Artificial Intelligence Approach for Seismic Control of Structures

Abstract In the first part of this research, the utilization of tuned mass dampers in the vibration control of tall buildings during earthquake excitations is studied. The main issues such as optimizing the parameters of the dampers and studying the effects of frequency content of the target earthquakes are addressed. Abstract The non-dominated sorting genetic algorithm method is improved by upgrading generic operators, and is utilized to develop a framework for determining the optimum placement and parameters of dampers in tall buildings. A case study is presented in which the optimal placement and properties of dampers are determined for a model of a tall building under different earthquake excitations through computer simulations. Abstract In the second part, a novel framework for the brain learning-based intelligent seismic control of smart structures is developed. In this approach, a deep neural network learns how to improve structural responses during earthquake excitations using feedback control. Abstract Reinforcement learning method is improved and utilized to develop a framework for training the deep neural network as an intelligent controller. The efficiency of the developed framework is examined through two case studies including a single-degree-of-freedom system and a high-rise building under different earthquake excitation records. Abstract The results show that the controller gradually develops an optimum control policy to reduce the vibrations of a structure under an earthquake excitation through a cyclical process of actions and observations. Abstract It is shown that the controller efficiently improves the structural responses under new earthquake excitations for which it was not trained. Moreover, it is shown that the controller has a stable performance under uncertainties

Semi-Active Control Systems in Bridge Engineering: A Review of the Current State of Practice

In view of the grave socioeconomic consequences of earthquake damage to bridge structures, along with their critical role in modern and older road and rail networks, this article attempts to identify and summarise the current trends in the use of semi-active control technology in bridge engineering, as an enhanced seismic response control solution, combining increased adaptability and reliability, compared to passive and active schemes. In this context, representative analytical and experimental studies, as well as some full-scale applications of semi-active control devices are first reviewed and a brief description of relevant benchmark studies is subsequently presented, with a view to serving as a point of reference for further research and development. A framework of performance-based control principles aiming at the aforementioned objectives is finally set forth

Invited Review: Recent developments in vibration control of building and bridge structures

This paper presents a state-of-the-art review of recent articles published on active, passive, semi-active and hybrid vibration control systems for structures under dynamic loadings primarily since 2013. Active control systems include active mass dampers, active tuned mass dampers, distributed mass dampers, and active tendon control. Passive systems include tuned mass dampers (TMD), particle TMD, tuned liquid particle damper, tuned liquid column damper (TLCD), eddy-current TMD, tuned mass generator, tuned-inerter dampers, magnetic negative stiffness device, resetting passive stiffness damper, re-entering shape memory alloy damper, viscous wall dampers, viscoelastic dampers, and friction dampers. Semi-active systems include tuned liquid damper with floating roof, resettable variable stiffness TMD, variable friction dampers, semi-active TMD, magnetorheological dampers, leverage-type stiffness controllable mass damper, semi-active friction tendon. Hybrid systems include shape memory alloys-liquid column damper, shape memory alloy-based damper, and TMD-high damping rubber

A semi-active H∞ control strategy with application to the vibration suppression of nonlinear high-rise building under earthquake excitations

Different from previous researches which mostly focused on linear response control of seismically excited high-rise buildings, this study aims to control nonlinear seismic response of high-rise buildings. To this end, a semi-active control strategy, in which H∞ control algorithm is used and magneto-rheological dampers are employed for an actuator, is presented to suppress the nonlinear vibration. In this strategy, a modified Kalman–Bucy observer which is suitable for the proposed semi-active strategy is developed to obtain the state vector from the measured semi-active control force and acceleration feedback, taking into account of the effects of nonlinearity, disturbance and uncertainty of controlled system parameters by the observed nonlinear accelerations. Then, the proposed semi-active H∞ control strategy is applied to the ASCE 20-story benchmark building when subjected to earthquake excitation and compared with the other control approaches by some control criteria. It is indicated that the proposed semi-active H∞ control strategy provides much better control performances by comparison with the semi-active MPC and Clipped-LQG control approaches, and can reduce nonlinear seismic response and minimize the damage in the buildings. Besides, it enhances the reliability of the control performance when compared with the active control strategy. Thus, the proposed semi-active H∞ control strategy is suitable for suppressing the nonlinear vibration of high-rise buildings

Accelerated Controller Tuning for Wind Turbines Under Multiple Hazards

During their lifecycle, wind turbines can be subjected to multiple hazard loads, such as high-intensity wind, earthquake, wave, and mechanical unbalance. Excessive vibrations, due to these loads, can have detrimental effects on energy production, structural lifecycle, and the initial cost of wind turbines. Vibration control by various means, such as passive, active, and semi-active control systems provide crucial solutions to these issues. We developed a novel control theory that enables semi-active controller tuning under the complex structural behavior and inherent system nonlinearity. The proposed theory enables the evaluation of semi-active controllers’ performance of multi-degrees-of-freedom systems, without the need for time-consuming simulations. A wide range of controllers can be tested in a fraction of a second, and their parameters can be tuned to achieve system-level performance for different optimization objectives

Fuzzy logic based adaptive vibration control system for structures subjected to seismic and wind loads

In this study, an attempt has been made to develop a Fuzzy Logic Multi Verse Optimal Control (FLMVOC) system as a new adaptive real-time vibration control mechanism for structures subjected to seismic excitation and wind load by utilizing the capability of the stochastic optimization method and fuzzy logic technique.The magnetorheological damper (MR) is deployed as a controllable vibration damping system in this study due to its excellent damping performance and low energy consumption. Therefore, the analytical model for the MR damper is formulated and integrated with the developed fuzzy logic optimal control (FLOC) algorithm. The story drift and absolute acceleration have been defined as the inputs of the fuzzy logic controller (FLC), while the MR commanding voltage is considered as the controller’s output. Then, the membership functions and fuzzy rule base have been formulated. To derive the optimal controller, the FLC with full parameters has been trained with multi objective multi verse algorithm (MOMVO). For this purpose, the MATLAB program and its Simulinks have been integrated and hybridised with finite element package to simulate and evaluate structure response for various input parameters.The developed FLMVOC system has been implemented in three story shear building subjected to seismic load and 60 story wind induced high rise building in order to evaluate its efficiency in diminishing the dynamic response of the structure.The result revealed that FLMVOC system successfully reduced structural drifts by 60%, 53%, and 41% under the effect of El Centro, Kobe, and Northridge earthquakes, respectively, while the floor absolute acceleration was reduced by 38%, 17%, and 10%, respectively. For the wind induced structure, the proposed system showed the ability to maintain the floor acceleration within people’s comfort criterion in addition to the reduction in story drift

Seismic Behaviour of Cable-Stayed Bridges: A Review

Cable-stayed bridges represent backbones in the infrastructure networks and their adequate seismic response must be ensured. These structures present complex interactions between the deck, the cables, the towers and their foundation. This, in combination with the reduced damping and the outstanding slenderness of cable-stayed bridges, renders a unique dynamic response. A complete review on the state of knowledge about the seismic behaviour of cable-stayed bridges is presented here, with special attention to the analysis techniques. The current design trends in the seismic design and control of cable-stayed bridges are also presented

Optimal Structural Control Using Wavelet-based Lqr Algorithm

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2014Dünyada yapı alanında yürütülen faaliyetler incelendiğinde, yapıların daha yüksek ve daha hafif yapılması yönünde ilerleme olduğu görülmektedir. Bu özelliklerinden dolayı söz konusu yapılar daha esnek ve sönüm oranları da daha azdır. Bunun sonucunda yapıların yaşam konforunda azalma olmaktadır. Günümüzde yapıların titreşimini minimuma indirmek için çeşitli teknikler mevcuttur. Bu araştırmada yapıların titreşim kontrolü için kullanılan LQR (doğrusal kuadratik düzenleyici) algoritmalarında wavelet tekniği ile yapılacak iyileştirme incelenmiştir. Deprem gibi rastgele yükler karakter itibariyle dinamik ve değişken frekans özelliğine sahiptir. Bundan dolayı sistemin doğal frekansı ve depremin baskın frekanslarının birbirlerine çok yakın olduğu durumlarda rezonans benzeri durumlara oluşur. Klasik LQR kontrolunda ağırlık matrisleri önceden belirlenir ve yapı dış kuvvetlerin etkisinde kontrol edilirken sabit kalırlar. Bu sebepten dolayı rezonansın yapıya etkisini göz önüne almak için LQR kontrol yönteminde iyileştirme amaçlı değişiklik yapmak gerekmektedir. Eğer R ağırlık matrisinin elemanları depremin tüm kontrol aralığında Q ağırlık matrisinin elemanlarından çok daha fazla olursa yapının tepkisi azalır. Fakat buna karşılık kontrol kuvvetleri ve dolayısıyla da maliyet artar. Bu sorunu çözmek için, ağırlık matrisini yapının her andaki ihtiyacına göre değiştirmek uygun bir çözüm olabilir. Rezonansın olduğu frekanslarda yapının tepkisini azaltmak için ağırlık matrislerini belirtilen frekans bantlarında revize etmek gerekir. Eğer R ağırlık matrisi rezonansın ortaya çıktığı alt aralıklarda azaltılırsa kontrol enerjisinin gereksiz artışı önlenebilir. Bunun için deprem sinyalini ayrıştırmak gerekir ki; deprem frekansları her zaman aralığında belirlensin. Sinyalleri ayrıştırmak için çeşitli yollar mevcuttur. Fourier analizi sinyalleri zaman alanından frekans alanına dönüştüren klasik bir yöntemdir. Fourier analizi tekniğinin en önemli kusurlarından biri frekans alanına dönüştürmede zaman alanındaki bilgiler silinmektedir. Sonuç olarak, Fourier dönüşümündeki bir sinyale bakınca belirli bir olayın ne zaman olduğunu belirtmek zordur. Eğer sinyal özellikleri dönüşüm süresince fazla değişmedi ise, başka bir değişle sinyal sabit (stationary) kalırsa hiçbir sorun yaşanmaz. Ama deprem sabit olmayan özelliklere sahiptir ve bundan dolayı Fourier dönüşümüyle belirtilen özellikleri gözlemek mümkün değildir. Belirtilen sorunu çözmek için bu çalışmada daha önce geliştirilen Wavelet yöntemi kullanılmıştır. Wevelet yönteminin her andaki zaman-frekans dönüşüm özelliğinden yararlanarak LQR algoritmasını iyileştirmek mümkündür. İlk andan itibaren son kontrol anına kadar, her frekans bandında deprem nedeniyle oluşan enerji sonucunda Wavelet in her andaki ayrık kontrol değeri güncellenir. Bu bilgiler her frekans bandındaki ağrılık matrislerini güncellemek için kullanılır. Bu nedenle kazanç matrisleri zamanla değiştiği için karşı gelen Riccati matris denklemleri de değişmektedir. Klasik LQR kontrol yönteminde Q ve R ağırlık matrisleri sabit iken, bu çalışmada incelenen yöntemde kazanç matrislerinin önceden belirlenen ağırlık matrislerinden elde edilmesi yerine her andaki tepkiye bağlı olarak wavelet yaklaşımı ile güncellenen ağırlık matrislerinden elde edilen kazanç matrisleri kullanılmaktadır. Önerilen yöntemin etkinliğini gösterebilmek için, deprem etkisinde ve en üst katında aktif sönümleyici olan ve fay hattına yakın 10 katlı bir binanın dinamik davranışı araştırılmış ve önerilen yöntemin LQR yaklaşımını iyileştirmek için kullanılabileceği gösterilmiştir.Current trends in construction industry demands taller and lighter structures, which are also more flexible and having quite low damping value. This increases failure possibilities and also problems from serviceability point of view. Now-a-days several techniques are available to minimize the vibration of the structure. In this study to control the response of buildings, a modified linear quadratic regulator (LQR) algorithm based on wavelet analysis has been proposed. The formulation of the proposed wavelet-LQR algorithm uses the information derived from the discrete wavelet transform (DWT) analysis of the motivation in real time. The real time DWT controller is applied to obtain the local energy distribution over frequency bands for each time interval. This information is used to adaptively design the controller by updating the weighting matrices. The optimal LQR control problem is solved for each time interval with updated weighting matrices, through the Riccati equation, leading to time-varying gain matrices. The positive aspect of current work is that, the gain matrices are achieved adaptively in real time. The method is tested on a 10-story structure subject to several historical pulse-like near-fault ground motions.The results indicate that the proposed method is more effective at reducing the displacement response of the structure in real time than conventional LQR controllers.Yüksek LisansM.Sc

Lateral and torsional seismic vibration control for torsionally irregular buildings

During strong earthquakes or wind gusts, it is likely that buildings with torsional irregularity in the plan can be seriously damaged, partially collapsed or fully collapsed. This is because Torsionally Irregular Buildings (TIBs) may have significant aerodynamic torsion loads that increase the eccentricity between the center of mass and the center of rigidity, especially in dominant torsion modes. For this reason, torsion leads to excessive increase in lateral motions when dynamic loads excite the buildings. Torsional irregularity is one of the main failure causes during strong dynamic excitations due to earthquakes or wind gusts. Ignoring torsional irregularity in seismic design analysis can cause unexpected damages and losses. To enhance the safety and performance of buildings, most of the current seismic provisions address this irregularity in two main ways. The first is computing torsional moment at each floor by using equations provided in various current seismic code provisions. After they are applied on each floor, the seismic analysis will be performed. The second is shifting the center of mass (CM) or stiffness (CS) to eliminate the eccentricity by putting additional masses or structural components such as braced frame systems on buildings. This research developed and validated a new torsionally effective control system for the purpose of enhancing the performance/safety and mitigating structural failure in Torsionally Irregular Buildings (TIBs) under bidirectional strong earthquake loads. It introduces the new integrated control system (ICS) applied to a benchmark 9-story steel building developed for the SAC project in California to suppress the undesirable lateral and torsional coupling effects due to eccentricity. The dynamic responses of the system were evaluated under N-S and W-E components of the real earthquake excitations of the El Centro (1940), Loma Prieta (1989) and Kocaeli (1999) earthquakes. First the traditional method (cross-braced frame systems) was implemented in the benchmark building with different pre-determined placement layouts. The most effective placement was determined and the benchmark building was analyzed with that for comparison purpose. Secondly, tuned mass dampers (TMDs) were designed and applied to start from the center of mass (CM) through two translational directions under bi-directional seismic loads such as N-S and E-W components of selected ground motions. Then the performance evaluation for TMDs was determined. The effectiveness of the TMD system was evaluated in terms of energy analyses and performance evaluation criteria including maximum floor displacement, maximum drift, and maximum floor acceleration. Based on these comparisons, there is a substantial reduction of the amplitudes of the frequency response validated the effectiveness of the ICS in controlling the seismic responses for two-way eccentric elastic buildings. Unlike traditional TMDs placed in two orthogonal directions, the ICS is more comprehended to control not only two orthogonal (x- and y-) directions, but also effectively control rotational (θ-) direction. By means of the proposed system configuration, the structures first-three dominants modes can effectively be controlled by the ICS regardless of any external energy sources. The ICS is also more robust in restricting the inter-story drift ratio as compared with TMDs. It sufficiently mitigates the RMS and peak displacement on the top floor of the Benchmark building. Thus, the ICS has a better performance than the TMDs and the CFs placement in terms of response reductions. According to the performance evaluation criteria, there are substantial reductions for both the tuning case and the detuning case. For both cases, the performance indexes are overall less than the bare Benchmark building and its respective application with the TMDs. FOR FULL-TEXT READ, PLEASE CLICK ON THE LINK BELOW https://repository.lib.fit.edu/handle/11141/280