20 June 2017, Volume 30 Issue 6
    

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  • Review on China's Automotive Engineering Research Progress:2017
    Editorial Department of China Journal of Highway and Transport
    China Journal of Highway and Transport. 2017, 30(6): 1-197.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To promote the development of automotive engineering disciplines in China, the research progress, hot topics, existing problems, specific countermeasures and development prospects of academic research in automotive engineering at home and abroad were systematically summarized from five aspects, including automobile noise-vibration-harshness (NVH) control, electrification and low-carbon, electronization, intellectualization & connection, and collision safety technologies. In the aspect of NVH control of vehicles, the sound quality from silence, the NVH control technique of new energy automobile, the NVH control technology of the car body and chassis, the initiative vibration control technology and so on were reviewed. As for the automotive electrification and low-carbon, the traditional automotive powertrain energy-saving technology hybrid power electric vehicle technology and so forth were summarized. Reviews of the automotive electronization included the electronic control technology of automobile engines, the electronic control technology of motor steering, the electronic control technology of automobile brake and the electronic control technology of automotive suspension, etc. Reviews of the intellectualization & connection of vehicles included summaries of intelligent and connected vehicles (ICV) studies in China and America, complex traffic environment perception, high precision map as well as vehicle navigation and location, self-organization character and trajectory planning of vehicles, lateral control and longitudinal dynamics control of vehicles, and ICV test, etc. Meanwhile, practical examples of advanced driver assistance systems (ADAS), vehicle to X (V2X), human-machine copilot, and so on were analyzed as well. In light of automobile collision safety technologies, the vehicles collision, occupant protection, pedestrian protection, crash safety and protection of children, the crash safety of new energy automobile and so forth were summed up. It is supposed to provide new perspectives and basic data for academic researches on automotive engineering discipline.
  • Experimental Research on Permeability Coefficient Under Influence of Loess Collapsibility
    LI Xi-an, HONG Bo, LI Lin-cui, WANG Li
    China Journal of Highway and Transport. 2017, 30(6): 198-208,222.
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    In allusion to a series of engineering problems, resulting from a complex process of permeation-collapsibility-permeation in the construction of collapsible loess area, permeability test after loess collapsibility was carried out. Based on the indoor wetting penetration test, combined with scanning electron microscopy (SEM) and image-pro plus (IPP) analysis, changes of permeability coefficient, microstructure, pore size distribution, pore shape and connectivity were comparatively investigated to reveal the influence of loess collapsibility on its permeability as well as its microcosmic mechanism. The results show that the penetration process and the collapse process are interactional and the porous structure of loess is a main internal factor influencing permeability and collapsibility. Collapsibility after permeability is worse than that of undisturbed loess, resulting from the destruction of the porous structure of undisturbed loess, changes of the contact mode of particles, the dense arrangement of particles, the decrease of pore connectivity and the dramatic decrease of permeability coefficients (from a quarter to a third of undisturbed soil). The permeability after loess collapsibility is influenced by various factors, including the soil structure and construction, the soluble salt in the collapsibility, cementation dissolution, size and quantity of soil pore as well as the connectivity and changes. Soil permeability coefficients after collapsibility decrease under the action of multi factors. The results provide a theoretical basis for the engineering design and construction in collapsible loess district.
  • Evaluation of Adhesion Property in Asphalt-aggregate Systems Based on Surface Energy Theory（in English）
    LUO Rong, ZHENG Song-song, ZHANG De-run, TU Chong-zhi, FENG Guang-le
    China Journal of Highway and Transport. 2017, 30(6): 209-214.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to quantitatively analyze the adhesion between asphalt and aggregate, based on surface energy theory, the Wilhelmy plate method was used to measure the surface free energy of 2 kinds of asphalt (A-70# and B-70#) and the vapor adsorption method was used to test the surface free energy of 5 kinds of aggregates (namely, limestone, basalt, granite, quartz sandstone, gravel). Subsequently, the adhesive bond energies with and without water and the surface energy matching index of the asphalt-aggregate combination were calculated. The adhesion properties of different asphalt-aggregate combinations were evaluated by surface energy matching index. The matching index was verified by improved boiling water test and the relationship between the two was established. The results show that the surface energy matching index is consistent with the asphalt residual ratio index of the improved boiling water method, and the descending order of adhesion of five aggregates is:basalt, limestone, granite, quartz sandstone and crushed gravel. The reliability of the surface energy evaluation system is verified and surface energy method can be used as a test method for quantitative analysis of asphalt and aggregate adhesion properties. Through the analysis of the surface energy matching indexes and the asphalt residual ratio indexes, it is found that the two indexes have a linear positive correlation. Taking the asphalt residual ratio whose adhesion level is 4 as threshold, the range of the matching index of surface energy is further derived for the two kinds of asphalt respectively.
  • Reinforced-effect Analysis of Geogrid Treatment in Old Road Widening
    GUAN Zu-bao, YANG Ting, WU Ju-gui, CHEN Xin
    China Journal of Highway and Transport. 2017, 30(6): 215-222.
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    The problem of inadequate anchorage length of the ordinary geogrid in old road widening could be solved in view of the baffle-type geogrid, so it was significant to evaluate the reinforced effect of the baffle-type geogrid in old road widening. Based on field tests on reconstruction project of the Riverside Road in Liaocheng city of Shandong Province, a calculation model of geogrid treatment in old road widening was established to investigate the synergistic deformation characteristics of embankment filling with the baffle-type geogrid and the ordinary geogrid respectively under the gradation loading of roads. Moreover, the reinforcement effect, layer effect and width effect of geogrid in different conditions were analyzed by the finite element method. The analysis results were compared with test results, with analyzing the horizontal stress of the baffle. The results show that in old road widening, the strain value of baffle-type geogrid is greater than that of the normal geogrid. As the baffle at the end of geogrid plays a lateral resistance role, it is more effective for baffle-type geogrid to reduce the differential settlement of the road, with the result of improving the reinforced effect. It is discovered that the closer the geogrid is to the road base, the better the role of geogrid plays. The design width of ordinary geogrid should be more than 6 meters. When the width of connection step between the old and the new road is less than 3 meters, it is conductive to solve the problem of the insufficient anchorage length of the ordinary geogrid through laying the baffle-type geogrid. These conclusions may provide references for the settlement of interface between new and old embankments.
  • Experiment on Bolted Joints of Pultruded GFRP Laminates
    LIU Yu-qing, DU Ao, XIN Hao-hui, ZUO Yi-ze
    China Journal of Highway and Transport. 2017, 30(6): 223-229.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the failure modes and load-carrying capacity of pultruded glass fiber reinforced polymer (GFRP) laminates used in the bridge engineering, tensile tests were conducted on 36 single-lap specimens with single bolt by regarding the bolt-diameter to plate-thickness ratio (1.0, 1.2, 1.4), splice plate configuration (GFRP-GFRP, GFRP-steel) and loading direction (longitudinal:parallel to the pultrusion direction, transverse:perpendicular to the pultrusion direction) as variable parameters. Based on the results of load-displacement, load-strain curves and failure modes, the influence of test parameters on the mechanical performance of bolted joints of pultruded GFRP laminates was analyzed. The results show that as for joint failure modes, in longitudinal joints, GFRP-GFRP specimens with connecting diameter of 14 mm suffer from the bearing failure, and other test groups, including GFRP-GFRP and GFRP-steel joints exhibit bolt failure. While in the transverse joints, GFRP-GFRP joints suffer from net-section tension-bending failure, but GFRP-steel joints exhibit net tension failure. Joint strength and stiffness increase with the raising bolt-diameter to plate-thickness ratio. Compared with GFRP-GFRP joints, GFRP-steel joints can better restrain secondary bending of the single-lap bolted joint and increase joint stiffness. For the zero-dominated pultruded GFRP laminates, longitudinal joints show higher strength and stiffness than transverse joints but present relatively poorer secondary bending effect.
  • Axial Compression Performance of Reinforced Concrete Column Strengthened with TRC Under Chloride Dry-wet Cycles
    YIN Shi-ping, LI Yao, LI He-dong, PENG Chi, AI Shan-xia
    China Journal of Highway and Transport. 2017, 30(6): 230-238.
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    In order to further investigate the compression behavior of reinforced concrete (RC) columns strengthened with textile reinforced concrete (TRC) under dry-wet cycles of chloride salt, the axial compression test on 12 RC columns strengthened with TRC was carried out. The influences of different numbers (0, 60, 90 and 120) of dry-wet cycles, sustained load ratios (0, 0.1, 0.2 and 0.4), coupling effects of dry-wet cycles of chloride salt and sustained load were analyzed as well as the modified high-performance concrete with short-cut fibers on reinforcement effect of TRC were analyzed. The results show that the ultimate bearing capacity and deformation properties of TRC-strengthened columns tend to decrease under dry-wet cycles. After 120 times of dry-wet cycles, the ultimate bearing capacity of the TRC-strengthened column decreases by 6.71%. Compared with the single dry-wet cycle, the deformation and bearing capacities of TRC-strengthened columns decrease dramatically under coupling effects of dry-wet cycles of chloride salt and sustained load. When 90 dry-wet cycles remain constant, with the increase of the sustained load ratio, the reinforcement effect of TRC decreases. With the increase of coupling effects of both dry-wet cycling and sustained load, the failure pattern of the TRC-strengthened column may be changed. The modified high-performance concrete with short-cut PVA fibers, taken as matrix of TRC, contributes to improve the durability of RC columns. A simplified formula is given to describe the ultimate bearing capacity of the axial compression of RC columns reinforced with TRC. The calculated value is congruent with the experimental one.
  • Theoretical Analysis and Experiment on Flexural Strengthening Behaviors of Prestressed High-strength Steel Wire Ropes and Polymer Mortar
    ZHANG Yang, XU Shuo, YAO Xue-chang
    China Journal of Highway and Transport. 2017, 30(6): 239-248.
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    In order to provide references for the design and tensioning construction control of a new kind of strengthening method of prestressed high-strength steel wire ropes and polymer mortar, the tensile tests of 5 steel wire ropes were carried out. And a designing calculation formula for initial tension considering the loss of tension was firstly proposed according to the conversion of the exerted torque. Then, flexural tests on three reinforced concrete (RC) rectangle beams, that is, two strengthened by the proposed rehabilitation scheme and an un-strengthened beam, were conducted to investigate the failure mode as well as improvements of cracking resistance, bending bearing capacity and stiffness. Meanwhile, the cracking, yielding and ultimate state of strengthened RC beams were defined. The corresponding design formulas were theoretically deduced. Besides, those theoretical computing results were compared with experimental results. The results shows that with the proposed strengthening scheme, the more strands arranged in the beams, the smaller the crack width under the same load can be achieved. It illustrates that prestressed steel wire ropes can well restrain the generation and development of the cracks in the original concrete structure. In comparison with the un-strengthened beam, the cracking resistance of the strengthened RC beams increases by 60.3% to 101% and the bending bearing capacity increases by 17.3% to 35.8%. However, the mid-span deflection declines by 10.4% to 27.4%. That is to say, the cracking resistance, the bending bearing capacity and the stiffness of strengthened beams get improved apparently. The design formulas of the initial tension of steel wire ropes, the characteristic moments of strengthened beams in cracking, yielding and ultimate state and theoretical method to compute the mid-span deflection are in good agreement with the experimental results. It is possible to meet the required precision in engineering with conservative estimation.
  • Seismic Performance of Concrete Bridge Columns Under Bending-torsion Coupling Effect
    DENG Jiang-dong, LIU Ai-rong, SUN Zhuo, ZHU Wen-zheng, PENG Guo-xing
    China Journal of Highway and Transport. 2017, 30(6): 249-259,314.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to explore influence of the coupling effect of the compression, bending, shear and torsion on the consolidated bridge column connected with box girder in the earthquake, the quasi-static model tests of seven reinforced concrete bridge columns under the coupling effect were carried out. The different failure modes of bridge columns was determined, and the hysteretic curves and skeleton curves of shear force-displacement and torque-twist angle were analyzed. Meanwhile, the influence of parameters including torsion-bending ratio, slenderness ratio, reinforcement ratio and stirrup ratio on the bending-torsion coupling seismic performance was studied. Based on theoretical analysis and the quasi-static model tests, four-segment shear force-displacement theoretical skeleton curves and three-segment torque-twist angle theoretical skeleton curves of bridge columns were derived. The results show that theoretical skeleton curves coincide with experimental curves. And key influence factors and the coupling effect of bending and torsion of the concrete bridge columns present in the theoretical model. The shear force-displacement theoretical skeleton curve highly depends on the bending moment-curvature relation of the failure section of the bridge column. The torsional capacity is mainly from concrete and stirrups, and the twist angle of the column top can be calculated according to the elastic twist angle of concrete bridge column and the twist angle of torsional plastic hinge. The bending-torsion coupling effect changes the seismic performance of concrete bridge columns significantly. Large torsion effect causes the failure of bridge columns before reaching the maximum flexural performance. However the torsional capacity of the concrete bridge columns decreases influenced by the bending effect. With the decrease of the slenderness ratio, the maximum shear force increases, the ultimate displacement decreases and the maximum torque remains constant. The longitudinal reinforcement ratio mainly affects the flexural capacity of the concrete bridge columns, while it has little effect on the torsional behavior. The stirrup ratio mainly influences the torsional performance of the column. The methods considering the bending-torsion coupling effect should be used to perform the seismic design in the engineering.
  • Piecewise Truncation Probability Distribution Model of Vehicle Loads for Highway Bridges and Its Application（in English）
    ZHAO Shao-jie, REN Wei-xin
    China Journal of Highway and Transport. 2017, 30(6): 260-267.
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    In order to accurately describe the distribution characteristics of multiple-peaks and fat tails of actual vehicle loads of highway bridges, the probability density function and probability distribution expression of vehicle loads were obtained by data fitting method. And the multiple-gaussian mixture distribution model of piecewise truncation was established by piecewise function combined with multiple-gaussian distribution functions. The solving method of multiple-gaussian mixture distribution model was further derived based on EM algorithm. On the basis of characteristics of axial configuration, the probability distribution parameters of the piecewise truncation probability distribution models in typical areas were obtained. The results show that the fitting with high precision of the distribution function model can accurately reflect the load distribution characteristics of multiple-peaks and fat tails. The axle weight distribution in each region presents different features, but the first peak distribution of single axle weight in each region is basically similar. Almost all the axial configurations overload, especially in the regions of Guizhou, Hubei and Hunan. The average axle weights of tandem axles and tridem axles are about twice more than national standard values of vehicles in each region, and the average axle weight of tandem axles exceed 15% of the standard value of the current technical standard of highway engineering. The measured data shows that the average tridem-axle weight is about 50 tons at 95% guarantee rate.
  • Impact of Short Left-turn Lane on Maximum Throughput of Signalized Intersection
    MA Wan-jing, LIU Ye, LIU Hao-de, ZHAO Jing
    China Journal of Highway and Transport. 2017, 30(6): 268-278.
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    In order to investigate change regularities of maximum throughput and blockage probabilities of the approach of the double-flow blockage short left-turn lane with the exclusive left-turn symmetry phase, theoretical models for estimating maximum throughput were proposed by utilizing the probability theory and the traffic flow theory based on the Poisson arrival characteristics of traffic flow. Through non-parametric hypothesis test and relative error analysis in view of measured data and the VISSIM simulation, there was no significant difference between model values and measured values when confidence level was 5% and the absolute relative error was less than 10%. It was clear that the degree of fitting of the model was high. Intensive sensitive analyses on some critical factors influencing the maximum throughput, such as the storage capacity of short left-turn lane, cycle length, green split, phase sequence and traffic flow, were conducted. The results show that when the traffic flow is less than 500 pcu·h-1, cycle length has no effect on the throughput in approach. However, if the precondition is opposite, the throughput increases slowly and then decreases. The optimum cycle length ranges from 40 seconds to 80 seconds, increasing with the increase of the short left-turn lane capacity or the ratio of left-turn traffic flow. Meanwhile, the maximum throughput in approach increases with the increasing capacity of short left-turn lane when traffic flow is more than 700 pcu·h-1. Compared with the exclusive short left-turn lane, the larger the capacity of short left-turn lane is, the less the reduction can be. The influence of phase sequence on the throughput of approach is weak when cycle length is less than 60 seconds or traffic flow is less than 350 pcu·h-1. However, if the precondition is opposite, the influence is obvious. Giving priority to the traffic flow with high flow saturation, the throughput of approach can be improved. Compared with recommended storage capacity of short left turn lane in AASHTO, the suggestive values, calculated with the objective of maximizing the throughput in approach, are more appropriate for the situation that the proportion of left-turn or through vehicles exceeds 70%. Hence, it is possible to meet the requirements.
  • Operating Speed Model of Passenger Car at Single-lane Exit of Interchange
    ZHANG Chi, YAN Xiao-min, LI Xiao-wei, PAN Bing-hong, WANG Hai-jun, MA Xiang-nan
    China Journal of Highway and Transport. 2017, 30(6): 279-286.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to determine the characteristics and values of the operating speed of passenger cars at the single-lane exit of the interchange and ensure the coordination of operating speed in the convergence section for vehicle safety, the measured data of the operating speed of passenger cars on the freeway interchange was analyzed, and the operation rules of the vehicle at the exit were obtained. The chain kepler radar velocimeter was used to collect vehicle speed in real-time. The feature points (including the starting point of the tapered section, diversion point and the small nose point) of eight ramps were selected as the analysis sample of the vehicle speed in the free flow state. K-S test was used to test the normal distribution of samples. After meeting the requirements and analyzing, the speed and acceleration characteristics in the tapered section and deceleration section, the parameters of the independent variables were determined. Finally, SPSS software was used to make the regression, and the operating speed prediction model of passenger cars at diversion points and small nose points were established. Then the model was verified by data of four ramps. The results show that the operating speed at the diversion point increases with the increasing speed at the starting point in the tapered section, and decreases with the increasing length of the tapered section. The operating speed at the small nose point increases with the increase of operating speed at the starting point in the tapered section and decreases with the increase of length of the tapered section and the ratio of tapered section length and deceleration section length. In addition, predicted model is successfully tested by regression equation, regression parameters and the average relative error. The relative error of the predicted value and measured value is less than 10%, so the established regression model meets the accuracy requirements.
  • Post-earthquake Connectivity and Travel Time Analysis of Highway Networks Based on Monte Carlo Simulation
    HOU Ben-wei, LI Xiao-jun, HAN Qiang, LIU Ai-wen, LAN Ri-qing
    China Journal of Highway and Transport. 2017, 30(6): 287-296.
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    To assess the post-earthquake support capacity of highway networks, the post-earthquake connectivity reliability and traffic travel time analysis model of highway networks were established based on Monte Carlo simulation. The seismic damage states and corresponding probabilities of roads and bridges were evaluated by seismic fragility curves. The descending traffic capacity of road sections, caused by the seismic damages of roads and bridges, was calculated by the reduction factors of the connectivity, travel speed, and traffic capacity of roads and bridges. The Monte Carlo method, in consideration of the uncertainty on seismic damages of roads and bridges, was adopted to simulate the post-earthquake performance of highway networks with the descending traffic capacity. In each Monte Carlo sampling calculation, the highway network connectivity was verified by the breadth first search algorithm. The incremental assignment algorithm was adopted to evaluate the total travel time on basis of the statistic traffic assignment of the highway network. The mean values of connectivity reliabilities and travel time of highway networks were repeatedly calculated by the Monte Carlo simulation, with the result of denoting the post-earthquake state of the highway network. Characteristics and applicability of the highway network connectivity and travel time analysis model were analyzed by the numerical example. The results show that the descending post-earthquake traffic capacity is one of main factors of the increase of total travel time. The reliability node with the low connectivity corresponds to high post-earthquake travel time. And the enhancement of post-earthquake support capability of highway network can be achieved by the increase of origin nodes of network traffic flow. The connectivity reliability model, with a few input parameters, is appropriate for an initial analysis. Meanwhile, considering traffic capacity properties of road sections as well as traffic parameters of origin-destination (OD) networks, the analysis model of traffic travel time provides more precise results.
  • Research on Characteristics of Magneto-rheological Fluid Damper in Consideration of Apparent Slip Boundary Condition
    LIAO Chang-rong, WU Du-hua, SUN Ling-yi, XIE Lei, JIAN Xiao-chun
    China Journal of Highway and Transport. 2017, 30(6): 297-306.
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    In order to further investigate the damping characteristics of magneto-rheological fluid (MRF) damper, the effect of apparent slip on the damping characteristics of MRF damper was examined, regarding the MRF as a kind of high-concentration suspension composed of rigid suspended particles and liquid carrier. According to analyzing the flow field in the annular damping channel of the MRF damper, simplified into a parallel plate model, apparent slip boundary conditions of the MRF were considered in the theoretical analysis aiming at the phenomenon that the equivalent particle size of the rigid particles increased resulting from the rearrangement of the magnetic particles under the action of magnetic field. Through introducing conditions into the Herschel-Bulkley model, the flow field in the annular damping channel was divided into three regions, namely, the apparent slip region, yield region and non-yield region. At the same time, calculation formula of the output damping force of the damper was deduced based on the analysis of the rheological properties of three regions respectively. The output damping force was compared with the damping force under the same conditions without considering the apparent slip. Besides, a double coil electromagnetic piston head with configuration of annular damping channel and parallel bypass orifice was designed and the magnetic circuit model of the head was verified by finite element method. A prototype of the MR damper was designed and fabricated in terms of the suspension requirements of a domestic car. The results show that the damping coefficient of the damper decreases with the apparent slip. The apparent slip has a significant effect on the output damping force, especially in narrow channel, at low flow velocity and under high magnetic field. The designed bypass orifice has a good leakage effect and the floating piston has a good volume compensation effect. Moreover, the maximum deviation between the theoretical and the experimental damping forces is only 180 N when the peak velocity of piston is 0.3 m·s-1. It shows that the theoretical simulation result in consideration of the apparent slip is in good agreement with the experimental one.
  • Sound Quality Evaluation of Driveline System of Certain Automobile Based on Semantic Differential Method
    GUO Dong, SHI Xiao-hui, HU Wei-qing, LI Wen-li, YI Peng
    China Journal of Highway and Transport. 2017, 30(6): 307-314.
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    In allusion to the problem of the sound quality evaluation of an automobile driveline system, the driveline system was assessed subjectively. Meanwhile, the objective evaluation model corresponding to the subjective evaluation was established. Driveline noise was measured on a semi-anechoic chamber, with acceleration conditions over a full operating speed range as well as some conditions of constant speed. Noise samples for sound quality analysis were determined by consistency analysis of the test data. Considering the physical characteristics of the driveline system noise and the auditory characteristics of human ear, the semantic differential method was selected as subjective evaluation method of the sound quality in terms of its intension. The results show that the semantic space of semantic differential method under Chinese background is established from the perspectives of sound intensity, tone, timbre and so on. And the evaluation indexes for driveline system of sound quality in the semantic space are obtained and verified by expert consultation method, item discrimination, principal component analysis and factor analysis. The subjective evaluation results are obtained through listening test of the sound quality of the driveline system. The results are calculated by selecting loudness, sharpness, speech intelligibility and so on as evaluation indexes. Based on the single regression method, subjective evaluation results are closely related to objective metrics, such as loudness, sharpness and speech intelligibility, with subjective evaluation result as an independent variable and objective indicators as a dependent variable. Taking subjective evaluation result as a response and objective indicators as input, the regression model and artificial intelligence model are established and verified via the multiple regression method and the support vector machine, with the realization of objective and quantitative evaluation of the sound quality of the driveline system.
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