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  Subjects -> ENERGY (Total: 298 journals)
    - ELECTRICAL ENERGY (2 journals)
    - ENERGY (180 journals)
    - ENERGY: GENERAL (8 journals)
    - NUCLEAR ENERGY (27 journals)
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ENERGY (180 journals)                 | Last

Showing 1 - 200 of 406 Journals sorted alphabetically
ActaEnergetica     Open Access  
Advances in Building Energy Research     Hybrid Journal   (Followers: 9)
Advances in Energy and Power     Open Access   (Followers: 4)
Advances in High Energy Physics     Open Access   (Followers: 14)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 11)
American Journal of Energy Research     Open Access   (Followers: 8)
Annals of Nuclear Energy     Hybrid Journal   (Followers: 6)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 2)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 10)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Solar Energy     Hybrid Journal   (Followers: 14)
Archives of Thermodynamics     Open Access   (Followers: 4)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bulletin of Energy Economics and Technology     Open Access   (Followers: 2)
Atomic Energy     Hybrid Journal   (Followers: 4)
Atoms for Peace: an International Journal     Hybrid Journal   (Followers: 4)
Batteries     Open Access   (Followers: 3)
Biofuel Research Journal     Open Access   (Followers: 3)
Biofuels     Hybrid Journal   (Followers: 10)
Biofuels Engineering     Open Access  
Biomass Conversion and Biorefinery     Partially Free   (Followers: 9)
Bulletin de droit nucleaire     Full-text available via subscription   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 27)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 17)
Carbon Management     Hybrid Journal   (Followers: 6)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
CERN courier. International journal of high energy physics     Free   (Followers: 5)
Chain Reaction     Full-text available via subscription   (Followers: 1)
Clefs CEA     Full-text available via subscription   (Followers: 1)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Development of Energy Science     Open Access   (Followers: 4)
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (Followers: 3)
E3S Web of Conferences     Open Access  
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 6)
Electrical and Power Engineering Frontier     Open Access   (Followers: 18)
Electricity Journal     Partially Free   (Followers: 1)
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access  
Energy     Partially Free   (Followers: 22)
Energy & Fuels     Full-text available via subscription   (Followers: 22)
Energy and Buildings     Hybrid Journal   (Followers: 7)
Energy and Emission Control Technologies     Open Access   (Followers: 3)
Energy and Environment Focus     Free   (Followers: 4)
Energy and Environment Research     Open Access   (Followers: 11)
Energy and Environmental Engineering     Open Access   (Followers: 6)
Energy and Power     Open Access   (Followers: 8)
Energy and Power Engineering     Open Access   (Followers: 15)
Energy Conversion and Management     Hybrid Journal   (Followers: 7)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 2)
Energy Law Journal     Full-text available via subscription   (Followers: 4)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 17)
Energy Policy     Partially Free   (Followers: 56)
Energy Prices and Taxes     Full-text available via subscription   (Followers: 5)
Energy Procedia     Open Access   (Followers: 2)
Energy Reports     Open Access   (Followers: 3)
Energy Research & Social Science     Full-text available via subscription   (Followers: 1)
Energy Science & Engineering     Open Access   (Followers: 3)
Energy Science and Technology     Open Access   (Followers: 13)
Energy Strategy Reviews     Partially Free   (Followers: 9)
Energy Studies Review     Open Access   (Followers: 5)
Energy Systems     Hybrid Journal   (Followers: 12)
Energy Technology     Partially Free   (Followers: 4)
Energy Technology & Policy     Open Access   (Followers: 1)
Energy, Sustainability and Society     Open Access   (Followers: 17)
Environmental Progress & Sustainable Energy     Hybrid Journal   (Followers: 6)
EPJ Photovoltaics     Open Access   (Followers: 3)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Renewable Energy     Full-text available via subscription   (Followers: 1)
Frontiers in Energy     Hybrid Journal   (Followers: 3)
Frontiers in Energy Research     Open Access   (Followers: 2)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 4)
Functional Materials Letters     Hybrid Journal   (Followers: 1)
Gcb Bioenergy     Open Access   (Followers: 2)
Geothermal Energy     Open Access   (Followers: 3)
Green     Hybrid Journal   (Followers: 2)
Green Energy & Environment     Open Access  
IEA Electricity Information     Full-text available via subscription   (Followers: 2)
IEA Natural Gas Information     Full-text available via subscription   (Followers: 2)
IEEE Power and Energy     Full-text available via subscription   (Followers: 22)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 9)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 7)
IEEE Transactions on Power Systems     Hybrid Journal   (Followers: 19)
IET Power Electronics     Hybrid Journal   (Followers: 19)
Ingeniería Energética     Open Access  
Innovations : Technology, Governance, Globalization     Hybrid Journal   (Followers: 5)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 4)
International Journal of Ambient Energy     Hybrid Journal   (Followers: 1)
International Journal of Applied Power Engineering     Open Access   (Followers: 4)
International Journal of Clean Coal and Energy     Open Access   (Followers: 5)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 8)
International Journal of Emerging Electric Power Systems     Hybrid Journal   (Followers: 4)
International Journal of Emerging Multidisciplinary Fluid Sciences     Full-text available via subscription   (Followers: 1)
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 4)
International Journal of Energy and Power     Open Access   (Followers: 8)
International Journal of Energy and Statistics     Hybrid Journal  
International Journal of Energy Engineering     Open Access   (Followers: 9)
International Journal of Energy Research     Hybrid Journal   (Followers: 8)
International Journal of Energy Science     Open Access   (Followers: 1)
International Journal of Flow Control     Full-text available via subscription   (Followers: 4)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 7)
International Journal of Green Energy     Hybrid Journal   (Followers: 9)
International Journal of Hydrogen Energy     Partially Free   (Followers: 12)
International Journal of Marine Energy     Full-text available via subscription   (Followers: 1)
International Journal of Nuclear Desalination     Hybrid Journal  
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (Followers: 2)
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Hydrogen Production and Applications     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Knowledge Management     Hybrid Journal   (Followers: 1)
International Journal of Power and Energy Conversion     Hybrid Journal   (Followers: 2)
International Journal of Smart Grid and Green Communications     Hybrid Journal  
International Journal of Sustainable Energy     Hybrid Journal   (Followers: 12)
International Journal of Sustainable Energy Planning and Management     Open Access   (Followers: 2)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Thermodynamics     Open Access   (Followers: 7)
Journal of Alternate Energy Sources & Technologies     Full-text available via subscription  
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of China Coal Society     Open Access  
Journal of Energy     Open Access  
Journal of Energy & Natural Resources Law     Hybrid Journal   (Followers: 1)
Journal of Energy in Southern Africa     Open Access   (Followers: 2)
Journal of Energy Technologies and Policy     Open Access   (Followers: 5)
Journal of Energy, Environment & Carbon Credits     Full-text available via subscription   (Followers: 2)
Journal of Fusion Energy     Hybrid Journal   (Followers: 3)
Journal of International Energy Policy     Open Access   (Followers: 3)
Journal of Modern Power Systems and Clean Energy     Open Access   (Followers: 7)
Journal of Nano Energy and Power Research     Full-text available via subscription   (Followers: 4)
Journal of Nuclear Energy Science & Power Generation Technology     Hybrid Journal  
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 1)
Journal of Physical Chemistry C     Full-text available via subscription   (Followers: 27)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 6)
Journal of Radiological Protection     Full-text available via subscription   (Followers: 4)
Journal of Renewable Energy     Open Access   (Followers: 3)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
Journal of Solar Energy     Open Access   (Followers: 7)
Journal of Solar Energy Engineering     Full-text available via subscription   (Followers: 16)
Journal of Sustainable Bioenergy Systems     Full-text available via subscription   (Followers: 1)
Journal of Sustainable Energy Engineering     Full-text available via subscription  
Journal of Technology Innovations in Renewable Energy     Hybrid Journal  
Materials for Renewable and Sustainable Energy     Open Access   (Followers: 7)
MRS Energy & Sustainability - A Review Journal     Full-text available via subscription  
Natural Resources     Open Access   (Followers: 2)
Nature Energy     Hybrid Journal   (Followers: 3)
Nigerian Journal of Technological Research     Full-text available via subscription  
Nuclear Data Sheets     Full-text available via subscription  
Nuclear Engineering and Design     Hybrid Journal   (Followers: 10)
Nuclear Law Bulletin     Full-text available via subscription   (Followers: 2)
Nuclear Materials and Energy     Open Access   (Followers: 1)
Oil and Gas Journal     Full-text available via subscription   (Followers: 10)
Oil, Gas, Coal and Electricity - Quarterly Statistics - Electricite, charbon, gaz et petrole - Statistiques trimestrielles     Full-text available via subscription   (Followers: 8)
Open Journal of Energy Efficiency     Open Access   (Followers: 2)
Power Technology and Engineering     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Energy     Hybrid Journal   (Followers: 3)
Progress in Nuclear Energy     Hybrid Journal  
Radiochimica Acta     Hybrid Journal   (Followers: 5)
Radioprotection     Hybrid Journal   (Followers: 1)
Science and Technology of Nuclear Installations     Open Access   (Followers: 1)
Smart Grid and Renewable Energy     Open Access   (Followers: 8)
Solar Energy     Hybrid Journal   (Followers: 18)
Solar Energy Materials and Solar Cells     Hybrid Journal   (Followers: 27)
SourceOCDE Energie nucleaire     Full-text available via subscription  
SourceOECD Nuclear Energy     Full-text available via subscription   (Followers: 1)
South Pacific Journal of Natural and Applied Sciences     Hybrid Journal  
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 6)
Surface Science Reports     Full-text available via subscription   (Followers: 15)
Sustainable Energy     Open Access  
Sustainable Energy Technologies and Assessments     Full-text available via subscription  
Sustainable Energy, Grids and Networks     Hybrid Journal  
Technology Audit and Production Reserves     Open Access  
The International Journal of Ocean and Climate Systems     Full-text available via subscription   (Followers: 6)
The Journal of Computational Multiphase Flows     Full-text available via subscription  
Universal Journal of Applied Science     Open Access   (Followers: 2)
Washington and Lee Journal of Energy, Climate, and the Environment     Open Access   (Followers: 3)
Waste Management     Hybrid Journal   (Followers: 10)
Water International     Hybrid Journal   (Followers: 10)
Wiley Interdisciplinary Reviews : Energy and Environment     Hybrid Journal   (Followers: 4)
Wind Energy     Hybrid Journal   (Followers: 2)
Wind Engineering     Full-text available via subscription   (Followers: 2)
Wireless Power Transfer     Full-text available via subscription   (Followers: 2)

       | Last

Journal Cover Structural Control and Health Monitoring
  [SJR: 1.351]   [H-I: 26]   [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  [1598 journals]
  • Impact load identification for composite structures using Bayesian
           regularization and unscented Kalman filter
    • Abstract: In structural health monitoring of composite structures, one important task is to detect and identify the low‐velocity impact events, which may cause invisible internal damages. This paper presents a novel approach for simultaneously identifying the impact location and reconstructing the impact force time history acting on a composite structure using dynamic measurements recorded by a sensor network. The proposed approach consists of two parts: (1) an inner loop to reconstruct the impact force time history and (2) an outer loop to search for the impact location. In the inner loop, a newly developed inverse analysis method with Bayesian inference regularization is employed to solve the ill‐posed impact force reconstruction problem using a state‐space model. In the outer loop, a nonlinear unscented Kalman filter (UKF) method is used to recursively estimate the impact location by minimizing the error between the measurements and the predicted responses. The newly proposed impact load identification approach is illustrated by numerical examples performed on a composite plate. Results have demonstrated the effectiveness and applicability of the proposed approach to impact load identification. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-19T03:35:44.82534-05:0
      DOI: 10.1002/stc.1910
       
  • Semi‐active control of flexible structures using closed‐loop
           input shaping techniques
    • Authors: Tarek Edrees Alqado; George Nikolakopoulos, Leonidas Dritsas
      Abstract: In this research effort, a novel approach on the control of structures with magnetorheological (MR) dampers is presented, based on an appropriately adapted closed‐loop version of the generic input shaping control theory. The MR damper is a very promising kind of semi‐active control system (actuator), mixing the advantages of the active and passive structural control systems, hence their increasing use as attenuators that reject the effects of dynamic loads on civil engineering structures. The main contribution of this article is the application and performance evaluation of the novel ‘Linear Matrix Inequality‐based’ feedback version of the input shaping control theory for the first time in the area of structural control. The need for the use of a feedback version of input shaping control stems from the design trade‐off between robustness and speed of response requirements. A simulation of a benchmark three‐story building with one MR damper is employed to verify the efficiency of the proposed control approach. The nonlinear behaviour of the MR damper, rigidly connected between the first floor of the structure and the ground, is captured by the well‐known Bouc–Wen model. The superiority and effectiveness of the proposed scheme in reducing the responses of the structure were proved using seven quantifiable evaluation criteria and by comparing these results with those achieved by classical and well‐established alternative control schemes. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-11T02:58:18.261795-05:
      DOI: 10.1002/stc.1913
       
  • Polygonal damage shape reconstruction in plates using guided Lamb wave
    • Authors: Amir Ashkan Mokhtari; Abdolreza Ohadi, Hamidreza Amindavar
      Abstract: Tomographic reconstruction of the damaged region using guided Lamb waves provides important information about the health condition of structures. Two general types of shape reconstruction techniques are discussed before: transform based methods and algebraic iterative methods. There are some limitations associated with each method such as high sensitivity to noise and incomplete data sets, limitations for damage size and contrast, bulky setup for scanning the damaged region, or low speed of reconstruction. In this paper, the concepts of a novel method for reconstructing the contour of damage based on the Polygon Reconstruction Technique are introduced. First, the projections (Radon transform) of the damaged region are generated from a small number of angles with the aid of beamforming method. Then, the damaged region is modeled by a polygon, which its optimal number of vertices is estimated using the minimum description length (MDL) principle. Finally, using the polygon reconstruction technique, the coordinates of the vertices are determined. As the proposed method is at its preliminary stage, two finite element models of an aluminum plate with two different holes as the damage are designed in ABAQUS to examine the feasibility and performance of the method. Results show that the introduced technique based on polygonal damage shape reconstruction is fast and accurate. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-06T23:55:40.944939-05:
      DOI: 10.1002/stc.1907
       
  • Structural displacement measurements using DC coupled radar with active
           transponder
    • Authors: Shanyue Guan; Jennifer A. Rice, Changzhi Li, Yiran Li, Guochao Wang
      Abstract: Continuous wave (CW) radar sensors are a promising technology for structural displacement measurement. However, the commonly employed passive backscattering measurement configuration has some limitations for low‐power applications of CW radar. To improve displacement measurement performance using the low‐power CW radar, an active transponder configuration is introduced. Compared with passive backscattering, the active transponder configuration is capable of increasing the radar's signal power, thereby increasing the signal to noise ratio for more accurate displacement measurement. A series of laboratory experiments to demonstrate the performance of the transponder configuration was conducted, and the experimental results were compared with the results of using the backscattering configuration. The investigation revealed that the signal improvement provided by the transponder is a function of the distance between the transponder and the radar. In addition, a full‐scale bridge test with the active transponder configuration was conducted to verify the improved performance. An oblique angle test using the transponder was conducted in the laboratory to demonstrate the potential for flexible installation strategies when deploying the radar/transponder pair for bridge displacement measurements. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-06T02:46:07.386326-05:
      DOI: 10.1002/stc.1909
       
  • Estimation of wind loads on a tall building by an inverse method
    • Abstract: Many engineering applications require the knowledge of wind loads on structures. However, it is difficult or even impossible to measure these excitation forces from prototype structures directly. In this paper, a Kalman filtering‐based inverse approach is developed to estimate the wind loads on tall buildings. The inverse method allows estimating the wind forces on a tall building based on limited structural responses. The optimum solution of Kalman filter gain by solving the Riccati equation is used to update the wind load identification. The practicability and accuracy of the developed inverse method are evaluated based on wind tunnel testing results of a square‐shaped tall building. The wind loads identified by the developed method are compared with those by an augmented Kalman filtering‐based technique for further verification of the effectiveness and reliability of the presented inverse approach. The influences of key factors such as the type of wind‐induced response, covariance matrix of external loads, covariance matrix of noise, errors of structural modal parameters, and levels of noise involved in the measured responses on the wind load estimations are examined and discussed. It is shown through the comparative studies that the developed inverse method is an effective tool for estimating the wind loads on tall buildings based on limited structural responses. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-06T02:35:36.920985-05:
      DOI: 10.1002/stc.1908
       
  • Remaining stiffness estimation of buildings using incomplete measurements
    • Authors: Edward L. Eskew; Shinae Jang
      Abstract: After hazardous events, it is important to be able to quickly identify the remaining stiffness of affected structures for condition evaluation. Model updating can be used to update structural models to reflect current conditions based upon experimental measurements. Direct model updating is a simple and quick method of damage detection, but does not guarantee physical relevance. Least‐squares optimization can be used to accurately identify damage with physical relevance, but needs more measurements then updating parameters in order to produce an accurate solution. However, after an extreme event sensors on the structure may be damaged, creating a scenario with limited measurements which can render optimization techniques incapable of assessing the remaining stiffness. To address this issue, this paper proposes a two‐phase method to localize and then quantify the remaining stiffness of the structure. Direct model updating with limited measurements is used to localize potential damage to a subset of parameters, and a least‐squares optimization using the localized parameters is used to quantify the remaining stiffness in the structure. Numerical simulations using a simplified model based upon the phase I IASCE‐ASCE structural health monitoring benchmark problem with missing first floor sensors have been employed to demonstrate, and experiments using a five‐story steel frame structure are conducted to validate the methodology. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-06T02:30:36.939442-05:
      DOI: 10.1002/stc.1899
       
  • Full‐field deformation measurements during seismic loading of
           masonry buildings
    • Authors: S. Rajaram; P. A. Vanniamparambil, F. Khan, M. Bolhassani, A. Koutras, I. Bartoli, F. Moon, A. Hamid, P. Benson Shing, J. Tyson, A. Kontsos
      Abstract: This article demonstrates the potential of the digital image correlation (DIC) method to provide accurate full‐field deformation measurements and successfully monitor the development of damage during seismic excitation of a partially grouted reinforced masonry building. The building was subjected to a sequence of earthquake ground motion records using the Large High Performance Outdoor Shake Table at the University of California, San Diego. The DIC setup was capable of measuring surface deformations of the single‐story building with high frame rate cameras located at a distance greater than 50 ft away. The accuracy of the measurements was assessed with data obtained using mounted displacement transducers. The full‐field deformation data collected by the DIC system was capable to detect strain localization patterns associated with the onset of wall cracking before it could be shown by the displacement sensor data or by post mortem visual inspection. The research findings reported herein demonstrate, for the first time to the authors' best knowledge, the potential of in situ monitoring of actual structures for damage induced by non‐stationary loading profiles using optical metrology. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-07-04T03:11:52.604838-05:
      DOI: 10.1002/stc.1903
       
  • Experimental damage evaluation of open and fatigue cracks of
           multi‐cracked beams by using wavelet transform of static response
           via image analysis
    • Authors: Ugo Andreaus; Paolo Baragatti, Paolo Casini, Daniela Iacoviello
      Abstract: In this study, a method for crack detection and quantification in beams based on wavelet analysis is presented. The static deflection is measured at particular points along the length of (i) real damaged structures, using few displacement transducers and a laser sensor, and (ii) simulated structures, using closed‐form analysis, for a given location of a concentrated load along the beam. Furthermore, the measurement of the beam displacements in a large number of spatially distributed points is made by processing digital photographs of the beam. The smoothed deflection responses of the cracked beams are then analyzed using the wavelet transform. For this purpose, a Gaus2 wavelet with two vanishing moments is utilized. The wavelet transform spikes are used as indicators to locate and quantify the damage; furthermore, the multi‐scale theory of wavelet is employed, in order to eliminate or at least reduce the spurious peaks and enhance the true ones. Simply supported beams with single and double cracks are used to demonstrate the devised methodology. Open and fatigue cracks of different sizes and locations have been used in the examples. In a closed‐form analysis, the damage is modeled as a bilinear rotational spring with reduced stiffness in the neighborhood of the crack location. Damage calibration of simply supported steel beams with open and fatigue cracks has been carried out experimentally using this technique. A generalized curve has been proposed to quantify the damage in a simply supported beam. Based on the experimental study, the spatial wavelet transform is proven to be effective to identify the damage zone even when the crack depth is around 3% of the height of the beam. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-29T03:20:31.139805-05:
      DOI: 10.1002/stc.1902
       
  • Damage evaluation of structures with uncertain parameters via interval
           analysis and FE model updating methods
    • Authors: Enrique Sevillano; Rui Sun, Ricardo Perera
      Abstract: Experimental and numerical uncertainties are always present in structural identification problems. The quantification of the uncertainty on the results of a finite element updating procedure is commonly carried out in a probabilistic framework, which requires working with a‐priori known probability distributions for the uncertain parameters. In this paper, the modal interval analysis method to estimate damage structural problems with uncertain‐but‐bounded parameters is presented. With this method only the bounds on the magnitude of uncertain parameters are required. The formulation of this method in a single objective framework is equivalent to minimizing the average value and the deviation of the uncertain objective function in the considered interval with which it is actually a multi‐objective problem. Furthermore, its implementation requires the analytical evaluation of the sensitivities of the objective functions with respect to the uncertain parameters, which is derived. Numerical and experimental results evidence the accuracy and the effectiveness of the proposed approach to evaluate damage in uncertain environments. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-29T03:10:49.358053-05:
      DOI: 10.1002/stc.1901
       
  • Field monitoring and numerical simulation of the thermal actions of a
           supertall structure
    • Abstract: Structural temperature is an important loading that must be considered during the design, construction, and safety assessment. The thermal action of supertall structures has rarely been investigated because of insufficient real measurement data, as compared with that on bridges. In this study, the thermal action of the 600‐m‐tall Canton Tower is investigated on the basis of the comprehensive long‐term SHM system installed on the structure and the numerical simulation. First, the temperature model of the entire structure is derived by using the field monitoring and numerical heat transfer analysis data. In particular, (i) the temperature difference between different facades of the inner tube, (ii) the temperature difference profile of the outer tube, and (iii) the distribution of the temperature difference between the inner and outer tubes along the structural height are presented in detail. Results show that the nonuniform distribution of the temperature field between the different components of the structure is significant and should be carefully considered in the analysis of such a complex supertall structure. Second, the temperature effects on structural displacement, stress, and internal forces consisting of (i) the tower top horizontal displacement during different seasons, (ii) the stresses of different levels/components, and (iii) the bending moments/shear forces along the structural height are investigated. The simulated results obtained by using the global finite element model of the tower are verified through a comparison with the measurements. This study provides first‐hand data for the design of supertall structures in the tropical region of China. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-23T00:06:16.376685-05:
      DOI: 10.1002/stc.1900
       
  • Experimental study and numerical simulation on a new type of viscoelastic
           damper with strong nonlinear characteristics
    • Authors: Shunming Gong; Ying Zhou
      Abstract: In this study, a new type of viscoelastic (VE) damper with strong nonlinear characteristics, showing both softening and hardening, is investigated. Firstly, its performance tests are executed, and its mechanical properties summarized. Then, a shaking table test on a three‐story viscoelastically damped structure is designed to investigate the dissipation characteristics and control effect of this type of VE damper. Six VE dampers were installed in pairs at each story and connected vertically to the upper and lower beams. The structure with additional VE dampers and that without additional VE dampers was subjected to three ground motions whose peak ground accelerations varied from 0.1 to 0.6 g. The experimental results indicate that the control effect on the displacements was remarkable, while the effect on accelerations and shear forces was limited, due to the damper's additional stiffness. With the increment of the damper deformation, the additional stiffness decreased, while the additional effective damping ratio increased at first and then declined. Finally, a simplified analytical method is proposed and applied to simulate the shaking table test using OpenSees. The simulating results validate the analytical method of this type of VE damper. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-21T01:26:08.636177-05:
      DOI: 10.1002/stc.1897
       
  • An innovative sensitivity‐based method for structural model updating
           using incomplete modal data
    • Authors: Akbar Esfandiari
      Abstract: This paper presents an innovative sensitivity equation to detect changes of stiffness parameters using mode shape data. Most of the sensitivity‐based model updating methods use changes of mode shapes for structural model updating. However, the proposed method uses the mode shape data to estimate changes of the structural parameters directly. The proposed method sets up a relation between the change of structural parameters and the mode shapes of the damaged structure. The proposed formula uses the measured natural frequencies of the damaged structure and the mode shapes of the intact structure. The formulation yields to a set of accurate sensitivity equations. The proposed method is successfully applied to a plane truss and a frame structure using simulated error‐contaminated mode shapes data. Results prove robustness of the proposed method against mode shape, natural frequency, and mass modeling errors. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-21T01:21:55.316413-05:
      DOI: 10.1002/stc.1905
       
  • Transducer placement optimisation scheme for a delay and sum damage
           detection algorithm
    • Authors: M. S. Salmanpour; Z. Sharif Khodaei, M. H. Aliabadi
      Abstract: In this work, a transducer placement scheme based on wave propagation is proposed, which enhances damage localisation. The method was tailored to seek an optimal transducer network placement for a delay and sum damage detection algorithm. The proposed method determines a coverage index map and utilises a genetic algorithm to determine an optimal transducer network. It can also minimise the impact of faulty transducers, incorporate the effect of stiffeners and different damage types. The method is initially verified using numerically simulated signals. The optimal network outperformed the suboptimal for detection of holes and debonding in a stiffened panel. It is also shown that the coverage index reflected the localisation accuracy. The method is then validated with experimental results and the generated optimal transducer network compared with a suboptimal arrangement. The optimal network is shown to locate an actual crack with significantly higher accuracy than the suboptimal arrangement. © 2016 The
      Authors . Structural Control and Health Monitoring published by John Wiley & Sons, Ltd.
      PubDate: 2016-06-21T01:21:35.761321-05:
      DOI: 10.1002/stc.1898
       
  • Dynamic displacements‐based model updating with motion capture
           system
    • Authors: Byung Kwan Oh; Jin Woo Hwang, Se Woon Choi, Yousok Kim, Tongjun Cho, Hyo Seon Park
      Abstract: In this paper, a dynamic displacements‐based model updating method using a motion capture system (MCS) is proposed. The dynamic characteristics from MCS are used to find the parameters that minimize the difference between updated model and direct measurement. Using a multi‐objective optimization algorithm of non‐dominated sorting genetic algorithm‐II, the number of objective functions for model updating is set to the same number of modes under consideration, and all the objective function are simultaneously minimized. To consider the contribution of each mode on model updating and to avoid biased results, a rule for weighting of solutions associated to each mode based on modal participation factors is suggested and tested. Using a free vibration experimental test of a three‐story shear model, the performance of model updating method is verified by the comparison of the dynamics characteristics between the updated model and direct measurement by MCS. In addition, time histories of displacements from the updated model are compared with the direct measurement. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-21T01:00:44.257955-05:
      DOI: 10.1002/stc.1904
       
  • A baseline‐free and non‐contact method for detection and
           imaging of structural damage using 3D laser vibrometry
    • Authors: P. Aryan; A. Kotousov, C. T. Ng, B. S. Cazzolato
      Abstract: Detection and characterisation of structural damage using guided waves is very promising technique in non‐destructive testing and structural health monitoring systems. Because of their simplicity and low cost, current techniques normally utilise traditional piezo‐electric or optical fibre sensors to capture a directional scattered field from a defect or damaged area. However, the practical implementation of these techniques usually requires an extensive preliminary study in order to identify a suitable location and polarisation of the sensors, as well as determine the optimal parameters for wave excitation, which vary depending on the size and type of damage and structure. Recent advances in 3D laser vibrometry provide an opportunity to avoid many of the restrictions and limitations associated with traditional (1D) sensing systems by capturing the transient 3D displacement/velocity fields rather than the displacement/strain along a single axis and limited to a small number of discrete locations. Using 3D laser vibrometry, this paper suggests a non‐contact, baseline‐free method for imaging structural defects such as corrosion spots, cracks and dents as well as delamination damage. It focuses on the mode conversion effects and investigates the sensitivity of the in‐plane and out‐of‐plane scattered fields in relation to the presence of common defects. The experimental measurements are presented in terms of the root mean square (RMS) values of the velocity field. The outcomes of the present study can help in a number of ways, including selecting an appropriate strategy for defect detection using guided wave techniques. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-10T03:22:06.282057-05:
      DOI: 10.1002/stc.1894
       
  • Damage detection of multi‐story shear buildings due to earthquakes
           by model updating method
    • Authors: J.Y. Zhang; T. Aoki
      Abstract: In this paper, we present a novel model updating method for damage detection of multi‐story shear buildings during severe earthquakes. The story stiffnesses are explicitly presented in an incremental manner; this enables a simple and robust algorithm for the purpose of identification of the story stiffnesses. The estimated modal data, including natural frequencies and mode shapes of lower modes, are used in the proposed algorithm; moreover, sensitivity analysis of natural circular frequencies is incorporated to reduce possible errors. The story stiffnesses are identified by an iterative algorithm, and the window shift technique is adopted to present change of the story stiffness due to damages in the buildings during earthquakes. Numerical examples demonstrate that the proposed method is of high accuracy, even when the recorded responses are polluted by a relatively high level of (white) noises. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-10T03:15:36.476483-05:
      DOI: 10.1002/stc.1895
       
  • A leverage‐type stiffness controllable mass damper for vibration
           mitigation of structures
    • Abstract: Tuned mass dampers (TMDs) are well recognized as an effective technology for mitigating structural vibration caused by wind loads. Therefore, some researchers have advocated applying TMDs for the vibration mitigation of structures subjected to earthquakes. Nevertheless, the seismic performance of a conventional TMD may not be as effective as expected because the frequency content and magnitude of an earthquake usually fluctuate and are far more complex than wind loads. To resolve this problem, the leverage‐type stiffness controllable mass damper (LSCMD), a semi‐active mass damper, is proposed in this paper. The LSCMD has a lever arm with a movable pivot, allowing it to control the damper stiffness and restoring force in real time by adjusting the pivot position. To evaluate the control effectiveness of the LSCMD, the seismic responses of a structural system equipped with the LSCMD were simulated and compared with those of the same structure controlled by two optimally designed passive TMDs and a hybrid mass damper (HMD) with the same control law as that of the LSCMD. The results of the simulation demonstrate that the control performance of the LSCMD system can be enhanced by varying the LSCMD stiffness. Although the LSCMD and HMD are equally effective in suppressing the maximum responses of the structure, the former requires less control energy. This indicates that the proposed LSCMD is more desirable when the damper installation space and energy consumption are major concerns. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-10T03:11:54.501524-05:
      DOI: 10.1002/stc.1896
       
  • Semiactive control for a distributed mass damper system
    • Authors: Tat S. Fu; Erik A. Johnson
      Abstract: Recently, a distributed mass damper (DMD) has been proposed for architectural design considerations. By placing a mass damper in every story of a building, building designers can (1) integrate shading fins (that are typically installed in every story) and mass dampers to synergistically improve safety and energy efficiency, and (2) solve many architectural design and implementation issues (e.g., complications of a large damper mass near the top or the prime space of a building) with small damper masses. The passive DMD system was shown effective in response mitigation as a conventional tuned mass damper. In this paper, two semiactive DMD strategies are evaluated: a conventional semiactive clipped‐optimal LQR strategy, and a proposed gain‐scheduled semiactive DMD strategy. A conventional clipped‐optimal approach turns individual dampers off when their control forces are nondissipative, whereas the proposed strategy uses a redesigned control force, using an alternate control gain, to maximize the number of dampers exerting dissipative forces. A five‐story shear structure with one semiactive tuned mass damper per floor is used as a testbed to evaluate these control strategies. Both semiactive DMD strategies best the passive DMD system in reducing structural response; further, the semiactive gain‐scheduling strategy notably outperforms the established clipped‐optimal semiactive control strategy. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-10T03:05:35.634683-05:
      DOI: 10.1002/stc.1888
       
  • Compressive sensing based structural damage detection and localization
           using theoretical and metaheuristic statistics
    • Authors: Ruigen Yao; Shamim N. Pakzad, Parvathinathan Venkitasubramaniam
      Abstract: Accurate structural damage identification calls for dense sensor networks, which are becoming more feasible as the price of electronic sensing systems reduces. To transmit and process data from all nodes of a dense network is a computationally expensive BIG DATA problem; therefore scalable algorithms are needed so that inferences about the current state of the structure can be made efficiently. In this paper, an iterative spatial compressive sensing scheme for damage existence identification and localization is proposed and investigated. At each iteration, damage existence is identified from randomly collected sparse samples and damage localization is iteratively detected via sensing–processing cycles with metaheuristic sampling distribution updating. Specifically, simulated annealing and ant colony analogy are used for guidance in future selection of sensing locations. This framework is subsequently validated by numerical and experimental implementations for gusset plate crack identification. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-06T02:35:40.21143-05:0
      DOI: 10.1002/stc.1881
       
  • Simultaneous identification of stiffness, mass, and damping using an
           on‐line model updating approach
    • Abstract: The development of damage identification methods that enable rapid implementation holds great promise for assessing structural integrity to avoid further damage or catastrophic failure. Here, an on‐line model updating approach is proposed to rapidly and simultaneously identify the mass, stiffness, and damping properties of a structural model. The proposed approach facilitates identification of these unknown parameters using two steps: first, energy equilibrium equations are used to establish a relationship between structural energy and unknown parameters; second, the Kalman filter is adopted to obtain the unknown parameters in a short period of time. Numerical verification is conducted on a 158‐degree‐of‐freedom truss model with 324 unknown parameters based on a real‐world structure. The results indicate that the proposed approach can simultaneously identify the model parameters for the mass, stiffness, and damping of both the damaged and undamaged structures online, and also can effectively identify the stiffness damage and mass change, even in an environment with noise. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-06-03T02:05:45.606515-05:
      DOI: 10.1002/stc.1892
       
  • Traffic volume estimation in a cable‐stayed bridge using dynamic
           responses acquired in the structural health monitoring
    • Authors: Kaiwan Wattana; Mayuko Nishio
      Abstract: This paper presents the traffic volume estimation by constructing a statistical model using dynamic response data acquired by a structural health monitoring system installed on an in‐service cable‐stayed bridge. The structural health monitoring system consists of various sensors, including accelerometers, tilt sensors, temperature sensors, and the vehicle counting system. In this paper, the correlations between the response features from dynamic data, peak frequencies and amplitudes of responses, and the temperature and the traffic volume were firstly investigated. The results revealed that the traffic volume was a dominant factor that influenced on variances of the extracted features, while the temperature showed low effects on them in the target bridge. Some of the response features that showed high correlations were then selected for constructing a linear regression model to estimate the total traffic volume per 5 min. The constructed model then showed the accurate fitting performance to the data, and it was also capable of predicting the traffic volume on the bridge. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-31T23:50:44.522429-05:
      DOI: 10.1002/stc.1890
       
  • Genetic‐based EM algorithm to improve the robustness of Gaussian
           mixture models for damage detection in bridges
    • Abstract: During the service life of bridges, the bridge management systems (BMSs) seek to handle all performed assessment activities by controlling regular inspections, evaluations, and maintenance of these structures. However, the BMSs still rely heavily on qualitative and visual bridge inspections, which compromise the structural evaluation and, consequently, the maintenance decisions as well as the avoidance of bridge collapses. The structural health monitoring appears as a natural field to aid the bridge management, providing more reliable and quantitative information. Herein, the machine learning algorithms have been used to unveil structural anomalies from monitoring data. In particular, the Gaussian mixture models (GMMs), supported by the expectation‐maximization (EM) on the parameter estimation, have been proposed to model the main clusters that correspond to the normal and stable state conditions of a bridge, even when it is affected by unknown sources of operational and environmental variations. Unfortunately, the performance of the EM algorithm is strongly dependent on the choice of the initial parameters. This paper proposes a hybrid approach based on a standard genetic algorithm (GA) to improve the stability of the EM algorithm on the searching of the optimal number of clusters and their parameters, strengthening the damage classification performance. The superiority of the GA‐EM‐GMM approach, over the classic EM‐GMM one, is tested on a damage detection strategy implemented through the Mahalanobis‐squared distance, which permits one to track the outlier formation in relation to the chosen main group of states, using real‐world data sets from the Z‐24 Bridge, in Switzerland. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-29T23:05:39.214157-05:
      DOI: 10.1002/stc.1886
       
  • Damage detection for high‐speed train axle based on the propagation
           characteristics of guided waves
    • Authors: Jianxi Qiu; Fucai Li, Jifeng Wang
      Abstract: The currently defect identification techniques based on guided wave is not feasible for high‐speed train axle because the structure complicates wave propagation. A novel damage detection method especially for train axle is proposed in this paper. Piezoelectric patches are used as actuator to excite waves in the axle. Guided wave generated by single actuator and circumferential, limited number of actuator configurations is discussed to optimize the transducer network. The axle is simplified to a variable cross‐sectional and thick‐walled hollow cylindrical structure. Eight piezoelectric actuators that evenly distributed at the axle end surface are used to excite simplex longitudinal waves. Signals of circumferential and axial displacement of the monitoring points are researched before and after introducing the flaw on the surface, and their sensitivity to the depth and length of defect are also discussed. From the view of practical feasibility, the difference of signals from two axisymmetrical measure points of same axial position is proposed for the defect identification. Experimental verification is conducted, and the results demonstrate that the proposed approach is reliable in the axle inspection. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-29T22:40:41.038835-05:
      DOI: 10.1002/stc.1891
       
  • Identification of time‐varying cable tension forces based on
           adaptive sparse time‐frequency analysis of cable vibrations
    • Authors: Yuequan Bao; Zuoqiang Shi, James L. Beck, Hui Li, Thomas Y. Hou
      Abstract: For cable bridges, the cable tension force plays a crucial role in their construction, assessment and long‐term structural health monitoring. Cable tension forces vary in real time with the change of the moving vehicle loads and environmental effects, and this continual variation in tension force may cause fatigue damage of a cable. Traditional vibration‐based cable tension force estimation methods can only obtain the time‐averaged cable tension force and not the instantaneous force. This paper proposes a new approach to identify the time‐varying cable tension forces of bridges based on an adaptive sparse time‐frequency analysis method. This is a recently developed method to estimate the instantaneous frequency by looking for the sparsest time‐frequency representation of the signal within the largest possible time‐frequency dictionary (i.e. set of expansion functions). In the proposed approach, first, the time‐varying modal frequencies are identified from acceleration measurements on the cable, then, the time‐varying cable tension is obtained from the relation between this force and the identified frequencies. By considering the integer ratios of the different modal frequencies to the fundamental frequency of the cable, the proposed algorithm is further improved to increase its robustness to measurement noise. A cable experiment is implemented to illustrate the validity of the proposed method. For comparison, the Hilbert–Huang transform is also employed to identify the time‐varying frequencies, which are then used to calculate the time‐varying cable‐tension force. The results show that the adaptive sparse time‐frequency analysis method produces more accurate estimates of the time‐varying cable tension forces than the Hilbert–Huang transform method. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-29T22:35:37.479509-05:
      DOI: 10.1002/stc.1889
       
  • Dynamic investigation of a large historical cathedral
    • Authors: Ahmed Elyamani; Oriol Caselles, Pere Roca, Jaime Clapes
      Abstract: The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Island, Spain) under ambient sources of vibration and seismic events. The cathedral is one of the greatest built masonry structures worldwide. It is characterized for its audacious dimensions and slender structural members. Because of it, the study of its dynamic behavior is a clear concern. The cathedral dynamic properties were firstly identified using ambient vibration testing. Afterwards, a dynamic monitoring system was implemented to continuously measure, record, and wirelessly transfer the acceleration records without having to set up an activating threshold. This monitoring type was implemented because of the low seismic intensity of Mallorca Island with a basic ground acceleration of only 0.04 g according to the Spanish seismic standard. The continuous monitoring allowed for capturing some seismic events and some drops in the natural frequencies were noticed because of a breathing crack effect. Using both ambient vibration testing and continuous monitoring system, global modes could be more accurately identified than more local ones. The identification of the global modes was more attainable than in the case of more local ones. The temperature was a more influential environmental parameter than humidity and wind for all of the identified modes except for one more directly depended on wind. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-29T22:20:55.347784-05:
      DOI: 10.1002/stc.1885
       
  • A trajectory method for vibration based damage identification of
           underdetermined problems
    • Authors: Stavros Chatzieleftheriou; Nikos D. Lagaros
      Abstract: The problem of structural damage identification based on vibration measurements (eigenfrequencies and incomplete mode shapes) is generally formulated as an inverse problem aiming to identify changes encountered on the global stiffness matrix. In most cases, the measured quantities are less than the damage parameters to be identified; thus, an infinite number of possible damage configurations are expected to satisfy the measurements. Therefore, damage identification problems are often proven to be ill‐conditioned. The problem becomes more complex when measurements' noise and model uncertainties are considered. Therefore, depending on the structural system, damage scenario and available vibration measurements, additional eigenmode data may need to be considered in order to increase the robustness of the damage identification procedure. In this work, a new two‐loop trajectory method is presented, that relies on an iterative nonlinear sensitivity analysis procedure. The main advantage of the proposed method is its ability to identify damage scenarios that match the measured data with high accuracy as well as to explore effectively the solution space. This feature can be exploited in order to assess the adequacy of the measurements in noisy and/or uncertain environment. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-26T23:35:48.701966-05:
      DOI: 10.1002/stc.1883
       
  • Optimal configurations for a linear vibration suppression device in a
           multi‐storey building
    • Authors: Sara Ying Zhang; Jason Zheng Jiang, Simon Neild
      Abstract: This paper investigates the use of a two‐terminal vibration suppression device in a building. The use of inerter‐spring‐damper configurations for a multi‐storey building structure is considered. The inerter has been used in Formula 1 racing cars and applications to various systems such as road vehicles have been identified. Several devices that incorporate inerter(s), as well as spring(s) and damper(s), have also been identified for vibration suppression of building structures. These include the tuned inerter damper and the tuned viscous mass damper. In this paper, a three‐storey building model with a two‐terminal absorber located at the bottom subjected to base excitation is studied. The brace stiffness is also taken into consideration. Four optimum absorber layouts, in terms of how spring, damper and inerter components should be arranged, for minimising the maximum relative displacements of the building are obtained with respect to the inerter's size and the brace stiffness. The corresponding parameter values for the optimum absorber layouts are also presented. Furthermore, a real‐life earthquake data is used to show the advantage of proposed absorber configurations. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-26T23:15:35.854082-05:
      DOI: 10.1002/stc.1887
       
  • Acoustic emission‐based analysis of bond behavior of corroded
           reinforcement in existing concrete structures
    • Authors: Ahmed A. Abouhussien; Assem A. A. Hassan
      Abstract: This experimental study exploits acoustic emission (AE) monitoring to assess the bond behavior of corroded bars in reinforced concrete prism samples under pull‐out tests. The analysis of AE parameters obtained in this study including amplitude, duration, cumulative number of hits, and signal strength was performed to identify different stages of bond degradation. The results of bond behavior and free end slip were analyzed and compared with the corresponding AE data. An intensity analysis of AE signal strength was also completed to quantify the bond damage using two additional AE parameters: historic index (H (t)) and severity (Sr). The outcomes of AE analysis enabled the detection of early stages of bond deterioration (micro‐cracking) as well as identification of the macro‐cracking stage prior to the occurrence of bond splitting failure. The results also showed a good correlation between AE cumulative number of hits and AE signal strength parameters with the steel‐to‐concrete bond degradation because of corrosion. Finally, the results of H (t) and Sr were employed to generate intensity classification charts to characterize the stages of micro‐ and macro‐cracking and range of slip of corroded reinforcement. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-26T23:10:34.517081-05:
      DOI: 10.1002/stc.1893
       
  • Online Bayesian model assessment using nonlinear filters
    • Authors: Thaleia Kontoroupi; Andrew W. Smyth
      Abstract: Model assessment is an integral part of many engineering applications, because any analytical or numerical mathematical model used for predictive purposes is only an approximation of the real system. The Bayesian approach to model assessment requires the calculation of the evidence of each candidate model considered given the available measured data, which is a nontrivial task, and it is usually attempted offline, e.g., by using a stochastic simulation scheme or some deterministic approximation. Very few authors, in general, and hardly any in the field of structural dynamics, have investigated online application of model assessment. The current work explores how Bayesian model assessment and an online identification scheme for joint state and parameter estimation, in particular the unscented Kalman filter, whose computational efficiency has been widely recognized, could be integrated into a single method. This hierarchical Bayesian modeling approach involves two inference levels, namely, model assessment and parameter estimation. There is the possibility of adding another level within the hierarchy for noise estimation. An illustrative example involving several hysteretic candidate models is presented to demonstrate the implementation of the proposed procedure in structural health monitoring applications. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-19T04:35:30.849928-05:
      DOI: 10.1002/stc.1880
       
  • Correlation between global damage and local damage of RC frame structures
           under strong earthquakes
    • Authors: Zheng He; Yichao Xu
      Abstract: In order to reasonably incorporate local and global monitoring response data into dynamic update in the weighted combination models for a closer correlation between global damage and local damage, a logical time‐variant correlation between global damage and local damage is established for reinforced concrete structures under strong earthquakes. Two sets of dynamic weight coefficients used to characterize the relative damage contribution of floors through modal information and energy information are suggested in the correlation. The modal information‐based weight coefficients that are defined as the normalized accumulative times of reserved floors could be capable of retaining the necessary information of relatively weak floors or sensitive regions with localized damage significance, while the energy information‐based weight coefficients based on the normalized curvature difference of ‘jerk energy’ are helpful to quantify the relative degree of floor damages accumulated by hysteretic dissipated energy. The combination factors corresponding to the proposed dynamic weight coefficients, together with static weight coefficients, are calibrated by a macroscopic global seismic damage model. The results from the example study indicate that these factors show different changing rules with increasing peak ground acceleration level. Modal information‐based weight coefficients have been found to have a desirable agreement with the inter‐story pure translation ratios. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-19T04:31:30.934734-05:
      DOI: 10.1002/stc.1877
       
  • Particle filtering and marginalization for parameter identification in
           structural systems
    • Authors: Audrey Olivier; Andrew W. Smyth
      Abstract: In structural health monitoring, one wishes to use available measurements from a structure to assess structural condition, localize damage if present, and quantify remaining life. Nonlinear system identification methods are considered that use a parametric, nonlinear, physics‐based model of the system, cast in the state‐space framework. Various nonlinear filters and parameter learning algorithms can then be used to recover the parameters and quantify uncertainty. This paper focuses on the particle filter (PF), which shows the advantage of not assuming Gaussianity of the posterior densities. However, the PF is known to behave poorly in high dimensional spaces, especially when static parameters are added to the state vector. To improve the efficiency of the PF, the concept of Rao–Blackwellisation is applied, that is, we use conditional linearities present in the equations to marginalize out some of the states/parameters and infer their conditional posterior pdf using the Kalman filtering equations. This method has been studied extensively in the particle filtering literature, and we start our discussion by improving upon and applying two well‐known algorithms on a benchmark structural system. Then, noticing that in structural systems, high nonlinearities are often localized while the remaining equations are bilinear in the states and parameters, a novel algorithm is proposed, which combines this marginalization approach with a second‐order extended Kalman filter. This new approach enables us to marginalize out all the states/parameters, which do not contribute to any high nonlinearity in the equations and, thus, improve identification of the unknown parameters. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-19T04:25:52.892868-05:
      DOI: 10.1002/stc.1874
       
  • Improving performance of a super tall building using a new
           eddy‐current tuned mass damper
    • Authors: Xilin Lu; Qi Zhang, Dagen Weng, Zhiguang Zhou, Shanshan Wang, Stephen A. Mahin, Sunwei Ding, Feng Qian
      Abstract: Two kinds of methods have been primarily used to improve the vibration performance of high‐rise buildings. One approach is to enhance the structural lateral stiffness, which may increase the component size and inefficiently use material. The other approach is to employ vibration control devices, such as tuned mass dampers (TMDs), tuned liquid dampers (TLD) and other supplemental damping devices. This latter approach has proved to be quite economical and efficient, and as such, increasingly used in practice. The Shanghai Center Tower (SHC) is a super high‐rise landmark building in China, with a height of 632 m. In order to mitigate its vibration during wind storms, a new eddy‐current TMD was installed at the 125th floor. Special protective mechanisms were incorporated to prevent excessively large amplitude motion of the TMD under extreme wind or earthquake scenarios. Results of reduced‐scale laboratory tests and field tests are presented in this paper to characterize the dynamic properties of the damping device and validate the fidelity of the numerical results. Results of structural analyses indicate that for SHC the eddy‐current TMD was able to reduce wind‐induced structural acceleration by 45%–60% and earthquake‐induced structural displacement by 5%–15%. The installation of the TMD was completed in December 2014, and the performance observed to date is judged to be good. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-18T04:12:42.556007-05:
      DOI: 10.1002/stc.1882
       
  • A model‐based method for damage detection with guided waves
    • Abstract: Defect detection techniques, which utilise guided waves, have received significant attention over the past twenty years. Many of these techniques implement the baseline signal subtraction approach for damage diagnosis. In this approach, the baseline signal previously recorded for a defect‐free structure is compared with/or subtracted from the actual signal recorded during routine inspections. A significant deviation between these two signals (or residual signal/time‐trace) can be treated as an indication of the presence of critical damage. However, the accuracy of this common approach can be compromised by various uncontrolled factors, which include ambient temperature variations, unavoidable inconsistencies in the PZT installation procedure and degradation of mechanical properties with time. This paper presents a new method for reconstruction of the baseline signal, which can compensate for the above influences and improve the accurateness of damage diagnosis. The method utilises 3D laser vibrometry measurements in conjunction with high‐fidelity FE simulations. This paper also describes an application of this method to the reconstruction of the baseline signal and detection of damage in beam and plate structures. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-18T04:12:11.718728-05:
      DOI: 10.1002/stc.1884
       
  • Assessing the effect of nonlinearities on the performance of a tuned
           inerter damper
    • Abstract: In this paper, the use of a tuned inerter damper (TID) as a vibration absorber is studied numerically and experimentally, with civil engineering applications in mind. Inerters complete the analogy between mechanical and electrical networks, as the mechanical element equivalent to a capacitor and were developed in the 2000s. Initially, inerters were used for applications in automotive engineering, where they are known as J‐dampers. Recently, research has suggested that inerter‐based networks could be used for civil engineering applications, offering interesting advantages over traditional tuned mass dampers. In the civil engineering context, research has been mainly theoretical, considering ideal inerters. Because the dynamics of an inerter device include nonlinearities, especially at the low frequencies associated with civil engineering applications, the performance of the TID device using an off‐the‐shelf inerter has been experimentally tested in the work presented here. The chosen system, comprising a host structure with a TID attached to it, was tested using real‐time dynamic substructuring (RTDS) or hybrid testing. The inerter was tested physically, while the remaining components of the TID device, the spring and damper, together with the host structure, were simulated numerically. Displacements and forces at the interface between numerical and physical components are updated in real time. This numerical–physical split allows the optimisation of the TID parameters, because the values of the spring and the damper can be changed without altering the experimental setup. In addition, this configuration takes into account the inerter's potentially complex dynamics by testing it experimentally, together with the characteristics of the host structure. Developing RTDS tests for physical inertial substructures, where part of the fed back interface forces are proportional to acceleration, is a challenging task because of delays arising at the interface between the experimental and the numerical substructures. Problems associated with stability issues caused by delay and causality arise, because we are dealing with neutral and advanced delayed differential equations. A new approach for the substructuring algorithm is proposed, consisting of feeding back the measured force deviation from the ideal inerter instead of the actual force at the interface. The experimental results show that with appropriate retuning of the components in the TID device, the performance in the TID incorporating the real inerter device is close to the ideal inerter device. © 2016 The
      Authors . Structural Control and Health Monitoring published by John Wiley & Sons, Ltd.
      PubDate: 2016-05-15T22:40:32.973161-05:
      DOI: 10.1002/stc.1879
       
  • Real‐time experimental validation of a novel semi‐active
           control scheme for vibration mitigation
    • Authors: Mohammad S. Miah; Eleni N. Chatzi, Vasilis K. Dertimanis, Felix Weber
      Abstract: This study performs an experimental investigation of a novel, semi‐active control strategy for effective vibration mitigation. The implemented approach comprises a combination of the linear quadratic regulator with a nonlinear observer, namely, the unscented Kalman filter, for the control of systems described by uncertainties. Indeed, numerical models of structural systems often result as inadequate because of inherent uncertainties, such as noise, modeling errors, unknown system properties, or influence of varying operational and environmental conditions. In tackling this issue, the unscented Kalman filter is herein employed for adaptive joint state and parameter estimation refining the accuracy of the model employed by the controller and resulting in enhanced vibration mitigation. A scaled five‐story shear frame attached to a hydraulic cylinder comprises the tested structure, where actuation is provided by means of a rotational magnetorheological damper operating on the relative motion between the ground floor and the first floor plate. The experimentally obtained results demonstrate a good agreement with simulations and encourage further implementation of the proposed framework in field applications of structural control. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-15T22:35:57.414218-05:
      DOI: 10.1002/stc.1878
       
  • Vibration‐based system identification of wind turbine system
    • Abstract: The goal of this study was to investigate the use of vibration‐based system identification methods for detecting wind turbine blade delamination during operating conditions and when subjected to other excitations such as earthquake ground motion. In particular, multivariate singular spectrum analysis and two subspace identification techniques were tested for detecting the dynamic characteristics of the wind blade. A total of two series of experiments was conducted to verify the proposed algorithms. In both cases, accelerometers were installed on the blades for measuring their vibration response. The first test series were performed in the laboratory; a motor spun a small‐scale customized wind turbine at controlled angular velocities, and the shaking table excited the entire structure. Artificial damage was introduced by loosening bolts at the blade‐rotor connection. The second test was conducted in the field, and vibration data was collected from an operating small‐scale wind turbine. The blade's vibration response was analyzed through time‐frequency analyses and subspace identification. These tests confirmed that the estimation of dynamic characteristics of blade and rotating frequency of the turbine system was feasible, and the results will guide future monitoring studies planned for larger‐scale systems. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-10T03:15:55.377285-05:
      DOI: 10.1002/stc.1876
       
  • Distributed sensing of a masonry vault during nearby piling
    • Authors: Sinan Acikgoz; Loizos Pelecanos, Giorgia Giardina, James Aitken, Kenichi Soga
      Abstract: Piles were constructed inside historic brick barrel vaults during the London Bridge Station Redevelopment. In order to ensure safe operation of the tracks above, movements of the vaults were monitored regularly by total stations. Concurrently, two distributed sensing technologies, fibre optic cables and laser scanners, were used to investigate the vault response to settlements. This paper discusses the monitoring data retrieved from these ‘point’ and ‘distributed’ sensing technologies and evaluates their use in structural assessment. The total station data are examined first. It is characterized by high precision and limited spatial coverage due to the use of optical targets. As a result, the total station data are useful for threshold detection but do not provide a detailed understanding of structural response or damage. In contrast, by utilizing distributed fibre optic sensors based on Brillouin optical domain reflectometry, the strain development in the structure during piling is quantified. The location and width of resulting crack openings are also determined, providing useful indicators for damage evaluation. The comparison of point clouds from laser scanners obtained at different stages of pile construction further expands the spatial coverage by detecting global movement of the structure on all visible surfaces. Using these data, the two hinge‐response mechanism of the vault is revealed. The rich distributed data enable the calibration of the 2D mechanism and the finite element models, elucidating the contribution of arch stiffness, arch and backfill interaction, potential lateral movements and inter‐ring sliding to the response. © 2016 The
      Authors . Structural Control and Health Monitoring published by John Wiley & Sons, Ltd.
      PubDate: 2016-05-10T03:00:37.839851-05:
      DOI: 10.1002/stc.1872
       
  • Efficient optimal design and design‐under‐uncertainty of
           passive control devices with application to a cable‐stayed bridge
    • Authors: Subhayan De; Steven F. Wojtkiewicz, Erik A. Johnson
      Abstract: Structures today may be equipped with passive structural control devices to achieve some performance criteria. The optimal design of these passive control devices, whether via a formal optimization algorithm or a response surface parameter study, requires multiple solutions of the dynamic response of that structure, incurring a significant computational cost for complex structures. These passive control elements are typically point‐located, introducing a local change (possibly nonlinear, possibly uncertain) that affects the global behavior of the rest of the structure. When the structure, other than these localized devices, is linear and deterministic, conventional solvers (e.g., Runge–Kutta, MATLAB's ode45, etc.) ignore the localized nature of the passive control elements. The methodology applied in this paper exploits the locality of the uncertain and/or nonlinear passive control element(s) by exactly converting the form of the dynamics of the high‐order structural model to a low‐dimensional Volterra integral equation. Design optimization for parameters and placement of linear and nonlinear passive dampers, tuned mass dampers, and their combination, as well as their design‐under‐uncertainty for a benchmark cable‐stayed bridge, is performed using this approach. For the examples considered herein, the proposed method achieves a two‐orders‐of‐magnitude gain in computational efficiency compared with a conventional method of comparable accuracy. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-06T00:50:43.953337-05:
      DOI: 10.1002/stc.1846
       
  • Adaptive block backstepping control for civil structures with unknown
           parameters subjected to seismic excitation
    • Authors: Pedram Ghaderi; Fereidoun Amini
      Abstract: This paper presents an active control scheme for structures with unknown parameters subjected to ground acceleration. It is assumed that the mass, stiffness and damping matrices are unknown to the designer, and no measurement of the ground acceleration is available. Instead, the displacement and velocity vectors are accessible for control purposes. Adaptive block backstepping is used to propose a control force vector which makes the response of the structure follow a predefined reference signal as closely as possible. The provided numerical examples in this paper show the admissible performance of the proposed closed‐form solution for the control force. The benefits and drawbacks of this approach are discussed as well. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-04T03:01:52.512187-05:
      DOI: 10.1002/stc.1875
       
  • Set‐membership identification technique for structural damage based
           on the dynamic responses with noises
    • Authors: Qinghe Shi; Xiaojun Wang, Lei Wang, Yunlong Li, Xiao Chen
      Abstract: Based on the availability of measured acceleration signals of structures, the interval analysis technique and set‐membership identification concept are combined to identify the structural damage in this paper. Because of the insufficiency and uncertainty of information obtained from measurements, the noises of measurements are enveloped by interval numbers. Via the first‐order Taylor series expansion, the interval bounds of the element stiffness parameters (ESPs) of both undamaged and damaged structures are derived by updating the reference finite element model. Through the intersection operations of intervals of the ESP obtained from dynamic responses in different time periods, the estimate intervals of the ESP are refined. Three damage indexes as stiffness reduce factor, possibility of damage existence, and damage measure index are introduced to identify the damage in the structure. Even though the dynamic responses are with low signal‐to‐noise ratio, the injury of structure can be detected by the proposed method. Two numerical examples and an experimental example are performed to demonstrate the feasibility and effectiveness of the proposed technique. The results show that the proposed method can improve the accuracy of damage diagnosis compared with the deterministic damage identification method. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-04T02:56:41.287311-05:
      DOI: 10.1002/stc.1868
       
  • Real‐time control of shake tables for nonlinear hysteretic systems
    • Authors: Ki P. Ryu; Andrei M. Reinhorn
      Abstract: Shake table testing is an important tool to challenge integrity of structural and non‐structural specimens by imposing excitations at their base. When shake tables are loaded with specimens, the interaction between the tables and specimens influences the system dynamics that may result in undesired performance. In order to compensate the effects of the interaction, open loop feedforward compensation methods have been widely used successfully in current practice of table controls, assuming that the specimens remain linear. On the contrary, unsatisfactory signal performances during shake table testing were observed when flexible and heavy specimens experience nonlinear behavior. While lack of high fidelity might be acceptable for the purpose of exploration research of specimens subjected to random excitations, a high fidelity of signal reproduction is necessary for shake table qualification testing where specific target motion is required to challenge the specimens. In this study, a nonlinear tracking control scheme based on the feedback linearization method is proposed for the control of shake tables to simulate target motions at specific locations of test structures, having nonlinear hysteretic behavior. Additionally, a real‐time estimator using the extended Kalman filter is adopted and combined with the controller in order to account for the changes and uncertainties in system models due to nonlinearities and yielding caused by extreme excitations. The proposed adaptive tracking control method has been applied to a realistic shake table–structure test setup by means of numerical simulations, and the results show good tracking and estimation performance. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-04T02:56:20.901021-05:
      DOI: 10.1002/stc.1871
       
  • Modeling and analysis of a structure semi‐active tuned liquid damper
           system
    • Authors: I. M. Soliman; M. J. Tait, A. A. El Damatty
      Abstract: A tuned liquid damper (TLD), which is similar to a tuned mass damper (TMD), is a type of dynamic vibration absorber (DVA) that can be employed to reduce wind induced resonant vibrations of a structure. Improved TLD performance could be realized by equipping TLDs with variable energy dissipating capabilities such as damping screens, which can be adjusted through a certain mechanism, permitting optimal control performance to be maintained over a wide range of loading conditions in a semi‐active mode of control. In this paper, a control strategy based on a gain scheduling scheme is utilized by controlling the inclination angle of the damping screen(s) and consequently the screen loss coefficient value(s). The gain scheduling control strategy is employed on a simple single‐story structure equipped with a semi‐active TLD (SA‐TLD) in order to maintain the optimal damping value (ζTLD − opt) based on averaged or instantaneous structural response tracking and a prescribed look‐up table. Results are assessed using experimental values from tests conducted on conventional passive TLDs. A performance comparison between a semi‐active TLD control system and a conventional passive TLD control system is carried out. The fluid response amplitude for a SA‐TLD is also investigated and compared to that of a passive TLD. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-05-04T02:51:35.520825-05:
      DOI: 10.1002/stc.1865
       
  • Experimental investigation of the re‐centring capability of curved
           surface sliders
    • Authors: Virginio Quaglini; Emanuele Gandelli, Paolo Dubini
      Abstract: The re‐centring capability is recognized as a fundamental function of the isolation system, because it is intended to prevent substantial permanent deformation at the end of the earthquake that may affect the serviceability of the structure and eventually limit the capability of the isolators to withstand aftershocks and future earthquakes. In this study, the re‐centring behaviour of isolation systems composed of sliding bearings with curved surfaces is investigated in shake‐table tests carried out on a one‐storey steel frame with rectangular plan, scaled at one third‐length scale and isolated with four bearings. The coefficient of friction of the bearings is varied by changing the material or lubrication condition of the pads, providing different equivalent damping ratios to the isolation system. The response of the base isolated structure to selected natural ground motion waveforms is assessed in terms of the residual displacement after a single event and the accrual of displacements during a sequence of quakes, and considerations on the influence of the coefficient of friction on the re‐centring behaviour, as well as on the effect of an initial displacement offset are drawn. The re‐centring provision of the current European design code is eventually checked against the experimental data. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-29T02:05:53.820196-05:
      DOI: 10.1002/stc.1870
       
  • Driving effects of vehicle‐induced vibration on long‐span
           suspension bridges
    • Authors: Yang Liu; Xuan Kong, C.S. Cai, Da Wang
      Abstract: Vehicle‐induced vibration is important to consider in assessing the structural safety of bridges. This issue has been widely investigated in recent years in the open literature. The current research studies mainly emphasize the effects of bridge span and vehicle; however, the driving effects, such as the driving speed, vehicle model parameters, and driving conditions, have rarely been investigated. In this study, researches on the driving effects of vehicle‐induced vibration on long‐span suspension bridges were conducted. First, a typical three‐dimensional vehicle model with multi‐axils was proposed, and three different road roughness models rated as excellent, good, and normal were generated with a power spectral density, and a random traffic flow with 16 vehicle types was simulated using the proposed random traffic flows model generation program. Next, an effective finite element model with Ishikawa beams stiffening girder was established to investigate the driving effects of the vehicle‐induced vibration. The calculations of the effects on the vehicle body parameters, road roughness, driving direction, and speed were performed. Possible reasons for the driving effects of vehicle‐induced vibration on long‐span suspension bridges were also discussed. In addition, conclusions and recommendations for future bridge analysis and design were provided based on the results of the study. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-26T01:30:53.788696-05:
      DOI: 10.1002/stc.1873
       
  • Effect of different steel‐reinforced elastomeric isolators on the
           seismic fragility of a highway bridge
    • Authors: Farshad Hedayati Dezfuli; M. Shahria Alam
      Abstract: Seismic fragility assessment of highway bridges is a technique to predict the probability of the structure reaching a certain level of damage under a given seismic excitation. Vulnerable structural components have significant contributions to the failure probability of a bridge system. The effect of elastomeric isolators on the seismic fragility of highway bridges has been discussed in the literature; however, the impact of different types of rubber bearings, including natural rubber bearing, high‐damping rubber bearing, and lead rubber bearing has not been investigated yet. The objective of this study is to address this problem in detail. Seismic fragility of isolated bridges is analytically estimated by considering pier and isolation system as two major vulnerable components. Results showed that the isolation system is more fragile than the bridge pier. This finding represents those scenarios where the structure (and especially its seismic isolation system) is designed only according to the usually adopted probabilistic seismic hazard assessment, with a frequently insufficiently too short useful life. The bridge isolated by natural rubber bearing, which has the lowest lateral stiffness and energy dissipation capacity among considered bearings, is the most vulnerable system, and the bridge quipped with HDRB has the minimum risk to undergo damage. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-20T00:55:53.801823-05:
      DOI: 10.1002/stc.1866
       
  • Pipe dampers as passive devices for seismic control of isolated bridges
    • Authors: Saeed Mahjoubi; Shervin Maleki
      Abstract: During an earthquake, pounding of bridge superstructure into abutments is potentially destructive to structural elements and may cause unseating failure and collapse. By using energy dissipative devices such as passive dampers, the harmful pounding force may be prevented. One of the most economical passive dampers for structural applications is the pipe damper, recently introduced by the authors. In this paper, computer models of a two‐span 60‐m long conventional overpass bridge are equipped with different lengths of two types of pipe dampers, namely the dual‐pipe (DPD) and infilled‐pipe (IPD) dampers. A simplified lumped‐mass model for the bridge considering soil stiffness is proposed and used in the study. A connection detail for connecting pipe dampers to the plate girders is also presented. The detail ensures that pipe dampers act only in the longitudinal direction, and no moment is transferred to the girders. A parametric study is performed on pipe damper length and excitation peak acceleration. Seismic responses of the bridge model with and without pipe dampers are investigated. The results of the study prove that both types of pipe dampers are effective in eliminating pounding force and significantly reducing seismic responses of bridges at a very low cost. A simple displacement‐based procedure for design of dual‐pipe damper and infilled‐pipe damper elements to prevent deck‐abutment impact in bridges with expansion joints is suggested in this study. An example of the suggested design procedure is then presented. The design example demonstrates an acceptable correspondence with the results obtained from the parametric analysis. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-19T03:40:54.503406-05:
      DOI: 10.1002/stc.1869
       
  • Railroad bridge monitoring using wireless smart sensors
    • Authors: F. Moreu; R. E. Kim, B. F. Spencer
      Abstract: Railroads carry more than 40% of the freight, in terms of tons per mile transported in North America. A critical portion of the railroad infrastructure is the more than 100,000 bridges, which occur, on the average, every 1.4 miles of track. Railroads have a limited budget for capital investment. Therefore, decisions on which bridges to repair/replace become critical for both safety and economy. North American railroads regularly inspected bridges to ensure safe operation that can meet transport demands, using inspection reports to decide which bridges may need maintenance, replacement, or further investigation. Current bridge inspection practices recommend observing bridge responses under live load to help assess bridge condition. However, measuring bridge responses under train loads in the field is a challenging, expensive, and complex task. This research explores the potential of using wireless smart sensors (WSS) to measure bridge responses under revenue service traffic that can be used to inform bridge management decisions. Wireless strain gages installed on the rail measure real‐time train loads. Wireless accelerometers and magnetic strain gages installed in the bridge measure associated bridge responses. The system is deployed and validated on a double‐track steel truss bridge on the south side of Chicago, Illinois, owned by the Canadian National Railway. A calibrated finite element model of the bridge with known train input load estimated the responses of the bridge at arbitrary, unmeasured locations, showing the possibility of applying the system for decision making process. These results demonstrate the potential of WSS technology to assist with railroad bridge inspection and management practice. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-19T03:37:16.699845-05:
      DOI: 10.1002/stc.1863
       
  • Influence of high austenite stiffness of shape memory alloy on the
           response of base‐isolated benchmark building
    • Authors: Sharad Ghodke; R.S. Jangid
      Abstract: The influence of high austenite stiffness of shape memory alloy (SMA) on the response of base‐isolated benchmark building has been investigated. Dynamic analysis was performed by solving the governing equations of motion using Newmark‐beta method under three near‐fault earthquake motions. The super‐elastic behavior of SMA was modeled by the Grasser–Cozzarelli model. Structural response parameters such as top‐floor acceleration, base displacement, and base shear were chosen for investigation. Three near‐fault earthquakes with bidirectional ground motions were considered. It was observed that because of high austenite stiffness of SMA, higher accelerations associated with high frequencies are transmitted to the superstructure. The isolation device with high austenite stiffness of SMA excites the higher modes of the base‐isolated structure and thus magnifies the floor accelerations. This phenomenon can be detrimental to the high‐frequency internal equipments mounted in the base‐isolated structure. On the other hand, the high austenite stiffness of SMA does not affect the base displacement and base shear of the base‐isolated structure significantly. Furthermore, the influence of high austenite stiffness of SMA is dependent on the transformation strength of SMA and flexibility of the isolator. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-19T03:36:48.110784-05:
      DOI: 10.1002/stc.1867
       
  • Feasibility of shape memory alloy in a tuneable mass damper to reduce
           excessive in‐service vibration
    • Abstract: The applications of shape memory alloy (SMA) in vibration reduction are benefited by its superelasticity and thermomechanical properties. This study is a part of a series of research projects focused on reduction of timber floor vibration. In this study, the feasibility of this tuneable mass damper is tested for in‐service vibration reduction. At first, the effect of temperature ranging from 11 °C to 120 °C on the dynamic characteristics of SMA was investigated under different pre‐stressed levels. At higher temperatures, the damping ratio reduces while stiffness increases, and vice versa with decreasing temperature. SMA is sensitive to temperature when the pre‐stressed level is near the phase transformation stress. Next, the analytical model of timber floor system was built and idealised as a two‐degree‐of‐freedom system. Thirdly, a series of lab tests were carried out, and a damper consisting of an SMA bar was added on a cantilever beam with different natural frequencies, which represents floor system in the model. The results show that the vibration response of the system can be significantly reduced by the damper developed in this project, when the damper has resonance with the system. The mass of the system was then changed so as to make the damper out‐of‐tuned; the damper was then retuned by cooling/heating on SMA. After retuning of the damper, the response of the system was effectively reduced, which demonstrates the effectiveness and feasibility of employing SMA in the damper system. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-19T03:15:50.536692-05:
      DOI: 10.1002/stc.1858
       
  • Assessment of long‐term coordinate time series using
           hydrostatic‐season‐time model for rock‐fill embankment
           dam
    • Authors: Sonja Gamse; Michael Oberguggenberger
      Abstract: The safety control of dams is based on monitoring activities and modelling of registered observations. The statistical hydrostatic‐season‐time model was originally developed and proposed for analyzing of monitoring data on concrete dams. In some later works, the model was implemented for earth‐fill embankment dams. The model admits a simultaneous estimation of hydrostatic load, temperature influences and irreversible deformations. In our study, we analyze long‐term coordinate time series of a geodetic point on the crest of a rock‐fill embankment dam. Coordinate time series are result of an adjustment of the observations in a permanent geodetic network for different epochs. An optimal model is defined using a multiple linear regression by combined process of exclusion and inclusion of individual parameters. In the process, different statistical parameters are observed. The analyses confirmed that not all parameters are significant. The most interesting and important conclusion of computations can be stated as follows: after inclusion of significant coefficients of the hydrostatic load and long‐term trend, the residual time series still expose underlying periodicities. They can be removed by inclusion of at least one parameter of the seasonal term, where the temperature influences (i.e. air, water and soil) are modelled. The influences of the temperature on the dam are not significant in any direction, but the inclusion of the parameters improves the statistical performance of the used model. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-06T00:17:35.493541-05:
      DOI: 10.1002/stc.1859
       
  • Introduction of the convex friction system (CFS) for seismic isolation
    • Abstract: This work introduces an innovative seismic isolation system named the convex friction system (CFS). This newly introduced isolation system has a sliding concavity with a circular cone‐type surface, and exhibits some distinct features compared to conventional isolation techniques, such as increased uplift stability, improved self‐centring capacity, and resonance dodge when subjected to near‐fault earthquakes. A series of comprehensive analytical and numerical investigations are performed to verify these features of the CFS. First, the force–displacement relation of the CFS is established to describe the underlying philosophy of the system. The analytical model is then incorporated into numerical simulations to evaluate the seismic isolation performance of the CFS. Various ground accelerations, such as near‐fault shakings, are included in these numerical calculations. Furthermore, the numerical results are rigorously investigated to illustrate the feasibility of the CFS. Finally, the limitations of the CFS study are discussed, and conclusions are drawn. The analytical and numerical results show that the CFS performs well in seismic isolation applications. The structural response can be reduced by approximately 30% with the CFS when compared to that with the Curved Surface Slider (CSS) with a spherical‐surface concavity for some near‐fault earthquakes, which verifies the aforementioned advantages of the CFS. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-04T03:15:29.887194-05:
      DOI: 10.1002/stc.1861
       
  • Damage detection for shear structures based on wavelet spectral
           transmissibility matrices under nonstationary stochastic excitation
    • Authors: Jun Luo; Gang Liu, Zongming Huang
      Abstract: A new method of spectral transmissibility function extraction and damage detection for shear frame structures under nonstationary stochastic excitation is proposed. A new concept named wavelet spectral transmissibility function is proposed as damage feature. It is demonstrated that the wavelet spectral transmissibility function can characterize the structure while closing to the natural frequencies of the structure. Subsequence, the singular value decomposition of wavelet spectral transmissibility matrices with different references is proposed as an identification method of natural frequencies, and wavelet spectral transmissibility functions between two neighborhood measurement points at the natural frequencies under nonstationary stochastic excitation. At last, a new damage indicator is developed to locate and quantify the damage of shear frame structure, based on the wavelet spectral transmissibility functions and constraint linear least square method. A numerical model and a lab‐scale frame structure successfully verify the validity of the proposed algorithm. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-04-01T03:51:12.983197-05:
      DOI: 10.1002/stc.1862
       
  • Seismic performance of a damping outrigger system for tall buildings
    • Authors: Ying Zhou; Cuiqiang Zhang, Xilin Lu
      Abstract: A novel damping outrigger system is proposed for tall buildings by replacing the diagonal members with buckling restrained bracings. To investigate the conceptual design of the system, a simplified mechanical model for the outrigger system is first put forward in this paper. Four configurations of outriggers, which are commonly used in practical engineering, are compared from the aspects of stiffness, strength, and energy‐dissipating capacity. The damping outriggers of the best configuration with buckling restrained braces acting as diagonal web members of outriggers are then proposed. The effect of the system on the whole structure is demonstrated through a 632‐m‐tall building. The results indicate that the damping outrigger can serve as stiffness member under the frequently occurred earthquakes and energy dissipating member under the rarely occurred earthquakes to protect the main structure from severe damages. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-31T00:15:52.068766-05:
      DOI: 10.1002/stc.1864
       
  • Shape‐memory alloys as macrostrain sensors
    • Authors: Filipe Amarante dos Santos
      Abstract: The present paper studies the feasibility, through physical experimentation, of efficient and low‐cost macrostrain sensors, based on shape‐memory alloy technologies. The motivation of this work is to explore the intrinsic relation between electrical resistivity and strain, associated with the development of the stress induced martensitic transformation in superelastic shape‐memory alloys. This property enables the material to endure deformations up to 8% without any residual strains, making shape‐memory alloy wires excellent candidates for kernel elements in innovative strain transducers with dynamic ranges 4 to 5 times larger than the currently available strain transducers. An experimental prototype of a beam with a set of SMA macrostrain sensors is presented, featuring a timed scanning sequential algorithm to successfully perform the resistance readings. The aim of this work is to provide an additional insight into the potential of SMAs in new macrostrain measurement applications. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-30T02:40:48.657146-05:
      DOI: 10.1002/stc.1860
       
  • Reliability‐based performance optimization of TMD for vibration
           control of structures with uncertainty in parameters and excitation
    • Authors: Amit Kumar Rathi; Arunasis Chakraborty
      Abstract: Recent development of system identification using Bayesian models or stochastic filtering provides probabilistic descriptions (i.e., probability density function or statistical parameters like mean and variance) of the identified model parameters (e.g., mass, stiffness, and damping). Optimal design of passive controllers for these systems whose parameters are uncertain has remained an open problem. With this in view, the present study aims to develop numerical solution scheme for the optimal design of tuned mass damper (TMD) operating in uncertain environment. Deterministic design of TMD in these cases suffers detuning as the system parameters are random. Thus, a reliability‐based design optimization (RBDO) scheme is presented in this paper for better performance of the TMD when exposed to uncertainties. To solve the RBDO problem, response surface methodology is used along with the moving least squares technique. Dual response surfaces are used for separate handling of optimization and reliability analysis. First response surface performs optimization of the design variables of TMD, while the second response surfaces are used for the estimation of the statistical properties like mean and variance to satisfy the constrained conditions. Numerical analysis is presented to show the effectiveness of the proposed algorithm for RBDO of single degree of freedom‐TMD system as a proof of concept. The proposed meta‐model‐based algorithm can be applied for the optimal design of controller for large structures where conventional technique may face difficulty to handle both optimization and uncertainty quantification simultaneously. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-14T07:43:46.857224-05:
      DOI: 10.1002/stc.1857
       
  • Improved control performance of sloped rolling‐type isolation
           devices using embedded electromagnets
    • Abstract: Sloped rolling‐type isolation devices incorporating built‐in friction damping and pounding preventer have been verified to be effective for mitigation of seismic risks posed to critical equipment and facilities. Although the built‐in damping design can effectively suppress excessive displacement responses, it also increases the acceleration transmitted to the protected object above the isolation device. In this study, a novel mechanism using embedded electromagnets is proposed to improve the control performance of the isolation device. By varying the input currents to the electromagnets, the corresponding magnetic force becomes controllable and can appropriately adjust the normal force applied to the sliding interface, leading to indirect semi‐active control of friction damping force. The efficacy of the proposed mechanism is verified through several shaking table tests. Experimental results demonstrate that the control target of the isolation device can be semi‐actively achieved using the electromagnetic mechanism. Accordingly, a numerical model of such a smart isolation system, the incorporation of the proposed controllable damping mechanism into the conventional sloped rolling‐type isolation device, is proposed and calibrated by the experimental data. Its effectiveness and advantage can be clearly observed particularly when appropriate control algorithms are applied to calculating input currents for the electromagnets. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-09T02:05:18.872243-05:
      DOI: 10.1002/stc.1853
       
  • Robust data transmission and recovery of images by compressed sensing for
           structural health diagnosis
    • Authors: Yongchao Yang; Satish Nagarajaiah
      Abstract: Digital cameras are cost‐effective vision sensors and able to directly provide two‐dimensional information of structural condition in monitoring and assessment applications. For example, digital cameras are essential components of unmanned aerial vehicles (UAVs) and robotic agents for mobile sensing and inspection of pipelines, buildings, transportation infrastructure, etc, especially in post‐natural disaster and man‐made extreme events assessment. Additionally, while surveillance cameras have been widely used for transportation systems (e.g., traffic monitoring), if appropriately mounted on the large‐scale structures such as the bridges, they can continuously monitor the structural condition under operational loads and hazards, complementing the regular visual inspection and assessment conducted by experts. In these or other applications, efficiently and reliably transferring the structural images or videos, which are as such large‐scale, are important and challenging, especially in wireless platform that is either required (e.g., UAVs and robotic agents) or more suitable (e.g., camera monitoring networks) with only limited power and communication resources. This paper studies the computational algorithms for efficient and reliable transmission of the structural monitoring images; in particular, the compressed sensing (CS) technique is explored for robust data transmission and recovery. The sparse representation or data structure of the structural images is exploited, leading to the CS based central strategy: on some sparse domain, randomly encode large‐scale image data into few relevant coefficients, which are then transferred (robust to random data loss) and recovered (in base station) for subsequent structural health diagnosis. Image data of bench scale pipe structure, concrete structure and full scale stay cable are employed for validation of the CS based method. Its performance is also compared with traditional transform coding and low‐dimensional encoding (sampling), and their advantages and drawbacks are discussed. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-03-01T03:48:26.209965-05:
      DOI: 10.1002/stc.1856
       
  • Automated modal identification and tracking: Application to an iron arch
           bridge
    • Abstract: Challenges concerning the automation of modal identification and tracking procedures in permanent monitoring systems for Structural Health Monitoring purposes are discussed. In this context, an automated procedure based on parametric identification methods that involve the interpretation of stabilization diagrams is proposed. The methodology comprehends two key points: (i) automatic analysis of stabilization diagrams, performed through a first check of reasonable damping ratio, a subsequent modal complexity check and a final clustering of structural modes; (ii) automated tracking of the evolution in time of the identified modal properties. The proposed modal clustering and tracking steps exploit the introduction of self‐adaptable dynamic thresholds, that do not require any a priori manual tuning for the different recorded data set. Finally, the proposed approach was successfully validated using real data collected on a historic iron arch bridge. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-28T23:50:20.206439-05:
      DOI: 10.1002/stc.1854
       
  • Completely contactless structural health monitoring of real‐life
           structures using cameras and computer vision
    • Authors: Tung Khuc; F. Necati Catbas
      Abstract: A newly developed, completely contactless structural health monitoring system framework based on the use of regular cameras and computer vision techniques is introduced for obtaining displacements and vibrations of structures, which are critical responses for performance‐based design and evaluation of structures. To provide contactless and practical monitoring, the current vision‐based displacement measurement methods are improved by eliminating the physical target attachment. This is achieved by means of utilizing imaging key‐points as virtual targets. As a result, pixel‐based displacements of a monitored structural location are determined by using an improved detection and match key‐points algorithm, in which false matches are identified and discarded almost completely. To transform pixel‐based displacements to engineering units, a practical camera calibration method is developed because calibration standard on a physical target no longer exists. Moreover, a framework for evaluating the accuracy of vision‐based displacement measurements is established for the first time, which, in return, provides users with the most crucial information of a measurement. The proposed framework along with a conventional sensor network and a data acquisition system are applied and verified on a real‐life stadium during football games for structural assessment. The results obtained by the new method are successfully validated with the data acquired from sensors such as linear variable differential transformers and accelerometers. Because the proposed method does not require any type of sensor and target attachment, common field works such as sensor installation, wiring, maintaining conventional data acquisition systems are not required. This advantage enables an inexpensive and practical way for structural assessment, especially for real‐life structures. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-02-25T02:27:55.385148-05:
      DOI: 10.1002/stc.1852
       
  • Issue Information
    • Pages: 1071 - 1073
      Abstract: No abstract is available for this article.
      PubDate: 2016-07-05T01:25:38.976564-05:
      DOI: 10.1002/stc.1793
       
  • Localized genetically optimized wavelet neural network for
           semi‐active control of buildings subjected to earthquake
    • Authors: S. M. A. Hashemi; H. Haji Kazemi, A. Karamodin
      Pages: 1074 - 1087
      Abstract: Control algorithm is one of the most important aspects in successful control of buildings against earthquake. In recent years, because of their capabilities, soft computing methods, stemmed from human brain abilities, have become of particular interest to researchers. In this paper, a wavelet neural network‐based semi‐active control model is proposed in order to provide accurately computed input voltage to the magneto rheological dampers to generate the optimum control force of structures. This model is optimized by a localized genetic algorithm and then applied to a nine‐story benchmark structure subjected to 1.5× El Centro earthquake. The results show an average of 43% reduction of maximum drift in the controlled structure versus the uncontrolled one. The capability of the controller is also validated by applying other far‐field and near‐field earthquakes. The capability and efficiency of the proposed model are demonstrated in terms of drift, acceleration and base shear reduction. The proposed wavelet neural network is also compared with a tangent hyperbolic‐based feed forward neural network, linear quadratic Gaussian, clipped optimal controller, and genetic algorithm‐based fuzzy inference systems to show the superiority of the proposed controller. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-05T23:44:08.115232-05:
      DOI: 10.1002/stc.1823
       
  • Output‐only damage detection using vehicle‐induced
           displacement response and mode shape curvature index
    • Authors: Dongming Feng; Maria Q. Feng
      Pages: 1088 - 1107
      Abstract: Most of the existing bridge superstructure damage detection methods are based on acceleration or strain response due to ambient excitation. This paper proposes a bridge damage detection procedure that utilizes vehicle‐induced displacement response without requiring prior knowledge about the traffic excitation and road surface roughness. This study is partially motivated by the recent advances in convenient measurement of structural displacements enabled by video‐based sensors. Vehicle–bridge interaction analysis shows that when subjected to moving vehicles, the bridge displacement response is dominated by the first‐order mode component. This justifies the proposed damage detection method that only requires the first‐order mode shape curvature. While conventionally the mode shapes are extracted based on operational modal analysis, the first‐order mode shape is extracted by directly analyzing the power spectral density functions of measured bridge displacement responses under vehicle excitations. Numerical simulations are carried out to investigate the feasibility and performance of the proposed damage detection method using three damage scenarios including damage at single, double, and multiple locations, each involving several extents of damage defined by the reduction in element stiffness. The results reveal that all the damage cases can be successfully identified. Furthermore, the damage detection performance is evaluated for cases involving different classes of road surface roughness and less measurement points. The study demonstrates the potential of the proposed model‐free and time‐efficient method for damage detection of bridge structures. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-06T00:06:16.780407-05:
      DOI: 10.1002/stc.1829
       
  • Enhanced nonlinear crack‐wave interactions for structural damage
           detection based on guided ultrasonic waves
    • Authors: Kajetan Dziedziech; Lukasz Pieczonka, Piotr Kijanka, Wieslaw J Staszewski
      Pages: 1108 - 1120
      Abstract: The paper presents a new damage‐detection method based on nonlinear crack‐wave interaction. Low‐frequency vibration excitation is introduced to perturb damage, and high‐frequency interrogating wave is used to detect damage‐related nonlinearities. However, in contrast to other crack‐wave interaction approaches, localised wave packets are used for high‐frequency excitation. The synchronisation of the low‐frequency vibration with the interrogating high‐frequency wave packets is a key element of the proposed method. Numerical simulations and simple experimental tests in cracked aluminium beams are performed to demonstrate the method. The results show that the proposed method can detect and localise damage‐related and intrinsic nonlinearities, allowing for reliable damage detection. The method does not require baseline measurements representing an undamaged condition, and it is not sensitive to temperature variations. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-10T22:08:34.190044-05:
      DOI: 10.1002/stc.1828
       
  • Posicast control of structures using MR dampers
    • Authors: Tarek Edrees Alqado; George Nikolakopoulos
      Pages: 1121 - 1134
      Abstract: In this article, a novel application of a semi active posicast control scheme for structures with magneto‐rheological (MR) dampers is presented. MR dampers are considered to be highly promising of semi‐active control systems, which are becoming increasingly popular for alleviating the effects of dynamic loads on civil engineering structures because they combine the merits of both passive and active control systems. The main contribution of this article relates to the design, application, tuning and performance evaluation of the novel posicast control scheme for structural control. The efficiency of the suggested control strategy was evaluated by performing numerical simulations of a benchmark three‐storey building with an MR damper, rigidly attached between the first floor and the ground. The damper's behaviour was simulated using the Bouc–Wen model. Seven evaluation criteria were used to assess the performance of the proposed posicast control scheme in reducing the excited structure's responses to dynamic loading. The simulation's results indicated that the posicast control scheme had significant advantages over conventional alternatives in terms of performance and efficiency. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-13T03:09:56.500907-05:
      DOI: 10.1002/stc.1832
       
  • Structural damage detection using wireless passive sensing platform based
           on RFID technology
    • Authors: Mateusz Lisowski; Przemyslaw Gonek, Jakub Korta, Tadeusz Uhl, Wieslaw J. Staszewski
      Pages: 1135 - 1146
      Abstract: A wireless and battery‐free passive sensing platform is proposed for structural damage detection. The platform is based on the radio‐frequency identification (RFID) technology, where a standard RFID transponder device serves as an interface between low‐power sensors – used for damage detection – and RFID reading devices. Sensor data are transmitted remotely from this sensing platform to a Personal Computer (PC) that controls the entire system. Energy harvesting is the major novelty of the proposed approach. The magnetic field produced by an antenna of the RFID reading device is used for energy harvesting. The platform supports different types of sensors that can be positioned in remote locations and used for structural damage detection. The sensing capability and the damage detection performance of the proposed system are demonstrated using two simple application examples, that is, vibration measurements in a beam‐like structure subjected to the force excitation and temperature measurements in a bearing that supports a rotating shaft. The results illustrate the great potential of the proposed sensing platform for structural health monitoring applications, particularly in remote, difficult‐access, or hazardous conditions. Copyright © 2016 John Wiley & Sons, Ltd.
      PubDate: 2016-01-19T21:23:20.652087-05:
      DOI: 10.1002/stc.1826
       
 
 
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