Journal of Chongqing Jiaotong University(Natural Science)

Mechanical Characteristics of EarthAnchored CableStayed Bridge with Single Inclined Pylon and Single Span

WANG Gaosi

2017, 36(5): 1-6. DOI: 10.3969/j.issn.1674-0696.2017.05.01

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Furongjiang River Bridge is an earthanchored single span and single inclined pylon cablestayed bridge, with five major characteristics, that is “pylon”, “earthanchored”, “single span”, “full concrete”, and “large span”. Five key parameters, namely, the earth anchorage box position, the inclination angle and oblique height of pylon, selfstiffness of pylon and girder were selected to study their impacts on bridge stress. And then, more reasonable parameter values of the fullbridge stress state were obtained. The results show that anchor cable has more contribution on the overall stiffness of the pylon when the earth anchorage box position is far away from the pylon, but it has little impact to the vertical stiffness of girder. Increasing selfstiffness of pylon and girder has very little effect on the fullbridge stiffness and vibration frequency, while adjusting key parameters, for example, the position of earth anchorage box, is more efficient.

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Shear Lag Effect of Steel Box-Truss Composite Girder of Cable-Stayed Bridge

MA Guofeng

2017, 36(5): 7-11. DOI: 1674-0592（2017）05-007-05

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To analyze the shear lag effect of the overall box girder bridge deck, a finite element model of overall steel box-truss composite girder was established, which took a long span rail-cum-road cable stayed bridge in the construction as the research object. The influence rule of the transverse diaphragm distance, bridge deck thickness and cross-section height on the shear lag effect was also studied. The research results show that there are shear lag phenomena in the steel box-truss composite girder. Due to the low stress level and the bearing stress complexity, shear lag phenomena are more evident in the side span than in other areas. The uneven coefficient of maximum stress is 9.27 at the point of transition pier. The shear lag effect of most segments of middle span is small; the uneven coefficient of stress is 1.06 at top plate of and 1.09 at bottom plate; the stress uniformity of the top plate is higher than that of the bottom plate. The uneven coefficient gradually decreases from the middle section of middle span to the section near the tower. The stress uneven coefficient of top and bottom plates decreases with the increase of transverse diaphragm distance, bridge deck thickness and cross-section height, meanwhile its decreasing range is less than 5%.

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Multi-lane Transverse Reduction Factor Based on Measured Traffic Data and Reliability Theory

DU Baisong1, LI Ming1, LUO Ling2

2017, 36(5): 12-16. DOI: 10.3969/j.issn.1674-0696.2017.05.03

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Based on the measured traffic loading data, the reliability theory was employed to analyze the traffic flow characteristics. The probability distribution of the given type heavy truck was a double Weibull distribution, which was put forward according to the measured traffic volume and vehicle weight information. On the basis of the measured wheelbase, the wheelbase representative values were obtained by using kernel density estimation method. In accordance with the measured vehicle velocity, the distribution type of vehicle velocity was also obtained. Moreover, the distribution of 0.05 tantile was used as the representative vehicle velocity. A relational expression among the maximum loading (Wmax), mean (μ), and standard deviation (σ) of vehicle weight could be fitted by using regression analysis. Furthermore, the variation coefficient could be obtained by using statistics method based on vehicle weight’s samples. Finally, the multi-lane transverse reduction factors suitable for the current traffic condition were proposed by the probabilistic algorithms.

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Calculation Method Study of the Deep Soil Displacement Induced by the Tunnel Excavation

TIAN Xiaoyan, LIU Jing，DAI Jianbo

2017, 36(5): 17-23. DOI: 10.3969/j.issn.1674-0696.2017.05.04

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First of all, based on the principle of the plane strain, considering the incompressibility of the rock and soil mass, the Peck formula which was quite applicable at home and abroad was applied. The influence of the factors considering the tunnel diameter, the buried depth, the soil cutting, the caudal space and the surrounding rock properties of soil factors on the influence angle parameter, the arbitrary width coefficients of seelement trough on the value and value range was verified by the Peck formula. Aand then, the proposed specific parameters were used in the stochastic medium theory. Finally,the influence of the parameter change on the three-dimensional displacement of the soil at arbitrary depth in tunnel axis caused by the third mode of the Park displacement mode was discussed. Through the relative case studies, the results show that:the parameters considering the nature of the surrounding soil are more rational and inclined to be safe in engineering application.

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Unified Mechanical Index of Multiple Damage Phenomena of Asphalt Pavement Based on M-C Criterion and Its Application

LI Xiaojun, XIE Xiaoting, YUAN Gaoang

2017, 36(5): 24-29. DOI: 10.3969/j.issn.1674-0696.2017.05.05

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Based on the M-C criterion, a unified mechanical control index of asphalt pavement with multiple damage phenomena was proposed, that is asphalt pavement potential damage index(APPDI). Taking asphalt pavement of 5 highways as examples, using APPDI to analyze the mechanical models of pavement damage was studied on the basis of FEM calculation. The results indicate that the composition of the principal stress has a great influence on asphalt pavement damage. The different components of the principle stress are corresponding to different rutting, Top-Down cracks and bottom floor tension under different temperature. Combined with Mohr circle and the location in the pavement structure, APPDI can be used to judge damage forms of the asphalt pavement, which provides a certain theoretical basis for the interpretation of pavement failure mechanism and the optimization of pavement design.

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Performance Research of Bed Course Graded Crushed Stone

LIU Ke1，2

2017, 36(5): 30-34. DOI: 10.3969/j.issn.1674-0696.2017.05.06

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In order to get appropriate composition of the graded crushed stone, the indoor studies of heavy compaction, California bearing ratio (CBR), coefficient of permeability and water stability test on six kinds of the graded crushed stone were conducted. Results show that penetration can change the gradation distribution of the graded crushed stone. Permeability coefficient will be stabilized with the increase of the penetration frequency. Permeability coefficient of the graded crushed stone with 0.075 mm passive rate （P0.075）is smaller than that of 3% graded crushed stone; and smaller CBR strength is >0.011 6 cm3/s. The discrepancy of P0.075 of the graded crushed stone in the range of 3.6%~5.0% is small, and selecting the upper limit of passive rate can coordinate the confliction between the permeability and the strength. CBR of the graded crushed stone whose P0.075 is 7.6% can be up to 196% and is hardly permeable. P0.075 of the graded crushed stone with the drainage requirement is less than 5%, as the reduction of the filler causes the compaction of the material insensitive to the variation of water content, and there is no the optimum compaction water content. Heavy compaction breaks the aggregate seriously when P0.075 of the graded crushed stone is less than 3%. The abnormal increase of dry density is not suitable to be the compaction standard. Graded crushed stone at the early stage after forming is slightly collapsible, and its water stability is significantly associated with strength. CBR of the graded crushed stone is higher and the water stability is stronger.

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Attenuation Law of Mechanical Properties of Road Aggregate and Its Correlation

KONG Lingyun1, CAO Huiping2, TANG Fanlong2, SHEN Juan3

2017, 36(5): 35-39. DOI: 10.3969/j.issn.1674-0696.2017.05.07

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The polishing value test, wear value test, impact value test, crushing value test and soundness test on four kinds of aggregates, such as limestone, sandstone, basalt, and granite were analyzed. And the sliding and wearing resistances of the above aggregates were also studied. It is indicated that the mechanical indexes of the above aggregates at the standard test conditions are correlated at a certain degree. It is feasible in technology that using the proposed limestone and sandstone to be the aggregates of the anti-sliding layer of the asphalt road pavement. When the traffic volume is not large and the landform is even, using limestone as the aggregate of the anti-sliding layer can basically satisfy the requirements of slide and wear resistance of highway in operation (before the medium and large repair). Through the research on above aspects, the feasibility of using four kinds of aggregates, such as limestone, sandstone, basalt and granite as the material of asphalt anti-sliding surface was comprehensively analyzed and evaluated from the point view of slide and wear resistance.

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Time-Dependent Behavior of Geosynthetic-Reinforced and Pile-Supported Embankment of the Soil with Medium-Low Compressibility

DING Liemei1, GUO Chaoxiang2

2017, 36(5): 40-44. DOI: 10.3969/j.issn.1674-0696.2017.05.08

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A three-dimensional coupled mechanical and hydraulic model was built by using the finite-difference continuum program (FLAC3D) based on an inter-city railway. The comparison analysis of the time-dependent behavior of the GRPS embankment of the soil with medium-low compressibility was carried out. The variation rule of excess pore water pressure, settlement at the center of sub-grade surface, and horizontal displacement at the embankment toe changing with the time under the condition of the unreinforced ground and the ground reinforced with GRPS were elaborated in detail. The results show that GRPS could effectively control the ground deformation of soil with medium-low compressibility during and after the embankment construction, which prevents the failure and instability of foundation under the embankment load.

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Literature Review on the Performance of Amorphous Alloy Fiber and Its Application in Reinforced Concrete

JIANG Chaohua, LUAN Zhiyong, ZHANG Weiwei, HUANG Shanshan

2017, 36(5): 45-50. DOI: 10.3969/j.issn.1674-0696.2017.05.09

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Fiber addition in the reinforced concrete is one of the effective ways to improve the toughness of matrix, restrain the shrinkage cracking and obtain high performance concrete. Amorphous alloy fiber (or named metal glass tape) has excellent mechanical and corrosion resistance property. Amorphous alloy fiber reinforced concrete material shows high strength, large modulus, well flexibility and corrosion resistance. The development and main characteristics of amorphous alloy fiber were introduced. The current research on mechanic properties and corrosion resistance of amorphous alloy fiber reinforced concrete was elaborated in detail. And the application prospect and main problems of amorphous alloy fiber reinforced concrete were put forward.

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Laboratory Study on Producing Foam Mixed Lightweight Soil from Barren Phosphorus Slag

LI Mingdong1, 2, FAN Gongjun3, JI Fengling4, TIAN Anguo1

2017, 36(5): 51-56. DOI: 10.3969/j.issn.1674-0696.2017.05.10

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Laboratory study was used to study the technology and performance of producing foam mixed lightweight soil from phosphorus slag. The results show that: when the foam is produced by foaming machine, the stability of Coconut oil fatty acryl diethanolamine ［C11H23CON(CH2CH2OH)2］ is better than that of sodium dodecyl sulfate ［CH3(CH2)10CH2-OSO3Na］, and the optimal concentration of AES is 3%. Leaving mortar stationary is helpful to the reduction of de-foaming and the optimal time before being mixed with foam is 60~90 min after leaving mortar stationary. The density of phosphorus slag foam mixed lightweight soil is mainly influenced by foam content, and the appropriate foam content is 100%~200% in practical engineering. The unconfined compression strength is increased with the increase of cement content, and decreased with the increase of foam content. The 28d unconfined compression strength can reach 1.5 MPa and even above, which can be used for roadbed filling, mine pit backfilling, building backfilling and etc. The strength will be greatly increased after 28 days.

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Correlation Between Sediment Acoustics and Geotechnical Properties in Jiaozhou Bay

ZHENG Jiewen1, LIU Baohua2, KAN Guangming3, LIU Xiaolei4, LI Guanbao3, PEI Yanliang3

2017, 36(5): 57-63. DOI: 10.3969/j.issn.1674-0696.2017.05.11

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Sediment columnar samples were collected from coastal areas of Jiaozhou Bay to conduct the measurement of acoustics and physical and mechanical properties, together with in-situ measurement of mechanical properties. Mathematical statistics was used to analyze the sediment acoustics and physical and mechanical properties of different types of sediments in the above sea. The study demonstrates that a significant discrepancy of compression wave speed and shear wave speed exists in different types of sediments at coastal areas of Jiaozhou Bay. Among them, compression wave speed and shear wave speed of silty sand are the highest. The compression wave speed of clayed sand, sandy silt, sandy clay, and silty clay take the secondary place, and that of clay is the lowest. The discrepancy of compression wave speed is generally lower than 50 m/s and shear wave speed is generally lower than 20 m/s for the same type of sediments. The variation rule of the dynamic elasticity modulus and dynamic shear modulus of different types of marine sediments is basically accordant with the acoustics properties, but with a non-obvious variation. There is a good quadric relationship between sediment acoustics and physical properties, and the relevance degree between acoustics and physical properties is obviously higher than sediment mechanical properties. In addition, within the range of the measured parameters of sediment physical and mechanical properties, sediment compression wave speed and shear wave speed are increased with the increase of sediment bulk density and strength, while decreased with the increase of sediment water content and porosity.

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Mechanical Properties of Saturated Clay under Effect of over Consolidation Ratio

WEI Song1, 2, 3, ZHANG Wenjin1, XIAO Shuxia1, 3, CHEN Qing1

2017, 36(5): 64-70. DOI: 10.3969/j.issn.1674-0696.2017.05.12

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Quick shear tests were performed on the undisturbed and remolded clay of a subway station foundation-pit in Hefei under 5 over consolidation ratio (OCR) states. The change regulations of the shear behavior, shear strength and strength indexes (cohesion c and internal friction angle φ) of the above soils under different OCR were investigated. The results show that: under different OCR, the undisturbed clay mostly shows strain hardening performance, and the remolded clay mostly shows strain softening performance at over-consolidation state and strain-hardening performance at under-consolidation state. With the same vertical stress, the peak shear strength of remolded clay would increase with the increase of OCR. Under the same OCR, the peak shear strength of remolded clay would increase with the increase of vertical stress. With the same pre-consolidation stress pc and OCR, the peak shear strength of the undisturbed clay was larger than that of the remolded clay. For the remolded clay, when solving shear strength indexes is according to the same OCR samples, with the OCR increase, the value of c will decrease and the value of φ will increase. For the remolded clay, when solving shear strength indexes is according to the same pc samples, with the pc increase, the value of c will increase at first but decrease later, and the value of φ will increase. The undisturbed clay shear strength failure curves show significant bending performance at pc.

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Sensitivity Analysis of Debris Flow along Highway in Wenchuan County after Earthquake Based on Hazard Entropy Theory

XIANG Lingzhi 1, 2, CUI Peng3, CHEN Hongkai2, SHEN Na1, 2

2017, 36(5): 71-78. DOI: 10.3969/j.issn.1674-0696.2017.05.13

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Strong disturbance and destruction of the earthquake zone surface was produced by the Wenchuan earthquake in 2008 which released great energy. And it caused many non-debris flow gullies change into high frequency debris flow gullies after the earthquake. For frequent occurrence of debris flow disaster at the earthquake zone in recent years, the debris flow gullies along the main highway (Du-Wen highway and provincial highway 303) in Wenchuan County were chosen as the research object. According to formation conditions and activity characteristics of debris flow after the earthquake, the key factors which influenced disaster occurrence were selected. Furthermore, considering the influence among various factors, hazard entropy model was applied to calculate the weight of every factor, and the sensitivity of debris flow in the study area was zoned. Analysis results show that the quantity of high sensitivity of debris flow gullies is as many as 47, accounting for 78.3% of the total. And these gullies are intensely distributed on the hanging wall of the center fault, especially in the valley where Yingxiu is the storm center. The proposed analysis results provide theoretical reference for debris flow prevention and mitigation in earthquake area.

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Assessment Model for Traffic Capacity after Seismic Disaster

DUAN Manzhen1, 2, YA Hongying1, LI Shanshan1, CAO Huiyun1

2017, 36(5): 79-85. DOI: 10.3969/j.issn.1674-0696.2017.05.14

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A modified coefficient model was proposed to evaluate the traffic capacity of the rescue road after earthquake. The coefficients include the reduction coefficient of the damaged road, the impact coefficient of the damaged bridge and the damaged buildings along the street in seismic disaster were used to modify the traffic capacity model. In order to guarantee the practicability of the model, the high intensity seismic quantitative value, the influence coefficients of high pier and long-span bridge in seismic disaster were improved, and the statistical probability of buildings damage under different earthquake intensity was given as the reference value of the evaluation process. Some real data in Wenchuan earthquake were used to illustrate the applicability and reliability of the proposed model. The results show that the modified coefficient model can accurately predict the damage degree of the roads and bridges after seismic disaster, which shows that the proposed model can be used to evaluate the traffic capacity of the rescue road after earthquake.

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Traffic Forecast of Highway Based on Improved “Four-Stage Method”

DING Zhikun1, ZHU Menglian1, SONG Yiyong2

2017, 36(5): 86-90. DOI: 10.3969/j.issn.1674-0696.2017.05.15

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Based on the “four-stage method”, a better traffic volume forecast method was proposed by adding the improved economic-traffic combination model. The proposed method was applied to predict annual average daily traffic (AADT) of Hangzhou highway from 2015 to 2029, and the composition and sources of traffic volume were also analyzed. The results indicate that the proposed forecast method has theoretical and practical value, which can improve the prediction accuracy of traffic volume and reduce the error of prediction results.

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Impact of Traffic Volume Distribution on Reliability of Road Network Structure by Using Ant Colony Algorithm

XU Xu, ZHENG Weishun

2017, 36(5): 91-97. DOI: 10.3969/j.issn.1674-0696.2017.05.16

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The road network structural reliability which reflected situation more actually was obtained by combining the road structure reliability solved by self-edit Monte Carlo MATLAB program and the road network reliability, and the mathematical model of its calculation was also presented. Saturation 0.6 was proposed to be the standard of the traffic volume distribution. Aiming at the insufficiency of the current theory of ant colony algorithm, the traffic volume assignment method under the improved ant colony algorithm was compared quantitatively with traditional mature analytical algorithm according to the road network structural reliability. Through the comparison of specific examples, ant colony algorithm is proved to be correct and reliable in road network traffic flow distribution at a certain extent. At the same time, through the comparison results before and after the traffic assignment of the congested road through the improved ant colony algorithm, it is indicated that the road network structural reliability of the same road network will reduce after traffic assignment. Therefore, when the traffic assignment is implemented in the congested roads, the traffic volume of others will increase and its reliability will reduce; finally, the reliability of the whole road network will reduce.

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Calculation on Stopping Sight Distance of Two-Lane Mountainous Highway Intersection Based on Driver’s Visual Characteristics

LIU Lang1, BAI Bin2, YAN Nan3,GAO Jianping3

2017, 36(5): 98-103. DOI: 10.3969/j.issn.1674-0696.2017.05.17

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For the phenomenon of poor sight distance at two-lane mountainous highway intersection, the driver’s more head or body rotation time in the process of driving at two-lane mountainous highway intersection than that at plain district was researched by analyzing the characteristics of the driver’s recognition at intersection. The Smart eye 5.7 eye tracker was used to the road test of driver’s recognition at two-lane mountainous highway intersection. And according to the driver’s gaze time (including blinking, saccade and fixation time) and the geometry data of mountainous highway intersection (including the intersection angle and branch slope), the stopping sight distance calculation models at uncontrolled intersections and let-stop intersections were established based on driver’s visibility. Then, the recommended value of stopping sight distance at the two-lane mountainous highway intersection was calculated out according to the proposed model, which could provide a theoretical basis for the design of mountainous highway intersection.

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Prediction of Car Ownership Based on Principal Component Analysis and Logistic Regression

ZHANG Lanyi, HU Xisheng, CHEN Qingyao, QIU Rongzu

2017, 36(5): 104-109. DOI: 10.3969/j.issn.1674-0696.2017.05.18

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Car ownership is the amount of data with relatively complex and nonlinear changes. There is a need for a rapid and accurate prediction method for fast, accurate and reasonable prediction of car ownership, whose prediction results can be used as an important basis for the sustainable development of the city economy. A case study of Fujian province was carried out. 8 indicators were selected as main influence factors of car ownership in Fujian province from 2000 to 2014, such as total population, per capita GDP, primary industry proportion of GDP, the second industry proportion of GDP, the third industry proportion of GDP, urban per capita disposable income, rural per capita net income and urbanization level. Through principal component analysis on 8 indicators, the prediction equation of comprehensive economic development value was obtained, which was predicted and verified by Logistic regression model. It is indicated that the prediction accuracy of the proposed method is high, which can predict the car ownership exactly and provide reference basis for urban development planning.

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Design of Steering Suspension Guide Device with Large Angle Based on ADAMS Simulation and Linear Regression Analysis

LI Zhanyu1, DONG Zhurong1, 2, DENG Zhijun1, REN Shaoyun1

2017, 36(5): 110-114. DOI: 10.3969/j.issn.1674-0696.2017.05.19

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A double lateral arms independent suspension guide device was designed for 4WID-4WIS electric vehicle (electric vehicle with four wheels driven and independent steering of four wheels), whose arms were with unequal length. The proposed suspension guide device could achieve 90°steering angle of the wheel. The lateral displacement of wheel and the variation volume of camber angle when the wheel jumped up and down were chosen as the key evaluation factors in the design of suspension guide device. The proposed suspension guide device was established in ADAMS simulation software, and several different sizes of guide devices were chosen to carry out the simulation test. Therefore, the samples of lateral displacement volume and variation volume of camber angle were obtained. The optimal values of two arms in the independent suspension guide device with double lateral arms in unequal length were obtained by the data relevance and the linear regression statistics analysis.

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Two Levels of Parameter Identification of Magic Formula Tire Model Based on Genetic Algorithm

BIAN Wei1, GONG Jiahui2, WEN Aimin1, CHEN Linshan1, LIU Yiguan1，2

2017, 36(5): 115-120. DOI: 10.3969/j.issn.1674-0696.2017.05.20

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To improve the identification accuracy and speed of magic formula (MF) tire model, a method that dividing all parameters into two levels was used. The formula-related parameters B, C, D, E were defined as the first level parameters and the characteristic parameters of the tire model as the second level. Firstly, the first level parameters were identified by Matlab genetic algorithm toolbox, and then the second level parameters were identified by genetic algorithm again based on the former results. At the same time, the identification results were brought into the magic formula to calculate the tire force, and then the curve of longitudinal force of MF tire model changing with slip rate under different loads was fitted. The identification result shows that the relative residual error of first level parameter identification is 2.196 8%, and the result is converged within 40 iterations; the relative residual error of the second level is 0.840 3%, and the result is converged within 20 iterations. It is concluded that the method that two levels of parameter identification of MF tire model based on genetic algorithm can ensure the parameter identification accuracy and improve identification efficiency, which provides an efficient and reliable method for real-time parameter identification.

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