To study the regular properties of modified bio-asphalt, analytical and measuring methods, including softening point, penetration, and ductility tests, were employed to analyze the improvement of properties in different mixing proportions of bio-asphalt and modified asphalt. Results indicated that after mixing bio-asphalt with modified asphalt, the penetration of bio-asphalt declined constantly with an increment proportional to the modified asphalt. The excellent performance at high temperature of the two kinds of bio-asphalts was affected by the mixing of modified asphalt. According to the analysis of temperature stability, the ductility of bio-asphalt significantly improved after mixing with modified asphalt, although the softening point declined. The stiffness and brittleness of bio-asphalt at low temperature improved as well, particularly in SBS and SBR modified asphalts. Results improved as the proportion of modified asphalt increased.

The deficiencies of analyzing and calculating asphalt mixture as a perfectly elastic body in the existing structural design theory of asphalt pavement were amended by numerically simulating the splitting (indirect tensile) test of AC-16, AC-20, and OLSM-25 (open-graded large stone asphalt mixture) from the microscopic view based on the discrete element method and 2D particle flow code. The aggregate particle contact forces, displacement vectors, numbers of micro-cracks as well as the distribution laws of the cylindrical specimens of AC-16, AC-20, and OLSM-25 were also analyzed and compared by numerically simulating the splitting test. Results indicated that under the influence of peak axial force, the distribution form of the contact force between the aggregate particles in the specimens changed from being basically uniform into being relatively discrete. When the cylindrical specimen of asphalt mixture cracked, the displacement vector greatly varied from one another with the increase of the nominal maximum size and porosity of asphalt mixture as well as with the decrease of asphalt-aggregate ratio of such mixture. Moreover, the number of micro-cracks was determined to gradually reduce. Compared with AC-16 and AC-20, the anti-cracking effect of OLSM-25 in the indirect tensile test was more significant and remarkable.

Automatic pavement cracking detection is of great practical value for pavement maintenance, pavement performance evaluation and prediction, and material and structure design. However, detecting pavement cracks rapidly, precisely, completely, and robustly remains a challenge. Thus, literature review on automatic pavement crack detection was conducted, which included pre-processing methods aiming at image enhancement and de-noising, space-domain recognition algorithms based on thresholding, edge detection and seed growing, frequency-domain recognition algorithms, such as wavelet transform, and supervised learning methods. Shortcomings of these crack detection algorithms were summarized as follows: (1) illumination and oils tend to affect algorithm performance; (2) crack maps have poor continuity; (3) processing speed and recognition precision are not satisfying. Research prospects were also proposed as references to improve crack recognition algorithms, including (1) removing influences of texture and noises by combining boundary and area features, (2) designing optimization-based recognition algorithms that consider local and global features, and (3) detecting pavement cracks based on 3D images.

To determine the modification mechanism of Trinidad Lake asphalt, ash was isolated for microscopic property testing, technical index analysis, and research on ash interaction with asphalt, Ash was compared with two types of filler. Based on the separation effect and operational feasibility, the use of centrifugation for ash separation is better than the other methods. The test of microscopic particle morphology and the crystals reveal the small size and rough surface structure of ash. Ash is mainly composed of quartz and clay and exhibits large density, fine granularity and a large specific surface area. The G^*/sinδ of ash mortar shows that ash reinforces stiffness better than that two kinds of filler. When the ratio of filler binder exceeds 1.2, the growing rate is larger than that of ordinary filler. Thus, ash could enhance the high-temperature performance and strength of asphalt owing to its small size, large surface area, and rough surface.

To study the shrinkage and creep of the new steel-concrete composite deck system of a suspension bridge, an equivalent calculation method based on the existing calculation theory of shrinkage and creep with changing temperatures and creep guidelines was proposed. Two different validation analysis models were established for the same structure using two large popular finite element programs. The validity and accuracy of the equivalent results were verified, and the equivalent method was found to be practical, feasible, and highly accurate. A fine segment model for the steel-concrete composite bridge deck system of a suspension bridge was created with the use of ANSYS finite element program. Further research was conducted on the effect of shrinkage and creep on a composite structure using the proposed equivalent calculation method. Research results for the new class of steel-concrete composite bridge deck indicate that the concrete shrinkage effect is dominant, but the creep effect is relatively insignificant. These results may be related to the concrete loading age. The effect of shrinkage and creep on the stress state of the bridge deck and the longitudinal steel truss are significant. However, the effect on the steel truss is not significant.

The shear lag effect distribution law of a single-box, three-room cantilever box girder under double-deck uniform loads is discussed through experimental research and analysis of the flexural behavior within the girder. Results show that with different load cases used, the cantilever roots generate a positive shear lag effect, whereas the half cantilever generates a negative shear lag effect. The distance of the positive and negative shear lag critical points from the cantilever roots is 18% to 23% of the cantilever length. The shear lag effect is most obvious under the roof uniform load in which the distance of the positive and negative shear lag critical points from the cantilever roots is the shortest. The same effect is less obvious under the double-deck uniform load, and it is least obvious under the floor uniform load. The bending structure of a double-deck traffic concrete cantilever box girder should be designed in accordance with the shear lag effect under roof loads to ensure safety.

A finite element method (FEM), which implements ANSYS to analyze the performance of concrete-filled steel tubular (CFST) latticed column with initial stress, was presented. Studies showed that the FEM results agree well with the test results. The full loading process of the CFST latticed column subjected to axial load was analyzed by combining FEM with two parameters of initial stress degree and slenderness ratio. Research results indicated that the initial stress in the steel tube of the CFST latticed column advances and elongates the elastic-plastic phase of the specimens and postpones the occurrence of ultimate load bearing capacity and relevant displacement. Furthermore, the ultimate load exhibits a significant decrease of up to 12% for long columns with large ISD, but not for short columns.

The concept, basic principle, and characteristics of twice-prestressed composite beam are introduced, and the mechanical performance, deformation performance, and creep stress redistribution of the horizontal interface of twice-prestresed beam are discussed. In addition, previous studies regarding the application of twice-prestressed composite beams in highway bridges are summarized and analyzed. It is concluded that the twice-prestressed composite beam can decrease the creep camber of a prestressed concrete beam by more than 50%; thus, the contradiction of reducing creep camber and improving the safety of section crack resistance can be effectively resolved. Moreover, twice-prestressed composite beam can save approximately 10% of prestressed tendons and has comprehensive technical and economical advantages in highway ultrathin beam bridges and urban overpass bridges. Future research of twice-prestressed composite beam will focus on the design method, connection model, structure, and shear performance of horizontal interface in addition to, and the construction technology.

In this study, international cases of bridge damage are analyzed to bridges crossing fault (BCF). It is pointed out that bridge damage can be affected by fault type, the orientation of a bridge to a fault, and ground conditions, etc. And the insufficient consideration of seismic design is the important factor in the damage to BCF. Some positive enlightenment is gained in seismic design from the analysis of seismic damage of BCF.

An ultra high-rise pier railway bridge in Guizhou province, China, is selected as an engineering example to study the effect of spatially varying site conditions on the seismic performance of mountainous ultra high-rise pier railway bridges. A seismic performance analysis and a numerical simulation of the bridge are conducted while subjecting the bridge to spatial varying site conditions using the pseudo excitation method. The influence of the distribution of different spatially varying combinations of firm, medium, and soft site conditions on the stochastic seismic response of this type of bridge are then considered for seismic analysis under multi-directional earthquake excitations. Results show that (1) combinations of different site conditions have varying influences on the seismic response of the ultra high-rise pier railway bridge, and in particular, the influence of local site conditions has the greatest structural response on the highest pier; (2) it is of considerable importance to avoid the most unfavorable condition of soft soil beneath the highest pier, and to avoid hard soil conditions beneath other piers; and (3) to ensure that structural responses are not underestimated, it is necessary to consider the spatially varying site conditions when conducting a seismic analysis of ultra high-rise pier railway bridge structures that are likely to be subjected to earthquake action.

To improve the application of uplift piles, the calculation method for ultimate bearing capacity is analyzed to study the significant difference between the calculation and test values of bearing capacity. The computational methods for the ultimate capacity of uplift piles are analyzed on the basis of three failure surfaces. A comparative analysis of the results is performed on the basis of the field test. Results show that (1) the standard, Meyerhof and Das methods ignore the self-weight of pile, thus making the calculation value smaller than the test value, such that these methods can be applied only to uplift piles with small length-diameter ratio; (2) the Chattopadhyay method can predict the bearing capacity of sand, but the process is complicated; (3) the Shanker method considers the value of embedded length-diameter ratio and can therefore be used to predict the bearing capacity when the ratio is larger than 20; and (4) the truncated inverted cone considers the self-weight of pile, the Kotter method is based on the Kotter equation, and the horizontal slice method assumes that the failure surface is curved, and all three methods base their calculation of bearing capacity on ultimate equilibrium theory. The values from the three methods are close to that of Vesic test, such that these approaches can be used to compute for the ultimate capacity of uplift pile with uniform cross section under different soil conditions.

Illumination for pedestrian detection at nighttime is weak, and detection is easily affected through variations in illumination. Thus, a bicharacteristic method of pedestrian detection at nighttime based on hierarchical tree cascade classification is presented according to "coarse-to-fine" principle. The proposed method consists of two stages of cascade classifiers. Coarse cascade classifiers are constructed in complete binary tree architecture. These classifiers use Haar-like features for the rapid identification of candidate pedestrian areas. By contrast, fine cascade classifiers have a parallel structure. Edge let features are used for detection along three parts: the head-shoulder, trunk, and leg parts of candidate pedestrian areas. Bayesian decision-making is adopted to achieve pedestrian target detection and a comprehensive analysis of the detection results from these three parts. Experiments show that the proposed method has high accuracy, ideal real-time performance, and strong reliability. Research works, such as the present study, can serve as reference for vehicle safety driving technology.

To prevent effectively the occurrence of traffic congestion and to reduce the traffic accident rate, traffic flow stability is analyzed by molecular kinetics based on the Lyapunov stability criterion, and a model is developed regarding the traffic flow in a state of uniform synchronous flow as the object, considering the integrated effect of people, vehicles, roads, environment, etc. With a trajectory graph of vehicles and state diagrams of traffic flow, the evolution process of traffic flow stability influenced by various factors of traffic disturbance is analyzed. The mechanism inducing the phenomenon of traffic flow instability is revealed. The traffic flow stability can be improved by considering traffic scenes such as people, vehicles, roads, and the environment.

Although electronic toll collection (ETC) systems are widely used in China, domestic studies on the capacity of such systems remain insufficient. Most previous studies focus on the improvement of calculation methods for determining common charging channel capacity because such methods fail to identify the characteristics of traffic flow. On the basis of in-depth research on ETC system design, this study analyzes the characteristics of the ETC channel traffic flow, compared the calculation methods for road link capacity, for which a calculation method is then proposed. An analysis of the delay of ETC vehicles in charge channels is used as a basis for proposing an ETC channel service level classification method. The maximum service traffic volumes under different service levels are calculated. Findings provide a reference for ETC channel management and application.

Based on the summarization and analysis of existing bus scheduling models and according to Chinese conditions, the bus route scheduling problem is studied using the theory of stochastic service system (queuing theory). A mathematical model is established to achieve the bus route scheduling with travel demand as the fundamental data and with bus company interests and passenger satisfaction as the objective functions. The process of objective function construction is described, the passenger satisfaction function is introduced, and the algorithm of each component of constraints is designed. Finally, a case study is conducted on the basis of data from the national mathematical modeling competition. The model is soLÜed using Matlab software. Results show that the model has advantages in soLving and applicability and is thus practical for use in bus scheduling.

This paper discussed the planning and selection of optimization model for distribution routing of cold chain items with variable customer demand. We established a distribution model of cold chain items to minimize the total distribution cost based on the model of vehicle routing problem (VRP) with time window. Distribution routing was then optimized by saving algorithm. Finally, we compared the optimal routes planned by the stochastic distribution model (considering demand variation of customers) and the deterministic distribution model (based on a given demand expected value) by using a numerical example. Results show that (1) planning by using the stochastic model is superior to planning by using the deterministic model when demands fluctuate wildly and vice versa; (2) the total distribution costs obtained by the two models increase with the increase of the degree of demand change. Therefore, we proposed several suggestions to reduce the demand uncertainty of customers.