High-rate global navigation satellite system (GNSS) has emerged as an effective method to recover seismic waveforms without saturation and drifts, but it has the limitation of relatively lower sampling rate and higher noise level compared to seismic instruments. In this study, we present a new seismogeodetic method by integrating GNSS and accelerometer data to obtain optimal real-time seismic waveforms. Unlike traditional integration methods based on GNSS techniques of relative positioning or precise point positioning, the new method uses a GNSS time difference technique and inherits its unique advantage in real-time and high-accuracy velocity solutions. Furthermore, by incorporating the tightly coupled structure, it can overcome the cascading problem and provide more accurate and robust waveforms compared to its loosely coupled counterpart. The performance of this method is first compared with the traditional loosely coupled approach in challenging environments through a set of shake table experiments. With three GNSS satellites, this approach method can improve the accuracy of velocities and displacements by 42 and 87 per cent, respectively. With four or more GNSS satellites, the average improvements of the method reach 25 and 41 per cent for the velocities and displacements, respectively. We then validate the full performances of the method through simulated shake table experiments and collocated GNSS and accelerometer data during the 2016 Mw 6.6 central Italy earthquake. The simulated and real-event analyses demonstrate that the new integration method can take full advantage of the complementary characteristics of GNSS and accelerometer sensors. By providing more accurate and broad-band velocity and displacement waveforms in a real-time or near-real-time manner, this method is quite promising in earthquake early warning and rapid source inversion.

The aim of this research is to develop a novel design of interval type-2 neuro-fuzzy (IT2NF) controller for active vibration control of a flexible structure during an earthquake. For this purpose, two adaptive neural network based fuzzy logic controllers are designed and combined to create the novel design of an IT2NF controller to reduce the vibrations of two-storey flexible building model that occur during earthquake disturbance effects. Accordingly, dynamic modeling of a flexible structure is realized and simulated using the MATLAB / SimMechanics. Then, an experimental setup consisting of two-storey flexible structure, active mass damper (AMD) and shaker is established. Additionally, IT2NF controller is implemented in simulation and experimental models, and the effectiveness and performance of the IT2NF controller are tested under the scaled Northridge Earthquake acceleration. The obtained simulations and experimental responses are evaluated in terms of cart displacements, deflections, and accelerations of the flexible floors showing a good agreement between the simulations and the experimental results. The results show that the designed novel IT2NF controller reduced the total deflections of first and second floor by 72.3% and 68.7%, respectively, when compared with the uncontrolled system. Additionally, it is also found that the designed IT2NF controller is able to reduce the accelerations of the first and second floor by 64.8% and 54.6%, respectively. The proposed and designed control method reported in this study can be employed as an active vibration controller for multi-degree of freedom of flexible systems under the disturbances such as earthquake excitations.

A new analysis method, called aeroelastic real-time hybrid simulation (aeroRTHS), is proposed to study aeroelastic vibrations of a tall building model in a wind tunnel. The aeroRTHS method captures dynamic interactions between an aeroelastic structure and the wind loading to more accurately analyze unstable wind phenomena such as vortex induced vibration (VIV) and in doing so broadens the application of RTHS from sesimic applications to wind engineering and eventually to multi-hazard analyses. A 1 meter tall rigid model with an aspect ratio of 7.3 was mounted on a modified single-axis shake table, which is able to convert translational motions to the corresponding rotations at the base of the model, to allow for the model to behave in the wind tunnel as an aeroelastic structure. A total of 128 pressure sensors on both crosswind surfaces of the model measured the envelope pressure loading in the real-time condition. Compensation techniques were developed and utilized with respect to pneumatic fluctuations either from the shake table or pressure measurements along with testing the robust stability of the aeroRTHS. This proof-of-concept study validates the proposed aeroRTHS framework by conducting a series of tests in a boundary layer wind tunnel. A further step of the aeroRTHS testing was to assess the effects of including a passive tuned mass damper (TMD) to the numerical substructures; and their performance in suppressing VIV were investigated. Parameter studies were conducted by varying dynamic properties of the building models and also by utilizing two different mass ratios of the TMD to the building model. Results demonstrate that the feasibility of the aeroRTHS method to investigate aero-structures under VIV and reveal that the augmentation of buildings with TMDs is an effective way to attenuate cross-wind vibration in tall buildings.

The behavior of rigid structures on rigid base or deformable media such as soil has been addressed by many researchers in the past. The behavior of a rigid body on the soil under static or cyclic actions, such as self-weight, wind or earthquake, is of great concern for both structural and geotechnical engineers. The engineers have to take into consideration the effects of such forces on the structure itself and on the soil as well. Here, a very significant role is in the soil-structure interaction. The paper presents the behavior of a rigid block on a uniform, medium dense, sand under horizontal acceleration of the base. A 6 cm wide rigid aluminum block with different height to width ratio (H/B) has been used. Hight to width ratio used in this research was 2.25, 3.75 and 4.5. The block was either placed on the sand (D = 0 cm) or was embedded in the sand prior to subjecting it to horizontal excitation using small shake table. The embedment depth D varied from 0 to 6 cm. The horizontal excitation was a sinusoidal displacement function with different amplitude and frequency. Frequency varied from 0.5 to 3 Hz while the amplitude varied from 0.5 to 5 cm. Combination of various frequencies and amplitudes were used to determine the critical combination of amplitude and frequency for a given height to weight ratio which was later used for more detailed analysis and numerical verification. Displacements of a rigid block and sand below the rigid block were measured using a contactless measurement system, ARAMIS. The results obtained through ARAMIS system were later used as a reference displacement for numerical analysis. Numerical simulations were performed using Rocscience RS2 software. Mohr-Coulomb model was used in numerical simulation.

The paper refers to a shaking table on a single axis designed to test the acceleration sensors used in the evaluation of seismic waves. Studying P waves in order to evaluate the intensity of S waves is a continuous challenge in the field of earthquake research and requires expensive equipment to perform seismic wave simulation, such as shaking table. In this context, it is presented the realization of a shaking table actuated by an electrodynamic actuator of diffuser type controlled by means of a power amplifier. The seismic wave configuration is transmitted to the amplifier via SCPI commands on a computer running a LabVIEW application.

This paper proposes an automatic tuning algorithm for a sliding mode controller (SMC) based on the Ackermann's formula, that attenuates the structural vibrations of a seismically excited building equipped with an Active Tuned Mass Damper (ATMD) mounted on its top floor. The switching gain and sliding surface of the SMC are designed through the proposed tuning algorithm to suppress the structural vibrations by minimizing either the top floor displacement or the control force applied to the ATMD. Moreover, the tuning algorithm selects the SMC parameters to guarantee the following closed-loop characteristics: 1) the transient responses of the structure and the ATMD are sufficiently fast and damped; and 2) the control force, as well as the displacements and velocities of the building and ATMD are within acceptable limits under the frequency band of the earthquake excitation. The proposed SMC shows robustness against the unmodeled dynamics such as the friction of the damper. Experimental results on a reduced scale structure permits demonstrating the efficiency of the tuning algorithm for the SMC, which is compared with the traditional Linear Quadratic Regulator (LQR).

@article{morales-valdez_2020,
title = {Automated damage location for building structures using the hysteretic model and frequency domain neural networks},
author = {Morales-Valdez, J.; Lopez-Pacheco, M.; Yu, W.},
journal = {Structural Control Health Monitoring},
year = {2020},
institution = {CONACyT, Mexico; CINVESTAV-IPN, Mexico},
abstract = {his paper presents a novel and accurate model‐reference health monitoring system for the location of damage to building structures using the dissipated energy approach, frequency domain convolutional neural networks (CNNs), and principal component analysis (PCA). Due to the fact that the earthquake introduces several stress cycles in different directions in the structure, load–strain curves can be used as an indicator of damage. The CNN in the frequency domain (CNNFI) is used to estimate the hysteretic displacement of the reference of the Bouc–Wen model. Automated damage locations are resolved with the CNN classification models (CNNFC). The comparison study for damage location is presented by using classical neural networks. The results of the damage location of a two‐story building prototype confirmed that the proposed method is promising for real applications. },
keywords = {Structural health monitoring, damage location, convolutional neural network, principal component analysis},
language = {English},
publisher = {John Wiley & Sons, Inc.}
}

his paper presents a novel and accurate model‐reference health monitoring system for the location of damage to building structures using the dissipated energy approach, frequency domain convolutional neural networks (CNNs), and principal component analysis (PCA). Due to the fact that the earthquake introduces several stress cycles in different directions in the structure, load–strain curves can be used as an indicator of damage. The CNN in the frequency domain (CNNFI) is used to estimate the hysteretic displacement of the reference of the Bouc–Wen model. Automated damage locations are resolved with the CNN classification models (CNNFC). The comparison study for damage location is presented by using classical neural networks. The results of the damage location of a two‐story building prototype confirmed that the proposed method is promising for real applications.

@article{lopez-pacheco_2020,
title = {Frequency domain CNN and disipate energy approach for damage detection in building structures},
author = {Lopez-Pacheco, M.; Morales-Valdez, J.; Yu, W.},
journal = {Soft Computing},
year = {2020},
institution = {CINVESTAV-IPN, Mexico},
abstract = {Recent developments tools and techniques for Structural Health Monitoring (SHM) allows the design of early warning systems for the damage diagnosis and structural assessment. Mosts method to damage detection involves vibration data analysis by using identification systems, that generally required a mathematical model and much information about the system, as parameters and states that are mostly unknown. In this paper, a novel Frequency Domain Convolutional Neural Network (FDCNN) proposed aims to design an identification system for damage detection based on Bouc-Wen hysteretic model. FDCNN, unlike other works, only requires acceleration measurements for damage diagnosis , that are very sensitive to environmental noise. In contrast with Neural Network (NN) and Time Domain Convolutional Neural Network (TDCNN), FDCNN reduces the computational time required for the learning stage and add robustness against noise in data. The FD-CNN includes random filters in the frequency domain to avoid measurement noise using a spectral pooling operation , which is useful when the system bandwidth is unknown. Inappropriate filtering can produce unwanted results, as a shifted and attenuation signal relative to the original. Moreover, FDCNN allows overcoming the parameterization problem in nonlinear systems, which is often difficult to achieve. In order to validate the proposed methodology, a comparison between two different architectures of convolutional neural networks are present, showing that proposed CNN in frequency domain brings better performance in the identification system for damage diagnosis in building structures. Experimental results from reducing scale two-storey building confirm the effectiveness of the proposed. },
keywords = {Structural health monitoring, Damage detection, Convolutional neural network, Identification system},
language = {English}
}

Recent developments tools and techniques for Structural Health Monitoring (SHM) allows the design of early warning systems for the damage diagnosis and structural assessment. Mosts method to damage detection involves vibration data analysis by using identification systems, that generally required a mathematical model and much information about the system, as parameters and states that are mostly unknown. In this paper, a novel Frequency Domain Convolutional Neural Network (FDCNN) proposed aims to design an identification system for damage detection based on Bouc-Wen hysteretic model. FDCNN, unlike other works, only requires acceleration measurements for damage diagnosis , that are very sensitive to environmental noise. In contrast with Neural Network (NN) and Time Domain Convolutional Neural Network (TDCNN), FDCNN reduces the computational time required for the learning stage and add robustness against noise in data. The FD-CNN includes random filters in the frequency domain to avoid measurement noise using a spectral pooling operation , which is useful when the system bandwidth is unknown. Inappropriate filtering can produce unwanted results, as a shifted and attenuation signal relative to the original. Moreover, FDCNN allows overcoming the parameterization problem in nonlinear systems, which is often difficult to achieve. In order to validate the proposed methodology, a comparison between two different architectures of convolutional neural networks are present, showing that proposed CNN in frequency domain brings better performance in the identification system for damage diagnosis in building structures. Experimental results from reducing scale two-storey building confirm the effectiveness of the proposed.

@article{ariba_2020,
title = {Performance analysis for time-delay systems and application to the control of an active mass damper},
author = { Ariba, Y.; Gouaisbaut, F.},
year = {2020},
institution = {LAAS-MAC, France},
abstract = {This paper proposes a method to analyze, beyond stability, the performances of linear time-delay systems. Using robust analysis techniques, a sufficient condition that analyzes the location of eigenvalues in the complex plane is presented. More precisely, a set of quadratic inequality constraints are designed to define an admissible region for the infinitely many eigenvalues of a time-delay system and the quadratic separation theorem is applied to assess that the eigenvalues are effectively belonging to that stability region. This method is then used for the control of an active mass damper. A standard state feedback control is replaced with a static output feedback plus a static delayed output feedback. This strategy avoids the full measurement of the state and shows that delays in the dynamic may be helpful for stabilization. The closed-loop system is then expressed as a time-delay system and the performance criterion is exploited to analyze the stability and the damping properties. Simulations and experimental tests support the approach. }
}

This paper proposes a method to analyze, beyond stability, the performances of linear time-delay systems. Using robust analysis techniques, a sufficient condition that analyzes the location of eigenvalues in the complex plane is presented. More precisely, a set of quadratic inequality constraints are designed to define an admissible region for the infinitely many eigenvalues of a time-delay system and the quadratic separation theorem is applied to assess that the eigenvalues are effectively belonging to that stability region. This method is then used for the control of an active mass damper. A standard state feedback control is replaced with a static output feedback plus a static delayed output feedback. This strategy avoids the full measurement of the state and shows that delays in the dynamic may be helpful for stabilization. The closed-loop system is then expressed as a time-delay system and the performance criterion is exploited to analyze the stability and the damping properties. Simulations and experimental tests support the approach.

In terms of vibrations along bidirectional earthquake forces, several problems are faced when modelling and controlling the structure of a building, such as lateral-torsional vibration, uncertainties surrounding the rigidity and the difficulty of estimating damping forces.

In this paper, we use a fuzzy logic model to identify and compensate the uncertainty which does not require an exact model of the building structure. To attenuate bidirectional vibration, a novel discrete-time sliding mode control is proposed. This sliding mode control has time-varying gain and is combined with fuzzy sliding mode control in order to reduce the chattering of the sliding mode control. We prove that the closed-loop system is uniformly stable using Lyapunov stability analysis. We compare our fuzzy sliding mode control with the traditional controllers: proportional–integral–derivative and sliding mode control. Experimental results show significant vibration attenuation with our fuzzy sliding mode control and horizontal-torsional actuators. The proposed control system is the most efficient at mitigating bidirectional and torsional vibrations.

@article{paul_2017,
title = {A method for bidirectional active control of structures},
author = {Paul, S.; Yu, W.},
journal = {Journal of Vibration and Control},
year = {2017},
institution = {Departamento de Control Automatico, CINVESTAV-IPN (National Polytechnic Institute), Mexico City, Mexico},
abstract = {Proportional-derivative (PD) and proportional-integral-derivative (PID) controllers are popular control algorithms in industrial applications, especially in structural vibration control. In this paper, the designs of two dampers, namely the horizontal actuator and torsional actuator, are combined for the lateral and torsional vibrations of the structure. The standard PD and PID controllers are utilized for active vibration control. The sufficient conditions for asymptotic stability of these controllers are validated by utilizing the Lyapunov stability theorem. An active vibration control system with two floors equipped with a horizontal actuator and a torsional actuator is installed to carry out the experimental analysis. The experimental results show that bidirectional active control has been achieved. },
keywords = {PID control, bidirectional control, active vibration control, stability, building structure},
language = {English},
publisher = {SAGE}
}

Proportional-derivative (PD) and proportional-integral-derivative (PID) controllers are popular control algorithms in industrial applications, especially in structural vibration control. In this paper, the designs of two dampers, namely the horizontal actuator and torsional actuator, are combined for the lateral and torsional vibrations of the structure. The standard PD and PID controllers are utilized for active vibration control. The sufficient conditions for asymptotic stability of these controllers are validated by utilizing the Lyapunov stability theorem. An active vibration control system with two floors equipped with a horizontal actuator and a torsional actuator is installed to carry out the experimental analysis. The experimental results show that bidirectional active control has been achieved.

@conference{paul_2017,
title = {Bidirectional Fuzzy PD Control for Active Vibration Control of Building Structure},
author = {Paul, S.; Yu, W.},
booktitle = {2017 IEEE International Conference on Industrial Technology (ICIT)},
year = {2017},
institution = {CINVESTAV-IPN, National Polytechnic Institute, Mexico City, Mexico},
abstract = {Proportional-derivative (PD) is a popular algorithm in the field of building structure vibration control, but there are infrequent broadcasted theory results of PD controller in connection to structural vibration control applications. In order to maintain minimum regulation error, a PD control requires sufficiently high proportional and derivative gains. The effect of these diminishes the transient performances of the vibration control. In this paper, a straight forward combination of PD control with fuzzy compensation is laid down. We state comprehensive sufficient conditions for choosing the PD gains. The stability theories are verified through numerical simulations and a two-story building prototype. The extracted results validates our theory analysis. },
language = {English},
publisher = {IEEE},
isbn = {978-1-5090-5321-6 }
}

Proportional-derivative (PD) is a popular algorithm in the field of building structure vibration control, but there are infrequent broadcasted theory results of PD controller in connection to structural vibration control applications. In order to maintain minimum regulation error, a PD control requires sufficiently high proportional and derivative gains. The effect of these diminishes the transient performances of the vibration control. In this paper, a straight forward combination of PD control with fuzzy compensation is laid down. We state comprehensive sufficient conditions for choosing the PD gains. The stability theories are verified through numerical simulations and a two-story building prototype. The extracted results validates our theory analysis.

@article{zheng_2017,
title = {Building Vibration Control by Active Mass Damper with Delayed Acceleration Feedback: Multi-objective Optimal Design and Experimental Validation},
author = {Zheng, Y.G.; Huang, J.; Sun, Y.; Sun, J.-Q.},
journal = {Journal of Vibration and Acoustics},
year = {2017},
institution = {Nanchang Hangkong University, China; Beijing University of Chemical Technology, China; Xian Jiaotong University, China; University of California, Merced, USA},
abstract = {The building structural vibration control by an active mass damper with delayed acceleration feedback is studied. The control is designed with a multi-objective optimal approach. The stable region in a parameter space of the control gain and time-delay is obtained by using the method of stability switch and the numerical code of NDDEBIFTOOL. The control objectives include the setting time, total power consumption, peak time, and the maximum power. The multi-objective optimization problem for the control design is solved with the simple cell mapping method. The Pareto set and Pareto front are found to consist of two clusters. The first cluster has negative feedback gains, i.e. the positive acceleration feedback. We have shown that a proper time-delay can enhance the vibration suppression with controls from the first cluster. The second cluster has positive feedback gains and is located in the region which is sensitive to time-delay. A small time-delay will deteriorate the control performance in this cluster. Numerical simulations and experiments are carried out to demonstrate the analytical findings. },
keywords = {Vibration control, Dampers, Design, Feedback, Delays, Energy consumption, Stability, Computer simulation, Vibration suppression, Pareto optimization},
language = {English},
publisher = {ASME}
}

The building structural vibration control by an active mass damper with delayed acceleration feedback is studied. The control is designed with a multi-objective optimal approach. The stable region in a parameter space of the control gain and time-delay is obtained by using the method of stability switch and the numerical code of NDDEBIFTOOL. The control objectives include the setting time, total power consumption, peak time, and the maximum power. The multi-objective optimization problem for the control design is solved with the simple cell mapping method. The Pareto set and Pareto front are found to consist of two clusters. The first cluster has negative feedback gains, i.e. the positive acceleration feedback. We have shown that a proper time-delay can enhance the vibration suppression with controls from the first cluster. The second cluster has positive feedback gains and is located in the region which is sensitive to time-delay. A small time-delay will deteriorate the control performance in this cluster. Numerical simulations and experiments are carried out to demonstrate the analytical findings.

@article{tinkir_2013,
title = {Experimental Investigation of Full-Order Observered and LQR Controlled Building-Like Structure Under Seismic Excitation},
author = {Tinkir, M.; Kalyoncu, M.; Sahin, Y.},
journal = {Applied Mechanics and Materials},
year = {2013},
volume = {307},
institution = {Necmettin Erbakan University, Turkey; Selcuk University,Turkey},
abstract = {In this paper, the dynamic behaviour of two degree of freedom building-like structure system against unexpected input such as seismic excitation is considered by experimentally. Proposed system consists of two floors structure with active mass damping (AMD) and shaker. Passive and active mode deflection responses of the floors are investigated and also a cart is used to suppress vibrations, which moves linear direction and is mounted on the second floor. PV (proportional and velocity) control of the cart is realized in passive mode. Moreover LQR (Linear Quadratic Regulator) control is designed to control the cart in active mode while system under excitation. For this aim a full-order observer is designed and implemented to control strategy. Displacements of cart, deflections and accelerations results of the floors are presented separately for passive and active mode responses of the system in the form of graphics. },
keywords = { Active Mass Damping, Deflection, LQR Control, Observer, PV Control, Structure},
language = {English},
publisher = {Trans Tech Publications},
pages = {316-320}
}

In this paper, the dynamic behaviour of two degree of freedom building-like structure system against unexpected input such as seismic excitation is considered by experimentally. Proposed system consists of two floors structure with active mass damping (AMD) and shaker. Passive and active mode deflection responses of the floors are investigated and also a cart is used to suppress vibrations, which moves linear direction and is mounted on the second floor. PV (proportional and velocity) control of the cart is realized in passive mode. Moreover LQR (Linear Quadratic Regulator) control is designed to control the cart in active mode while system under excitation. For this aim a full-order observer is designed and implemented to control strategy. Displacements of cart, deflections and accelerations results of the floors are presented separately for passive and active mode responses of the system in the form of graphics.

@article{tinkir2_2013,
title = {Hybrid Controller Design for Two-Floors Structure Against Northridge Earthquake},
author = {Tinkir, M.; Kalyoncu, M.; Sahin, Y.},
journal = {Applied Mechanics and Materials},
year = {2013},
volume = {307},
institution = {Necmettin Erbakan University, Turkey; Selcuk University,Turkey},
abstract = {In this study, an adaptive neural network based fuzzy logic controller (ANNFLC) and a PI (Proportional and Integral) controller are used together as hybrid controller for deflection control of two degree of freedom building-like structure system against scaled Northridge Earthquake experimentally. Proposed structure consist of two floors with a shake table and a cart which is mounted on the second floor as active mass damping (AMD) and controlled by hybrid controller. Training and testing data of ANNFLC are determined by using behaviour of PI controlled system against Northridge. Thus, ANNFLC is created and it's control performance is combined with PI controller's effect to achieve small deflection responses of the floors. Obtained hybrid controlled results are compared with passive and PI controlled results and presented in the form of graphics. },
keywords = {Active Mass Damping, Deflection, Hybrid Controller, Northridge Earthquake, Structure},
language = {English},
publisher = {Trans Tech Publications},
pages = {57-61}
}

In this study, an adaptive neural network based fuzzy logic controller (ANNFLC) and a PI (Proportional and Integral) controller are used together as hybrid controller for deflection control of two degree of freedom building-like structure system against scaled Northridge Earthquake experimentally. Proposed structure consist of two floors with a shake table and a cart which is mounted on the second floor as active mass damping (AMD) and controlled by hybrid controller. Training and testing data of ANNFLC are determined by using behaviour of PI controlled system against Northridge. Thus, ANNFLC is created and it's control performance is combined with PI controller's effect to achieve small deflection responses of the floors. Obtained hybrid controlled results are compared with passive and PI controlled results and presented in the form of graphics.