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Wang X.,Chongqing Jiaotong University | Wang X.,Key Laboratory of Structure and Wind Tunnel of Guangdong Higher Education Institutes | Wu L.,East China Jiaotong University | Zhou Y.,Chongqing Jiaotong University | Wang Y.,Wenzhou University
Shock and Vibration

The Beijing-Shanghai high-speed railway is one of the milestones of China's high-speed railway development and its security plays a significant role in China's economic and social development. However, the evaluation methods used for large-scale security operations and important infrastructure systems, such as the high-speed railways, are discrete and nonlinear; thus they cannot issue emergency warnings in a timely manner. The emergence of optical fiber sensing technology can solve this problem. This technology has progressed rapidly in its application to the monitoring of railway security and it has attracted much attention within the industry. This study considers the newly built passenger railway line between Shijiazhuang and Jinan as an example. The web-based, all-in-one fiber Bragg grating static level is described as well as a set of online monitoring systems, which is automated, real-time, remote, visual, and adaptable to the standards of the Beijing-Shanghai high-speed railway. According to our theoretical analysis, the planned automated monitoring of settlement deformation for the Beijing-Shanghai high-speed railway and the real-time analysis and calculation of monitoring data can ensure the operational security of this section of China's high-speed railway system. Copyright © 2015 Xu Wang et al. Source

Yu X.-F.,South China University of Technology | Yu X.-F.,Key Laboratory of Structure and Wind Tunnel of Guangdong Higher Education Institutes | Gu M.,Tongji University | Xie Z.-N.,South China University of Technology
Zhendong yu Chongji/Journal of Vibration and Shock

Internal and external pressures on a flat roof structure were tested in a uniform wind field by applying the synchronous pressure measurement technique. To obtain the accurate Helmholtz resonance frequency, the scaling requirement of internal pressure was strictly ensured. The flat roof structure was designed as a typical plate type truss structure, and the effects of opening area, background porosity, wind direction and damping ratio on the vertical displacement of roof were analyzed. The results show that the root-mean-square value of vertical displacement increases with the increase of opening area and with the decrease of background porosity. The damping ratio has nothing to do with the roof displacement response. The vertical displacement in the case of windward opening is significantly larger than in the case of other wind direction opening. The contribution of fluctuating internal pressure on roof displacement response is mainly attributed to its background component. ©, 2015, Chinese Vibration Engineering Society. All right reserved. Source

Li G.,Shantou University | Li G.,Hong Kong University of Science and Technology | Li G.,Key Laboratory of Structure and Wind Tunnel of Guangdong Higher Education Institutes | Wang L.,Shantou University | And 10 more authors.
RSC Advances

The piezoresistivity of carbon black/cement mortar (CB/PC) makes it a potential candidate for the development of smart structures with sensing capability. To ensure reliable sensing results in different environments, a hydrophobic styrene-butadiene rubber (SBR) was incorporated to reduce the effect of moisture on the piezoresistivity. The influence of SBR content (0, 5, 10 and 15 wt%) on the electric conductivity and piezoresistivity of SBR/CB/PC mortar with different moisture content was experimentally studied. Results indicate that the electric conductivity and piezoresistivity effect of SBR/CB/PC mortars increase with increasing SBR content. Also, compared to pure CB/PC mortars, the electrical properties of SBR/CB/PC mortars were significantly less sensitive to the variation of moisture. Under cyclic loading, both positive (PP) and negative piezoresistivity (NP) are found to occur in SBR/CB/PC mortars. This behavior can be explained in terms of a mechanism with both the tunneling effect and capacitance effect between CB particles during compression. © The Royal Society of Chemistry 2015. Source

Li G.,Shantou University | Li G.,Hong Kong University of Science and Technology | Wang Z.,Shantou University | Wang Z.,Key Laboratory of Structure and Wind Tunnel of Guangdong Higher Education Institutes | And 7 more authors.
Journal of Cleaner Production

Using waste rubbers as aggregates in concrete is a feasible approach to recycle the material. However, due to the poor adhesion of rubber to cement paste, the replacement of normal aggregate with rubber will lead to a reduction in the mechanical strength of concrete. This paper presents a new approach to overcome this deficiency by treating waste rubbers with silane coupling agent (SCA) and carboxylated styrene-butadiene rubber (CSBR) latex to develop chemical bonds between rubbers and cement paste. This study investigates the influence of this surface treatment on the mechanical strength and chloride penetration resistance of rubberized concrete. Experiments were conducted with six different volume fractions of rubbers (between 0% and 30%) to replace fine aggregate in the concrete. The experimental results showed that the compressive strength and flexural strength of concretes incorporating proper amount of treated rubbers could be improved by 4% and 13% respectively as compared to the control concrete with no rubbers. Moreover, the chloride penetration resistance was also improved by 35%. The good adhesion of waste rubbers to cement paste, the formation of rubber networks and the embedding effect of rubbers as shown in SEM images are explanations for the enhancement in the mechanical strength and durability for the treated rubber concrete. © 2015 Elsevier Ltd. Source

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