Time filter

Source Type

Pei J.-Z.,Chang'an University | Chen Y.,Xian Municipal Engineering Design and Research Institute Co. | Wang B.-G.,Chang'an University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2011

In order to analyze dynamic response characteristics of asphalt pavement under multi-axle moving load, a three-dimensional finite element model of asphalt pavement was established by field investigation. The influences of axle load with uniform distribution of single rear axle, dual rear axles and three rear axles and the axle load with non-uniform distribution of three rear axles and the three rear axles vehicles with impending front axle on pavement were studied respectively. Results show that the effect of each axle on pavement is independent when the wheelbase of multi-axle vehicle is bigger than 3 m. Increase of number of axle makes the vertical displacement of pavement superpose and makes the maximal shear stress and compressive stress of pavement change inconspicuously. The influence of the middle axle of three rear axles vehicle on the vertical displacement of pavement is the greatest which increases by 23.7% and 18.2% compared with those of the front axle and rear axle respectively. Besides, the middle axle and rear axle has certain influence on the shear stress of pavement, but each axle has almost no influence on the maximal compressive stress of pavement. The research results indicate that the non-uniform distribution of axle load of multi-axle vehicle has significant influence on pavement failure.

Qi D.-Y.,Xian Municipal Engineering Design and Research Institute Co. | Yu D.-M.,China Communications Construction Company Ltd. | Li W.-H.,China Communications Construction Company Ltd. | Liu J.-S.,Xian Municipal Engineering Design and Research Institute Co. | Guo H.-J.,Xian Municipal Engineering Design and Research Institute Co.
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2013

For further deepening the research of the existing theory on composite beam shear lag effect so as to optimize the existing engineering design, the shear lag effect of a sea-crossing concrete bridge panel was analyzed through the establishment of the whole bridge and segment space finite element model. By establishing the whole model of double I shaped steel girder and concrete panel composite beam bridge, the stress values of different sections such as the midspan, tower root and 1/4 mainspan were compared and the distribution of effective width coefficients was found out. By establishing segment space finite element model, effective width coefficients in different construction conditions, different cable forces or different vehicle loads were analyzed. The results show that different sections have different influences on shear lag effect, for example, the shear lag effect of the midspan section is bigger than the tower root section. The shear lag effect of construction stage is small, which could be modified from elementary beam theoretic calculation results to meet the engineering requirements. The influence of the cable force and vehicle load on shear lag effect is not great. The conclusion of the study has a certain universal applicability for composite beam, which can provide reference for the design of similar bridges.

Zhou Y.-C.,Chang'an University | Hu S.-N.,North China University of Water Conservancy and Electric Power | Song L.,Xian Municipal Engineering Design and Research Institute Co. | Li Z.-Q.,North China University of Water Conservancy and Electric Power
Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering | Year: 2013

The temperatures of steel-concrete composite beam cross-sections under nature condition were tested, the formulae of steel-concrete composite beam interfacial shear force, shear stress, relative slide strain and deformation, flexural deformation curvature were derived by using temperature gradient calculation model and elastic theory. Analysis result shows that there is temperature difference in the cross-section, and the temperature distribution of concrete flange slab is uneven. The maximum interfacial shear force is at the midspan and decreases to zero at the end of beam. The maximum interfacial shear stress, relative slide strain and deformation are at the end of beam and decrease to zero at the midspan. Interfacial force and deformation are linearly proportional to temperature difference, and the slope is associated with the temperature distribution modes of concrete slab. The temperature distribution mode and thickness of concrete slab are the main influence factors of interfacial force and deformation.

Ma X.Q.,Hainan Province Highway Survey and Design Institute | Xue X.,Chang'an University | Cheng X.P.,Xian Municipal Engineering Design and Research Institute Co.
Advanced Materials Research | Year: 2013

In order to study the effect of several factors on the shrinkage performance of lime-fly ash stabilized crushed stone, temperature shrinkage coefficients and dry shrinkage coefficients of mixtures with different gradations, lime and fly content and age were measured. Results indicate that mixture with a stone-on-stone contact has better shrinkage-resistance performance; For the same gradation, both dry shrinkage coefficient and temperature coefficient become improved with lime-fly content increasing; when the lime-fly content is the same, temperature shrinkage coefficient increases with longer age; Results of analysis of variance show that to the temperature shrinkage coefficient, the effect of age and lime and fly content are important, and the latter is greater. To the dry shrinkage coefficient, gradation and lime and fly content are important factors, and the former is greater. © (2013) Trans Tech Publications, Switzerland.

Like Q.,Xi'an University of Science and Technology | Jun D.,Xi'an University of Science and Technology | Juntian Z.,Xian Municipal Engineering Design and Research Institute Co.
Electronic Journal of Geotechnical Engineering | Year: 2015

The research on the temperature inside the rock and the characteristics of the distribution and evolution of stress can not only contribute to the understanding of the mechanism of the microwave assisted rock breakage, but also provide scientific basis for the designing of microwave devices. The study takes the wave-absorbing pyrite and the wave-transparent calcite as the object of study, adopts finite element technique to calculate the temperature distribution and stress distribution of the rock particles, and considers the impact of irradiation time, power density, and particle size. The result shows that under different irradiation time, temperature distributions of the rock particles are similar. The temperature inside the pyrite changes little, while the temperature of calcite decreases in a hyperbolic curve from inside to outside. The stress concentration phenomenon exists in the conjunction of minerals. The greater the temperature gradient is, the higher the thermal stress is in the conjunction of minerals. The microwave of higher power can create greater temperature gradient and higher thermal stress inside the rock within extremely short irradiation time. Therefore, it is suggested to use high-power microwave in the microwave assisted rock breaking. When the size of the rock is fixed, the smaller the pyrite crystal is, the smaller the temperature gradient is, the lower the thermal stress is, and the more difficult the rock breaking is. © 2015 ejge.

Li Y.,Chang'an University | He S.,Chang'an University | Wang C.,The First Highway Survey and Design Institute of China | Luo S.,Xian Municipal Engineering Design and Research Institute Co.
Applied Mechanics and Materials | Year: 2014

Through the long-term deflection observation results and the measured data of effective pre-stress of Humen bridge before and after reinforcement, using three-phase bridge long-term deflection calculation method, compare the measured data and the calculation conditions in three kinds. Basing on the measure value of construction degradation, presenting the long-term deflection correction coefficient of long-term deflection to predict construction deflection. Analysis results show that the calculation model considering the construction degradation is more close to the practical situation. The long-term deflection calculation method based on the coefficient of correction can be used in the prediction calculation. © (2014) Trans Tech Publications, Switzerland.

Pei J.-Z.,Chang'an University | Chen Y.,Xian Municipal Engineering Design and Research Institute Co. | Zhang J.-P.,Chang'an University | Bi Y.-F.,Bureau of Highway
Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering | Year: 2010

Jiefang CA141 was selected as a representative vehicle, the four possible kinds of driving behaviors at climbing section were analyzed, and the acceleration was calculated based on the parameters of dynamics performance when vehicle shifted to accelerate or decelerate at climbing section. A 3D finite element model was established for the transient dynamics analysis of asphalt pavement under moving load. The compressive stresses, shear stresses and vertical displacement characteristics under different driving behaviors were analyzed. Calculation result shows that under the effect of moving load, the mechanics response of pavement structure not only has fluctuation, but also presents alternating feature within a certain region, and there is reversal of changes on tension and compression stresses in the area. Specifically, compressive stress concentrates in the area of 0~6 cm for road surface, the maximum shear stress moves from wheel joint to wheel centre as the speed of vehicle reduces and the horizontal force increases, and its peak shifts from middle surface layer to road surface along depth direction. The speed variation and low speed are the main reasons for pavement rutting at climbing section.

Du X.,Tsinghua University | Kong Q.,Xian Municipal Engineering Design and Research Institute Co. | Ge W.,Tsinghua University | Zhang S.,Tsinghua University | Fu L.,Tsinghua University
Journal of Environmental Sciences | Year: 2010

In China, the health risk from overexposure to particles is becoming an important public health concern. To investigate daily exposure characteristics to PM2.5 with high ambient concentration in urban area, a personal exposure study was conducted for school children, and office workers in Beijing, China. For all participants (N = 114), the mean personal 24-hr exposure concentration was 102.5, 14.7, 0.093, 0.528, 0.934, 0.174 and 0.703 μg/mc for PM2.5, black carbon, Mn, Al, Ca, Pb, and Fe. Children's exposure concentrations of PM2.5 were 4-5 times higher than those in related studies. The ambient concentration of PM2.5 (128.5 μg/mc) was significantly higher than the personal exposure concentration (P < 0.05), and exceed the reference concentration (25 μg/mc) of WHO air quality guideline. Good correlation relationships and significant differences were identified between ambient concentration and personal exposure concentration. The relationships indicate that the ambient concentration is the main factor influencing personal exposure concentration, but is not a good indicator of personal exposure concentration. Outdoor activities (commute mode, exposure to heating, workday or weekend travel) influenced personal exposure concentrations significantly, but the magnitude of the influence from indoor activities (exposure to cooking) was masked by the high ambient concentrations. © 2010 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.

Chen J.,Chang'an University | Chen J.,Xian Municipal Engineering Design and Research Institute Co. | Yang S.-W.,Chang'an University
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology | Year: 2011

Vehicles of 4-direction streams wanting to pass the double-crossing continuously must choose different way according to the information from the display monitor. It is discovered that running rate V85, the path top rake, reaction time of driver, the distance from the branch end to the stop line as well as vehicles' characteristics are important factors affecting the opportunity of information conversion. Obtained through the computation analysis, regardless of the choice of the upper crossing or the lower crossing, the opportunity determining the information conversion is the same, i.e., the vehicles arriving at the stop line can pass the crossing continuously if the green time is also left over time T, and after the information display monitor's information changes, the vehicles choose in the T time through the upper formation way just right travel to the upper stop line, while the upper formation's green light opening at that time(necessary to wait while the information light turning from green to red if the lower way was adopted).

Guo B.,Xi'an University of Architecture and Technology | Sun K.,Xian Municipal Engineering Design and Research Institute Co.
Proceedings - 2010 International Conference on System Science, Engineering Design and Manufacturing Informatization, ICSEM 2010 | Year: 2010

At present, because of different environment among cities, enhance liquidity of the labor force between different cities. At the same times, housing price is the main expense of resident flowing between cities, which stands for the willingness to pay for the urban environment. Through the demonstration of 35 major cities in this research, it shows that the urban environment dominates the urban housing price in China's, especially in urban housing market. The better urban area position, with the better environment of economic, market, social service and infrastructures, will cause the higher housing price. This reveals that there are some influence factors, such as convenience level, income level, and job opportunities etc, which depend how much the resident want to pay. © 2010 IEEE.

Loading Xian Municipal Engineering Design and Research Institute Co. collaborators
Loading Xian Municipal Engineering Design and Research Institute Co. collaborators