This study proposes a finite element model to simulate traffic loads on continuously reinforced concrete pavement (CRCP) by using basalt fiber reinforced polymer (BFRP) bars considering the void below the concrete slab and the load transfer efficiency (LTE) at the transverse cracks of the slab. Sensitivity analysis of mechanical responses and LTE at the transverse cracks of the BFRP-reinforced CRCP slab under the void below concrete slab condition is conducted using the following parameters: slab thickness and elastic modulus, base elastic modulus, elastic modulus and design of BFRP bars, and foundation modulus. Results show that (1) the mechanical condition of the concrete slab can be significantly improved by increasing the thickness, not the elastic modulus, of the slab. (2) In the case of wide width of the void area below the concrete slab, the mechanical condition of the slab may be worsened by increasing the base elastic modulus. (3) The mechanical condition of the concrete slab can be slightly improved by increasing the elastic modulus of BFRP bars and the percentage of longitudinal reinforcement. (4) The maximum transverse tensile stress on top of the loading slab increases, whereas LTE at the transverse cracks significantly decreases with increasing foundation modulus; these phenomena damage the concrete slab near the transverse cracks in BFRP-reinforced CRCP.

After defining fatigue damage variable and constructing residual flexural strength damage model,nonlinear mathematical equations of residual flexural strength and parameters,such as number of loads andfunction time in low temperature and dry environment,were established to research residual flexural strength and fatigue life of cement concrete pavement in northern cold regions under low-loading and temperature-drying conditions, to identify mechanism of fatigue damage in concrete pavements and residual life prediction model, and to verify accuracy of the model through experiments.These equations can better reflect lawsgoverning mechanical property damage of concrete pavements after fatigue. S-N fatigue life curvilinear equation and failure probability were introduced to analyze fatigue life of concrete pavements. Results indicated that the single logarithmic equation can be used to predict fatigue life of concretes with different failure probabilities, and in this case, fatigue life curve conforms to Weibull distribution function. This paper also provides specific double-parameter Weibull distribution function under loading-low temperature-drying conditions.

This study proposes a design index and model for controlling the permanent deformation of the granular base course for asphalt pavements by adopting two types of graded macadam. Three levels of confining pressure stresses and different stress ratios were set as the test loading conditions. The permanent deformation shakedown characteristics of the graded macadam were examined by conducting triaxial repeated load testing based on shakedown theory. Statistical regression and curve fitting were applied to the test results to overcome the limitation on the number of repeated loads. In accordance with the fitting results, the testing curves were extended to analyze the limit stresses for the shakedown under different shakedown statuses of the permanent deformation of the aggregates. A new design model was established for controlling the permanent deformation of the granular base course in zone A (plastic shakedown status). The permanent deformation of granular base courses of typical asphalt pavement structures was calculated by adopting the layer-wise strain summation and employing the evaluation model currently adopted by the United States Mechanical-Empirical Pavement Design Guide for the permanent deformation of granular base courses. Consequently, the critical standard values of the permanent deformation and the permanent strain of granular base courses were determined. The stress ratio is recommended as a design index for controlling the permanent deformation of the granular base course. The control model of the regression formula between the stress ratio and the number of axial loading was originally created based on laboratory tests.

The asphalt mortar specimens of AC-13 asphalt mixture with removed coarse aggregates are prepared using a static pressing method to study the changes in the dynamic modulus of asphalt mortar with different asphalt contents at different temperatures and to obtain the dynamic moduli with wider frequency and temperature ranges. The dynamic moduli of asphalt mortars with different asphalt contents at different temperatures are measured using a simple performance test. The master curve equation of the dynamic modulus of asphalt mortar is calculated based on the time-temperature equivalence principle. The results show that (1) under the same asphalt content and temperature condition, the dynamic modulus of asphalt mortar increases with the increase in loading frequency, the dynamic modulus of asphalt mortar decreases with the increase in asphalt content, the minimum difference in dynamic moduli with different asphalt-aggregate ratios under the same frequency is 1.28%, and the maximum difference is 23.90%; (2) the dynamic modulus of asphalt mortars decreases as the temperature rises, and the difference in dynamic moduli is small at 5 ℃ and 10 ℃; and (3) dynamic moduli with wide frequency and temperature ranges can be obtained from the master curve of the dynamic modulus of asphalt mortars.

A finite element model was established by ABAQUS to investigate the mechanical characteristics of continuously reinforced concrete pavement (CRCP) with basalt fiber reinforced polymer (BFRP) based on existing experimental results. Influences of crack width, BFRP modulus, reinforcement ratio, as well as void under the pavement were analyzed, especially their influences on the stress situation of the cement concrete pavement structure and load transfer capacity. Results show that compared to pavements with traditional steel rebars, the crack width, distance, and transverse tension stress increased in pavements with BFRP rebars. Moreover, crack width and void beneath pavement clearly influence both mechanical state and load transfer efficiency. The concrete loses load transfer ability when crack width surpasses 1.1 mm, and the load transfer between slabs depends on rebars. The BFRP modulus and reinforcement ratio show little effect on either mechanical state or load transfer efficiency. Therefore, amplifying the BFRP modulus or reinforcement ratio to increase the load transfer coefficient is uneconomical. The findings provide guidelines for the design of CRCP reinforced by BFRP.

The strength characteristics of solidified desert aeolian sandy soil are investigated to expand its scope of application in road engineering. Its suitability as sub-base of pavement structure is analyzed in terms of its strength. The unconfined compressive strengths of the solidified desert aeolian sandy soil specimens with different contents of curing agent are measured using a pavement material strength meter. The microstructures of aeolian sand and the solidified aeolian sandy soil to which the curing agent PX is added are analyzed by scanning electron microscopy(SEM). The strength characteristics and strength formation mechanism of the solidified Aeolian sandy soil are revealed by the analyses. The results point to the following conclusions: (1) the solidified aeolian sandy soil with 10% PX and cured for 7 d achieves an unconfined compressive strength that meets the strength requirement of the pavement sub-base. (2) the strength of the solidified soil is associated with the content of PX, and the optimal dosage is10%. (3) the SEM image shows that intergranular filling consisting of gel and cumularspharolith is formed after adding the curing agent PX. This formation changed the adhesive strength between the soil particles, accounting for the chief cause of the increase in overall strength.

A box girder bridge was simulated by ANSYS software, where the interlaminar relation of the bridge deck pavement was assumed to be frictionally sliding rather than continuous. Stresses of the asphalt concrete pavement were calculated when various disengaging areas between the layers appeared in the load region. Results showed that the size of the disengaging area in the load region had a significant influence on the stresses of the asphalt concrete. The position where the disengaging area appeared obviously changed the stresses of the asphalt concrete; when the disengaging area appeared under the load region, the horizontal load increased the shear stresses of the asphalt concrete. The relative positions of the disengaging area and the load region also influenced the stresses of the asphalt concrete.

This paper investigated the mechanism of resistor network for road deicing with finite element analysis. It also derived the differential equations and boundary conditions of a mathematical model during numerical analysis, applied load, achieved pavement and distribution temperatures, and observed the warming law within the structural layer at different power and environmental conditions. Furthermore, the temperature of the pavement and its structural layer under the same experimental conditions with finite element analysis. Furthermore, the connected ideas of the device were designed, and obtain the temperature of the pavement and theitsstructural layer under the same experimental conditions with the finite element analysis. Compare the were obtained.The experimental and numerical simulation results were in good agreement when compared. A certain degree of error analysis with numerical simulation and experimental processes was found. Thus, finite element analysis and ANSYS were suitable for simulating the resistor network process of deicing, which is an unsteady heat conduction process. Results showed that this simulation provides a new method and basis for guiding the resistor network for road deicing engineering design and temperature control. The application prospects of this approach are broad.

A method for constructing load spectra based on the distributions of road roughness and velocity was proposed to improve the authenticity and validity of the target load spectra of customer reliability. A road was divided into eight types according to GB/T7031-2005, and the velocity of a vehicle was divided into n ranges. Then, the proportion of every velocity range for the eight road types to total mileage was analyzed. The load time history of per unit mileage for the eight road types with different velocities was collected, and a 100 km standard load spectrum was constructed and combined with the velocity distribution by using the rain flow counting method. The target load spectra of users were extrapolated with the total mileage of the user target. Results show that the target load spectra of customers constructed with consideration of the distributions of road roughness and velocity accurately and effectively reflect customers’ actual use conditions.

The evolution of hinged joint structures in Chinese hinged hollow-slab bridges was summarized to study the mechanical performance of hinged joint structures in hinged hollow-slab bridges with gate-type steel bars. Parameter analysis was conducted with the nonlinear finite element method for a hollow slab bridge with a span of 8 m. The failure mode of the hinged joint structure with different parameters, including crack-occurring load and crack distribution, was studied. Countermeasures to improve the hinged joint structure were also discussed. Results showed that adopting a gate-type steel bar at the bottom of the junction surface did not improve the crack-occurring load of the hinged joint, but the load of the full-length crack was improved, and the occurrence of vertical full-length cracks on the junction surface and longitudinal cracks on the hinged joint was delayed. Increasing the diameter of the gate-type steel bar did not enhance the crack-occurring load, the load of full-length cracks on the junction surface, and the final distribution of cracks. Enhancement of the concrete strength did not improve the mechanical property of hollow slab and the junction surface remarkably. By contrast, enhancement of the bond strength of the junction surface improved the crack-occurring load of the hinged joint and reduced the distribution of cracks. Three layouts of reinforcement in the hinged joint and increasing the diameter of the gate-type steel bar, as proposed in existing references, did not fundamentally improve the mechanical property of the junction surface.

This study investigated the cooperative and competitive lane-changing behavior characteristics with limited traffic resources. The behaviors were described based on previous research. Data were obtained using video capture on a pedestrian bridge and vehicle trajectory extraction software. The internal relations between trans-line ride distance and time were discussed. The acceptance gaps, speed changes of target vehicles, and lateral deviations of lag vehicles were analyzed. Based on the measured data, the probabilistic density functions on the acceptance gap of cooperative and competitive lane changing were obtained. The threshold of the acceptance gap was extracted through "minimum value of overlap area method." Lane changing probability choice model was established for different acceptance gaps. Results indicated that the threshold of the acceptance gap that can differentiate cooperative and competitive lane-changing behavior was 19.28 m. When the gap is greater than 30 m, the probability that the target vehicle chooses cooperative LC is more than 94.49%.

Urban expressways can be built with various patterns, resulting in complex traffic conversions. In practice, implementing identical design control parameters under different patterns or traffic conditions is unreasonable, and further analysis is therefore necessary to improve the flow of traffic. Control parameters, regardless of whether they are reasonable, affect the safety and efficiency of urban expressways. Design speed and minimum curve radius are the control parameters of the ramp. Acceleration/deceleration lane length and width-transition length are the control parameters of the speed-change lane. The factors influencing the control parameters of the ramp and the speed-change lane can be determined by analyzing the characteristics of the entrance/exit. To elucidate the mechanism of effects of the design speed and the stopping sight distance on the minimum ramp radius, the effects of traffic flow rate and ramp design speed on the length of the speed-change lane and the width-transition were analyzed. Calculation models for the control parameters of the ramp and the speed-change lane were established based on kinematics theory, traffic flow theory, and probability theory. The following conclusions can be drawn from the analysis and calculation. The design speed of the ramp can be classified according to ramp patterns and the properties of urban roads connected by ramps on both ends. The minimum curve radius of the structure pattern ramp that meets the requirement of the stopping sight distance is greater than that determined by the side-way force coefficient. The calculated lengths for the two-lane acceleration lane and the width-transition under traffic flow are greater than that demanded by the current specifications.

The differences in arrival time at transfer stations, including internal hierarchy and between levels based on layout mode and service characteristics, were considered to maximize the cohesion efficiency of transfer stations and improve the utilization ratio of the network in a multi-level public transit system. In this paper, a timetable model that aims to minimize the cost incurred by passengers and companies was created in terms of departure time and interval. The timetable model was solved by genetic algorithms and subsequently achieved a multi-level bus line running timetable. The model was verified by a numerical example. Calculation results show that although this model increases the investment in public vehicles by 8.5%, the timetable shortens the waiting time of passengers by 23.5% and reduces the overall cost. In the actual operation, the interests of the passengers and public transport companies should be balanced when considering the actual demand.

OD matrix estimation of freight transportation is important in urban traffic and logistic planning. In this process, passenger traffic does not require participating in the mode of distribution and estimation. Thus, the accurate calculation of the impedance caused by passenger traffic on freight vehicles on the road is one of the urgent problems in OD matrix estimation of freight transportation. One of the functions of the Bureau of Public Roads (BPR) is conducting research on road traffic impedance. Flaws were determined in the BPR function. Thus, an approach to improve initial impedance must be suggested. This study proposed the impedance model. The parameters of different road types were calibrated, and the calibration for different methods and road types was comparatively analyzed. Methods of improving the BPR function were studied to estimate the OD matrix of freight transportation under certain conditions.

The key of improving performance requirements for longitudinal collision avoidance system under collaborative vehicle is the accurate judgment and the estimation of vehicle driving state and appropriate safety distance model. In order to improve performance requirements of longitudinal collision avoidance system under collaborative vehicle, the longitudinal safety distance model based on vehicle driving state estimation is proposed. First through the establishment of the vehicle kinematics mode which considers the vehicle front and rear axle centre position and the state equation of vehicle running state parameter estimation, using the extended kalman filter to realize the accurate estimation of vehicle driving state parameters; then based on the accurate estimation of vehicle driving state parameters, according to the front vehicle' different state, the longitudinal safety distance models are built when the front vehicle is stationary, in uniform motion and braking. The simulation platforms of vehicle state estimation and longitudinal safety distance model are built based on Matlab/Simulink, the simulation results show that the accuracy of vehicle driving state parameters estimation and the effectiveness of longitudinal collision avoidance safety distance model.