The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Aly Mousaad Aly - One of the best experts on this subject based on the ideXlab platform.
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pressure integration technique for predicting wind induced Response in high rise buildings
alexandria engineering journal, 2013Co-Authors: Aly Mousaad AlyAbstract:Abstract This paper presents a procedure for Response prediction in high-rise buildings under wind loads. The procedure is illustrated in an application example of a tall building exposed to both cross-wind and along-wind loads. The Responses of the building in the lateral directions combined with torsion are estimated simultaneously. Results show good agreement with recent design standards; however, the proposed procedure has the advantages of accounting for complex mode shapes, non-uniform mass distribution, and interference effects from the surrounding. In addition, the technique allows for the contribution of higher modes. For accurate estimation of the Acceleration Response, it is important to consider not only the first two lateral vibrational modes, but also higher modes. Ignoring the contribution of higher modes may lead to underestimation of the Acceleration Response; on the other hand, it could result in overestimation of the displacement Response. Furthermore, the procedure presented in this study can help decision makers, involved in a tall building design/retrofit to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, damping enhancement, and/or materials change, with an objective to improve the resiliency and the serviceability under extreme wind actions.
Arturo Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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identification of sudden stiffness changes in the Acceleration Response of a bridge to moving loads using ensemble empirical mode decomposition
Mechanical Systems and Signal Processing, 2016Co-Authors: Hussein Aied, Arturo Gonzalez, Daniel CanteroAbstract:Abstract The growth of heavy traffic together with aggressive environmental loads poses a threat to the safety of an aging bridge stock. Often, damage is only detected via visual inspection at a point when repairing costs can be quite significant. Ideally, bridge managers would want to identify a stiffness change as soon as possible, i.e., as it is occurring, to plan for prompt measures before reaching a prohibitive cost. Recent developments in signal processing techniques such as wavelet analysis and empirical mode decomposition (EMD) have aimed to address this need by identifying a stiffness change from a localised feature in the structural Response to traffic. However, the effectiveness of these techniques is limited by the roughness of the road profile, the vehicle speed and the noise level. In this paper, ensemble empirical mode decomposition (EEMD) is applied by the first time to the Acceleration Response of a bridge model to a moving load with the purpose of capturing sudden stiffness changes. EEMD is more adaptive and appears to be better suited to non-linear signals than wavelets, and it reduces the mode mixing problem present in EMD. EEMD is tested in a variety of theoretical 3D vehicle–bridge interaction scenarios. Stiffness changes are successfully identified, even for small affected regions, relatively poor profiles, high vehicle speeds and significant noise. The latter is due to the ability of EEMD to separate high frequency components associated to sudden stiffness changes from other frequency components associated to the vehicle–bridge interaction system.
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an investigation into the Acceleration Response of a damaged beam type structure to a moving force
Journal of Sound and Vibration, 2013Co-Authors: Arturo Gonzalez, David HesterAbstract:Abstract In recent years there have been a growing number of publications on procedures for damage detection in beams from analysing their dynamic Response to the passage of a moving force. Most of this research demonstrates their effectiveness by showing that a singularity that did not appear in the healthy structure is present in the Response of the damaged structure. This paper elucidates from first principles how the Acceleration Response can be assumed to consist of ‘static’ and ‘dynamic’ components, and where the beam has experienced a localised loss in stiffness, an additional ‘damage’ component. The combination of these components establishes how the damage singularity will appear in the total Response. For a given damage severity, the amplitude of the ‘damage’ component will depend on how close the damage location is to the sensor, and its frequency content will increase with higher velocities of the moving force. The latter has implications for damage detection because if the frequency content of the ‘damage’ component includes bridge and/or vehicle frequencies, it becomes more difficult to identify damage. The paper illustrates how a thorough understanding of the relationship between the ‘static’ and ‘damage’ components contributes to establish if damage has occurred and to provide an estimation of its location and severity. The findings are corroborated using Accelerations from a planar finite element simulation model where the effects of force velocity and bridge span are examined.
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a wavelet based damage detection algorithm based on bridge Acceleration Response to a vehicle
Mechanical Systems and Signal Processing, 2012Co-Authors: David Hester, Arturo GonzalezAbstract:Abstract Previous research based on theoretical simulations has shown the potential of the wavelet transform to detect damage in a beam by analysing the time-deflection Response due to a constant moving load. However, its application to identify damage from the Response of a bridge to a vehicle raises a number of questions. Firstly, it may be difficult to record the difference in the deflection signal between a healthy and a slightly damaged structure to the required level of accuracy and high scanning frequencies in the field. Secondly, the bridge is going to have a road profile and it will be loaded by a sprung vehicle and time-varying forces rather than a constant load. Therefore, an algorithm based on a plot of wavelet coefficients versus time to detect damage (a singularity in the plot) appears to be very sensitive to noise. This paper addresses these questions by: (a) using the Acceleration signal, instead of the deflection signal, (b) employing a vehicle–bridge finite element interaction model, and (c) developing a novel wavelet-based approach using wavelet energy content at each bridge section, which proves to be more sensitive to damage than a wavelet coefficient line plot at a given scale as employed by others.
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empirical mode decomposition of the Acceleration Response of a prismatic beam subject to a moving load to identify multiple damage locations
Shock and Vibration, 2012Co-Authors: Jill Meredith, Arturo Gonzalez, David HesterAbstract:Empirical Mode Decomposition (EMD) is a technique that converts the measured signal into a number of basic functions known as intrinsic mode functions. The EMD-based damage detection algorithm relies on the principle that a sudden loss of stiffness in a structural member will cause a discontinuity in the measured Response that can be detected through a distinctive spike in the filtered intrinsic mode function. Recent studies have shown that applying EMD to the Acceleration Response, due to the crossing of a constant load over a beam finite element model, can be used to detect a single damaged location. In this paper, the technique is further tested using the Response of a discretized finite element beam with multiple damaged sections modeled as localized losses of stiffness. The ability of the algorithm to detect more than one damaged section is analysed for a variety of scenarios including a range of bridge lengths, speeds of the moving load and noise levels. The use of a moving average filter on the Acceleration Response, prior to applying EMD, is shown to improve the sensitivity to damage. The influence of the number of measurement points and their distance to the damaged sections on the accuracy of the predicted damage is also discussed.
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empirical mode decomposition of the Acceleration Response of a prismatic beam subject to a moving load to identify multiple damage locations
International Conference on Structural Engineering Dynamics - ICEDyn 2011 Tavira Portugal 20-22 June 2011, 2011Co-Authors: Jill Meredith, Arturo Gonzalez, David HesterAbstract:International Conference on Structural Engineering Dynamics - ICEDyn 2011, Tavira, Portugal, 20-22 June, 2011
Daniel Cantero - One of the best experts on this subject based on the ideXlab platform.
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identification of sudden stiffness changes in the Acceleration Response of a bridge to moving loads using ensemble empirical mode decomposition
Mechanical Systems and Signal Processing, 2016Co-Authors: Hussein Aied, Arturo Gonzalez, Daniel CanteroAbstract:Abstract The growth of heavy traffic together with aggressive environmental loads poses a threat to the safety of an aging bridge stock. Often, damage is only detected via visual inspection at a point when repairing costs can be quite significant. Ideally, bridge managers would want to identify a stiffness change as soon as possible, i.e., as it is occurring, to plan for prompt measures before reaching a prohibitive cost. Recent developments in signal processing techniques such as wavelet analysis and empirical mode decomposition (EMD) have aimed to address this need by identifying a stiffness change from a localised feature in the structural Response to traffic. However, the effectiveness of these techniques is limited by the roughness of the road profile, the vehicle speed and the noise level. In this paper, ensemble empirical mode decomposition (EEMD) is applied by the first time to the Acceleration Response of a bridge model to a moving load with the purpose of capturing sudden stiffness changes. EEMD is more adaptive and appears to be better suited to non-linear signals than wavelets, and it reduces the mode mixing problem present in EMD. EEMD is tested in a variety of theoretical 3D vehicle–bridge interaction scenarios. Stiffness changes are successfully identified, even for small affected regions, relatively poor profiles, high vehicle speeds and significant noise. The latter is due to the ability of EEMD to separate high frequency components associated to sudden stiffness changes from other frequency components associated to the vehicle–bridge interaction system.
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railway infrastructure damage detection using wavelet transformed Acceleration Response of traversing vehicle
Structural Control & Health Monitoring, 2015Co-Authors: Daniel Cantero, Biswajit BasuAbstract:SUMMARY This paper proposes the use of vertical Accelerations of a moving train to detect local track irregularities produced by weaker sections of the infrastructure. By analysing the vehicle Accelerations using the wavelet transform, it is possible to clearly identify the location of damaged sections. A wavelet-based indicator is proposed to facilitate an algorithm for recognition of deteriorated segments. The proposed indicator is validated by means of a 2-DOF vehicle model excited by randomly generated track irregularities together with the presence of various local track defects. A Monte Carlo analysis is performed to evaluate the performance of the proposed indicator for a variety of model parameters, including vehicle mechanical properties, shape of isolated track irregularities and levels of damage. Copyright © 2014 John Wiley & Sons, Ltd.
Vitomir Racic - One of the best experts on this subject based on the ideXlab platform.
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Acceleration Response spectrum for prediction of structural vibration due to individual bouncing
Mechanical Systems and Signal Processing, 2016Co-Authors: Jun Chen, Vitomir Racic, Lei Wang, Jiayue LouAbstract:Abstract This study is designed to develop an Acceleration Response spectrum that can be used in vibration serviceability assessment of civil engineering structures, such as floors and grandstands those are dynamically excited by individual bouncing. The spectrum is derived from numerical simulations and statistical analysis of Acceleration Responses of a single degree of freedom system with variable natural frequency and damping under a large number of experimentally measured individual bouncing loads. Its mathematical representation is fit for fast yet reliable application in design practice and is comprised of three equations that describe three distinct frequency regions observed in the actual data: the first resonant plateau (2–3.5 Hz), the second resonant plateau (4–7 Hz) and a descension region (7–15 Hz). Finally, this paper verifies the proposed Response spectrum approach to predict structural vibration by direct comparison against numerical simulations and experimental results.
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Acceleration Response spectrum for predicting floor vibration due to occupants jumping
Engineering Structures, 2016Co-Authors: Jun Chen, Vitomir RacicAbstract:Abstract This paper proposes an Acceleration Response spectrum to predict floors’ Responses due to occupants jumping. Experiments were conducted on individual jumping loads resulting in 506 records. Each record was applied to a single-degree-of-freedom system with various frequencies and damping ratios to obtain a corresponding Acceleration Response spectrum. Statistical analysis of the results led to a representative spectrum, which is further used to derive an analytical design spectrum curve. The suggested design spectrum covers a structural frequency range of 0.5–15 Hz and consists of three main parts: the first plateau, the second plateau and the descent. Design values for spectrum parameters were determined by fitting each part’s mathematical function to actual data. The proposed spectrum was verified by comparing its predictions with measured Responses from an experimental floor model and floors of existing structures induced by both single individuals and crowds jumping.
Deqing Yang - One of the best experts on this subject based on the ideXlab platform.
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vibration reduction design method of metamaterials with negative poisson s ratio
Journal of Materials Science, 2019Co-Authors: Haoxing Qin, Deqing YangAbstract:This work proposes a topology optimization design method of metamaterials for improving the vibration reduction performance. Firstly, an optimization mathematical model of the functional element is established with the objective of maximizing the origin mechanical impedance level, and the functional element with optimal vibration reduction effect is obtained by the calculation of the mathematical model. Then, the optimized functional elements are periodically arranged to generate the metamaterials, and thus a series of metamaterials with negative Poisson’s ratio ranging from − 0.5 to − 2.0 are designed. Numerical simulation shows that the amplitudes of the Acceleration Response are reduced by 66.5% after the vibration is passed through the metamaterials. Comparison shows that the novel designed metamaterials achieve at least 12% improvement in vibration reduction performance over the traditional honeycomb.
