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Zhou Y.,Beijing Jiaotong University | Zhu E.,Beijing Jiaotong University | Li X.,Beijing Jiaotong University | Li X.,China Tiesiju Civil Engineering Group Co. | Zhong M.,Beijing Jiaotong University
Beijing Jiaotong Daxue Xuebao/Journal of Beijing Jiaotong University | Year: 2014

The temperature difference control measures of circulating water through prestressed ducts and ventilating through the box girder cavity are put forward in the paper due to the temperature cracks resulted from excessive temperature difference between inside and outside the concrete. The parameters of the thermal stress field simulation are determined. Parameter values are verified accurately according to the comparison between simulation results and the test results. Thermal stress fields of simply supported box girder are simulated respectively in the state of nature curing and temperature control measures. The results show that the maximum compressive stress reduces from 2.77 MPa of fulcrum section to 2.21 MPa of mid-span section, and the maximum tensile stress reduces from 1.255 MPa of fulcrum section to 1.00 MPa of mid-span section, which makes the temperature crack effectively controlled. In addition, the limited value of 15°C of temperature difference of the specification appears to be too rigorous, and can be relaxed to 20°C. Source


Li X.,Beijing Jiaotong University | Li X.,China Tiesiju Civil Engineering Group Co. | Zhu E.,Beijing Jiaotong University | Zhou Y.,Beijing Jiaotong University | Qin Y.,North China University of Water Conservancy and Electric Power
Applied Mechanics and Materials | Year: 2011

Due to the usage of high-strength concrete, excessive hydration heat is generated in the whole span box girder of high-speed railway. The maximum allowable temperature should not exceed 60°C according to the Technical Guide on Railway Bridge Construction of Passenger Dedicated Line. However, according to the field measurement and simulation to the maximum temperature of box girder concrete, we find that the maximum hydration temperature of concrete is generally more than 60°C which is the limited value of the specification. The research results show that the limited value of maximum hydration temperature for box girder concrete can be relaxed to 60°C. © (2011) Trans Tech Publications. Source


Li X.M.,Beijing Jiaotong University | Li X.M.,China Tiesiju Civil Engineering Group Co. | Zhu E.Y.,Beijing Jiaotong University | Zhou Y.Z.,Beijing Jiaotong University
Applied Mechanics and Materials | Year: 2012

The construction of precast box girder plays a pivotal role in the process of building passenger dedicated lines. But the high temperature and low-speed of cooling rate inside the box girder will seriously reduce the box girders' quality and delay the project duration. So, some methods such as cooling by means of circulating water in drill way etc. are presented in this paper. Then temperature tests are carried out for the box girders with different cooling measures, and the respective data are analyzed. The results show that the proposed cooling methods can effectively reduce the highest temperature, speed up the cooling rate inside the box girder and decrease the temperature difference between the interior and the exterior of the concrete. © (2012) Trans Tech Publications. Source


Deng X.F.,China Tiesiju Civil Engineering Group Co. | Chen S.G.,Southwest Jiaotong University | Zhu J.B.,Hong Kong Polytechnic University | Zhou Y.X.,Defence Science and Technology Agency | And 2 more authors.
Rock Mechanics and Rock Engineering | Year: 2014

In this study, numerical modeling of a large-scale decoupled underground explosion test with 10 tons of TNT in Älvdalen, Sweden is performed by combining DEM and FEM with codes UDEC and AUTODYN. AUTODYN is adopted to model the explosion process, blast wave generation, and its action on the explosion chamber surfaces, while UDEC modeling is focused on shock wave propagation in jointed rock masses surrounding the explosion chamber. The numerical modeling results with the hybrid AUTODYN–UDEC method are compared with empirical estimations, purely AUTODYN modeling results, and the field test data. It is found that in terms of peak particle velocity, empirical estimations are much smaller than the measured data, while purely AUTODYN modeling results are larger than the test data. The UDEC–AUTODYN numerical modeling results agree well with the test data. Therefore, the UDEC–AUTODYN method is appropriate in modeling a large-scale explosive detonation in a closed space and the following wave propagation in jointed rock masses. It should be noted that joint mechanical and spatial properties adopted in UDEC–AUTODYN modeling are determined with empirical equations and available geological data, and they may not be sufficiently accurate. © 2014, Springer-Verlag Wien. Source


Li X.,Beijing Jiaotong University | Li X.,China Tiesiju Civil Engineering Group Co. | Zhu E.,Beijing Jiaotong University | Zhou Y.,Beijing Jiaotong University | Qin Y.,North China University of Water Conservancy and Electric Power
Applied Mechanics and Materials | Year: 2011

in the process of steam curing to high-speed railway's simply-supported box girder, there are some problems must be faced such as the difficulty to determine steam curing system and to achieve automatic temperature control. With the construction site conditions of simple-supported box girder in Longwang beam field which is located on Shijiazhuang-Wuhan (Shi-Wu) section of Beijing-Guangzhou high-speed railway, the paper proposes the appropriate steam system for simply-supported box girders, determines the appropriate equipments, explores the temperature control system in the process of steam curing to the simply-supported box girder's concrete, and takes the temperature test of steam curing in the field. Results show that, the steam curing technology in this paper can increase the production efficiency of beam in production site, and effectively guarantee the prefabricated quality of simply-supported box girder. © (2011) Trans Tech Publications. Source

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