Abstract:In order to analyze the failure mechanisms, an underdeck cablestayed simply supported model bridge with a span of 10m is tested under the action of increasing midspan load. The failure mechanisms are analyzed by means of both load test and ANSYS finite element analysis. A parameter analysis is performed aiming at the area of cable section, depthspan ratio of strut and section form of the deck. The results show that the failure mode of the model is caused by the fact that the cables break before the deck collapses. According to finite element analysis, when the concrete of the deck enters the plastic state, the flexural rigidity of the deck decreases and the structure efficiency increases. Since the growth rate of the tensioning force of the cables increases under the increasing midspan load, the growth rate of the resistance moment in the deck increases and the growth rate of the load moment decreases. Therefore, the failure mode occurs. The results show that the deck collapses before the cables break by increasing the area of cable section and decreasing the depthspan ratio of strut. The failure mode of the structure with slab deck with a higher slenderness ratio is the same as that of the model, but the maximum midspan load of structure with slab deck is slightly lower than that of the model and its material costs are also lower than that of the model.

Abstract:Based on elastic strain energy, it is assumed that Poisson’s ratio is 0.5 in yield of the material, which may be one of the important reasons for the poor calculation precision of the MC strength criteria. Therefore, based on the fact that releasing of elastic strain energy is the essential attribute of material yield, the internal relations between elastic strain energy, the second invariant of stress deviator, and the second invariant of stress tensor and Poisson’s ratio are explored. Consequently, the generalized second invariant of stress deviator is proposed. Secondly, MC strength criteria are set as the basis, and the generalized MC strength criterion is established based on energy release and material yield. Lastly, the failure strength is calculated using strength criterion. The results show the generalized MC strength criterion is more accurate and the error is more stable because of the consideration of Poisson’s ratio and the intermediate principal stress. The generalized strength criterion breaks the hypotheses that Poisson’s ratio is always 0.5, which is of great significance for accurate quantitative analysis of failure characteristics of the material.

Abstract:Experiments on the bending bahavior of Hsteel beams with a bolted splice were conducted, in which the influnce of the number of bolts in the splice plate on the connection behavior was considered. The failure mode, bending strength, and rigidity of the bolted splice were investigted. It was found that the initial slip of the bolts had an obviously adverse effect on both loadbearing capacity and rigidity at the subsequent stage. The strain distribution at the cross section of the bolted splice did not accord with the planesection assumption. The force in flange splice plate and the deflection of the beam were larger than those in the Hsteel beam without a bolted splice. The flange splice plate yielded earlier than the flange of Hsteel beam, but the experimental value of ultimate bending moment of the bolted splice came up to the calculation value of fullsection yield bending moment of the Hsteel beam. The bolted splice could not be simlply regarded as a rigid joint after the initial slip of bolts took place. The method and formula for calculatong the deflection of boltspliced Hsteel beams, dealing with the influence of rotational rigidity of a bolt splice, were proposed and validated by the experimental data.

Abstract:The multi-ribbed composite wall consists of the frame made of reinforced concrete rib and lightweight aerated concrete block, which are the two principal bearing members. Frame cell is the essential weighted element. Therefore, numerical analysis on frame cell was conducted according to the thermodynamic performance of each material in the multiribbed composite wall. Finite element analysis was carried out based on temperature field contours in different fire loads with ISO834 international heating curves. It was found that the rate of residual bearing capacity increased and then decreased as the heating time increased and mechanical performance are different between one side and double side by the fire. The heated side achieved ultimate load earlier under vertical displacement load. Because of the damage of the fire, the multiribbed composite wall cell is more likely to have outplane displacement.

Abstract:Three kinds of thick leadrubber bearings(TLRB) with different thicknesses of rubbers were designed in this paper. The basic mechanical properties of the TLRB were studied through mechanical properties test, such as vertical stiffness, equivalent horizontal stiffness, postyield stiffness, yield shear force, and equivalent damping ratio. The effects of pressure stress and shear strain on mechanical properties of TLRB were studied. The comparison of mechanical properties between test and formula were analyzed. It is concluded that the difference of vertical stiffness of TLRB between test and formula is apparent and the difference is increasing as the thickness of rubber increases. The fitting formula of vertical stiffness about test was given, and the effect of fitting was satisfying. Because of the limit of samples, the applicability of the fitting formula should be checked in future work. The test value of horizontal properties of TLRB are similar to the formula value.

Abstract:In the analytical analysis of the lateral displacement caused by pile installation, an elasticplastic model of soils and the effects of the ground surface boundary were synchronously considered in this study. To be specific, the modified Cam Clay constitutive model was used to capture the soil behavior after yielding. The initial solution of ground displacement induced by installation of pile with infinite was derived based on the theory of cavity expansion. The effects of boundary surface and depth of pile buried in soils were considered by introducing a modified function into the initial solution. The analytical solution was validated using the field measure data first. Then it is exploited to undertaken parameter analysis. The results show that the soil displacement caused by pile installation increases nonlinearly with the increase of pile diameter and the decrease of preboredhole diameter. In addition, the displacement also increases with OCR, which can be attributed to the obvious squeezing effect of the heavily consolidated soils with compact structures.

Abstract:A series of speciemens, including three batches, of giant concretefilled steel tubular columns (called giant CFT columns hereinafter) with detailings of distributive beam under axial load were completed. The failure mode, the loadcarrying capacity of specimens and the strain distribution on distributive beam of specimens were comprehensively compared and analyzed based on experimental results. It can be observed from the test results that the load shared by core concrete is proportional to the crosssection area of distributive beam and is considerably larger than the load transmitted by the nature bond between steel tube and core concrete. Thereout, the conclusion could be drawn that the distributive beam set in giant CFT columns could transfer vertical load effectively and reliably. Meanwhile, the load transferred by distributive beam remained constant after shear plastic hinges at both ends of distributive beam were developed, and obvious plastic deformation from shear yielding to failure at the area of distributive beam ends could be observed. Finally, it could also be concluded from the results that giant CFT columns with both distributive beams and inner diaphragms gained much higher loadbearing capacity than those only with distributive beams by comparing the two kinds of specimens. Therefore, coworking performance between core concrete and steel tube could be effectively improved by distributive beam set in giant CFT columns, so that excellent axial load bearing behavior of giant CFT columns could be ensured.

Abstract:A method to measure strain distribution on the asphalt mixture surface was developed based upon DIC (digital image correlation) in order to compare the measurement accuracy of insitu asphalt pavement strain sensors. First, the displacement was distinguished at subpixel level using the DIC technique. Then an algorithm to calculate average tensile strain was proposed to eliminate the adverse effect caused by asphalt mixture inhomogeneous deformation in strain measurement. After testing the reliability of the algorithm, the measurement accuracy of two common insitu asphalt pavement strain sensors were calibrated. It was found that the error of the DIC method was less than 12×10-6 at the 90% confidence level, which met the requirement of accuracy comparison. Besides, it was proved that the measurement accuracy could be reflected by the error between the measurement result of the sensors and the method developed in this paper. It was also proved that load type had an influence upon sensor’s accuracy. Utilization of calibration function or eliminatation of the cumulative plastic strain all contributed to the improvement of accuracy.

Abstract:The mixture specimen was selected as the research object and the preparation method of samples using atomic force microscopy were discussed. The maximum longitudinal distance and surface roughness of the sample surface were applied to evaluate samples in different storage conditions. The freezing method at lower temperature was recommended to ensure the flattnesss of sample surface. Then three areas in asphaltmineral filler mastic of mixtures surface were investigated using the function of quantitative Nano mechanical of atomic force microscopy(AFMQNM).The results show that the sample with freezing preservation and low temperature cutting could ensure the flatness of mixture samples， which meets the demand of AFM observation. The technology of AFMQNM can directly measure the microscale mechanic modulus and adhesion properties in mixture and effectively distinguish different material components. This study could provide a new idea for insitu evaluating aging degree of RAP asphalts.

Abstract:In order to provide reference for design and construction of lownoise asphalt road, the effect of flatelongated particle content on driving vibration noise was studied. The relationship between driving vibration noise and tireroad contact pressure was investigated by theoretical analysis, field noise tests, and simulations via the discrete element method (DEM). Besides, a new evaluating method for driving vibration noise based on tireroad contact pressure was proposed. The asphalt pavement models with four flatelongated particle contents were built using particle flow code (PFC). Meanwhile, the movement of wheels on these four different pavement surfaces was simulated and the contact pressures were calculated. Finally, the volatility of contact pressure was analyzed. The results show that the effect of flatelongated particle content on driving vibration noise is insignificant at the level of 0, 10%, and 15%. However, the driving vibration noise of asphalt pavement with 20% flatelongated particles is greater than those with lower flatelongated particle content. Thus it can be concluded that excessive flatelongated particle content has a negative influence not only on workability and strength of asphalt mixture, but also on driving vibration noise.

Abstract:Based on the analysis of intercity travel links, this paper analyzes the influencing factors of passenger travel choice and introduces the psychological latent variables into the Logit model, and builds the SEMLogit model of passenger intercity travel choice based on travel chain. Through the investigation of the passenger flow in the ShanghaiHangzhou transport corridor, the application of the model and the parameter calibration are carried out, and the choice of intercity passenger travel chain is predicted with the relative error of less than 2%. The results show that the improved model that takes into account the psychological latent variables has a good explanatory power and can intuitively reflect and predict the traveler’s choice of travel modes in intercity travelling.

Abstract:In consideration of low carbon emission and efficiency when trucks transport containers to multiple container terminals, and truck appointment system which is taken by container terminals to cope with the problem of irregular arrival of trucks, a scheduling model was established for trucks delivering containers from an outside yard to multiple container terminals, with the objective of minimizing the quantity of the dispatched outside yard’s trucks and the total carbon emission of the scheduling plan. A modified ant colony algorithm was designed to solve the model, and the truck scheduling plan for delivering containers from outside container yard to multiple container terminals in different time periods could be determined. Numerical experiments show that the proposed model and designed algorithm are effective. The study demonstrates that the trucks scheduling scheme can reduce the amount of trucks that the yard must hold and truck drivers’ working time. Therefore, the trucks scheduling scheme can balance and meet lowcarbon emission and truck efficiency requirements.

Abstract:Based on the rear-end incidents extracted from the China naturalistic driving data, the DREAM (driving reliability and error analysis method) was modified and used to identify contribution factors and causation patterns in these incidents. Those rearend incidents were respectively classified in different driving scenarios, and the logic diagrams of the contribution factors with different detailed categories were obtained. The results showed that the main factors behind the rearend incidents was the adoption of “insufficient force” and “small safety margins”. The characteristics of critical events of four detail categories in the rearend scenarios were also analyzed. In contrast to the results obtained from previous studies in the US and Europe, the deepseated contribution factors was driver’s habitual expectation for the specific driving behavior of other traffic users, instead of the second driving behavior.

Abstract:This paper presents an active guidance control method by changing the output torque of the longitudinal drive motor for tramcar using independently rotating wheelsets (IRWs) with longitudinal coupling bogie, to improve the guidance ability and reduce the wheelrail wear. The robust μsynthesis method is used to tackle the nonlinear characteristic and parameter uncertainty of the tramcar which generate mainly from the wheelrail interface, the measurement noise and external disturbances. Three control schemes are proposed based on the single wheel controller. The effect of the controller is verified by the cosimulation of MATLAB and SIMPACK. The results show that when the front and rear wheelset states are used as the controller input signal, the relative best control effect can be obtained, the total wear number of the front and rear wheelsets is reduced by 38% on a straight track, and by 54% on a curved track.

Abstract:Aiming at a seriesparallel hybrid powertrain system which contains engine, motor and planetary gear subsystems, this paper considered a typical working condition which is based on the power control strategy and established the torsional vibration mechanical model of a hybrid powertrain system. The inherent characteristics and transient vibration response of the electric mode, hybrid mode and parking charging mode were studied. It was discovered that the repetitive frequency of the powertrain system in the three working modes is the same which is only related to the inertia and meshing stiffness of the planetary gear system. The nonrepetitive frequency and corresponding vibration modes in the electric mode and parking charging mode are almost identical. The transient response of body acceleration has the same frequency component as the interference torque of the excitation sources, the body vibration caused by torque ripple become obvious when the starter drives the engine and stays in the regenerative braking mode at low engine speed. The angular acceleration of the planetary gear system significantly increases due to the torque fluctuations caused by the working mode switches.

Abstract:The effect of air/fuel ratio on ion current signal was studied with methane as the fuel in a highpressure constant combustion vessel. The results show that the peak value of ion current signal is the highest and the peak timing is also the most advanced when the excess air ratio is 0.90. The ion formation process, concentration, and distribution were numerically simulated with the established methane ionization mechanism model. The simulation results show that chemical ionization occurs in the flame front and the main ion product is H3O+ while thermal ionization occurs in the high temperature postflame area. The main ion product is NO+. Chemical reaction path analysis results indicate that when the excess air ratio is 0.90, and the neat production rate and concentration of H3O+ and NO+ are the highest, which results in the highest value of chemical ionization peak and thermal ionization peak.

Abstract:This paper summarizes the technical characteristics of wind parameter sensing methods in the traditional wind farms from two perspectives: measured sensing and predictive sensing and analyzes the limitations of the traditional methods from the aspects of comprehensiveness, accuracy, economy, time scale, and application mode of wind parameters. Then, based on the analysis of wind propagation, layout, and communication characteristics of wind turbines , as well as the correlation of operation data among units, a new idea and framework for wind parameters, such as wind speed, wind direction, and wind density have been proposed for “measurementassociationsharepredictionverification”. Finally, the key issues that need to be resolved are discussed. It can provide reference for the followup study.

Abstract:According to the mathematical model of permanent magnet synchronous motor, this paper uses the analytical method to obtain the current and torque equation of the permanent magnet synchronous motor under the active shortcircuit operation in different working conditions, and reveals the relationship between the motor output and motor parameters. The results are verified by simulations and experiments. The significance of this paper is that the advantages and disadvantages of using active shortcircuiting as a safety shutoff path is analyzed theoretically, and the current calculation formula for permanent magnet synchronous motor under active shortcircuit condition is proposed, which provides a basis for the motor controller to select a suitable power device.

Abstract:This paper constructs a data envelopment analysis (DEA) model to analyze the transport efficiency urban rail transit of 20 cities in China by using the data of 2015, and then uses the Tobit regression model to evaluate the correlation between the transport efficiency and various factors. The results show that the overall efficiency of urban rail transit in China is low. The pure technical efficiencies of the cities that began to operate urban rail transit systems in last three years are higher, while their scale efficiencies are lower. The rail transit systems in most cities are in the increasing stage of scale revenue. The transport efficiency of urban rail transit is related to the density of railway network, quantities of stations, and transfer stations. The density of railway network has more influence on transport efficiency.

Abstract:The recycle of power batteries of electric vehicles not only protect the environment, but also has a positive impact on the sustainable development of electric vehicles. To solve the electric vehicle battery recycling mode decisionmaking problem, an improved method which combines the 2dimensional uncertain linguistic variables (2dimension uncertain linguistic variables, 2DULVs) and the VIKOR method (called 2DULVIKOR method) is proposed. First, 2DULVs is used to evaluate the power battery recycling mode in consideration of criteria. Then, experts’ opinions are aggregated by using the 2DULVs aggregation operator. Next, the weights of criteria are calculated by the coefficient of the variation method. After that, the VIKOR method is used for selecting the best power battery recycling mode. Finally, an illustrative example is given to verify the effectiveness and practicability of the proposed method.