To attain the data of effective dynamic deflection basin utilized to implement modulus backcalculation of asphalt pavement, by dynamic finite element method, the solution method of damping coefficients of pavement structural layers is discussed, the estimation model of subgrade damping coefficients is established, and the influence of testing loading's dynamic effect and discontinuous contact behavior between structural layers on distribution features of surface dynamic deflection basin is investigated. The results demonstrate that (1) subgrade damping coefficient is a main factor affecting surface dynamic deflection distribution, which is mainly controlled by subgrade modulus, while influence of other structural parameters on subgrade damping coefficients is negligible; (2) when the asphalt pavement is imposed by static and dynamic loadings, the distribution features of dynamic deflection basin has a dynamic deflection basin for the same asphalt pavement; (3) performing back calculation of modulus parameters of structural layers should consider the actual FWD loading characteristics and the interface contact behaviors.

The single-side salt-freeze test was used to optimize the concrete mix design for improving the resistance of concrete to salt scaling. The results show that the resistance of concrete to salt scaling improves with decreasing water-cement ratio and increasing air content. Addition of silica fume also improves the resistance of concrete to salt scaling relative to fly ash, ground granulated blast-furnace slag, and other silica fume. To enhance the resistance to salt scaling of concrete pavements, the water-cement ratio should be less than 0.4, the air content higher than 3.8%, and the cementitious materials-aggregate ratio is 265:745 to 280:720. If fly ash and ground-granulated blast-furnace slag are used then extended curing is required to prevent salt scaling in early-age concrete. Finally, organic instead of inorganic snow-melting agents should be preferred.

Experimental research is conducted to determine the long-age statistical parameters of road pavement properties such as flexural strength, flexural elastic modulus, compressive strength, and splitting strength after 18 months. Changes in regularity are analyzed, and the functional equations of the performance indices with the age of pavement concrete material are fitted. The differences in performance under the conditions of standard indoor curing and outdoor natural curing are then compared. The regularity of concrete strength varying with age, the relationship between flexural strength and splitting strength, and relationship between compressive strength and flexural strength are discussed. A comprehensive summary of the development rule of the long-age performance of road pavement concrete materials is performed. Finally, by analyzing the data of the ratio of compressive strength to flexural strength, it is recommended that controlling the flexural strength and water-cement ratio can reduce the brittleness of the concrete slab.

This study derives the equation for the bearing capacity of shallow circular foundation on the basis of the upper bound theorem of limit analysis method. The equation is derived by considering the work of soil weight and by assuming that the foundation failure mode obeys Prandtl sliding mechanism, which consists of ABC, ADE rigid body, and ACD logarithmic spiral deformable-body. Using the equation, we determine the internal energy dissipation rate, gravity work, energy dissipation rate of overlaying soil, the total power of the force are obtained respectively. The solution for ultimate bearing capacity has been realized by analyzing the external power and internal energy dissipation rate of the soil under unrestricted plastic flow. The results calculated in this study are found to be higher than those reported in previous references. However, the error between the measured value and calculated value is in the range of 20%. The analytical solution deduced in this study can be used as a reference for calculating the bearing capacity of circular shallow foundation.

Based on the assumption that the hydrostatic pressure is maximum at half the total groundwater level, which improved the groundwater pressure distribution in the slope body, the safety factor expression for anti-slide stability of the rock slope along the river were deduced using the limit equilibrium theory. This deduction included various influencing factors, such as slope-top surcharge, seismic load, anchor load, river pressure on the slope surface, groundwater pressure, and scouring effect. The relationship diagrams between the safety factor and the influencing factors were constructed. Results show that the new assumption, which improved the hydrostatic pressure distribution, is reasonable. Hydrostatic pressure is an important influencing factor to the slope anti-slide stability. The higher river water level and the lower groundwater level are beneficial to improve the safety factor of the slope anti-slide stability. Whether the outflow joint blocking has significant effect on the slope stability against sliding, the outflow joint blocking has adverse effect on anti-slide stability of the rock slope along the river in the general case. The anti-slide stability safety factor of the outflow joint blocked is larger than that of the outflow joint unblocked only when H_r>H_w.

Based on surface energy theory, the surface energy parameters of SBS asphalt and cement concrete with different moisture contents are measured by the column wicking technique and the sessile drop method. Furthermore, the adhesion between cement concrete and SBS asphalt with different moisture contents is analyzed by calculating adhesion work. Then, the interlamination adhesive performance with different moisture contents is verified. The results indicate that (1) the adhesion work hit the maximum when moisture content is 0%, and the adhesion work decreases gradually as moisture content increases; (2) as moisture content decreases, the debond resistance performance of the waterproof adhesive layer improves, when the moisture content is 0.5%, the interlamination adhesive performance is insensitive to moisture content; (3) as moisture content decreases, the shear strength of waterproof adhesive layer on the bridge deck also improves, but the increment is not obvious after moisture contents is under 1.0%.

To study the fatigue prestress loss of prestressed concrete beams, four bonded post-tensioned bonded concrete simple supported beams were designed and constructed for constant-amplitude fatigue load displacement tests. Strain sensors were embedded into the pre-pressed zone of the mid-span of the simply supported concrete test beams, and the fatigue prestress losses were calculated by strain increments in the concrete. The experimental results show that the phenomenon of fatigue prestress loss was present and primarily occurred in the forepart of cyclic fatigue test, and appeared to fit an exponential function law regarding cyclic fatigue load under dynamic loading for prestressed concrete beams. The preliminary results may be useful as a reference to improve the theory for designing prestressd concrete bridges.

The lateral load distributions on a continuous composite box girder bridge with corrugated steel webs were investigated using the fixed eccentric lateral load distribution prediction method. Using an engineering example, the lateral load distribution on a continuous bridge, which contained one three-room composite box girder with corrugated steel webs, was calculated using the fixed eccentric pressure method and spatial finite element method (FEM) analyses, in which the torsional stiffness of the box girder was considered. The deflection of the bridge under an eccentric lateral load position was tested in the field. The results of the fixed eccentric pressure method and the spatial FEM analyses were compared with the results of the field test. The results indicate that an improved plane model, which considers the torsional stiffness of the box girder, is introduced to solve a spatial problem using the fixed eccentric lateral load distribution prediction method. The lateral load distribution factors in the fixed eccentric pressure method correspond with those in the spatial FEM analyses. The fixed eccentric pressure method is a feasible and conservative method for solving the lateral load distributions on a continuous composite box girder bridge with corrugated steel webs.

A theory for directly identifying shrinkage and creep in a structure, along with an embedded self-identification system, is proposed. The theory and system aim to obtain accurately the time-dependent regularity of shrinkage and creep in an actual structure. Moreover, they aim to improve the prediction accuracy for long-term deflection. A preliminary validation is then conducted through an experimental beam test. Results show that the identified creep coefficient curve of the test beam can represent the real creep in the structure better by using the same calculation method for structure deformation. In addition, the calculated mid-span deformation of the beam that uses a self-identification creep coefficient prediction approach is closer to the measured deformation than the theoretically predicted results. Therefore, the proposed embedded concrete creep self-identification system effectively identifies shrinkage and creep in a structure, and significantly improves the accuracy of predicting deformation in concrete structures, thus providing a new method for predicting long-term deflection in long-span beam bridges.

The deformation regularity of concrete beams after cracking is studied. Finite element (FE) models of a simply supported beam under distributed loading and a continuous beam under distributed loading are built using ANSYS. Cracks with different widths, depths, and locations are simulated after deleting some elements in these models, and the maximum displacement and deformation regularities are observed. The result of FE simulation shows that (1) the crack width has a negligible effect on the maximum displacement of the beam; (2) the crack depth evidently affects the maximum displacement, that is, a deeper crack results in a larger extent of the effect; and (3) the location of the crack affects the maximum displacement of the beam by changing the location of the maximum displacement in the beam, that is, a deeper crack results in a larger extent of the effect.

A three-dimensional elastic-plastic finite element model based on the elastic-plastic constitutive relation of the non-associated flow Mohr-Coulomb criterion is constructed to analyze the influence of inclination angles of loads and piles on the mechanical properties of batter piles under inclined loads. The results indicate that (1) the stiffness of batter pile depends on both its axial and horizontal stiffness under a smaller inclined load and does not become maximum under an axial force because of the existing stiffness balance in the axial and horizontal directions. (2) The relationship between the ultimate compressive bearing capacity of batter pile and the load inclination angle exhibits an M shape. The peak of this capacity appears near a small load inclination angle rather than under axial load. (3) The stiffness and bearing capacity of batter pile increase with pile inclination under positive inclined loads, whereas the results show the opposite behavior under negative inclined loads. (4) The ultimate loads on batter pile with different inclinations are significantly affected by the coefficient of friction between the pile and soil.

With the increasing demand for traffic information services as well as the extensive deployment of traffic video surveillance, there is a critical need for realizing automatic identification of congestion state with traffic video. To this end, this study proposes a traffic congestion evaluation model with adaptive learning ability. The qualitative process of the proposed model has been previously analyzed. In this method, the video image feature sets are extracted initially, followed by the state classification model training and learning via support vector machine. Subsequently, genetic algorithm is used to realize the online adaptive optimization. The field experimental results indicate that this method has high recognition accuracy, fast processing speed, and strong adaptive ability, and it can provide an appropriate solution for solving the problem of all-day traffic congestion states recognition based on the traffic video information.

In this paper, we first describe the concept of cooperative intelligent transport systems (C-ITS) and introduce how advanced ITS technology is being developed in some countries. We then review and analyze the policies, plans, projects, and deployment that support C-ITS development in Europe. We conduct our review according to the development goal of the white paper on European transport policy. We then discuss the allocation of radio frequency bands as it relates to C-ITS development and affects pan-European ITS development. In addition, we introduce and analyze the C-ITS standards applied in Europe, both in communication and applications, including ISO C-ITS standards. Finally, we provide a brief introduction to C-ITS development in China and make suggestions for the development of standards in China based on our analysis of C-ITS standards in Europe.

Determining relative vehicle positioning for vehicle safety warning services requires high level of accuracy. Positioning based on general satellite information has a large margin of error due to cost constraints. This paper proposes a method to determine relative vehicle position for vehicle safety warning, based on conditional extremum and relative vehicle history positioning. Special attention is paid to improve not only the computational efficiency but also the accuracy of determining the relative position of two vehicles or a vehicle and reference frame. Field test results demonstrate the significance of improved accuracy in determining relative vehicle position. Theoretical analysis and realistic systematic tests provide useful insights into potential applications in safety warning.

First, the importance of drivers' peripheral risk perception ability to traffic safety is discussed. Second, the detection of peripheral risk perception ability is put forward and its evaluation indexes are established. Third, 1 325 drivers are tested using the peripheral risk perception detector and the tested accident records of drivers in past three years are investigated. Through analysis of the test data, the objective existence of accident-prone drivers is verified, the effectiveness of the peripheral risk perception detector and the rationality of the evaluation indexes are proven, and the threshold of the peripheral risk perception indexes is identified. Results show that drivers' peripheral risk perception has a significant impact on traffic safety, and that the detection of peripheral risk perception ability can identify and screen out accident-prone drivers.

Incorporating safety performance measures into asset management can assist agencies in efficiently managing their aging assets and improve system-wide safety. Previous studies have revealed the relationship between individual asset performance and safety; however,the relationship between combined measures of operational asset condition and safety performance has not been explored. Thus, in this paper, the effect of pavement marking retroreflectivity and pavement condition on safety was investigated in a multiobjective manner. Data on one-mile segments for all primary roads from 2004 to 2009 were collected from a state of the U.S. and integrated by GIS tools. An Asset Condition Index (ACI) ranging from 1 to 3 was developed for each road segment by scoring and weighting the individual components. Finally, statistical models were then developed to estimatethe relationship between ACI and expected number of crashes, while controlling for exposure.Future studies will focus on developing a methodology to prioritize safety improvements on the basis of asset conditions.

A simple DTT is a problem to design a hybrid trucking route for single and double trailers as a new version of the routing problem using sub-tours for servicing truck customers. The local optimization approach, 2-opt, is employed to optimize the route. An 0/1 integer linear programming model is built to segment the route that visits all customers, and choose a sub-tours combination that minimizes the incremental cost of the sub-tours. A hybrid evolutionary algorithm is built upon them to search for an optimal hybrid route. Numerical samples are provided to show the features of the DTT problem. The performance of the sub-tours combination optimization model and the evolution of the fitness of the algorithm with or without 2-opt are studied by simulation. The results demonstrate the validity of the proposed approach.