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  Subjects -> ENERGY (Total: 241 journals)
    - ELECTRICAL ENERGY (3 journals)
    - ENERGY (159 journals)
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ENERGY (159 journals)                  1 2 | Last

Advances in Building Energy Research     Hybrid Journal   (10 followers)
Advances in High Energy Physics     Open Access   (12 followers)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (13 followers)
American Journal of Energy Research     Open Access   (2 followers)
Annals of Nuclear Energy     Hybrid Journal   (6 followers)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (1 follower)
Annual Review of Resource Economics     Full-text available via subscription   (10 followers)
Applied Nanoscience     Open Access   (7 followers)
Applied Solar Energy     Hybrid Journal   (9 followers)
Archives of Thermodynamics     Open Access   (3 followers)
Atomic Energy     Hybrid Journal   (4 followers)
Atoms for Peace: an International Journal     Hybrid Journal   (1 follower)
Biofuels     Full-text available via subscription   (7 followers)
Biomass Conversion and Biorefinery     Partially Free   (5 followers)
Bulletin de droit nucleaire     Full-text available via subscription   (1 follower)
Canadian Journal of Remote Sensing     Full-text available via subscription   (12 followers)
Canadian Water Resources Journal     Hybrid Journal   (17 followers)
Carbon Management     Full-text available via subscription   (4 followers)
Catalysis for Sustainable Energy     Open Access   (1 follower)
Chain Reaction     Full-text available via subscription  
Clefs CEA     Full-text available via subscription   (1 follower)
Computational Water, Energy, and Environmental Engineering     Open Access   (1 follower)
Continental Journal of Renewable Energy     Open Access   (8 followers)
Current Sustainable/Renewable Energy Reports     Hybrid Journal  
Dams and Reservoirs     Hybrid Journal   (2 followers)
Development of Energy Science     Open Access  
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (1 follower)
E3S Web of Conferences     Open Access  
Electrical and Power Engineering Frontier     Open Access   (7 followers)
Electronic Journal of Energy & Environment     Open Access   (6 followers)
Energy     Partially Free   (17 followers)
Energy & Fuels     Full-text available via subscription   (21 followers)
Energy and Buildings     Hybrid Journal   (6 followers)
Energy and Environment Research     Open Access   (7 followers)
Energy and Power Engineering     Open Access   (6 followers)
Energy Conversion and Management     Hybrid Journal   (6 followers)
Energy Efficiency     Hybrid Journal   (9 followers)
Energy Materials: Materials Science and Engineering for Energy Systems     Hybrid Journal   (16 followers)
Energy Policy     Partially Free   (33 followers)
Energy Prices and Taxes     Full-text available via subscription   (4 followers)
Energy Procedia     Open Access   (2 followers)
Energy Science & Engineering     Open Access   (2 followers)
Energy Science and Technology     Open Access   (9 followers)
Energy Strategy Reviews     Partially Free   (4 followers)
Energy Studies Review     Open Access   (3 followers)
Energy Systems     Hybrid Journal   (7 followers)
Energy Technology     Partially Free   (2 followers)
Energy, Sustainability and Society     Open Access   (14 followers)
Environmental Progress & Sustainable Energy     Hybrid Journal   (3 followers)
EPJ Photovoltaics     Open Access  
Frontiers in Energy     Hybrid Journal   (2 followers)
Frontiers in Energy Research     Open Access  
Fuel and Energy Abstracts     Full-text available via subscription   (5 followers)
Functional Materials Letters     Hybrid Journal   (1 follower)
Gcb Bioenergy     Hybrid Journal   (1 follower)
Geothermal Energy     Open Access  
GeoWorld     Full-text available via subscription   (2 followers)
Green     Full-text available via subscription   (1 follower)
Hyperfine Interactions     Hybrid Journal   (2 followers)
IEA Electricity Information     Full-text available via subscription   (5 followers)
IEA Natural Gas Information     Full-text available via subscription   (4 followers)
IEEE Power and Energy     Full-text available via subscription   (7 followers)
IEEE Transactions on Energy Conversion     Hybrid Journal   (5 followers)
IEEE Transactions on Nuclear Science     Hybrid Journal   (7 followers)
IEEE Transactions on Power Systems     Hybrid Journal   (9 followers)
IET Power Electronics     Hybrid Journal   (7 followers)
IngenierĂ­a EnergĂ©tica     Open Access  
Innovations : Technology, Governance, Globalization     Hybrid Journal   (6 followers)
International Journal of Alternative Propulsion     Hybrid Journal   (1 follower)
International Journal of Ambient Energy     Hybrid Journal   (2 followers)
International Journal of Applied Power Engineering     Open Access  
International Journal of Clean Coal and Energy     Open Access   (3 followers)
International Journal of Critical Infrastructure Protection     Hybrid Journal   (5 followers)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (3 followers)
International Journal of Emerging Electric Power Systems     Full-text available via subscription   (4 followers)
International Journal of Emerging Multidisciplinary Fluid Sciences     Full-text available via subscription  
International Journal of Energy and Environmental Engineering     Open Access   (2 followers)
International Journal of Energy and Power     Open Access   (4 followers)
International Journal of Energy Engineering     Open Access   (10 followers)
International Journal of Energy Research     Hybrid Journal   (8 followers)
International Journal of Energy Science     Open Access   (1 follower)
International Journal of Flow Control     Full-text available via subscription   (1 follower)
International Journal of Global Energy Issues     Hybrid Journal   (6 followers)
International Journal of Green Energy     Hybrid Journal   (5 followers)
International Journal of Hydrogen Energy     Partially Free   (7 followers)
International Journal of Marine Energy     Full-text available via subscription   (1 follower)
International Journal of Nuclear Desalination     Hybrid Journal   (2 followers)
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (1 follower)
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal   (2 followers)
International Journal of Nuclear Hydrogen Production and Applications     Hybrid Journal   (2 followers)
International Journal of Nuclear Knowledge Management     Hybrid Journal   (1 follower)
International Journal of Power and Energy Conversion     Hybrid Journal   (3 followers)
International Journal of Regulation and Governance     Hybrid Journal   (2 followers)
International Journal of Sustainable Energy     Hybrid Journal   (8 followers)
International Journal of Sustainable Engineering     Hybrid Journal   (7 followers)
International Journal of Thermodynamics     Open Access   (1 follower)
ISRN Power Engineering     Open Access   (1 follower)
ISRN Renewable Energy     Open Access   (5 followers)
Journal of Alternate Energy Sources & Technologies     Full-text available via subscription  
Journal of Building Performance Simulation     Hybrid Journal   (3 followers)

        1 2 | Last

Structural Control and Health Monitoring    [6 followers]  Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1545-2255 - ISSN (Online) 1545-2263
     Published by John Wiley and Sons Homepage  [1594 journals]   [SJR: 1.148]   [H-I: 21]
  • A multi‐purpose seismic test rig control via a sliding mode approach
    • Authors: Salvatore Strano; Mario Terzo
      Pages: n/a - n/a
      Abstract: The paper describes an experimental and theoretical research activity based on a versatile seismic test rig employed to characterize seismic isolators or structures. The system is hydraulically actuated and exhibits a high nonlinear behaviour because of the presence of the dead band and frictions. The double functionality of the test rig is based on two possible configurations concerning the hydraulic actuation system, which cause an induced variability in the parameters; moreover, the seismic isolators and the test structures are characterized by properties that are a priori unknown. Because of the several operating conditions, the test rig is affected by structured and unstructured uncertainties that require a robust approach for the control of the position. Starting from a nonlinear dynamic model, a sliding control is derived taking into account the dead band and a large variability of the hydraulic and geometric parameters. The simulations and the experimental results confirm the effectiveness, in terms of stability and tracking error, of the proposed control for the different configurations of the plant. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-19T21:29:35.155578-05:
      DOI: 10.1002/stc.1641
       
  • Local positioning systems versus structural monitoring: a review
    • Authors: Lijun Wu; Fabio Casciati
      Pages: n/a - n/a
      Abstract: Structural monitoring and structural health monitoring could take advantage from different devices to record the static or dynamic response of a structure. A positioning system provides displacement information on the location of moving objects, which is assumed to be the basic support to calibrate any structural mechanics model. The global positioning system could provide satisfactory accuracy in absolute displacement measurements. But the requirements of an open area position for the antennas and a roofed room for its data storage and power supply limit its flexibility and its applications. Several efforts are done to extend its field of application. The alternative is local positioning system. Non‐contact sensors can be easily installed on existing infrastructure in different locations without changing their properties: several technological approaches have been exploited: laser‐based, radar‐based, vision‐based, etc. In this paper, a number of existing options, together with their performances, are reviewed. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-19T21:29:12.401715-05:
      DOI: 10.1002/stc.1643
       
  • An optimised tuned mass damper/harvester device
    • Authors: A. Gonzalez‐Buelga; L. R. Clare, A. Cammarano, S. A. Neild, S. G. Burrow, D. J. Inman
      Pages: n/a - n/a
      Abstract: Much work has been conducted on vibration absorbers, such as tuned mass dampers (TMD), where significant energy is extracted from a structure. Traditionally, this energy is dissipated through the devices as heat. In this paper, the concept of recovering some of this energy electrically and reuse it for structural control or health monitoring is investigated. The energy‐dissipating damper of a TMD is replaced with an electromagnetic device in order to transform mechanical vibration into electrical energy. That gives the possibility of controlled damping force whilst generating useful electrical energy. Both analytical and experimental results from an adaptive and a semi‐active tuned mass damper/harvester are presented. The obtained results suggest that sufficient energy might be harvested for the device to tune itself to optimise vibration suppression. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-19T21:06:52.562676-05:
      DOI: 10.1002/stc.1639
       
  • A multi‐reference‐based mode selection approach for the
           implementation of NExT–ERA in modal‐based damage detection
    • Authors: S M Faisal Mahmood; Nicholas Haritos, Emad Gad, Lihai Zhang
      Pages: n/a - n/a
      Abstract: A modal‐based global method for identification, localization and quantification of damage of a shear frame structure is presented in this paper. The method involves identification of modal parameters from the vibration responses of the structure only (output only) using a combination of natural excitation technique (NExT) and eigensystem realization algorithm (ERA), and determination of stiffness parameters using very few identified modes by employing a least squares solution procedure. Finally, damage is indicated by comparing the stiffnesses of the (possibly) damaged structure with that of the undamaged structure. The implementation of NExT–ERA requires a reference channel for modal identification, but several limitations of using a single reference channel have been identified from the investigations of this study. To overcome the limitations, a new approach called multi‐reference‐based mode selection is proposed in this paper. The approach makes use of all the available DOFs, but one at a time, as reference channels and identifies the best representative modes of the structure by a mode screening process and a mode separation process. The approach is also automated for expediency and possible real‐time application. The presented damage detection methodology is implemented on the analytical phase I and experimental phase II of the IASC‐ASCE SHM benchmark problem and shows an accuracy of around 90% in damage detection. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-14T22:45:31.293928-05:
      DOI: 10.1002/stc.1638
       
  • Selective sensitive finite element model updating: an improved approach
    • Authors: Maximilian Billmaier; Christian Bucher, Christoph Adam
      Pages: n/a - n/a
      Abstract: This paper discusses the realization of dynamic excitations that are used to complete finite element model updating, based on the selective sensitivity approach. It is explained how structures with many DOFs respond in desired parameter (in‐) sensitive output patterns and how such patterns can be achieved without substantial previous theoretical knowledge. The excitation of selective sensitive response patterns has been defined in the literature as the fundamental requirement to perform parameter (in‐) sensitive model updating. Up to now, the practical generation of selective sensitive response patterns on existing and possible complex structures has been questionable. Consequently, in this paper, a major effort is dedicated to overcome this problem and to provide an excitation approach that can be realized in practice. In a test example, the system parameters of a continuous steel beam are identified, taking into account the minimum excitation configuration given by four available electro dynamic shakers. The realization of different and independent experimental configurations is shown. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-10T01:54:09.666842-05:
      DOI: 10.1002/stc.1640
       
  • Issue Information
    • Pages: i - ii
      Abstract: No abstract is available for this article.
      PubDate: 2014-01-09T23:08:14.515679-05:
      DOI: 10.1002/stc.1608
       
  • The technique of digital image correlation to identify defects in glass
           structures
    • Authors: Emanuela Speranzini; Stefano Agnetti
      Pages: n/a - n/a
      Abstract: The article describes an experiment using the technique of digital image correlation (DIC) to identify and analyse defects in glass structures. The investigation involved three sets of glass structures, that is, float glass sheets, with or without any defects and subjected to bearing tests. The DIC technique perfectly identified not only the position and size of the defect but also the magnitude of deformations around the defect itself. Low stress values also indicate that strains concentrate around the defects. This enables the DIC method to be used to investigate the quality of glass elements, to detect the presence of defects and to monitor the most critical structural elements. The results obtained with the DIC technique were confirmed by comparing them with data gathered from the analysis of the fracture surface. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-06T11:07:03.085378-05:
      DOI: 10.1002/stc.1629
       
  • Real‐time identification of time‐varying tension in stay
           cables by monitoring cable transversal acceleration
    • Authors: Hui Li; Fujian Zhang, Yizhou Jin
      Pages: n/a - n/a
      Abstract: Stay cables are critical components in bridges. However, stay cables suffer from severe fatigue damage. Therefore, a monitoring technique to obtain the time history of the tension in stay cables is important. Because the acceleration of stay cables is readily measurable, approaches to identify cable tension based on frequency analysis and monitored cable acceleration have been widely investigated and used in practice. However, this type of approach can only identify a time‐invariant tension of a stay cable over a specified duration, not the time‐varying tension. This paper proposes an approach to identify the time‐varying tension of stay cables by monitoring cable accelerations. The tension variation in stay cables is caused by vehicles passing over the bridge. The real‐time identification algorithm that determines the time‐varying tension of stay cables is proposed using an extended Kalman filter based on both the transversal monitored acceleration at a single location on the cable and the monitored wind speed on the bridge, where the time‐varying tension is a state variable that is identified. A stay cable from the Nanjing Yangtze River No. 3 Bridge was used for the numerical study. The time‐varying tension of the stay cable can be identified when either a single vehicle or multiple vehicles pass over the bridge. The robustness of the proposed approach is also investigated through deviations in the initial tension, initial displacement, and velocity of the stay cable. An experiment was conducted on a scaled stay cable with time‐varying tension excited by wind. The time‐varying cable tension of the cable was identified by the proposed approach and compared with the real time‐varying cable tension. The identification accuracy and robustness of the proposed approach is verified through the experiment and numerical study. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-17T05:03:39.488386-05:
      DOI: 10.1002/stc.1634
       
  • A low‐noise, real‐time, wireless data acquisition system for
           structural monitoring applications
    • Authors: Zhicong Chen; Fabio Casciati
      Pages: n/a - n/a
      Abstract: Structural health monitoring systems are conceived to automatically monitor the structural health state in real‐time. The high‐cost and the labor intensive installation of wired monitoring system suggest that structural monitoring systems be realized of a wireless nature. This study explores the development of a general and high‐performance wireless data acquisition system (WDAQS) specifically designed for sensors commonly adopted in structural health monitoring applications. When compared with wired sensor technology, wireless sensor technology suffers limited energy supply, long data collection delay, big noise floor, and data loss. Addressing these issues, in the design of the WDAQS, several features are pursued, including flexible sensor interfaces, high power efficiency, low‐noise data acquisition, and real‐time and lossless data transmissions. The design of the system is presented in detail in terms of hardware, firmware, and software. Several experiments are carried out to validate and evaluate the system. The results show that the WDAQS is able to acquire high‐quality data. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-17T05:02:58.731847-05:
      DOI: 10.1002/stc.1636
       
  • Leakage monitoring using percolation sensors for revealing structural
           damage in engineering structures
    • Authors: Helge Pfeiffer; Peter Heer, Mark Winkelmans, Wilson Taza, Ioannis Pitropakis, Martine Wevers
      Pages: n/a - n/a
      Abstract: There is a continuous need for the monitoring of engineering structures, especially when scheduled inspections are difficult to perform or if they are too expensive. The present paper gives some results on the performance of sensors on the basis of percolation thresholds that are able to detect leakage of diverse harmful liquids, such as water, hydraulic liquids, kerosene and jet engine oils. The focus here lies on sensor systems that give semi‐quantitative, fuse‐like information on the presence of harmful liquids, which indirectly gives evidence on the presence of structural damage. The common underlying principle is the interruption of percolation conductivity when the respective sensing material is exposed to harmful liquids; that is, the electrical conductivity is essentially lost by sorption and swelling of a dedicated matrix material. The temperature dependence and response times give valuable information on the usability of the sensor in the respective environments. The sensor can be manufactured as a cord sensor or as self‐adhesive patches where the functional layer is deposited by screen printing. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-17T05:02:46.139357-05:
      DOI: 10.1002/stc.1630
       
  • Application of sensor technologies for local and distributed structural
           health monitoring
    • Authors: C. Sbarufatti; A. Manes, M. Giglio
      Pages: n/a - n/a
      Abstract: The work presented in this paper deals with the application of different sensor technologies for fatigue crack damage monitoring of metallic helicopter fuselages. A test programme has been conducted, consisting of seven fatigue crack propagation tests on aluminium panels (skin with riveted stringers) representative of the rear fuselage of a helicopter. Electrical crack gauges and comparative vacuum monitoring sensors have been used locally to monitor propagating cracks. A network of optical fibre Bragg gratings is presented as a valid possibility for distributed monitoring (based on strain field dependence on damage), alternative to consolidated electrical resistance‐based strain gauges. A Smart Layer based on piezoelectric transducers that emit and receive Lamb wave signals has also been analysed in this paper for distributed monitoring. Two damages have been considered: a skin crack artificially initiated on a panel bay and a skin crack propagating from a rivet hole after stringer failure. Damage sensitivity has been evaluated and compared among the considered technologies, thus providing useful recommendations for each considered system, together with advantages and drawbacks concerning their suitability for on‐board installation and monitoring. The damage index sensitivity to operative condition, load in particular, is verified and compared with damage effect for distributed networks. A finite element model able to describe any selected feature sensitivity to the monitored damage is also presented as a useful tool for the optimization of the structural health monitoring system design process. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-09T06:40:20.193146-05:
      DOI: 10.1002/stc.1632
       
  • Design of viscous fluid passive structural control systems using pole
           assignment algorithm
    • Authors: A. R. Zare; M. Ahmadizadeh
      Pages: n/a - n/a
      Abstract: A methodology is developed for the design of optimum viscous fluid passive energy dissipation systems using pole assignment active control algorithm. In this method, the procedure to assign the new structural poles is slightly modified such that the resulting structural properties (i.e., the optimum locations of system poles) can be achieved merely by modification of structural stiffness and addition of a passive control system. A combination of stiffness reduction and increase of damping is utilized to reduce both acceleration and displacement response. It is shown that the control systems designed using this method provide structural performances slightly better than or close to those of ordinarily designed optimum passive systems. Furthermore, by an educated selection of the locations of the structural poles, the proposed method provides more versatility in the design of passive control systems. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-09T06:34:39.318324-05:
      DOI: 10.1002/stc.1633
       
  • Value of information: impact of monitoring on decision‐making
    • Authors: Daniele Zonta; Branko Glisic, Sigrid Adriaenssens
      Pages: n/a - n/a
      Abstract: Structural health monitoring (SHM) is a process aimed at providing accurate and in‐time information concerning structural health condition and performance, which can serve as an objective basis for decision‐making regarding operation, maintenance, and repair. However, at the current state of practice, SHM is less used on real structures, and one reason for this is the lack of understanding of the Value of Information obtained from SHM. Consequently, even when SHM is implemented, bridge managers often make decisions based on experience or common sense, frequently considering with reserve and sometimes disregarding the suggestions arising from SHM. Managers weigh the SHM results based on their prior perception of the state of the structure and the confidence that they have in the specific applied SHM system and then make decisions considering the perceived effects of the actions they can undertake. In order to address and overcome the aforementioned identified limitations in the use of the SHM, a rational framework for assessment of the impact of the SHM on decision‐making is researched and proposed in this paper. The framework is based on the concept of Value of Information and demonstrated on the case study of the Streicker Bridge, a new pedestrian bridge on Princeton University campus. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-01T23:36:00.914677-05:
      DOI: 10.1002/stc.1631
       
  • Free vibration of taut cable with a damper and a spring
    • Authors: Haijun Zhou; Limin Sun, Feng Xing
      Pages: n/a - n/a
      Abstract: The damping and frequency of taut cable with a damper and a spring are investigated in this paper, which is motivated by cross‐ties and damper that are both utilized in mitigation of oscillation of the stays in cable‐stayed bridges or damper located near cable anchorage with rubber bushing. The dynamic characteristics of the cable‐damper‐spring system are analyzed on the basis of the taut string theory and considering the compatibility requirements on each constraint point. By using a transfer matrix method, the complex frequency equation of the cable‐damper‐spring system is derived. The complex frequency equation is further re‐written in terms of real and imaginary parts. The special limiting solutions are presented. Asymptotic approximate solutions for damper and spring close to cable ends are developed with small frequency shifts between free cable and damped system mode. The effects of spring stiffness and location to maximum cable vibration damping, optimum damper constant, and frequency are also addressed when spring is not located near cable anchorage. The mode behaviors when damper and spring is parallel connected are given. The general solutions for arbitrary location of damper and spring along the cable are further discussed. The results of this study are helpful to understanding the damper parameter optimization of cable‐damper‐rubber‐bushing system and the basic dynamics of the complex cable‐cross‐ties‐damper system. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-21T06:45:36.001433-05:
      DOI: 10.1002/stc.1628
       
  • Controlled loop substructure identification for shear structures
    • Authors: Dongyu Zhang; Erik A. Johnson
      Pages: n/a - n/a
      Abstract: In this paper, a substructure identification method is proposed to estimate the parameters of any story in a shear structure by using only limited floor accelerations. A two‐story standard substructure is used to divide a shear structure into substructures; two identification problems are derived for the standard substructure, each of which identifies the parameters of one story given that the parameters of the other are known. By connecting these two identification problems in a loop manner, the loop substructure identification (LSI) method formulates a sequence of estimation problems to directly identify both story parameters of the standard substructure. If the structural masses are unknown, this loop identification method can still be applied to estimate mass‐normalized structural parameters as well as the relative mass distribution of the structure. An error analysis is carried out for the two identification problems, the results of which are used to derive the condition for convergence of the LSI. The result shows that the loop identification sequence is conditionally converged and some structural responses play a vital role in determining the convergence. To ensure the convergence and the subsequent accurate estimates, the controlled LSI method is proposed, which utilizes specially designed structural control systems to temporarily change the structural dynamic closed‐loop responses and achieve converged accurate identification results. A five‐story shear building is used to verify the convergence condition and to demonstrate that the specially designed control systems can provide the converged estimation results. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-18T23:28:21.337361-05:
      DOI: 10.1002/stc.1626
       
  • Monitoring of typhoon effects on a super‐tall building in Hong Kong
    • Authors: Q. S. Li; L. H. Zhi, J. Yi, Alex To, Jiming Xie
      Pages: n/a - n/a
      Abstract: A super‐tall building with height of 420 m and 88 floors is located in central Hong Kong. Field monitoring of wind effects on the high‐rise structure was conducted during the passage of several typhoons on the basis of a wind and movement monitoring system installed in the building. Field data such as wind speed, wind direction, pressures on cladding, acceleration and displacement responses were simultaneously recorded during the typhoons and then analyzed. Typhoon wind parameters including turbulence intensity, gust factor, peak factor, turbulence integral length scale and power spectral density were presented and discussed. The dynamic properties of the high‐rise structure were determined from the field measurements and compared with those calculated at the design stage. The damping ratios of the super‐tall building were evaluated by a random decrement technique, which demonstrates amplitude‐dependent characteristics. The relationships between the structural dynamic responses and the approaching wind speed were analyzed. Wind tunnel tests were conducted to investigate the wind effects on the super‐tall building. The field‐measured acceleration responses were found to be consistent with the model test results. Finally, the serviceability performance of the super‐tall building during the typhoons was assessed on the basis of the field measurement results. The findings of the paper are expected to be of considerable interest and practical use to professionals and researchers involved in wind‐resistant designs of super‐tall buildings. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-18T02:25:59.978656-05:
      DOI: 10.1002/stc.1622
       
  • Blind denoising of structural vibration responses with outliers via
           principal component pursuit
    • Authors: Yongchao Yang; Satish Nagarajaiah
      Pages: n/a - n/a
      Abstract: Structural vibration responses themselves contain rich dynamic information, exploiting which can lead to tackling the challenging problem: simultaneous denoising of both gross errors (outliers) and dense noise that are not uncommon in the data acquisition of SHM systems. This paper explicitly takes advantage of the fact that typically only few modes are active in the vibration responses; as such, it is proposed to re‐stack the response data matrix to guarantee a low‐rank representation, through which even heavy gross and dense noises can be efficiently removed via a new technique termed principal component pursuit (PCP), without the assumption that sensor numbers exceed mode numbers that used to be made in traditional methods. It is found that PCP works extremely well under broad conditions with the simple but effective strategy no more than reshaping the data matrix for a low‐rank representation. The proposed PCP denoising algorithm overcomes the traditional PCA (or SVD) and low‐pass filter denoising algorithms, which can only handle dense (Gaussian) noise. The application of PCP on the health monitoring data of the New Guangzhou TV Tower (Canton Tower) shows its potential for practical usage. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-06T00:40:24.349147-05:
      DOI: 10.1002/stc.1624
       
  • Study on semi‐active tuned mass damper with variable damping and
           stiffness under seismic excitations
    • Authors: Chao Sun; Satish Nagarajaiah
      Pages: n/a - n/a
      Abstract: In the present study, a semi‐active tuned mass damper (STMD) with variable damping coefficient and stiffness is evaluated under seismic excitations. Variation of the damping ratio of the STMD is implemented through tracking the displacement of the STMD.If the tracked amplitude of the STMD is increasing, damping ratio of the STMD is set to zero, or else it is set to an appropriate nonzero value. Stiffness of the STMD is tuned through tracking the displacement of the primary structure, which is analyzed using a short‐time Fourier transform‐based control algorithm. Both far‐field and near‐fault ground motions are used to examine the effectiveness of the STMD and the control algorithm. Displacement time history and response (displacement and acceleration) spectra are obtained for the cases of an optimal passive TMD and an STMD. It is found that the STMD with variable damping ratio and frequency can effectively attenuate the seismic responses and outperform the optimal passive TMD. In addition, results are obtained for the case that damage occurs to the primary structure during an earthquake. The study indicates that the STMD controlled by the proposed algorithm can rapidly capture the variation of the structure and remains tuned with the primary structure, whereas the optimal TMD becomes off‐tuned when damage occurs. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-06T00:23:13.249098-05:
      DOI: 10.1002/stc.1620
       
  • A robust decentralized control method based on dimensionless parameters
           with practical performance criterion for building structures under seismic
           excitations
    • Authors: Nicolas Giron; Masayuki Kohiyama
      Pages: n/a - n/a
      Abstract: A robust and decentralized control method for reducing vibration in a building, based on the Lyapunov‐control function, is proposed and investigated. A new parameter that gives flexibility to the control design is introduced, and the control law is expressed in terms of dimensionless parameters. In addition, an expression adapted for semi‐active control of which feedback gain is finite is proposed for a particular case. Analytical proof of the performance is completely derived for a system in which the control distribution matrix is not singular and a practical performance criterion is obtained. The influence of each parameter, along with the validity of the proposed performance criterion and the robustness to the uncertainties in the structural parameters, is extensively discussed with a single‐degree‐of‐freedom numerical example. The performance of a decentralized system and the controller design in the case where the control distribution matrix is singular are discussed with a two‐degree‐of‐freedom numerical application. A shaking table experiment using a small‐scale model of a high‐rise building with a vibration control device is conducted to verify the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-10-24T02:30:50.400157-05:
      DOI: 10.1002/stc.1621
       
  • Durability evaluation of reinforced masonry by fatigue tests and acoustic
           emission technique
    • Authors: Alberto Carpinteri; Alessandro Grazzini, Giuseppe Lacidogna, Amedeo Manuello
      Pages: n/a - n/a
      Abstract: An experimental analysis has been carried out on the long‐term behaviour of composite specimens and walls made with historical brickwork. The test pieces were subjected both to static and to cyclic loading tests (accelerate static creep) and to freezing‐thawing thermo‐hygrometric tests in order to study the durability of different strengthening mortars. The acoustic emission (AE) monitoring technique was also used to assess the damage localization and to predict the time to failure of the strengthened walls during fatigue tests. The AE is a very effective non‐destructive technique that permits to estimate the amount of energy released during fracture propagation. Damage evolution during fatigue compressive loading, in terms of measured strains and the AE counting number, can be divided into three stages; fatigue life can be predicted from the slope of the AE counting number rate diagram. Starting from an AE monitoring, a special methodology has been developed to predict the service life of creep damaged masonry structures. The novelty of this work consists in the experimental confirmation that the AE technique is able to analyse the creep curves of masonry strengthening mortars. Therefore, it demonstrated that by the AE technique, it is also possible to evaluate the durability of strengthening materials subjected to load histories in the time. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-10-17T08:41:43.494516-05:
      DOI: 10.1002/stc.1623
       
  • Determining the physical limits on semi‐active control performance:
           a tutorial
    • Authors: P. S. Harvey; H. P. Gavin, J. T. Scruggs, J. M. Rinker
      Pages: n/a - n/a
      Abstract: Control forces in semi‐active control systems are constrained by the dynamics of actuators that regulate energy transmission through variable damping and/or stiffness mechanisms. The potential benefit of the development and implementation of new semi‐active control devices and applications can be determined by optimizing the controlled performance subject to the constraints of the dynamics of the system being controlled (given by the state equations), the constraints associated with the dynamics of the semi‐active device, and the expected external forcing. Performance optimization of semi‐active control systems is a constrained two‐point boundary value problem. This paper shows how this constrained problem can be transformed into an unconstrained problem, and how to easily solve the related unconstrained problem with Matlab. The method is illustrated on the performance optimization of a simple semi‐active tuned‐mass‐damper for a structure subjected to ground accelerations. Several possible extensions of this method and application are offered. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-10-06T19:16:35.306279-05:
      DOI: 10.1002/stc.1602
       
  • Damage identification using combined transient power flow balance and
           acceleration matching technique
    • Authors: Cibu K. Varghese; Krishnapillai K. Shankar
      Pages: 135 - 155
      Abstract: This paper presents a multiobjective optimization formulation to detect and quantify crack damage in beam structures at variable locations. It is implemented at the substructure level where the concept is to balance the instantaneous power flow by equating the input power to the dissipated power and the time rate of change of kinetic and strain energies and power transferred to adjacent substructures. This imbalance is reduced to zero to identify the structural parameters or damages. For improved results, the power balance method is combined with conventional acceleration matching method where the objective is to minimize the deviation between measured and estimated accelerations—no additional sensors are required to incorporate the extra power flow balance criteria. Numerical simulations are performed for a lumped mass system, a planar truss structure, and a cantilever beam of 20 elements with multiple damages to evaluate the accuracy of the proposed method. Effects of noise are also taken into account by contaminating the measured responses with 3%, 5%, and 10% Gaussian noise. The particle swarm optimization is used as the optimization algorithm, and normalized fitness functions are defined for both power flow and acceleration components with weighted aggregation multiobjective optimization technique. The effects of various weighting factors for the combined objective function are also studied. The results demonstrate that improvement in accuracy of damage detection is achieved by the combined method, when compared with previous acceleration only matching method as well as other methods. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-04-04T05:29:14.910487-05:
      DOI: 10.1002/stc.1551
       
  • SMC structural health monitoring benchmark problem using monitored data
           from an actual cable‐stayed bridge
    • Authors: Shunlong Li; Hui Li, Yang Liu, Chengming Lan, Wensong Zhou, Jinping Ou
      Pages: 156 - 172
      Abstract: A structural health monitoring (SHM) system provides an efficient way to diagnose the condition of critical and large‐scale structures such as long‐span bridges. With the development of SHM techniques, numerous condition assessment and damage diagnosis methods have been developed to monitor the evolution of deterioration and long‐term structural performance of such structures, as well as to conduct rapid damage and post‐disaster assessments. However, the condition assessment and the damage detection methods described in the literature are usually validated by numerical simulation and/or laboratory testing of small‐scale structures with assumed deterioration models and artificial damage, which makes the comparison of different methods invalid and unconvincing to a certain extent. This paper presents a full‐scale bridge benchmark problem organized by the Center of Structural Monitoring and Control at the Harbin Institute of Technology. The benchmark bridge structure, the SHM system, the finite element model of the bridge, and the monitored data are presented in detail. Focusing on two critical and vulnerable components of cable‐stayed bridges, two benchmark problems are proposed on the basis of the field monitoring data from the full‐scale bridge, that is, condition assessment of stay cables (Benchmark Problem 1) and damage detection of bridge girders (Benchmark Problem 2). For Benchmark Problem 1, the monitored cable stresses and the fatigue properties of the deteriorated steel wires and cables are presented. The fatigue life prediction model and the residual fatigue life assessment of the cables are the foci of this problem. For Benchmark Problem 2, several damage patterns were observed for the cable‐stayed bridge. The acceleration time histories, together with the environmental conditions during the damage development process of the bridge, are provided. Researchers are encouraged to detect and to localize the damage and the damage development process. All the datasets and detailed descriptions, including the cable stresses, the acceleration datasets, and the finite element model, are available on the Structural Monitoring and Control website (http://smc.hit.edu.cn). Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-03-26T04:31:49.252054-05:
      DOI: 10.1002/stc.1559
       
  • An external rotary friction device for displacement mitigation in base
           isolation systems
    • Authors: Masato Saitoh
      Pages: 173 - 188
      Abstract: An analysis of the effect of recently observed near‐fault and anticipated long‐period ground motions indicates that conventional base isolation systems need an immediate retrofitting for improving their performance against earthquakes. In particular, the large displacement response of isolators, which might exceed the displacement limits, is of outmost importance. This study proposes a new external device for mitigating the displacement in conventional base isolation systems. The device consists of a rotary friction system with a wire wound on a shaft connected to a coil spring. The efficacy of the rotary friction is controlled by attaching a so‐called ‘ratchet switch’ to the isolated object, which works in accordance with the changes in the direction of the movement at the end of the wire. Through computations, this study verifies the improvement in the performance of base isolation systems by using the rotary friction device. The results show that the proposed device markedly reduces the lateral displacement response of the systems against both near‐fault and long‐period ground motions. Furthermore, the robustness of the system with respect to the mechanical properties of the friction device is also verified for practical use. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-03-26T04:11:53.992109-05:
      DOI: 10.1002/stc.1560
       
  • Structural health monitoring with a distributed mass damper system
    • Authors: Tat S. Fu; Erik A. Johnson
      Pages: 189 - 204
      Abstract: Recent developments of a distributed mass damper (DMD) system integrate structural and environmental control systems to improve building safety and energy efficiency. Such a system can also enhance Structural health monitoring (SHM) by using its multiple active mass dampers to excite the structure and analyze the resulting responses. SHM reliability depends on accurate estimations of structural characteristics from structural response measurements. However, some structural characteristics, such as structural modes, may not be well represented or identifiable depending on how structures are excited, thereby compromising the effectiveness of SHM. Utilizing combinations of the DMD's multiple active dampers to target structural modes of interest, the authors showed that damage detection in structures was significantly improved. In this paper, algorithms are derived for modal parameter estimations using the DMD system to excite the structure. Stiffness estimations and damage detections are then computed from the estimated model parameters. Harmonic excitations are used with the DMD system to target specific structural modes/frequencies and to amplify structural responses. Different configurations of excitations are then compared on the basis of the accuracy of stiffness estimations. A 20‐story model structure is simulated with four damage patterns to demonstrate accurate damage detection. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-04-04T03:42:45.460595-05:
      DOI: 10.1002/stc.1561
       
  • Dynamic response of identical adjacent structures connected by viscous
           damper
    • Authors: C. C. Patel; R. S. Jangid
      Pages: 205 - 224
      Abstract: In this paper, the dynamic behavior of two identical adjacent structures connected with viscous dampers is investigated under base acceleration. The base acceleration is modeled as harmonic excitation as well as stationary white‐noise random process. Each adjacent structure is modeled as a two‐degree‐of‐freedom system. The governing differential equations of motion of the coupled system are derived and solved for relative displacement and absolute acceleration responses. A parametric study is conducted to study the influence of important system parameters on the response behavior of damper connected structures. The important parameters considered are excitation frequency, mass ratio, and stiffness ratio of the structure. It is observed that the viscous damper is quite effective in controlling the dynamic response of identical connected structures. For a given coupled structure and excitation, it is found that there exists an optimum value of damping coefficient of damper for which the peak responses under harmonic excitation and the mean square response quantities under stationary white‐noise excitation attain the minimum value. The close‐form expressions for optimum parameter and corresponding response are derived for an undamped system. Finally, it is observed that the damping ratio of the connected structures does not have noticeable effects on the optimum damper damping. This implies that the proposed close‐form expressions of undamped structures can be used for the damped connected structures as well. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-03-18T07:05:40.44948-05:0
      DOI: 10.1002/stc.1566
       
  • Extended neural network‐based scheme for real‐time force
           tracking with magnetorheological dampers
    • Authors: Felix Weber; Subrata Bhowmik, Jan Høgsberg
      Pages: 225 - 247
      Abstract: This paper validates numerically and experimentally a new neural network‐based real‐time force tracking scheme for magnetorheological (MR) dampers on a five‐storey shear frame with MR damper. The inverse model is trained with absolute values of measured velocity and force because the targeted current is a positive quantity. The validation shows accurate results except of small current spikes when the desired force is in the vicinity of the residual MR damper force. In the closed‐loop, higher frequency components in the current are triggered by the transition of the actual MR damper force from the pre‐yield to the post‐yield region. A control‐oriented approach is presented to compensate for these drawbacks. The resulting control force tracking scheme is validated for the emulation of viscous damping, clipped viscous damping with negative stiffness, and friction damping with negative stiffness. The tests indicate that the proposed tracking scheme works better when the frequency content of the estimated current is close to that of the training data. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-04-05T04:26:03.512051-05:
      DOI: 10.1002/stc.1569
       
 
 
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