2008 Vol. 8, No. 2

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Traction rod arrangement modes of locomotive with six axles and driving equipment flexibly suspended on frame
ZHANG Hong-jun, LIAO Zhi-wei, LUO Yun, HUANG Zhi-hui
Abstract: The influence of traction rod arrangement modes on locomotive running safety was researched to develope new bogies with single traction rod for 200 km·h-1 locomotive with six axles(i.e.2C0), a dynamics model of locomotive with driving equipment flexibly suspended on frame and six axles was established by SIMPACK.Under the conditions of traction, braking and passing through irregularity track, when traction rods acted at the middle or two ends of car body, locomotive behaviors through tangent or curved tracks were analyzed.Analysis result shows that the positions of the rod have tiny effect on the dynamics performances of locomotive, and the plan of traction rod acting at two ends of car body is suggested to simplify the design and manufacture of car body.The locomotive can pass safely through the S shape curves with R400 m and R1 600 m radii; lateral force passing through the curve with R400 m radius is larger than that under driving and braking conditions, and wheel unloading ratio on braking condition is larger; lateral force under passing or tracting through the curve with R2 800 m radius is larger than that on braking condition.More>
2008, 8(2): 1-3.
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Crossing aerodynamic force analysis of tarpaulin for trains
LIU Tang-hong, TIAN Hong-qi
Abstract: In order to solve catching wind badly and goods being soaked and damaged easily for two-piece freight tarpaulin (X-type tarpaulin), and to test the using effect of new freight tarpaulin (D-type tarpaulin), defferent loading and reinforcing projects were considered, twelve using conditions with and without cord net were confirmed, the crossing pressure waves of trains and the tensile forces of tarpaulin cord and net cord were tested by full-scale train test.The result shows that when freight car at 80~120 km·h-1 passes by multiple unites at 200~210 km·h-1, the maximal magnitudes of air pressure waves are 577 Pa and 715 Pa separately for multiple unites and freight car; the maximal tensile force of cord is 1 055 N, and it appears at the corner cord of X-type tarpaulin without net, which satisfies the demand of correlative standards; catching wind of two kinds of tarpaulins without net is seriously, and at the same speed, the tensile force of X-type tarpaulin against wind is about 40% greater than that down wind; cord net has an important role, and the tensile force of cord without net is 50%~80% greater than that with net.Thus, D-type tarpaulin has better using performance than X-type tarpaulin under the same instance.More>
2008, 8(2): 4-8.
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Dynamic response of linear metro vehicle/track excited by track irregularity
LONG Xu-you, WEI Qing-chao, FENG Ya-wei, SHI Jin
Abstract: In order to improve the safety and riding comfort of linear metro vehicle, the structural characteristics of vehicle/track system was analyzed, and a dynamics vertical-lateral vehicle/slab track coupling model was developed.The random vibration characteristics of vehicle and track excited by track random irregularities were investigated, in which the time domain samples of track random irregularities were simulated by using trigonometry series.Track vertical and alignment irregularities were expressed as harmonic cosine forms, and the effect rules of their wave amplitudes and wavelengthes on the dynamic responses of the system were studied.The result indicates that the frequency distributions of air gap variation are mainly in low frequency field, ranging from 1.2 to 2.0 Hz; when the wavelengthes of track vertical and alignment irregularities are shorter than 10 m, the affect of the irregularities on wheel/rail interacting force, derailment coefficient and the reduction rate of wheel load is dramatical, which should be controlled seriously.More>
2008, 8(2): 9-13.
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Interlaminar connection design of continuous combined ballastless track on simply supported bridge
ZHAO Ping-rui, YANG Rong-shan, LIU Xue-yi
Abstract: The interlaminar shear force of continuous combined ballastless track on 32 m simply supported bridge was studied under train load, temperature difference between track slab and support slab and braking force with conversion section method, finite element method and rigid simplified method respectively, its distribution diagram was gotten, and the interlaminar connection design was proposed based on the diagram.The result shows that the shear force under train load linear decreases from the bridge end to the middle; the shear force is concentrated in the 5 m region next to the bridge end when there is a 10 ℃ temperature difference between track slab and support slab; the shear force under braking force evenly distributes along the bridge, which equals to the longitudinal resistance of fastener; when the three factors act together, the shear force is controlled by the temperature difference, so more dowels and connection rebars should be set in the 5 m region, which is heavily influenced by the temperature difference.More>
2008, 8(2): 14-17.
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Performances and emissions of a supercharged diesel engine fuelled with biodiesel
ZHANG Chun-hua, SONG Jian-tong, YANG Xuan
Abstract: In order to optimize the application of biodiesel for diesel engine, the emissions, fuel economies and power performances of biodiesels with different blend ratios were compared and analyzed by bench tests of a supercharged direct injection(DI)diesel engine, the exhaust emissions of smoke, NOx, CO and HC, effective energy consumption rate and power were investigated under different engine loads and speeds.Experiment result shows that compared with diesel fuel, B10, B20, B30, B50, B80 and B100 blends have, on average, a reduction of 34.69% for smoke emission, an increase of 25.01% for NOx emission, a reduction of 33.05% for HC emission, an increase of 11.13% for CO emission at full load, a reduction of 2.18% for effective energy consumption rate although effective fuel consumption rate is increased, an increase of 5.34% for power, the decreased percentages for smoke emission are 7.01%, 15.37%, 14.17%, 10.45%, 6.73% and 4.39% higher than the increased percentages for NOx emission respectively, so the blend ratio of B20 is optimum.More>
2008, 8(2): 18-22.
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Vehicle optimum maintenance period under availability objective
XU An, QIAO Xiang-ming
Abstract: In order to accurately decide vehicle optimum maintenance period under availability objective, the renewal function of renewal theory and optimum concept was analyzed, two mathematical models of optimum maintenance period were established, and their optimum objectives were the greatest availability and the shortest total unworkable time in unit time respectively.The parameter estimate and hypothesis testing of failure distribution were made, utilizing the operating failure and cost data collected from 78 given type commercial vehicles in several years.It is affirmed that vehicle operating failures obey Weibull distribution when the confidence level is greater than 0.95, and the optimum maintenance period solved by the established models is 15 617 km.The result of verifying group test indicates that vehicle availability gets its greatest value 0.955 1 when class Ⅱ maintenance period is 15 122 km; the relative error between the model's solution and the optimum period mileage of the test is only 3.27%, so the model's solution is accurate, reliable, and conforms to reality.Combining the result of model research with the result of vehicle test, the optimum class Ⅱ maintenance period under the meaning of greatest availability is 15 000 km.More>
2008, 8(2): 23-26.
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Structural behavior analysis of high strength steel-concrete composite girders
WANG Chun-sheng, SONG Tian-yi, FENG Ya-cheng, XU Yue
Abstract: In order to study structural behaviors of high strength steel-concrete composite girders, 14 group-components models with different geometry parameters and material properties were built by using ANSYS software under deuce symmetrical loads at mid-span.The analysis result indicates that steel girder bears about 77.0% of whole vertical shear strength in plastic state, and the ratios of maximum and minimum values of mid-span deflections for different material strength girders in elastic and plastic states are 79.5% and 28.0% respectively; the ratios of maximum and minimum values of mid-span deflections for different transverse bar ratios and widthes of concrete slab girders in plastic state are 62.1% and 53.3% respectively; the ratios of maximum and minimum values of longitudinal slips for different material strengthes, widthes of concrete slab, transverse bar ratios and thicknesses of concrete deck girders in plastic state are 25.0%, 41.9%, 63.2% and 70.7% respectively.Therefore, increasing the strength and section size of steel is economic and reasonable method to increase the vertical shear strength of the girders; the steel and concrete strengthes affect little on the mid-span deflection of the girders in elastic state, and the transverse bar ratio and the width of concrete slab have larger effect on the mid-span deflection in plastic state; the geometry parameters and material properties of the girders have little effect on the longitudinal slip in elastic state, but the material strength, width of concrete slab, transverse bar ratio and thickness of concrete deck have obvious effects on the longitudinal slip in plastic state.More>
2008, 8(2): 27-33.
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Analysis on rib rigidity of concrete filled steel tubular arch bridge
WEI Jian-gang, CHEN Bao-chun
Abstract: In order to study the effect of tube rigidity on the mechanical character of truss CFST(concrete filled steel tubular)arch bridge, a true arch bridge was taken as sample, and the parameter analysis for the rigidity was carried out by using finite element model.Based on the investigation of section composition for arch rib, a suggestion was presented to calculate tube rigidity, in which the rigidity reduced factor of concrete was adopted as 1.0 or 0.4 for different calculation demands.Analysis result indicates that for internal force, the rate of calculation value to reality value is between 1.2 and 1.5, for deformation the rate is between 1.5 and 1.9.So, the suggestion can secure some safety reserve for the design of truss CFST arch bridge.More>
2008, 8(2): 34-39.
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Buffeting performance of bridge tower under yawed wind during construction
HU Qing-an, QIAO Yun-qiang, LIU Jian-xin, LI Jia-wu
Abstract: In order to study the influences of different wind speeds and wind yawed angles on the buffeting performance of bridge tower during construction, a wind tunnel test of bridge tower aeroelastic model was made based on considering the action of tower crane.Test result shows that the buffeting displacement responses increase with the increase of wind speed, have a trend of conic curve approximately, the buffeting responses of bridge tower with the increase wind yawed angle is not monotonous, the longitudinal and lateral buffeting responses of bridge tower can reach their maximal values under non-cross wind attack; the maximal value during construction is 0.274 6 m under design wind speed, which is acceptable to the project, the test result of RMS(root mean square)is significantly greater than the analysis result in time domain, so buffeting analysis should consider the influence of construction stages and machineries in wind tunnel test.More>
2008, 8(2): 40-43.
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Changing rules of temperature field for tunnel in cold area
CHEN Jian-xun, LUO Yan-bin
Abstract: In order to discove the variation rules of tunnel temperature field, eleven sections of a highway tunnel in cold area were chosen, four positions were confirmed including crown, shoulder, wall and road face, their temperatures were tested in 1.5 a, and test data were analyzed by using mathematical statistic-sine function regression method.The result shows that the variation rule of yearly temperature in tunnel was periodical, basically accords with sine curve; vertical yearly temperature and shake amplitude decrease gradually with the increase of the distance entering into tunnel, and the changing rule was exponent curve; the relation between yearly temperature and radial depth was also exponent curve with in certain area, radial yearly temperature increases, but temperature shake amplitude decreases; water-proof layer was effective against thermal retardation.More>
2008, 8(2): 44-48.
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Research on viscosity property of asphalt mortar
LI Ping, ZHANG Zheng-qi, SUN Hong-wei, WANG Bing-gang
Abstract: In order to analyze the influence of mineral power on asphalt mortar viscosity, Brookfield viscometer was used to test the viscosities of asphalt mortars with different filler types and filler bitumen ratios, and the influencing factors were studied.Test result shows that there is 4.7 times gap among the viscosities of different mortars, and the gap is bigger with the increase of filler bitumen ratio; adding mineral power can reduce the temperature sensitivity of the mortar, but which is affected by mineral power type and dosage; the difference of construction temperatures among different asphalt mortars can reach about 30 ℃.So it is necessary to filtrate the mineral power type according to mineral power character for reducing the bad effect on asphalt mixture performance, and modify the determination method of active mixture construction temperature for considering the function of mineral power.More>
2008, 8(2): 49-52.
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Rational simplified model of finite element analysis for deck pavement of long-span steel bridge
DENG Qiang-min, NI Fu-jian, GU Xing-yu, CHEN Rong-sheng
Abstract: In order to improve the computation precision of simplified model for finite element analysis of deck pavement of long-span steel bridge, the size and boundary conditions of the model were optimized by using sub-model technology and comprehensive evaluation method, the parameters sensitivity of the model was analyzed, the reasonable dimension and constraints of a simplified finite element model were put forward, which had 3 longitudinal spans with free borders, 8 U-shape ribs in transverseness with simple supported borders, and 1.2 m-high diaphragms with fixed bottoms.Comparison result shows that simplified finite element model has high precision, the error of transverse tensile strain is only 0.7%, and the error of longitudinal tensile strain is 3.7%.More>
2008, 8(2): 53-58.
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Early crack of continuously reinforced concrete pavement
LIU Han-bing, ZHANG Yun-long, WEI Zhi-gang
Abstract: In order to accurately calculate the distribution and development laws of early crack for continuously reinforced concrete pavement(CRCP), the nonlinear bond-slip relation between reinforced steel bar and concrete was analyzed, the finite element stiffness equation of CRCP was established by using contact theory under the circumstances of temperature change and dry shrinkage of concrete, the finite element solutions of crack width and crack space were obtained, and the effects of concrete tensile strength, elastic modulus change, construction season, reinforcement ratio and steel bar diameter on early crack were studied.Calculation result shows that the changes of concrete tensile strength and elastic modulus have a greater impact on early crack within 28 d after concrete pouring completion, the impact is gradually stable with the increase of concrete age; the reinforcement ratio and reinforcement mode also have a great impact on early crack, multiple-strand small-diameter reinforcement mode is more reasonable for the control of early crack, and it is better that construction season is autumn.More>
2008, 8(2): 59-64.
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Development laws of transverse cracking for continuously reinforced concrete pavement
CHA Xu-dong
Abstract: In order to understand the real development laws of transverse cracking for continuously reinforced concrete pavement (CRCP), a CRCP trial road on Leiyang-Yizhang expressway of Hunan Province had been investigated and tested for 5.5 a, and the test results of crack space and crack width were analyzed by using statistical method.Analysis result shows that CRCP transverse cracking can be divided into 3 periods with its age increase according to cracking development speed, including hardened cracking, transition cracking and stabilized cracking; in general, the variance coefficients of crack space and crack width are respectively 0.30~0.35 and 0.20~0.25;there is a fine power function relation between average crack space and CRCP age, there is a good linear function relation between average crack width and air temperature, and crack space accords with normal distribution.More>
2008, 8(2): 65-68.
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Calculating method of vehicle dynamic load caused by uneven pavement
CAO Yuan-wen, LIANG Nai-xing, YU Qing, WU Yong
Abstract: In order to analyze the dynamic load character of vehicle running on uneven pavement, the surface of pavement was simulated by using sinusoid according to the evenness measure result of Xi-Bao freeway, a four-free-degree model of vehicle vibration was set when vehicle lean factor and tire damping were considered, a calculating method of vehicle dynamic load was presented through analyzing and solving vehicle vibration problem by using modal theory and programming calculation, when the left and right wheels of vehicle were not impelled at the same time, and vehicles ran at different speeds on different pavement models with different wavelengthes and amplitudes.Calculation result indicates that vehicle dynamic load caused by waveform pavement shows waveform distribution in longitudinal direction, vehicle running on uneven pavement may produce great dynamic load, and the maximum coefficient of dynamic load is above 2.0.More>
2008, 8(2): 69-73.
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Management and preventive maintenance countermeasures of airport asphalt pavement
SHI Bao-hua, XU Wei, QI Yong, HE Cheng-gang, CHEN Wei-xing
Abstract: In order to improve the service life of airport asphalt pavement and reduce the expenses of maintenance and management, different types, characteristics and actual application status of several asphalt pavements were analyzed, main influencing factors and damage mechanisms were studied, and relevant countermeasures of management and preventive maintenance were put forward.Analysis result shows that constituting strict management mechanisms, forbiding overload, enhancing daily maintenance and training pilots to use pavement reasonably are effective methods to reduce pavement damage; thin surface repair methods of topdressing and covering with modified asphalt mortar are put forward for existing damage styles; based on climate characteristics in different seasons, the change laws of water and temperature conditions, and the principle of putting prevention first and combining prevention with treatment, efficient technical measures aiming at local conditions are taken for seasonal pavement damage, seasonal maintenance work should be done well; enhancing pavement status evaluation, taking optimal maintenance occasion and constituting reasonable maintenance standards can effectively improve the service performance of airport asphalt pavement.More>
2008, 8(2): 74-79.
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Determining method of dangerous areas around tropical cyclone based on multisource forecasts
LIU Da-gang, LIU Zheng-jiang, WU Zhao-lin
Abstract: In order to improve the integrity and accuacy of tropical cyclone(TC) information, the present methods of determining the dangerous areas around TC were analyzed, and a new method based on multisource forecasts was proposed. According to the forecasting results of TC center positons made by China, Japan and the United States, forecasting discrete values were computed. From the relation between forecasting positions and average errors, the radius of 90% TC falling probability circle was got. Covering the radius of strong wind or rough sea area outside the probability circle, the dangerous areas around TC center were got based on considering different TC forecasting results. Obviously, the method improves the falling probability of TC forecasting circle, and strongly guarantees the safety of ships' avoiding TC.More>
2008, 8(2): 80-84.
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Estimating methods of passenger throughput for hub airport based on reverse gravity model
LIU Xiao-ming, XIA Hong-shan
Abstract: To accurately estimate airport passenger throughput based on airline passenger flow OD data, both full-connected linear network and hub-spoke network were discussed, according to passenger flow OD matrix between hub airports, a standard algebraic algorithm of reverse gravity model was developed, and a simplified algebraic algorithm was put forward with the Hamiltonian graphs, and the fitting precisions of two algorithms were studied under defferent ranging exponents.Analysis result indicates that two algorithms' deterministic coefficients of the best throughput regression lines are 0.84, their slope values are 0.91 and 0.87 respectively.So two algorithms have good fitting effects and high estimating precisions, and simplified algebraic algorithm needs only a very small data, which can be used for large-scale OD matrix analysis.More>
2008, 8(2): 85-89.
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Hybrid particle swarm optimization arithmetic for recovery scheduling of flight delays
DING Jian-li, WANG Xin-ru, XU Tao
Abstract: In order to optimize the recovery scheduling of flight delays, airline impact factors were defined, the economic benefit, social impact and loss constitution of flight delays were considered, a new recovery scheduling model of flight delays was created, a hybrid particle swarm optimization arithmetic (HPSOA) was put forward, and local search method was introduced into the arithmetic.Computation result shows that HPSOA can reduce the flight delay losses by 4.2% compared with first-come-first-serve (FCFS) strategy, and evenly reduce the flight delay losses by 2.0% compared with basic PSOA and evolutionary strategy (ES), so the advantage of HPSOA is more obvious with the increase of recovery scale in flight delays.More>
2008, 8(2): 90-95.
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Multidimensional analysis model of accident causes resulted from human factors
WANG Yong-gang, WANG Yan
Abstract: In order to improve air traffic safety, a multidimensional analysis model of accident causes(MAMAC)was put forward by integrating business process management(BPM), human factors analysis and classification system(HFACS), its using steps were proposed, and the accident causes of an actual case were analyzed by using the model.The result indicates that the model can lead investigators to find all holes of processes by using Swiss Cheese Model; the detailed level and completeness of business process are proportional to the detailed level and completeness of cause analysis; the degree of cause analysis hierarchy is proportional to the detailed level of analysis result; when the model is applied to the fields where business process is relatively stable, business process can be optimized, and the reliability of system can be increased; when the relationships of the causes are stored into a database, it is easy to realize event recurrence, and the data can be used in risk evaluation, safety forecast and alert.More>
2008, 8(2): 96-100.
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Computation models of capacity influenced by non-power-driven vehicle at signalized intersection
CHEN Xiao-ming, SHAO Chun-fu, ZHAO Yi
Abstract: In order to quantify the effect of non-power-driven vehicle on the capacity of signalized intersection, the influence ways of non-power-driven vehicle were analyzed, and the time durations of various influences were estimated, saturation flow rates in various conditions were obtained on the basis of speed-flow relation, and the capacity models of typical signalized intersection were built.Computation result indicates that the proposed models yield lower left-turn and through capacities compared with HCM method, right-turn capacities predicted by the models essentially agree with those by HCM method in low non-power-driven vehicle volume condition, and are higher in high non-power-driven vehicle volume conditions.So the models are applicable to calculate the capacity of signalized intersections influenced by non-power-driven vehicle.More>
2008, 8(2): 101-105.
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Planning methods and effect analysis of advance right-turn
QU Zhao-wei, JIN Yong, CHEN Yong-heng, WANG Dian-hai, WEI Wei
Abstract: Calculating models of passing capacity for fixed and variable weaving area lengths on advance right-turn were given by using gap acceptance theory and probability theory, and calculating models of increasing capacity by prolonging weaving areas were obtained, the application conditions of planning methods on advance right-turn were put forward, the running effects of motor vehicles were compared with the index of vehicle average delay in the weaving areas, and the capacities of left-turn and straight vehicles were analyzed by using Webster signalized timing methods at advance right-turn intersection.Analysis result shows that the capacities of straight and left-turn vehicles at intersection increase when advance right-turn planning method is adopted; when advance right-turn vehicles satisfy passing capacity, traffic conflict area can be decreased by using advance right-turn planning method, otherwise, prolonging weaving areas can be used to add passing capacity and decrease the average delays of right-turn motor vehicles.More>
2008, 8(2): 106-109.
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Research on trip distance distribution model and parameter
SHI Fei, LU Zhen-bo
Abstract: To study the trip distance distribution character in urban traffic planning, trip distance distribution function was analyzed by using probability theory and statistics theory under some hypothesis conditions, and was fitted by using resident trip data of ten cities, the rationality of hypothesis conditions was tested, the effect factors of the function parameters were discussed such as urban scale, urban shape and traffic structure, a general function of trip distance distribution was established through quantitative analysis and nonlinear regression, and the parameter ranges of different urban scales were analyzed.Calculation result indicates that trip distance accords with Rayleigh distribution, the ranges of distribution function parameter are from 0.035 to 0.076 for megalopolis and from 0.042 to 0.100 for big and medium cities.More>
2008, 8(2): 110-115.
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Analysis and simulation of traffic state on expressway during incident
ZHANG Hai-jun, ZHANG Jue, YANG Xiao-guang
Abstract: In order to research the influence of incident on the traffic operation of expressway, the process of local traffic state during incident was disassembled, the capacity in each phase was analyzed, the affecting factors of the capacity were induced to incident feature, blocked width, incident position, travelling order and upstream traffic volume, and traffic microsimulation was carried out when accident results to the closure of some lanes.Simulation result shows that traffic delay increases quickly during the closure till the lanes are opened, then starts to decrease, there are some fluctuations in the whole process; when traffic volume approaches capacity, the balance of traffic system is weak, incident will arouse traffic congestion in large area and long time, some necessary measures, such as traffic routing and ramp control, should be adopted to divert traffic volume partially and reduce incident influence.More>
2008, 8(2): 116-121.
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Virtual simulation test of perception factors for operating speed
CHEN Tao, WEI Lang, YUAN Wang-fang
Abstract: In order to study the prediction of operating speed on microsection for road safety evaluation, the driver's safety perception factor sets for third-class highway were determined, 3-D simulation model including 15 sections was built by using MultiGen Creator software, and the virtual simulation system was developed by using Vega.The perception evaluation tests with 53 drivers were carried out in three-channel cylinder projection system.Based on the analysis of 795 groups test data, the evaluation model including horizontal curve radius, longitudinal gradient and sight distance for third-class highway was presented by means of fuzzy statistics method.Computation result shows that the mean nearnesses between simulation tests and road tests of the individual evaluation levels on safety perception factors are 0.63, 0.74 and 0.70 respectively.So virtual simulation test is an effective means for the prediction of operating speed.More>
2008, 8(2): 122-126.
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