Papers by Keyword: Traffic Loading

Abstract: A multi-functional bridge bearing with built-in piezocomposite electricity generating element (PCGE) is being developed by our research team to respond to the growing demand of self-powered sensing devices for the monitoring of bridges by harvesting the energy produced by the traffic-induced vibrations. For the intended application, a multilayered piezoelectric PCGE structure composed of layers of piezoceramic, glass/epoxy, and carbon/epoxy, has been developed to improve the durability, output voltage and power of the piezoceramic. The output voltage of this PCGE can be used for real-time traffic monitoring like in bridge-weigh-in-motion systems and can eventually be exploited to generate the electricity needed for the lighting and functioning of other embedded sensors. This paper presents the results of the dynamic loading tests conducted on a prototype of the proposed multi-functional bridge bearing to enhance its design details and verify the accuracy of the measurement. The results show that the bearing provides reliable measurement for traffic monitoring and enable to conceive details for the improvement of the output voltage of the PCGE. Since bridge bearings, as indispensable devices transferring the loads and movements from the deck to the substructure and foundations of the bridge, are continuously subjected to traffic loads, the proposed bridge bearing appears to be a natural and economic solution that can be applied to existing or newly built bridges without modification of the conventional design while providing additional and valuable functions for the maintenance of the structure.

Abstract: Ground fissure is a kind of serious geological disaster. There will be more unprecedented challenges during the construction of the urban subway in ground fissures-developed zone. How to ensure the long-term operation safety of the subway crossing ground fissure belts are the first problems for the subway under construction in the cities with ground fissure developed. One of the important problems is that dynamic interaction and disaster effect control among ground fissure-stratum-subway tunnel under subway dynamic loading, which is also the important problem to be solved in the engineering. This problem involves the following three aspects: (a) the determination of subway dynamic loading; (b) the structure dynamic response of subway tunnel; (c) the interaction among stratum-ground fissure-subway tunnel. According to make a comment on these researches, some issues which are necessary to carry out in this field are suggested.

Abstract: In order to study the influence of reinforcement on the distribution of dynamic deviator stress along the depth of subgrade, reinforced and unreinforced subgrade of graded-broken-stone-based asphalt concrete pavement under traffic loading was modeled by implicit dynamic FEM. Analytical results show that reinforcement can improve the vertical compressive stress distribution, and decrease shear stress transmitted to the surface of subgrade. The deviator stress on the upper part of reinforced subgrade is reduced distinctly, which is one of the key factors that can cause residual deformation. Therefore, reinforcement can restrain the development of residual deformation of subgrade induced by traffic loading.

Abstract: This paper addresses the quantification of environmental variability of wavelet packet energy spectrum (WPES) extracted from the ambient dynamic responses of a suspension bridge using wavelet packet transform (WPT). The daily averaged WPES using multi-sample averaging technique are first obtained to eliminate the inherent randomness arising from the identification algorithm. Then the effect of temperature on the measured WPES is quantified using the seasonal correlation models. The traffic-induced and wind-induced variability are further quantitatively evaluated by establishing the traffic-WPES and wind-WPES correlation models. The analysis results reveal that temperature and inherent randomness are the critical sources causing WPES variability, and the WPES variability caused by wind speed and traffic loadings is negligible compared with temperature and inherent randomness. Considering seasonal correlation models of temperature-WPES can effectively eliminate the temperature effect and inherent randomness, it is suitable for structural damage warning of long-span bridges if future seasonal correlation models deviate from these normal models.

Abstract: The suspension bridge has more flexibility and repetitive vehicles produce stress cycles in members. Then fatigue of the member is accumulated with the daily traffic loadings. In order to evaluate the working condition of the Tsing Ma Bridge, the online monitoring health system has been installed in long suspension bridge. The location of the strain sensor is not exactly at the critical member locations. The hot spot stress analysis for critical members is necessary for accurate fatigue evaluation of the bridge. The global finite element analysis of the Tsing Ma Bridge under traffic loading is performed to determine the critical fatigue member locations. A detailed local finite element analysis for the welded connections is performed to determine the hot spot stress of critical fatigue location. As a case for study, the calculated stress concentration factor is combined with the nominal representative stress block cycle to obtain the representative hot spot stress range cycle block under traffic loading from online health monitoring system. The comparison result shows that the nominal stress approach cannot consider the most critical stress of the fatigue damage location and the hot spot stress approach is more appropriate for fatigue evaluation.