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Study and Implementation of Health Monitoring Process for Half-through and Through Arch Bridges
CHEN Huai;HE Rong;HE Wei;HU Feng
   2011, 31 (6): 172-175.   DOI: 10.3969/j.issn.1006-1355-2011.06.039
Abstract （1659）            Save
According to the structure characteristics of half-through and through arch bridges, the bridge health monitoring process and the concept of bridge health records are proposed. And the health indicators and characteristics of the bridge health records are analyzed. When monitoring the bridge health, the standard model and health records should be established firstly. Then, the inspection object and observation index can be determined, and the in-situ testing according to the monitoring process is carried out. Finally, comparing the measured data of each index with its reference value in the health records, the working condition of the bridge can be analyzed. Taking Liujiang Bridge on Beijing-Hong Kong-Macao expressway as an example, the implementation of health assessment is illustrated. The monitoring results show that the 4th span of the bridge was in good health at that time.
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Study on the Influence of Suspender Damage on Mechanics Characteristics of Suspender Sestem in Through and Half-through Arch Bridges
HE Wei;HE Rong;LI Ya-wei
   2011, 31 (6): 24-28.   DOI: 0.3969/j.issn.1006-1355-2011.06.006
Abstract （1087）            Save
Suspenders are important force-transmission components of through and half-through arch bridges. Their mechanical situation is closely related to the safety of the arch bridges. Since suspenders can only withstand tension, their tensile forces and the safety of the arch bridge will change when a suspender damages. In this paper, based on perturbation theory, the changing laws of the tensile forces and displacements of the suspenders due to the suspender damage are studied by means of a three-dimensional finite element model. Taking Liujiang Bridge in Beijing-Hong Kong-Macao expressway as an example, this model is verified. Results show that when a suspender damages, its internal force will reduce, but the reduction ratio is less than its damage extent. The forces of the other suspenders of the same arch rib with the damaged suspender increase, but the increasing reduces rapidly as the suspender getting far away from the damaged one. The forces of the suspenders of the opposite arch rib essentially keep unchanging. The displacements of suspender joints also change due to the suspender damage, but the change ratio is less than the damage extent and gradually reduces as the distance between the undamaged hanger and the damaged one increased. As the damage extent of suspender increases, the rates of changes of both forces and displacements of suspenders increase too.
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《Analysis of Sound Quality of Lowfrequency Noise for Fuel Cell Vehicles》
HE Rong;ZUO Shu-guang;SHEN Xiu-min;ZHANG Jiang-fen
   2010, 30 (3): 97-99.   DOI: 10.3969/j.issn.1006-355.2010.03.026
Abstract （2377）      PDF（pc） （163KB）（1372）       Save
The internal and external noises of a fuel cell vehicle (FCV) are collected. Considering that low frequency noise occupies a large amount of energy, the noise signals in the range from 20Hz to 150Hz are extracted through the lowpass filter. Then, based on Zwicker model, the objective evaluation index is calculated. The score of subjective evaluation of the noise sample is given by means of the paired comparison method. Finally, the multiple linear regression model for lowfrequency sound quality analysis is established according to the linear correlation between subjective score and objective index, in order to get more accurate evaluation of sound quality of FCV noise in low frequency range.
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《NonSteadyState Noise Signal Analysis of Fans》
GUO Wei;ZUO Shu-guang;CEHN Rui-feng;HE Rong
   2010, 30 (1): 78-81.   DOI: 10.3969/j.issn.1006-1355.2010.01.078
Abstract （2435）      PDF（pc） （990KB）（1520）       Save
Based on wavelet package transform technology, this paper proposes a method for analyzing the frequency characteristics of nonsteadystate signals in an energyratio and frequencyband coordinate system. Result of this method is compared with that of common frequency spectrum method. The correctness and feasibility of this method is verified. Meanwhile, taking the fan's noise signal of a fuel cell vehicle as an example with a lowfrequency sinusoidal interference signal chosen as the representation of periodic signals, the periodic signals hidden in the nonsteadystate signals are identified. Finally, the fan's noise signals are analyzed. The noise due to low and medium frequency vibration and the noise due to high frequency vibration in the signals are separated. Their information is extracted in timedomain. The measures for further noise reduction are proposed.
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