Papers by Keyword: Ambient Vibration

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Authors: Nurul Shazwin Idris, H.B. Koh, Ahmad Fahmy Kamarudin
Abstract: Bridge is one of the important facilities use in daily life as bridge is built to span physical obstacles such as a body of water, valley or road for the purpose of providing passage over the obstacle. Various testing conducted on the bridge in order to know the dynamic characteristics of the bridges. One of popular testing use is ambient vibration test. Ambient vibration is a non-destructive test conducted using highly sensitive sensor. This testing is easy to be conduct with less labour, time and also cost. This paper aim to provide up to date literature review on ambient vibration test on bridge includes sources of ambient vibration, procedure of conducting the measurement and results from ambient vibration test. It is important to known the dynamic characteristics of the bridge especially to determine the dynamic response of the structure and also as dynamic information for seismic design.
Authors: Mohamed Hanafiah bin Omar, Meng Hee Lim
Abstract: Energy harvesting has generated a lot of interest in low power devices and wireless sensing applications as a viable replacement to the batteries that are required to power them. Wireless sensors nodes on the other hand have gain considerable interests from researchers and industries alike. Wireless sensing have the potential to improve productivity of industrial systems by providing greater awareness, control and integration of business processes. This paper attempts to provide an overview of the available technologies and at the same time deduce a practical energy harvesting platform as applied to wireless sensor nodes based on current research.
Authors: Patricia-Florina Murzea
Abstract: The aim of the paper is to present the results of applying the formulae of a simplified stochastic model for the calibration of some macroscopic parameters of the ground motion, on the basis of rather rough estimates. For this purpose the basic records combinations results obtained with the aid of computer programs (DaisyLab and LABView) are used, after digital recordings on the large span and rather isolated structure of the ROMEXPO Pavilion in Bucharest were performed. A stochastic model of stationary, low intensity, ground motion (referred to in literature as microtremors or ambient vibrations) was proposed by H. Sandi (1982, 2005). This lay at the basis of the specification of input for a consistent analysis of 3D earthquake induced motion of structures, adopted in the Romanian earthquake resistant design codes.
Authors: A.W. Khairul Adly, Y. Wahab, A.Y.M. Shakaff, Mazlee Mazalan
Abstract: The ability to self-energize wireless sensor node promote the popularity of energy harvesting technique especially by using ambient vibration as the source of energy. In addition, the successful integration of the energy harvesting element on the same wafer as a wireless sensor node will promote the production in the MEMS scale and will reduce the overall cost of production. The usage of the cantilever structure as the transducer for converting mechanical energy (vibration) due to deflection of cantilever into the electrical energy is possible by depositing piezoelectric material on the cantilever. The usage of cantilever provide the simplest way for fabrication in the MEMS scale and also provide the ability to achieve low natural frequency. This paper present the work done on the simulation of the cantilever structure with the top end and back etch proof mass towards achieving low natural frequency in the MEMS scale by using IntelliSuite software.
Authors: Giosuè Boscato, Alessandra Dal Cin
Abstract: The Church of Gesù and the tower of the Cathedral were stricken and damaged by Emilia-Romagna earthquake sequence of May 2012. This paper presents the procedure for the structural identification of the most widespread types of religious monuments. The dynamic behavior was analyzed using the ambient vibrations test to measure the dynamical properties (mode of vibration, frequencies, displacements and damping ratios) of the constructions using a modal identification of output-only systems. The operational modal analysis OMA has been carried out to identify the modal characteristics through poly-reference Least Square Complex Frequency-domain (pLSFC) estimator. The global structural health monitoring was carried out to define the real dynamic behavior of the damaged constructions that are subjected to different mechanism. These researches are useful for the structural rehabilitation and to define the possible changes in the structural behavior.
Authors: S.H. Yoo, S.Y. Kim, S.W. Shin
Abstract: System identification(SI) techniques using dynamic responses and behaviors of structural systems become an outstanding issue of researchers. However the conventional SI techniques are identified to be non-practical to the complex and tall buildings, due to limitation of the availability of an accurate data that is magnitude or location of external loads. Thus a technique to estimate structural properties of building without input measurement data and using limited response is essential in structural health monitoring. In this study, the improved least square method for damage detection is proposed and verified by shaking table tests on three-story plane frame steel structures. In results damage detection was performed in each member level.
Authors: R.R. Sattarov, E.F. Galiakberova
Abstract: The area of smart and functional materials, in particular fabrics with electric heating, attracts the attention of researchers. The energy harvesters that convert ambient motion to electricity have greatly developed recently. The paper suggests an eddy current microscale mechanism for direct conversion from ambient motion to heat. The proposed mechanism can be used within fabrics for heating and drying moisture. The principles of eddy current heating and possible design of yarns are described. A fundamental estimation of available thermal energy has been obtained from the general basic consideration.
Authors: Li Xian Wang, Sheng Kui Di
Abstract: Based on random vibration theory, virtual response is obtained from the measured acceleration signal of Yantan Yellow River Bridge of Lanzhou under ambient excitation, Yantan Yellow River bridge's modal parameters were identified by using the peak picking and stochastic subspace identification, analyzed from theoretical and experimental aspects, compared with the finite element model results and verified the reliability of recognition results. The identified dynamic properties can be served as the basis in the finite element model updating, damage detection, condition assessment and health monitoring of the bridge.
Authors: Gwang Hee Heo, Joon Ryong Jeon, Chin Ok Lee, Gui Lee, Woo Sang Lee
Abstract: This paper presents an effective method of FE model updating for health monitoring of structures by applying ambient vibration. And this method is experimented through damage detection and proved to be valid. Experiment about ambient vibration is performed on cantilever beam, and the dynamic characteristics are analyzed by NExT and ERA. The results of such experiments are compared to those of FE analysis, and this comparison enables us to overcome some errors in experiments and analysis. On the basis of improved results by the comparison, model updating is performed in order to construct a basic structure for health monitoring. For model updating, we employ direct matrix updating method (DMUM) and Error matrix method (EMM) in which ambient vibration is easily applied. The model updating by the methods are again evaluated in terms of error ratio of natural frequency, comparing each result before and after updating. Finally, we perform experiments on damage detection to verify the method of updating presented here, and evaluate its performance by eigen-parameter change method. The evaluation proves that the method of FE model updating using ambient vibration is effective for health monitoring of structure, and some further application of this method is suggested.
Authors: Gang Xue, Wei Yu Bai, Xian Wang
Abstract: The finite element model modified technique based on optimization principle is benefit for the model updating of the large bridge structures. By the ambient vibration test information provided by health monitoring system of huanghe bridge II in baotou , this article adopted corrected parameter based on structural eigenvalue sensitivity analysis to update the bridge dynamic model.The fundamental vibrational frequency of updated finite element model is more closer to the measured result under ambient excitation, which indicates that the optimization algorithm provided by large-scale general software can carry out the model updating effectively.
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