high susceptibility to earthquake-induced vibration. It is challenging to mitigate the seismic vibration of the tower. In this study, a bi-directional tuned mass damper (BTMD) is proposed to mitigate the seismic vibration of the wind turbine tower. Meanwhile, a lumped-mass finite element model (LFEM) and a coupled blade tower finite element model (CBFEM) are used to investigate the vibration mitigation performance of the BTMD. First, the BTMD and corresponding dynamic equilibrium equations are systemically introduced. Accordingly, the optimum stiffness and damping of the BTMD at different mass ratios are investigated. Then, the dynamic prosperities of the LFEM and CBFEM are compared. Subsequently, the seismic responses of the wind turbine with the BTMD are conducted using the LFEM and CBFEM. Meanwhile, the mitigation performances of the BTMD under uni- and bi-directional earthquakes are investigated. The displacement, acceleration, and bending moment of the wind turbine tower are analyzed in time domain and frequency domain. Note that the influential factors, including mass ratio and structural frequency, on the vibration mitigation performance of the BTMD are investigated. Results show that the proposed BTMD can significantly mitigate the peak values of the top displacement and bottom bending moment. However, the blade tower coupling effect and frequency variation of the tower would have influences on the mitigation efficiency of the BTMD. The results enable a better understanding of the seismic vibration mitigation of the wind turbine tower using tuned mass dampers.

Seismic response of canisters embedded in a repository analyzed through centrifuge modeling

High-level waste (HLW), one of the most poisonous materials known to science, includes spent fuel from nuclear power plants. Therefore, nuclear engineers seek to isolate HLW from the Earth's biosphere by using multibarrier systems, including engineered and natural barriers deep below the surface of the earth. Typically, disposal holes are drilled into intact rocks. Canisters and buffer materials are then placed in the drilled holes. These highly stable canisters should not be easily affected by the natural environment, human activities, and tectonic movement. However, Taiwan is located in the Ring of Fire of the Pacific Ocean; thus, earthquakes threaten Taiwan frequently. Consequently, scholarly investigations must expand knowledge regarding the effects of earthquake-induced vibration on the canisters and buffer materials placed in the drilled holes and on the disposal system. This study assumes that the relevant disposal holes are created in granite deposit layers and have no deformations and cracks. The methods and geometry of the KBS-3 V system were examined; in this study a physical apparatus one-tenth the size of the KBS-3 V system was designed. The one-tenth-scale physical apparatus was subjected to an artificial acceleration field of 10 g as a simulation of the in-situ stress between the canisters and buffer material. The physical model was positioned on a shaking table and subjected to simulated seismic events. During shaking, sensors measured the acceleration, pore water pressure, and total pressure values to determine the interactive behavior between canisters and buffer materials during seismic activity. Six models were developed with different initial water content and hydration conditions; these models simulated the state of the buffer material after construction, after underground water invasion of the disposal hole, and after saturation of the buffer material. After centrifuge modeling had been conducted, the container was disassembled to check for crack development in the surrounding buffer material. The results can be used to distinguish the difference between each stage of buffer blocks and to determine the behavior of canisters during shaking; thus, these results can be employed to design HLW repositories in seismically active zones.

Effect of the primary structure on the seismic response of the cable-net façade

The cable-net supported façade is increasingly used in the modern buildings. In a cable-net façade, the ends of the cables are anchored to the primary structure along its elevation, and the façade’s seismic response is triggered by the earthquake-induced vibration of the primary structure. In this regard, the effect of the primary structure should be considered in the seismic response analysis of the cable-net façades. However, such an effect is ignored in most of the preceding research. In this paper, the effect of the primary structure on the seismic response of the cable-net façade is quantitatively studied. A group of cable-net models is subjected to two types of earthquake excitations. First, the ground accelerations are uniformly applied to the cable-net models. In this case, the effect of the primary structure is neglected. Second, the ground accelerations are applied to a series of primary structural models, generating the height-wise non-uniform dynamic excitations for the cable-nets, and the cable-nets are subjected to the non-uniform excitations. In this case, the effect of the primary structure is fully accounted for. A detailed comparison between the two groups of results is conducted. It is shown that the primary structure significantly influences the peak response of the cable-net façade, and such influences are strongly affected by the fundamental period ratio (RT) between the cable-net and the primary structure. For RT ≤ 0.6, it would be overly conservative to neglect the effect of the primary structure, while for RT ≥ 0.8 (especially at RT ≥ 1.0), it is unsafe to neglect such effects. If RT is around 1.0, the mid-span displacement of the cable-net façade under the non-uniform excitation (considering the effect of the primary structure) could be twice as large as that under the uniform excitation. Meanwhile, the tension of cables could exhibit a 20% increase due to the effect of the primary structure. The results obtained from different types of primary structures (varied lateral force resisting mechanism) are similar. From this study, it is inappropriate to ignore the effect of the primary structure in analyzing the seismic responses of the cable-net façades. This indicates the drawback of many preceding studies wherein the effect of the primary structure is neglected, and shows the necessity of developing a proper approach to account for this effect in the design of the cable-net façades.

Three-Dimensional Numerical Model for Seismic Analysis of Structures

Response Spectrum Analysis (RSA) and modal combination techniques are widely used to estimate the peak response of structures subjected to earthquake vibrations. This paper presents the numerical modeling and seismic analysis of structures. The response spectra based on Eurocode 8 is implemented for a five storey moment-resisting 3D structure to estimate peak response to earthquake-induced vibration. Eigenvector analysis is carried out to determine undamped free vibration mode shapes and frequencies. The lumped mass matrix, stiffness matrix of the full 3D structure is derived and natural periods, modal shapes, modal participation factors, and effective modal mass ratios are calculated. The structural response in different modes is combined to estimate the total dynamic response. The Square Root of Sum of Squares (SRSS), Complete Quadratic Combination (CQC), and Absolute Sum (AbsSum) rules are discussed and compared. The results of the SRSS and CQC rule for the examined building are almost identical as all cross-correlation coefficients are approximately equal to zero, and the responses of the individual modes are completely uncorrelated. CQC rule is appropriate when the natural frequencies are close to each other. AbsSum method shows an upper bound estimate of the total response since it assumes that all modal peaks occur at the same time. The simulation for numerical modeling and response spectrum analysis (RSA) is implemented in MATLAB® software.

Mitigation of coupled wind-wave-earthquake responses of a 10 MW fixed-bottom offshore wind turbine

In this paper we present a study on the mitigation of dynamic responses of a 10 MW monopile offshore wind turbine under coupled wind-wave-earthquake excitations. We have developed and validated the generic seismic coupled analysis and structural control architecture tool to overcome the limitation of numerical tools when examining the wind-wave-earthquake coupling effects. We investigated the dynamic responses of a 10 MW monopile offshore wind turbine under different loading combinations and found that the earthquake loading increases the tower-top displacement and pile-cap moment by 47.6% and 95.1%, respectively, compared to the wind-wave-only condition. It is found that the earthquake-induced vibration in the fore-aft direction is mitigated by the wind and wave loadings due to the energy dissipated by the aerodynamic and hydrodynamic damping. In addition, the tower responses are dominated by the earthquake excitation. In order to alleviate the tower vibration induced by the earthquake, we implemented the structural control capability within the tool using tuned mass dampers. The tuned mass dampers with appropriately selected design parameters achieve a larger mitigation on the tower-top displacement for the earthquake-only condition compared to the coupled-loading scenario. The reason is that the tuned mass damper is only effective in mitigating tower vibration, and it is not capable of reducing the tower elastic deformation which is the major contribution of the tower displacement for the coupled-loading condition. In addition, we have found that a heavier tuned mass damper requires a lower tuned frequency to achieve a larger mitigation. A configuration for the mitigation control of the 10 MW offshore wind turbine is suggested by using a 5% mass ratio of the tuned mass damper.

Application of Kalman filtering in optimized semi-active control of fixed metal platforms under earthquake

Semi-active control is one of the most effective methods for damage reduction in offshore platforms subjected to intense environmental forces. Despite its advantages, probable device time delays may drastically decrease the real performance of the control algorithm. Thus, the uncertainty could make the control process non-optimal. In this paper, a Kalman Filter is used to ponder previous responses and the history of the measured errors in order to estimate the real state variables of an offshore structure equipped with Magneto-Rheological (MR) dampers. In the current article, the amount of applied voltage to the MR damper is optimized via the Adaptive Particle Swarm Optimization (APSO) method. Furthermore, the structure is controlled by the Linear–Quadratic Regulator (LQR) algorithm. A newly installed offshore platform, located in the Persian Gulf at a depth of 64 m is considered as an example to demonstrate the performance of the controller. The offshore structure is assumed to be excited by near- and far-field earthquakes. The results of the parametric studies indicate that all the earthquake-induced vibrations of the platform can be effectively suppressed by the designed control system. Moreover, the life spans of the dampers may increase with the predicting-optimizing algorithm.

A continuous-discrete approach for pre-design of flexible-base tall buildings with fluid viscous dampers

An equivalent coupled-two-beam (CTB) discrete model is presented to compute the dynamic response in time domain of flexible-base buildings with linear fluid viscous dampers (FVDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allows the consideration of intermediate modes of lateral deformation. The effects of different lateral deformations on the pre-design stage of two high-rise buildings are showed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and three different distribution methods for linear FVDs: uniform-distribution (UD), story-shear-proportional-distribution (SSPD) and story-shear-strain-energy-distribution (SSSED). For UD method, the damping coefficients of FVDs increase as the flexural rigidity of the building decreases; whereas for SSPD and SSSED methods, the damping coefficients of FVDs vary along the height depending on the type of lateral deformation. For the three distribution methods and the same lateral deformation, the damping coefficients of FVDs decrease as the soil flexibility increases, which leads to a significant decrease in controlling earthquake-induced vibrations and wind-induced vibrations in the two high-rise buildings on a soft soil.

A combined control strategy using tuned liquid dampers to reduce displacement demands of base-isolated structures: a probabilistic approach

This paper investigates a hybrid structural control system using tuned liquid dampers (TLDs) and lead-rubber bearing (LRB) systems for mitigating earthquake-induced vibrations. Furthermore, a new approach for taking into account the uncertainties associated with the steel shear buildings is proposed. In the proposed approach, the probabilistic distributions of the stiffness and yield properties of stories of a set of reference steel moment frame structures are derived through Monte-Carlo sampling. The approach is applied to steel shear buildings isolated with LRB systems. The base isolation systems are designed for different target base displacements by minimizing a relative performance index using Genetic Algorithm. Thereafter, the base-isolated structures are equipped with TLDs and a combination of the base and TLD properties is sought by which the maximum reduction occurs in the base displacement without compromising the performance of the system. In addition, the effects of TLD properties on the performance of the system are studied through a parametric study. Based on the analyses results, the base displacement can be reduced 23% by average, however, the maximum reduction can go beyond 30%.

Effect of Soil Saturation On Seismic Performance of A Structure: A Numerical Approach

The aim of this study is to investigate the impact of soil saturation on the seismic performance of a structure when subjected to earthquake-induced vibration. More specifically, this paper examines the effect of the soil saturation level taking into account of soil-structure interaction (SSI) on the structural response. For this purpose, a two dimensional (2D) finite element model was developed with Mohr-Coulomb failure criterion under plane-strain conditions using geotechnical finite element code PLAXIS. To emphasize SSI problems in civil engineering applications, mechanical behavior and various saturation levels of the local soil condition is examined using a numerical model. As can seen from the analysis results, the saturation level of soils causes an increase on the lateral roof displacement of the saturated elasto-plastic soil. This situation was interpreted as the increase in the saturation levels of the soils caused a decrease in the rigidity. Furthermore, neglecting the effect of SSI leads to underestimated results of the structural behavior.

Multi-objective optimal design of inerter-based vibration absorbers for earthquake protection of multi-storey building structures

In recent years different inerter-based vibration absorbers (IVAs) emerged for the earthquake protection of building structures coupling viscous and tuned-mass dampers with an inerter device. In the three most popular IVAs the inerter is functioning either as a motion amplifier [tuned-viscous-mass-damper (TVMD) configuration], mass amplifier [tuned-mass-damper-inerter (TMDI) configuration], or mass substitute [tuned-inerter-damper (TID) configuration]. Previous work has shown that through proper tuning, IVAs achieve enhanced earthquake-induced vibration suppression and/or weight reduction compared to conventional dampers/absorbers, but at the expense of increased control forces exerted from the IVA to the host building structure. These potentially large forces are typically not accounted for by current IVA tuning approaches. In this regard, a multi-objective IVA design approach is herein developed to identify the compromise between the competing objectives of (i) suppressing earthquake-induced vibrations in buildings, and (ii) avoiding development of excessive IVA (control) forces, while, simultaneously, assessing the appropriateness of different modeling assumptions for practical design of IVAs for earthquake engineering applications. The potential of the approach to pinpoint Pareto optimal IVA designs against the above objectives is illustrated for different IVA placements along the height of a benchmark 9-storey steel frame structure. Objective (i) is quantified according to current performance-based seismic design trends using first-passage reliability criteria associated with the probability of exceeding pre-specified thresholds of storey drifts and/or floor accelerations being the engineering demand parameters (EDPs) of interest. A variant, simpler, formulation is also considered using as performance quantification the sum of EDP variances in accordance to traditional tuning methods for dynamic vibration absorbers. Objective (ii) is quantified through the variance of the IVA force. It is found that reduction of IVA control force of up to 3 times can be achieved with insignificant deterioration of building performance compared to the extreme Pareto optimal IVA design targeting maximum vibration suppression, while TID and TMDI achieve practically the same building performance and significantly outperform the TVMD. Moreover, it is shown that the simpler variant formulation may provide significantly suboptimal reliability performance. Lastly, it is verified that the efficacy of optimal IVA designs for stationary conditions is maintained for non-stationary stochastic excitation model capturing typical evolutionary features of earthquake excitations.

Risk-informed optimization of the tuned mass-damper-inerter (TMDI) for the seismic protection of multi-storey building structures

The tuned mass-damper-inerter (TMDI) is a recently proposed passive vibration suppression device that couples the classical tuned mass-damper (TMD), comprising a secondary mass attached to the structure via a spring and dashpot, with an inerter. The latter is a two-terminal mechanical device developing a resisting force proportional to the relative acceleration of its terminals by the “inertance” constant. In a number of previous studies, optimally tuned TMDIs have been shown to outperform TMDs in mitigating earthquake-induced vibrations in building structures for the same pre-specified secondary mass. TMDI design in these studies involved simplified modeling assumptions, such as adopting a single performance objective and/or modeling seismic excitation as stationary stochastic process. This paper extends these efforts by examining a risk-informed TMDI optimization, adopting multiple objectives and using response history analysis and probabilistic life-cycle criteria to quantify performance. The first performance criterion, representing overall direct benefits, is the life-cycle cost of the system, composed of the upfront TMDI cost and the anticipated seismic losses over the lifetime of the structure. The second performance criterion, introducing risk-aversion attitudes into the design process, is the repair cost with a specific return period (i.e., probability of exceedance over the lifetime of the structure). The third performance criterion, accounting for practical constraints associated with the size of the inerter and its connection to the structure, is the inerter force with a specific return period. A particular variant of the design problem is also examined by combining the first and third performance criteria/objectives. A case study involving a 21-storey building constructed in Santiago, Chile shows that optimal TMDI configurations can accomplish simultaneous reduction of life-cycle and repair costs. However, these cost reductions come at the expense of increased inerter forces. It is further shown that connecting the inerter to lower floors provides considerable benefits across all examined performance criteria as the inerter is engaged in a more efficient way for the same inerter coefficient and attached mass ratios.

Soil-buried wave barriers for vibration control of structures subjected to vertically incident shear waves

Traditionally, the effects of seismic forces on structures have been mitigated by installing supplemental energy dissipation systems. In this paper, a new approach is explored for the mitigation of earthquake-induced vibrations by obstructing the entrance of seismic energy to the structure through the insertion of some concrete wave barriers within the soil domain. To do so, genetic algorithm (GA) based adaptive optimization methodology is utilized that is capable of finding the efficient layout of the concrete barriers in a manipulated soil zone around the structure. The optimization methodology is coupled with finite element (FE) method for analyzing the complex wave propagation phenomenon in the medium. To investigate the effect of frequency, three single-degree-of-freedom (SDOF) structures with the natural frequencies of 1, 2, and 3 Hz are subjected to the time history ground motions with the predominant frequencies up to 8 Hz. The optimization analyses are performed in the frequency domain, and the efficiency of the obtained solutions is examined by applying time history ground motions in the time domain. The results show that the performance of the buried wave barriers is a complex function of the wave barriers layout, natural frequency of the structure, and the frequency content of the loading. It is observed that some optimal layouts of limited volume can attenuate the elastic demands of the structures to the extent of 30–80%.

Back analysis of ground vibrations which cause cracks in buildings in residential areas Karakuyu (Dinar, Afyonkarahisar, Turkey)

The Karakuyu village (Dinar) is located in the south-western Turkey. Karakuyu settlement area suffered from ground vibration. There are two reasons for ground vibration in that area. One of them is earthquake and other is rock blasting. Geological structure and tectonics have great influence on vibrations in the area. An earthquake of magnitude Ms = 6.1 occurred on 1 October 1995, causing causalities and damage to buildings in Dinar and its vicinity. The earthquake forces during the main shock were amplified by poor dynamic characteristics of alluvial soils, thus resulting in damage to buildings. Limestone quarries are other source of ground vibration because of blasting. In this study, the source of vibration causing cracks in buildings in the Karakuyu residential area was investigated. Blasting at limestone quarries and past earthquake activities are analysed of ground vibrations which cause cracks in buildings. In the scope of this study, the source of the vibrations which cause the observed cracks in buildings were investigated using back analysis. As a result of the study, earthquake-induced vibrations on structural behaviour of buildings were found critical.

Tuned liquid dampers for multi-storey structure: numerical simulation using a partitioned FSI algorithm and experimental validation

Wind-induced and earthquake-induced vibrations of structures such as super-tall towers and bridges can be efficaciously controlled by tuned liquid dampers (TLDs). This work presents a numerical simulation procedure to study the performance of TLDs–structure system through sigma (\( \sigma \))-transformation-based fluid–structure coupled solver. For this, a ‘C’-based computational code has been developed. The structural equations, which are coupled with the fluid equations in order to achieve the transfer of sloshing forces to structure for damping, are solved by the fourth-order Runge–Kutta method, while the fluid equations are solved using finite-difference-based sigma-transformed algorithm. Different iterative and error schemes are used to optimize the code for larger convergence rate and higher accuracy. For validation, a few experiments are conducted with a three-storey structure using TLDs arrangement. The present numerical results of response of TLD-installed structures match well with the experimental results. The minimum displacement of structure is observed when the resonance condition of the coupled system is achieved through proper tuning of TLDs. Since real-time excitations are random in nature, the performance study of TLDs under random excitation has also been carried out in which the Bretschneider spectrum is used to generate the random input wave.

Semi-active seismic control of an 11-DOF building model with TMD+MR damper using type-1 and -2 fuzzy algorithms

Nowadays, vibration control of structures is considered as a challenging field among scientists and engineers. Structural damage and financial losses due to recent earthquakes in different countries have more than ever before accentuated the importance of controlling earthquake-induced vibrations. In recent years, semi-active control has been introduced as an efficient and reliable type of structural control which provides the reliability of passive control and flexibility of active control systems at the same time. In this study, the performance of a semi-active tuned mass damper (TMD) with adaptive magnetorheological (MR) damper is investigated using type-1 and -2 fuzzy controllers for seismic vibration mitigation of an 11-degree of freedom building model. The TMD is installed on the roof and the MR damper is located on the 11th story. The MR damper has a capacity of producing a 1000 kN control force. The fuzzy system is designed based on the acceleration and velocity of the top floor determining the input voltage needed to produce the control force based on accelerating or decelerating movements of structure. The seismic performance of semi-active type-2 controller, which considers the uncertainties related to input variables, is higher than that of the type-1 fuzzy controller. The type-2 fuzzy controller is capable of reducing further the maximum displacement, acceleration, and base shear of the structure by 11.7, 14, and 11.2%, respectively, compared to the type-1 fuzzy controller.

岩盤タンクの気相圧変化による傾斜応答を用いたタンクの力学的安定性評価

In addition to hydrological characterization of water-sealed type underground rock caverns, their mechanical stability is constantly monitored by measuring several properties, such as earthquake-induced vibration, strain, and tilt. Among them, tilt measurement is the most accurate monitoring method for rock deformation because of the tiltmeter's high resolution of 10-9 rad, which enables the detection of minute deformations caused by earth tide, rock responses to earthquake, change in atmospheric pressure, and artificial disturbance by operation. This study aimed to correctly extract these responses from long-term tilt data measured by a high precision tiltmeter at the Kushikino station and clarify the mechanism of tilt change as a result of deformation of rock mass. Tilt changes due to a small change in the gas phase pressure at the top of the rock cavern, approximately 10 kPa pressure fluctuation, were analyzed and discussed. The gradient response due to the gas pressure change was extracted from the measurement data by BAYTAP-G, and its magnitude was identified as 2 to 8 nrad, which was almost the same tilt response magnitude observed at an issuance of stored crude oil. This tilt response to the increase in tank gas pressure was numerically confirmed to originate from minute elastic deformation of rock masses, by using finite element method. Because fluctuation of the gas phase pressure can be continuously monitored, the effectiveness of tilt measurement was proved as a minute strain sensor for deformation of the water-sealed type underground rock cavern.

A direct design procedure for frame structures with added viscous dampers for the mitigation of earthquake-induced vibrations

A direct procedure for the seismic design of building structures with added viscous dampers is described in this paper. The procedure is applicable to regular multi-storey frame structures which are characterized by a period of vibration lower than 1.5 s. It aims at providing practical tools for the direct identification of the mechanical characteristics of the manufactured viscous dampers as well as for the structural design of the frame members’ so that a target level of performance is achieved. The design philosophy is to limit the structural damages under severe earthquakes. First, a target damping reduction factor is selected to achieve the desired reduction in the peak structural response. The linear damping coefficients of the equivalent linear viscous dampers are calculated taking advantage of modal damping ratios properties of classically damped systems. Then, simple analytical formulas for the estimation of peak inter-storey velocities are used, together with an energy criterion to identify the non-linear mechanical characteristics of the manufactured viscous dampers. Finally, the internal actions in the structural elements are estimated through the envelope of two equivalent static analyses (ESA), namely: ESA1 in which the naked structure is subjected to a first set of equivalent lateral forces, and ESA2 in which the structure, with rigid diagonal braces substituting the added viscous dampers, is subjected to a second set of equivalent lateral forces. At this preliminary stage of the research, the procedure is targeted for the preliminary design phase, since correction factors to improve the accuracy in the estimation of the peak inter-storey velocities needs to be calibrate. Therefore, for final design, non-linear dynamic analyses are recommended.

Evaluation of the effect of smart facade systems in reducing dynamic response of structures subjected to seismic loads

To date the engineering community has seen facade systems as non-structural elements with high aesthetic value and a barrier between the outdoor and indoor environments. The role of facades in energy use in a building has also been recognized and the industry is also witnessing the emergence of many energy efficient facade systems. This paper will focus on using exterior skin of the double skin facade system as a dissipative movable element during earthquake excitation. The main aim of this study is to investigate the potential of the facade system to act as a damper system to reduce earthquake-induced vibration of the primary structure. Unlike traditional mass dampers, which are usually placed at the top level of structures, the movable/smart double skin facade systems are distributed throughout the entire height of building structures. The outer skin is moveable and can act as a multi tuned mass dampers (MTMDs) that move and dissipate energy during strong earthquake motions. In this paper, using a three dimensional 10-storey building structure as the example, it is shown that with optimal choice of materials for stiffness and damping of brackets connecting the two skins, a substantial portion of earthquake induced vibration energy can be dissipated which leads to avoiding expensive ductile seismic designs. It is shown that the engineering demand parameters (EDPs) for a low-rise building structures subjected to moderate to severe earthquakes can be substantially reduced by introduction of a smart designed double skin system.

Active Structural Control Based on Integration ofΗ∞Control and Equivalent-Input-Disturbance Approach

This paper describes an approach for suppressing earthquake-induced vibrations of building structures. The design of the control system is based on the equivalent-input-disturbance approach for improving the vibration rejection performance. A control system configuration with a vibration estimator is described, and a method of designing such a control system that employsΗ∞control is presented. The vibration rejection performance is guaranteed by the control structure, in which an equivalent vibration signal on the control input channel is estimated and directly incorporated into the control input. The validity of our method is demonstrated through simulations.