In order to explore the relationship between the microstructure characteristics and the macromechanics characteristic of rubber modified asphalt at different activation temperatures, on the basis of conventional performance testing, dynamic shear rheological test and multi-stress creep recovery test, the change rule of microstructure and macromechanics characteristic of rubber modified asphalt were obtained and the relationship between them was established through infrared spectrum test. And through the grey correlation analysis, the relationships among the macromechanics characteristic, the microstructure index and the macromechanics index of the rubber modified asphalt at different activation temperatures were obtained. Results showed that:under the infrared spectrum, the activation of the rubber powder mainly changed the stretching vibration intensity of the sulfoxide group and butadienyl groups at 1030 cm^-1 and 1600 cm^-1, respectively. With the increase of activation temperature, the sulfoxide group (S=O) and the butadienyl group (C=C) indexes under infrared spectra gradually decreased, the anti-rutting factor (G^*/sin δ) and creep recovery rate R3.2 showed a trend of gradual decrease, while the loss factor (tan δ) and non-recoverable creep compliance Jnr3.2 showed a trend of gradual increase. From the relationship model between micro and macro indexes, it could be seen that the S=O of rubber modified asphalt showed a good correlation with macromechanics characteristics. Among those, S=O showed the best linear correlation with the ductility, with the coefficient of determination R² 0.888 0. The C=C index showed a best linear correlation with Brookfield viscosity at 135℃, with the coefficient of determination R² 0.9909. It had a poor correlation with needle penetration. It can be seen from the grey correlation analysis that the rubber modified asphalt showed the best comprehensive mechanical properties when the activation temperature was 70℃, and the S=O index showed the best correlation with the Brookfield viscosity at 135℃, and the C=C index showed the best correlation with the softening point.

To explore the earth pressure distribution characteristics of high-speed loess subgrade culvert and improve the structural design of high fill culvert, taking an arch culvert from Lingjingdian to Longbai section of East 2nd Ring Expressway Project in Taiyuan city of Shanxi Province as an example, numerical analysis model of high fill culvert was established by using CANDE-2007 finite element software. The culvert setting method and filling height are taken as the main influencing factors. The distribution characteristics of vertical earth pressure and settlement of the culvert are revealed. The variation of earth pressure coefficient at culvert top under different filling height is analyzed. The variation characteristics of earth pressure at culvert top with filling height under two kinds of culvert construction methods, namely, buried culvert and trench culvert, are compared. The influence of culvert construction method and soil arching effect on culvert stress is discussed. The earth pressure gauge is arranged in the upper soil of the arch culvert structure to record the measured earth pressure data, and the numerical simulation results are verified with the measured data. The results show that the settlement of the soil in the center of the culvert is obviously different from that on both sides of the culvert, which leads to the soil arching effect and is an important factor affecting the vertical soil stress at the top of the culvert; The earth pressure on the top of culvert increases linearly with the change of filling height; When the filling height is greater than 5 m, the earth pressure coefficient of the buried culvert increases sharply at first and then decreases slowly with the increase of the filling height, and the stress concentration occurs at the top of the culvert; However, the coefficient of earth pressure decreases with the increase of height and then tends to be stable, and the vertical earth pressure on the top of culvert decreases; The central settlement value of trench culvert is always greater than that of buried culvert at the same height; Compared with the field monitoring and numerical simulation results, the measured earth pressure is greater than the numerical simulation results, and the stress concentration on the top of the culvert is more obvious, which provides a reference for the culvert engineering design.

A comprehensive simulation method on shrinkage and creep effects of concrete during time-varying process which is relatively precise, simple and practical is studied, considering that the effects vary and interact each other during time, in order to analyze shrinkage and creep effects of concrete structures in continuous and composite bridges with complex construction stages to ensure their safety. The finite element incremental method is applied as theoretical basis, which works through calculating and accumulating the results in every incremental load step. By setting time steps according to incremental loads, the finite element incremental method can simulate well shrinkage and creep effects on concrete structures during whole time-varying process. Secondary development is carried out with APDL to improve the calculating approach of temperature effects and the metal creep criteria in the finite element software ANSYS, so a finite element comprehensive simulation method is formed for calculating simultaneously shrinkage and creep effects of concrete in structures of bridge during whole time-varying process. Using standard shrinkage and creep models in specifications, shrinkage and creep effects of a concrete column with multiple loading cases are analyzed simulatedly and theoretically during time-varying process. Appling an experimental creep model, creep effects are computed on experimental non-glued prestressed beams of high performance fly ash concrete. The results are studied by comparing them between simulation and theory and between simulation and experiment. The result shows that shrinkage and creep effects obtained by the comprehensive simulation method display obvious characters of loading stages and time-varying process, the simulation results are in good agreement with the theoretical calculation results during the whole time-varying process. The result also shows that the comprehensive simulation method can easily be combined with experiment, and can make full use of findings of experimental researches, and the calculated results from this method are in good agreement with those measured values of modal beams in the experiment. Therefore, the comprehensive simulation method is completely feasible and easy to connect with specifications and experimental researches, and the whole calculation can be conducted automatically with the finite element software, so the method is very convenient and easy for wide application.

The increasingly prominent durability problem of bridge cables not only leads to costly replacement but also causes safety concerns. This paper studies the time-varying reliability of corroded bridge cables through considering fuzzy failuare criterion. Firstly, the resistance degradation model of the corroded cable is established based on the corrosion rate of the steel wire and the corrosion propagation law of the cable section. Then, a time-varying reliability model of cable corrosion considering fuzzy failure criterion is proposed based on safety factor and the fuzziness of cable failure in operation period. A case study was carried out to compare the proposed model and the one with clear failure criterion with considering the time-varying reliability of service cable under different corrosion environment. The results show that the proposed model can reflect the variation of cable reliability in different corrosion environment and service time. Compared with the clear failure criterion, the gradual change rule of time-varying reliability index under the fuzzy failure criterion is better and is more consistent with the engineering practice. It avoids the difficulty in selecting the safety factor under the clear failure criterion at a certain degree. The time-varying reliability index of corroded cables has obvious time division, and it gradually decreases with the corrosion degree of steel wires. The service life of the cable with local sheath damage is only 8-10 years. Due to the irreversibility of steel wire corrosion, avoiding sheath damage and strengthening early flaw detection capability are the key to ensure the cable durability.

In order to investigate the vehicle-induced vibration of suspension bridge with CFRP cables and suspenders, three different criteria were adopted to replace the cables or suspenders of Siduhe Bridge with CFRP. The influence of traffic direction and vehicle speed on the vehicle-induced vibration were analyzed. Vehicle-induced vibration properties of suspension bridges with CFRP cables and suspenders, with a pair of CFRP suspenders and with one CFRP suspender only were also studied by comparison with the suspension bridge with steel cables and suspenders. Results show that two-way vehicles may lead to smaller vibration response than one-way vehicles does though two-way vehicles have more vehicles than one-way vehicles. Besides, vehicle-induced vibration does not necessarily increase with the vehicle speed but strongly associate with speed range. In addition, no matter which criteria is adopted, the vehicle-induced responses of suspension bridges with CFRP cables and suspenders show little difference, but all larger than bridge with steel cables and suspenders, indicating that the impact of gravity stiffness on the vehicle-induced response is larger than that of elastic stiffness. Furthermore, no matter which replacement criteria is adopted, the replacement of a pair of suspenders and one suspender both have little influence on the vertical displacement of the bridge. The tensile force of replaced suspenders are nearly the same with the former steel suspenders when stiffness equivalence criteria is adopted, but higher than the tensile force of replaced suspenders when area equivalence criteria is adopted, and the tensile force of replaced suspenders is the smallest when adopting the strength equivalence criteria. The replacement of suspenders has little influence on the nearby suspender in the longitudinal direction. However, when only one suspender is replaced, the influence on the nearby suspender in transverse direction is much larger the influence on the nearby suspender in longitudinal direction.

In response to the design requirements of the landscape bridge tower of long span cable-stayed bridge, according to the mathematical equation of egg-shaped curve, a long span cable-stayed bridge with egg-shaped arch tower was proposed.Compared with the traditional cable-stayed bridge with the parabolic tower, the The two legs of the arch tower are closer the foundation size is reduced, the tower top is wider, and the three-dimensional spatial stayed-cables are arranged dispersedly, so the bridge landscape effect is better.Combined with practical engineering, the engineering parameters are designed, Midas finite element analysis model is established, static analysis and modal analysis are carried out. The analysis shows that the cable-stayed bridge with egg-shaped arch tower has good spatial structural stiffness.

This paper aims at the needs of 5 000 m super-long-span strait suspension bridge. According to the equation of quadric ruled surface, two new bridge types of univalent hyperboloid mixed spatial cable suspension bridge and hyperbolic paraboloid mixed spatial cable suspension bridge are proposed. The steel wire cables and the carbon fiber spatial cables in spatial mixed cable suspension bridges work together well, so the torsional mode appears much later than the parallel suspension bridge's. The torsion frequency, the torsion-bending ratio and the flutter critical wind speed are all greatly improved. The first-order positive symmetric torsion frequencies of the parallel suspension bridge, the univalent hyperboloid spatial cable suspension bridge and the hyperbolic paraboloid spatial cable suspension bridge are:0.079 88 Hz, 0.198 40 Hz and 0.155 78 Hz respectively. The torsion-bending ratios of the three are:1.22, 2.88 and 2.35 respectively, and the critical flutter wind speeds are:V_cr^p=20.83 m/s, V_cr^d=91.21 m/s and V_cr^s=71.18 m/s respectively. The two kinds of spatial mixed cable structure systems have good wind resistance and stability, which opens up the new train of thought for the future construction of 5 000 m super-long-span suspension bridges.

In this paper, according to the requirements of wind resistance stability of super long-span flat pull suspension bridge, a new structure system of flat pull suspension bridge with tube- net-shape spatial cable system is proposed. The parallel cable system of traditional flat pull suspension bridge is improved to univalent hyperboloid disperse space cable system, to improve its torsional vibration frequency and torsional bending ratio. Combined with a 200 m pedestrian landscape suspension bridge in the gorge of Tibet, the project parameter design was carried out, the MIDAS finite element analysis model was established, and the dynamic modal analysis was carried out, to verify the superiority of wind resistance stability of flat pull pedestrian landscape suspension bridge with spatial cable system in tube net shape.

Equivalent units of vehicles are important parameters for road capacity and service level analysis. However, due to the fact that our country's existing road network has not yet included access roads into the technical grade system and lacks corresponding design specifications and technical standards, access points often have great impacts on highway traffic operations. Based on the characteristics of different types of vehicles at the highway entrance, this paper analyzes the physical significance of occupying space-time resources of lanes on the highway section under different traffic flow statuses when the vehicle at the access point enters the highway section. Furthermore, taking the passenger car as the standard vehicle, estimation models for equivalent units of vehicles at the highway and the access point are proposed respectively. Finally, the UAV aerial photography is used to collect field data, and an access point on Zhengzhou G107 with multiple vehicle types is used as an example for empirical analysis. Calculation results show that:(1) At the access point, the equivalent unit of each entering vehicle type increases with the increase of road traffic; and the more lanes occupied during the entry process, the higher the vehicle equivalent unit. (2) At the access point, the equivalent unit of each vehicle type increases first and then decreases with the increase of the traffic flow speed on the highway section, which shows a boundary around 40km/h. That is because, in the steady flow state between the free flow and the saturated flow, the headway is between that of the free flow and that of the saturated flow. The vehicle at the access point is more convenient when driving into the highway section, but it affects many vehicles on the road highway. At this time, the vehicle equivalent unit is also large.

The response of the reserved demand is crucial to the operation of the customized bus, however, the demand of passengers is scattered in time and space. Transportation enterprises often rely on experience to determine whether to respond to the reserved demand and it is likely to reduce the attractiveness of the customized bus. The customized bus demand response mechanism based on temporal and spatial clustering was proposed. The reserved demands are filtered by response on space-time dimension. Firstly, in time dimension, the response is based on hierarchical clustering algorithm to reserve demand with close travel time. Then response from the spatial dimension using the DBSCAN cluster algorithm is to eliminate special request with relatively isolated spatial location and fewer people, obtaining popularization request with the convergence of time and space. In order to verify the effectiveness of the response mechanism, several examples are performed. The calculation results show that only 69% of reserved demand and 75% of passengers can be responded by setting the parameter empirical values. By appropriately adjusting parameters, when the minimum retention time span is not more than 3 minutes, the minimum number of passengers to get reserved demands is not greater than 2, the value of meeting the condition of proximity to the place of arrival is not less than 1000m, the input parameter neighborhood of the DBSCAN clustering algorithm is not less than 400m, and the lower limit of the number of passengers in a category is not more than 4, it can be respond to 75% of reserved demands and 80% of passengers. The principle of response that meets most of customized requirements and appropriately eliminates special demands was contented. It can be seen that the mechanism has great applicability to response customized demands, and can provide decision-making basis for transport enterprises to open customized bus lines.

In this paper, with the continuous expansion of cities in China, ring expressways have been adopted in most cities, playing a positive role in diverting urban transit traffic, relieving urban congestion, and improving traffic efficiency. However, few scholars have conducted comprehensive and systematic studies on ring expressways. Traffic flow characteristics, situation assessment and prediction, and operation management measures are still in research. Due to the disadvantages of the traditional models using single data sources and its limitation to describe and forecast specific roads, we demonstrate an algorithm-optimized model(TK-GCN) based on graph convolutional networks(T-GCN) for capturing multimodal spatial and temporal datasets and Kalman filtering for correcting the evolution of phase points, to describe the phenomena of the Chengdu ring expressway (National Expressway G4202) in China from May to October 2019, according to dynamic data observed from our intelligent transportation system. Experiments on traffic datasets show good performance of our deep architecture. Abundant experiments show that our approach achieved improvements over the state of the art. It is also presented that our model can improve the generalization performance of shared tasks. These positive results demonstrate that our model is promising in transportation research.

Detection technology based on machine vision is one of the important means of road environment perception. At present, detection technologies for vehicles and pedestrians increasingly mature, and many commercial products have been used. But machine vision in the dynamic weighing still needs to be further explored. This paper proposes a wheel recognition method based on machine vision technology used in Weigh in motion. Aiming at deal with the traditional Hough Transform is not robustness on detecting circle targets, we proposed a wheel detection method based on Histogram of Oriented Gradient (HOG) and Support Vector Machine (SVM). Firstly, HOG is used to extract the image features of the wheels. Secondly, positive and negative samples are sent to the SVM for training the classifier. Finally, the trained SVM classifier is employed for wheel detection. Experimental shows that the proposed method had higher performance compared with the traditional Hough transform, and the detection rate is over 96%, which can meet the requirements of vehicle wheel detection. In the engineering test, our method's detection rate has been improved by about 5% compared with the traditional piezoelectric wheel recognition sensor.