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Recent developments in semi-active control technologies enhance the possibility of an effective response reduction during a wide range of dynamic loading conditions. Most semi-active control schemes employ magnetorheological dampers (MRDs) as actuators. These devices exhibit nonlinear and hysterical behavior that complicates reactive force estimation to compensate for disturbances. In this paper, we present a novel robust schema to estimate MRD forces using a complex value convolutional neural network (CV-CNN) to overcome these problems. CV-CNN utilizes random complex value convolutional filters as parameters to reduce the measured noise by combining the training stage and the max-by-magnitude operation. Furthermore, CV-CNN is a hysteresis-model-free strategy that overcomes the parameterization in nonlinear systems. The proposed CV-CNN only requires displacement and voltage measurements for force estimation. Different metrics are used to compare results between the CV-CNN, genetic algorithm (GA), particle swarm optimization (PSO), and shallow neural network (SNN). Experimental results show the potential of the proposed CV- CNN for practical applications due to its simplicity and robustness. The CV-CNN computational time is less than that of GA and PSO. In the training stage, the CV-CNN uses 0.7% of GA's time and 1.4% of PSO. Although SNN uses 5.5% of the time consumed by the CV-CNN, the latter performs the force estimation for MRD better; its mean square error is 78.3% lower than the GA's and PSO's, and 71.4% lower than SNN's.

This article presents an active vibration control of seismically excited building structures. The control scheme is based on active disturbance rejection control, which is an attractive alternative technique for structural vibration suppression and practical motion control solution in the presence of parametric uncertainties and disturbances. The proposed active disturbance rejection control scheme uses a generalized proportional integral observer, which allows us to estimate in real time the unknown dynamics and disturbances in the building structure to cancel their effect using a part of the control signal. First, the active disturbance rejection control provides a proportional derivative controller with robustness to external disturbances and uncertainties, and its structure is expressed in a compact error-based form. An important advantage with respect to other methods is that the proposed scheme does not need the system parameters. Moreover, supposing that displacement and velocity cannot be measured directly, an online robust adaptive observer is introduced to estimate both data, required for the proportional derivative controller. The adaptive observer removes constant disturbance and attenuates measurement noise in acceleration data. Under this line, a second active disturbance rejection control scheme is introduced based on a proportional controller that, unlike proportional derivative, it only needs the velocities that can be directly estimated by integrating the acceleration signals and does not require the adaptive observer. An advantage of this scheme is its simplicity to be implemented because it only needs to tune the proportional gain. Furthermore, this scheme has a similar performance of the proportional derivative controller. The effectiveness of the proposed active disturbance rejection control schemes is demonstrated through experimental results of a reduced scale five-story building structure. The results are found to be a good step in that direction, confirming that the proposed method is promising for practical applications.

This paper presents the development of an ℋ ∞ controller synthesis designed based on the infinity norm and the frequency spectrum of the disturbance to achieve the reduction of vibrations in buildings structures subjected to seismic excitation. A feature of the proposed controller is that it can be designed around an experimental test. Through verifying Doyle’s assumptions in control ℋ ∞ theory ensure the stability of the closed-loop system. The mathematical model is introduced by means of mechanical elements and generalized through modal analysis. The effectiveness of the proposed controller is illustrated employing simulation results of a reduced scale two-stories building structure and the proposed algorithm is tested against the 1985’s Mexico city earthquake data.

This paper presents the development of an alternative Proportional-Derivative (PD) controller designed based only on system bandwidth to achieve the reduction of vibrations in buildings structures subjected to seismic excitation. A feature of the proposed controller is that it can be designed around an experimental test and the stability of the closed-loop system is ensured through the Kharitonov theorem and Bilharz criteria. The effectiveness of the proposed PD controller is illustrated using simulation results of a reduced-scale two-story building structure and the proposed algorithm is tested with data from the 1985 Mexico City earthquake. Due to the simplicity of the design, the methodology makes it a promising controller for practical applications.

A novel on-line system identification method for shear beam building models, based on a wave propagation approach, is developed as an alternative solution to modal analysis methods for the health assessment of multi-story buildings. A discrete shear beam model is introduced that is used to design an adaptive observer, allowing for the estimation of displacements and velocities, as well as the unknown shear wave velocities and damping coefficients in real-time. The adaptive observer design is based only on acceleration measurements, does not need a coordinate transformation, and uses the normalized recursive least squares method with forgetting factor and a parameter projection scheme to achieve stronger convergence. Moreover, the proposed identification scheme employs a novel parameterization based on linear integral filters, which eliminates constant disturbances and attenuates measurement noise. The algorithm efficiency is demonstrated through experimental results on a reduced scale five-story building.

A novel real time system identification method for structural health monitoring in a multi-story buildings is presented. The goal is to identify structural parameters in order to improve damage detection methods. Here, structural dynamics is modeled by means of a wave equation with Kelvin damping, that relates the stiffness loss with reduction of shear wave velocity propagation of seismic movements in structural elements. The identification system requires only acceleration signals and is based on the least squares method with forgetting factor. Moreover, a new parameterization is presented based on linear integral filters, which eliminates constant disturbances and attenuate measurement noise. The experimental results through an RC building, validate the feasibility of the proposed method.

The article deals with the development of active vibration control of seismically-excited building structures. The control scheme is based on an alternative proportional-derived (PD) controller designed based only on the bandwidth of the system, which is an attractive technique for structural vibration suppression purposes and practical motion control solutions. The tuning method is analyzed employing Kharitonov’s theorem and Routh-Hurwitz criteria, which give necessary and sufficient conditions for choosing the two PD range of gains. Based on modal analysis, the system is transformed into a set of decoupled ordinary differential equations to simplify the PD design. An important advantage concerning a classical PD controller is the proposed PD design only uses the natural frequencies, which are relatively easy to estimates around an experimental test. Moreover, the proposed approach does not need frequently tune the gains parameters, so the design procedure is greatly simplified and, the proposed scheme does not need the system parameters, which generally are unknown. This method allows generalizing the controller design for multi-story buildings without modifying the controller structure, by choosing a scalar parameter. The effectiveness of the proposed PD schemes is demonstrated through simulation and experimental results of a reduced scale two-story building prototype.

An algorithm for damage detection in a multi-story building modeled by a wave equation with Kelvin damping is presented. Damage detection is achieved by relating stiffness loss with reduction in the shear wave velocity of the seismic induced motion propagation through the structure. In order to estimate wave velocity and damping parameters, an identification system based on the least squares method with forgetting factor is used. In addition, a parameterization is presented based on linear integral filters, which eliminates constant disturbances, attenuate measurement noise and depend only on acceleration signals. Once parameters information is available, a detection threshold is designed that compares them with reference values. The experimental results validate the feasibility of the proposed method.

Summary A novel damage identification technique to estimate stiffness in a multistory building supported on solid ground is presented. Based on a shear building model, a 1-dimensional wave equation for a vertically propagating shear wave is derived. A Ricker pulse is used as excitation signal and propagated through the building. Wave propagation in the building is based on the Thomson–Haskell method, where each story is represented as a single layer in a multiple stratum model. The wave arrival times of the pulse at each story are used to calculate the stiffness of the columns. The involved calculations in this method grow only linearly with the number of stories, as opposed to other identification methods, as modal analysis, that grow geometrically; this makes this approach an interesting alternative method to asses building integrity. Simulation result for a building with heterogeneous characteristics across the stories confirms the feasibility of the proposal.

A novel technique to estimate stiffness in buildings is presented. In contrast with most of the available work in the literature that resorts to diverse forms of modal analysis, this local technique is based on the propagation of a Ricker pulse through the structure and on measuring the wave arrival times at each story of the building, represented as a single layer in a multiple stratum model. These arrival times are later used to recuperate building stiffness at each story. Wave propagation is based on the Thomson-Haskell method, that allows to generalize the wave propagation method to multi-story buildings without significant changes to the original formulation. The number of calculated parameters is small in comparison with methods based on modal analysis. This technique provides and quick and easy methodology to assess building integrity and is an interesting alternative to verify results obtained by other identification methods. Simulation results for building with heterogeneous characteristics across the stories confirm the feasibility of the proposal.Copyright © 2014 by ASME

Feasibility of recovering the parameters of a shear building model with three degrees of freedom per story using a least squares with forgetting factor algorithm is analyzed. Two orthogonal horizontal seismic signals, known as environmental noise, are used as excitation for the algorithm. Environmental noise are small magnitude signals induced by several causes: sensor noise, wind effects, machinery operation, vehicular traffic and others phenomena. These signals, in contrast with seismic excitation, do not produce structural damage and are easy to obtain by installing accelerometers on the building. The aim of this work is to show that these signals still contain relevant information related with building dynamic's response, and that with proper use of identification algorithms, precise information about the building model parameters can be obtained for use in the design of vibration control algorithms. As the identification with small magnitude signals can be executed on line before a large earthquake occurs, calculation of proper control signals would not have to wait for the results of an identification excited by a strong seismic signal, saving critical time and helping to avoid structure damage.

A novel technique for identification of buildings by the method of Thomson-Haskell is presented. The goal of this method is to detect changes in the arrival time of waves that propagate through the structure, and with this, to identify the natural frequencies of vibration. The use of this method has the advantage of identifying a relatively small number of parameters, in comparison with recursive methods based on building shear models commonly used in the literature. Simulation results show that the proposed technique is promising for identification and location of structural damage, using wave arrival times and changes on them over time.