2008 Vol. 8, No. 6

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Influence of structure mode on distortion stiffness of bogie frame
AN Qi, LI Fu
Abstract: The H-type welding frame of passenger car bogie was simplified to the model composed of straight girders with uniform sections, the measures to reduce the distortion stiffness of the bogie frame was researched by observing the deformation distributions of different girders under distortion load, and verified by using FEM. It is pointed that the distortion stiffness of the frame can be reduced by 3% when slotting on the cover plate of side sill, when changing the section of transom, the stiffness can be reduced by 19%, and the maximum von_Mises stress under over load can be reduced by 3%. The result indicates that there is less influence on the stiffness when slotting on the cover plate of side sill, but it will cause strong stress concentration in local areas. The bending and distortion stiffnesses of transom should affect the distortion stiffness of the frame strongly. Changing circular section to box section can reduce the distortion stiffness of the frame obviously. The maximum von_Mises stress of the frame under over load situation is lower because of the reduction of the distortion stiffness. The influence of track warping load on the strength of the frame has abated.More>
2008, 8(6): 1-5.
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Experimental research of MAC modified large stone porous asphalt mixture
WANG En-dong, ZHANG Hong-liang, WANG Xuan-cang
Abstract: In order to improve the road performances of base course made of large stone porous asphalt mixture(LSPM), MAC(multigrade asphalt cement) modified asphalt was used in LSPM, the performances of matrix aphalt, MAC modified asphalt and SBS modified asphalt were compared, the material composition design, construction technology and the road performances of MAC modified LSPM, such as high-temperature stability, anti-fatigue property, permeability and anti-reflective crack property, were studied, and test roads were constructed. Test result shows that the porosity of LSPM is between 13% and 18%, its asphalt membrane is thicker than 12 μm, its modulous is between 400 and 600 MPa, the rut depth of test road opening to traffic for two years is between 4 and 8 mm. Obviously, MAC modified LSPM has better road performances. 4 tabs, 2 figs, 16 refs.More>
2008, 8(6): 6-12.
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Fusion monitoring system of locomotive wheelset state
ZHANG Jian, FAN Xiao-ping, HUANG Cai-lun, CHEN Te-fang
Abstract: In order to improve the accuracy of fault diagnosis and the uncertainty of current online condition monitoring methods for locomotive wheelset, a fusion monitoring system of locomotive wheelset was designed based on multi-sensor information fusion principle. The state of locomotive wheelset was monitored by using feature level fusion adaptive weighting algorithm, and the measured values were weighted adaptively to obtain the least-mean-square error of the measured values. The results computed by feature level fusion adaptive weighting algorithm, fuzzy data association algorithm, variable structure multiple-model estimation algorithm and BP nerve network(BPNN) algorithm were compared. Comparison result shows that when the fault occurs in the bearings of wheelset, the measured values are 22.047 0 and 21.025 0 respectively, while the estimation value from the fusion algorithm is 4.264 2, so the system has high reliability and better anti-disturbance.More>
2008, 8(6): 13-19.
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Structural fatigue strength analysis of wheel for freight car base on axisymmetric model
XU Chuan-lai, MI Cai-ying, LI Fu
Abstract: In order to analyze the fatigue strength of wheel for railway freight car, an axisymmetric model was set up, the strength was computed according to the calculation load and load conditions of international railway union standards UIC510-5/2003, and the strength was assessed by using Goodman curve. Calculation result shows the maximum von_Mises stress appears on the spoke under the thermal load of emergency braking when the braking time is 70 s, the maximum von_Mises stress appears on the spoke under the thermal load and the mechanical load of emergency braking when the braking time is 43 s, the maximum von_Mises stress appears on the spoke under the calculation load of curvilinear emergency braking, and the fatigue strength of the spoke meets the relative requirement.More>
2008, 8(6): 20-23.
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Deformation properties of asphalt mixtures for steel bridge deck through repeated load triaxial test
YANG Jun, ZHU Hao-ran, CUI Juan
Abstract: In order to study the deformation properties of steel deck pavement under high temperature and their rutting predictions, two types of asphalt mixtures, mastic asphalt(MA) and stone mastic asphalt(SMA), were invited, and their high temperature performances were evaluated through repeated load triaxial test(RLTT). Through the multivariate linear regressive analysis of test result, the nonlinear parameters of asphalt mixtures were obtained, finite element software ABAQUS was applied to simulate the process of RLTT, and the calculalted deformation and measured deformation were compared. It is found that the natures of high temperature deformation developments for two mixtures, as well as the response manners to different load conditions, are completely different, SMA has an overwhelmingly excellent deformation resistance, and the calculation error of FEM is about 10%. The result indicates that it's reasonable to get the nonlinear parameters through multivariate linear regressive analysis from RLTT result, and it's qualified to apply these parameters to conduct the rutting prediction of asphalt pavement on steel bridge.More>
2008, 8(6): 24-28.
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Property analysis of Tahe road asphalt using simultaneous thermog-ravimetry-differential scanning calorimetry-mass spectrometry
MA Feng, SHA Ai-min
Abstract: In order to investigate the relation among the microstructure, thermal property and road performance of asphalt, three asphalts refined from Tahe rude oil were studied by using simultaneous thermogravimetry-differential scanning calorimetry-mass spectrometry(TG-DSC-MS), the volatilizations, pyrolysis behaviors and thermal properties of three asphalts were studied from 30 ℃ to 550 ℃, and the relation between asphalt microstructure and road performance was analyzed. Analysis result indicates that asphalt productions in volatilization and thermal decomposition courses are mainly H2O、H2、C2H4(or CO)and ionic groupion(OH) when its mass-to-charge ratio is below 60, there is an obvious trend of weight loss from 240 ℃ in Tahe asphalt's thermogravimetric curve, and the improvement of asphalt performance is related to the increase of pyrolysis caloric and the decrease of residue mass.More>
2008, 8(6): 29-33.
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Stress comparison of asphalt pavements with different base crack states
WANG Yan, NI Fu-jian, MA Xiang
Abstract: In order to compare the stress varieties in surface and base caused by different humidities, temperatures and base crack states, pavement models with different crack depthes, widthes and spaces were established by 3D finite element method. Using the test parameters of base, the maximum stress, stress distribution and the influence on asphalt pavement were analyzed under water losing condition and temperature decreasing condition for cement stabilized macadam base asphalt pavements with different base crack states. Analysis result indicates that, for new base, the influence of water losing on shrinkage stress is more remarkable than that of temperature dropping; it is the most favorable condition for reducing base crack when base modulus is about 4 000 MPa; whether water losing or temperature decreasing, the most marked factor of influencing structural stress is each layer-self modulus; when joint state between base and sub-base is bad, the tensile stress in surface bottom is larger than that in continuum state, and base crack easily reflects to pavement surface.More>
2008, 8(6): 34-39.
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Fatigue characteristic experiments of field airfield pavement structure
XU Wei, CEN Guo-ping, DAI Jing-liang
Abstract: In order to analyze the reasonable pavement structure of field airfield, indoor and outdoor trial roads were built in Xi'an of Shaanxi Province and Leiyang of Hunan Province, load circle induced by aircraft wheel was simulated by using rigid bearing plate with 30 cm diameter, the experimental equipments such as reaction frame, hoisting jack and fatigue machine were used, the taxiing of aircraft at the same point of the pavement was simulated through manual and mechanical repeated loadings, the fatigue characteristic of the pavement with thin asphalt concrete surface and cement stabilized fine grained soil base(or subbase) was studied. Experiment result shows that the early carrying capacity of the recommended pavement structure is better, holistic elastic modulus is between 200~300 MPa, and its deflection is less than 1 mm in 60 days. The structure has good using performance, and will not be destroyed after ten thousands to hundred thousands times of takeoff and landing of airplane. The fatigue characteristic of the structure can meet the emergency requirement of field airfield.More>
2008, 8(6): 40-43.
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Stress analysis on joint chamfer for cement concrete airport pavement
DU Hao, ZHOU Zheng-feng, LING Jian-ming, ZHANG Zhi-liang, SI Bi-feng
Abstract: In order to compare the improvement effects of stress concentration in airport rigid pavement joint notches caused by different chamfer shapes, and evaluate the effect of the chamfer on pavement performance, a finite element model of pavement joint opening was established by using ANSYS software, the joint loading-transfer character was simulated by using beam and spring elements, Boeing777 was adapted as aircraft load, the loading stresses and temperature stresses for 6 different chamfer forms at the edges of the joint openings were analyzed eontrastively, and the pavement roughness and friction coefficient were tested in field. Test result shows that all chamfers can improve the stress status at the joint opening edges, the closer the position from the joint opening is, the higher the improvement effect is; 6 chamfers have different improvement effects, and the arc chamfer with 6 mm radius is the best one; the effects of all chamfers on the roughness and friction coefficient are less, and all satisfy the technique requirements.More>
2008, 8(6): 44-48.
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Subgrade-filled material properties of fully weathered gravelly sandstone for railway passenger dedicated line
NIE Zhi-hong, XIANG Zhi-min, HU Yi-feng
Abstract: Fully weathered gravelly sandstone was taken as subgrade-filled material for railway passenger dedicated line, the mineral constituents of the material was analyzed by using X-diffraction, the expansion coefficient and cation exchange ratio were tested, the grain size distributions under loop compacting and field compacting were contrasted, disintegration cyclic tests under wetting and drying cycle were studied, and coarse granule compression test and relaxation behavior in site were analyzed. Analysis result indicates that the material does not contain hydrophilic mineral composition, its free-swelling index is 23.6%, its cation exchange rate is 70.7 mmol·kg-1, its disintegration rate is 0.81%, its fine particle content is 13.5% under dynamical force, its detection indexes are stable after rain, its secondary consolidation coefficient is 5.8×10-4 under load. The experimental data show that the material has good water suitability, dynamical stability and low compressibility, and is a kind of better subgrade-filled material for railway passenger dedicated line.More>
2008, 8(6): 49-52.
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Terminal development of a new type of W-beam guardrail
LU Guo-ren, YAN Shu-ming, BAI Shu-feng, TAI Yong-gang, MA Liang
Abstract: In order to reduce the serious accidents caused by impacting W-beam guardrail terminal, the properties of traffic flow were analyzed, the impact test methods and acceptance criteria for the terminal were brought out based on referring to correlative domestic and overseas standards, a new type of W-beam guardrail terminal was developed by using finite element analysis and full-scale impact tests, which meets acceptance criteria. It is pointed that passengers can be protected for that the acceleration of vehicle gravity center is less than 20 g by rolling W-beam to absorb accident car's kinetic energy, which keeps W-beam from piercing into car or accident car from turning over, and the containment level of standard section for barrier is guaranteed by enough restraining force at the guardrail terminal. The result indicates that the performances of the terminal meet acceptance criteria and can protect accident vehicles.More>
2008, 8(6): 53-56.
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Distribution mode determination and simulation method of effective prestress for post-prestressing tendon
GUO Qi, HE Shuan-hai, REN Wei
Abstract: In order to know the effective value and longitudinal distribution state of effective prestress in inspection and evaluation process on the present condition of prestressing tendon for middle-span and long-span concrete bridges, an unified simulation method of the distribution was put forward. Based on prestress loss theory, a simplified analytic algorithm of virtual frictional loss function was set up in a universal way. By the means of the obtained stress datum of steel tendon at control point, the subordinated mode of effective prestress distribution along longitudinal direction was determined. As regards the effective prestress of steel tendon with complicated geometry pattern, its distribution regularity was simulated after the recognition of nominal coefficients for prestress loss. Simulation result shows that the relative error of effective prestress threshold is 5%, so the simulation method is feasible.More>
2008, 8(6): 57-62.
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Experimental research of bending capacity for steel and concrete composite girder with concrete filled tub
WANG Yan-li, WANG Chun-sheng, ZHAI Xiao-liang, DUAN Lan, LI Bao-rui
Abstract: In order to study the bending capacity of steel and concrete composite girder with concrete filled tubular up-flange (SCCGCFTF) under static load, a static test for SCCGCFTF was performed, a finite element model of SCCGCFTF was established by using ANSYS, nonlinear static parameter analysis was presented, and a formula for the ultimate bearing capacity of normal section was proposed based on perfected elastic-plastic model for steel and restricted concrete model for inner concrete. Analysis result shows that the strain distribution of the girder agrees well with the assumption of plan section, its bending ultimate bearing capacity and ductility are high, and no skip was found between inner concrete and steel tube. The bending ultimate bearing capacity of SCCGCFTF increases with the increases of the ratio and yielding strength of steel. With the strength enhancement of inner concrete, the bending capacity does not increase obviously, but the ductility of steel can be utilized adequately. So the relationship between the yielding strength of steel and the strength of inner concrete should be adjusted according to design requirements. The ratio of experimental ultimate flexural bearing capacity to its calculated value was 1.07, therefore, the theoretical formula for calculating the bearing capacity is relatively safe.More>
2008, 8(6): 63-69.
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Influence of traveling wave effect on seismic mitigation control for long-span cable-stayed bridge
QI Xing-jun, LI Xiao-jun, WANG Jing-wei
Abstract: In order to study the influence of traveling wave effect on the seismic response of vibration mitigation control for cable-stayed bridge, a calculation method of seismic mitigation control for long-span bridge was presented under multiple ground motion inputs, and the vibration-suppressed effeetivenesses of semi-active control and passive control for a long-span floating cable-stayed bridge with dampers set on towers and piers were calculated and analyzed by its 3D finite element model. Calculation result indicates that semi-active control method can gently control the seismic response of bridge, passive control method can sharply control the response, so passive control method should be used carefully. Traveling wave effect makes little bad influence on the tower of cable-stayed bridge for uncontrol, semi-active control and passive control with the maximal augment of 10~ for internal force, but it can make serious bad influence on the beam with maximal augment of about 8 times for internal force. The bad influences of traveling wave effect on the vibration-suppressed effectivenesses of semi-active control and passive control are little with no obvious bad control effectivenesses.More>
2008, 8(6): 70-76.
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Planning method of bus main artery network based on point-area match
GUO Zi-zheng, JIANG Mei, ZHANG Dian-ye, DUAN Li
Abstract: In order to improve the accuracy and efficiency of bus network planning, a planning method was proposed based on point-area match theory, the boundary area equation of sensible searching range was determined, and the optimization model of bus lines was set up based on considering the match between area location and passenger flow. A "from left" algorithm was applied to get the enumeration of effective bus lines within sensible searching area, the optimal line was gained by using multi-objective decision, finally the new planning method was tested with an example. Analysis result shows that the line network scheme obtained by new planning method is consistent with the real line network scheme, the accuracy and efficiency are greatly improved because the searching process is greatly simplified by giving the key controlling point and effective area, so the method has practicability.More>
2008, 8(6): 77-81.
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Transport network design under demand forecast uncertainty
PAN Yan-rong, DENG Wei
Abstract: In order to analyze the influence of demand forecast uncertainty on transport network design, two kinds of models were established based on different forecast results, the one for continuous demand was transport network design model based on sensitivity analysis, and the other for discrete demand was transport network design model based on scenario forecast. There were two items in the models, the former was network benefit, and the latter was network stability. The establishment processes of the two models were put forward, and their calculation methods and applicable bounds were studied. Computation result shows that with the lessening of design parameter, traffic network benefit is smaller, traffic network stability is larger, and different network design results are got, so the models considering demand uncertainty can reflect the practical situations of traffic netwrok better.More>
2008, 8(6): 82-87.
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Estimating methods of link travel times based on data fusion technology
LIU Hong-hong, YANG Zhao-sheng
Abstract: In order to exactly predict link travel times, the advantages and disadvantages of existing prediction methods were analyzed, adaptive Kalman filter algorithm was used, and link travel time estimation models were presented by combining traffic data from probe vehicles and loop detection. Adaptive Kalman filter(AKF) algorithm-based link travel time estimation models were compared with loop detector data-based methods and probe vehicles-based methods under the circumstances of peak hours and traffic accident, the average absolute percentages of the computation error were analyzed. Analysis result indicates that AKF algorithm is an effective method that may fuse the traffic data from different sources, its predictive values are closer to the measured values so its prediction accuracy is higher.More>
2008, 8(6): 88-92.
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Description of architecture and rules of integrated operation dispatch system for passenger dedicated line
WANG Hong-gang
Abstract: In order to improve the intelligence of the integrated operation dispatch system for passenger dedicated line, using agent technology, the architecture of multi-agent system (MAS) was presented by regarding the process of transportation dispatch as the negotiating process among agents. Train traffic control subsystem, motor train unit dispatch subsystem, the power supply subsystem of electric traction and railway station were abstracted into agents respectively, and all these agents constituted an agent society, in which social rules were given. Based on MAS architecture, the structure of company's train traffic control agent was given, which was 2-way-4-layer vertical architecture, railway station agent architecture was given, which was reactive one, and their running principles were desicribed. Applied result shows that, for agent, the time of adjusting operation plans on train is less than 10 s, the time of choosing dispatch preplans is less than 5 s, so MAS architecture is feasible and has high intelligence under the control of the rules.More>
2008, 8(6): 93-98.
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Transmission index model of railway travel information based on travel behavior
JI Xiao-feng, LIU Lan
Abstract: In order to evaluate the transmission effectiveness of railway travel information accurately, the travel behavior of railway passenger was analyzed based on travel chain, and a searching model of travel information was proposed. Travel information demand was analyzed in detail based on travel decision-making characteristics, and the demand intensity distribution of travel information in whole travel process was described. Matter-element analysis method was used to build a transmission index model for the transmission effectiveness assessment. Evaluation result indicates that the transmission effectiveness of Chinese railway travel information is approximating to general level, travel information searching inconvenience has significant effect on travel satisfaction, therefore, the present transmission model of railway travel information must be improved, and public travel information service systems should be construct rapidly to improve the transmission effectiveness.More>
2008, 8(6): 99-103.
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Detection method of traffic signs in road scenes
ZHANG Ning, HE Tie-jun, GAO Chao-hui, HUANG Wei
Abstract: In order to quickly identify traffic signs in road scenes with vehicle visual navigation, a detection method was put forward by extracting the color characteristics of traffic signs and recognizing the shape characteristics of targets. The road scene image of RGB space was transformed into that of HSI space, a syncretic method of hue and saturation was used to extract the characteristic color area of sign in road scene, then traffic sign image was binarized, the noise was removed, and binarization target was projected to locate traffic sign. A red circular interdictory traffic sign was taken as example, and an improved Hough transform method was proposed to recognize the geometrics of the sign area. Analysis result shows that after 20 road scene tests, including interdictory traffic signs under different conditions, the detection rates of color area locations and geometric characteristics recognitions for traffic signs reach 100%, and the average detection time is 245 ms, so the method not only locates the sign area quickly and correctly, but also recognizes the geometric graph of interdictory traffic sign with real-time property and robustness.More>
2008, 8(6): 104-109.
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Online selection model and competitive analysis of vehicle routing in grid transportation network
SU Bing, XU Yin-feng, YU Shui
Abstract: In order to analyze the vehicle routing problem under sudden road blockage in grid transportation network, a vehicle routing model was proposed by using the methods of online problem and competitive strategy, direction greedy strategy and multi-alternative moving strategy were designed, and the competitive ratios of two strategies were computed. Analysis result indicates that the cost of direction greedy strategy is 3 times than the optimal cost under sudden road blockage state, multi-alternative moving strategy has a good performance with practical restriction for different cases, the cost of multi-alternative moving strategy is 2 times than the optimal cost in the worst case, the competitive ratios of two strategies are not more than the infimum of the competitive ratio for unexpected blockage problem in general networks.More>
2008, 8(6): 110-115.
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Internal function area layout method of logistics park
MA Cheng-lin, MAO Hai-jun, LI Xu-hong
Abstract: In order to avoid the service failure of logistics park because of its unreasonable internal functional area layout, its external conditions and internal factors were analyzed, its service reliability evaluation index system was established, and an internal layout method was put forward based on service reliability, fuzzy clustering theory and AutoMod simulation technology were applied, the qualitative analysis and quantitative account of logistics park were carried out, and the static and dynamic simulations of its layout project were realized. Analysis result shows that in logistics park, possible traffic jam is found, warehouse utilization ratio is improved, and the collaboration among functional areas is strengthened. Withal, the planning method has few subjective factors and high reliability, and is easily quantifiable and maneuverable.More>
2008, 8(6): 116-121.
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Acting sphere determination of logistics park and allocation calculation of logistics volume
CHENG Yao-rong, DAN Hua-yi, LIU Feng-gen
Abstract: In order to determine the acting sphere of logistics park and figure out reasonably the apportioned logistics volumes among logistics parks in an area, the calculation methods of breaking point and field intensity were used, the formula of computing the acting radius for logistics park was set up according to breaking point theory, and the idea and method were proposed to determine the acting sphere of logistics park. The composite service ability of logistics park was gained by using SE-DEA evaluation method, and a share model of logistics volumes was put forward based on goods categories among logistics parks in an area. Computation result shows that the acting radius of logistics park is 145 km based on field intensity, and the apportioned logistics volume of logistics park is 1.064 1×108 t, so the idea, method and model are scientific and reasonable.More>
2008, 8(6): 122-126.
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