This research explored the variation in the bond-breaking effect with a variety of bond-breaking layers installed between concrete pavement surface slabs and lean concrete base to determine the parameters for the structural analysis of pavements with bond-breaking layers and to optimize the selection of such layers for practical road engineering projects. This study tested the bond stresses and frictional forces at the slab-base interface of pavements under different bond-breaking conditions, Moreover, the dynamic stresses at the bottom of the pavement surface slabs atop different bond-breaking layers were tested via indoor straight pavement fatigue tests and field tests to determine the mechanical properties of slab-base interface treated with different bond-breaking layers in a number of highway projects in Hunan and Guangdong provinces. The bond-breaking media applied in this research includes a 3 cm asphalt concrete (AC), 1 cm emulsified asphalt slurry seal (EASS), geotextile, and emulsion wax curing agent (EWCA). The findings from the field tests for the bond stress between slab-base layers indicated that EASS and EWCA outperformed geotextile in terms of reducing friction or bond stress at the slab-base interface. Furthermore, the findings from the indoor straight pavement fatigue tests indicate that AC exhibited improved performance over EASS and EWCA with no bond-breaking layer in terms of alleviating stress. The mechanical properties of slab-base interface with different bond-breaking media derived from this research provide a scientific reference for pavement design and construction control in practical road engineering projects.

To establish a test data validation methodology for asphalt pavements as well as to explore and monitor the data calculation process for false data identification, data validation methods, such as abnormal data recognition, statistical tests, and variance analysis were integrated. The general process for the data validation of an asphalt pavement test was established considering the logical link, normality, and variance decomposition of the test data. The application results indicated that a logical test with abnormal data recognition could provide an improved data environment for a statistical test. Moreover, the statistical test requires the development of a three-tiered statistical test approach comprising the Kolmogorov-Smirnov test, F-test, and t-test to ensure the validity of data validation. As an important supplement to the validation method, variance analysis could promote the dispute resolution of quality sampling and ensure that the test and inspection development goals undergo standardized sampling and scientific analysis.

The applicability of the Sigmoidal Function to describe the fatigue law of asphalt mixtures at broad stress ratio conditions was examined. This application aimed to avoid the inaccessibility of the segment function. It also sought to address the inadequacy of traditional S-N fatigue equation in analyzing the fatigue characteristics of asphalt mixtures at broad stress ratio conditions. The asphalt mixture gradation and the optimum asphalt aggregate ratio were determined with raw material testing and mixture proportion design. Fatigue tests of the asphalt mixtures were performed at broad stress ratio conditions with Material Test System-810, and results were fitted by the Sigmoidal Function. An improved S-N fatigue model was established with the Sigmoidal Function at broad stress ratio conditions. This improved model, as well as conventional models, can predict the fatigue life of asphalt mixtures. The estimated results were then compared. The improved S-N fatigue model based on the Sigmoidal Function can simulate the fatigue law of asphalt mixtures at broad stress ratio conditions. Therefore, the advantages of the new model were confirmed. The model parameters exhibit clear physical meanings whose values can be obtained easily.

The simulation of dynamic water pressure is one of the basic methods that should be researched to improve the resistance of an asphalt mixture to water damage. In this study, a test system that generates dynamic water pressure in the voids of asphalt concrete by compressed air was designed. A cylindrical asphalt concrete specimen that had a space on its bottom and was covered with epoxy resin glue laterally was fabricated to orient water flow through the asphalt concrete voids into the established space. Thus, the oriented water erosion mode was formed. FEM analysis revealed that the drainage can reduce the pore pressure in the specimen along its depth, indicating that the pore pressure was higher in the semi-rigid base asphalt pavement than in the drainage base asphalt pavement. The test results were as follows. First, the splitting strength of the specimen gradually decreased because of water erosion. Second, powder escaped, shear failure occurred, and the asphalt film was stripped from the damaged surface during the oriented erosion to the specimen at 60℃, indicating the significant effect of the dynamic pore pressure. Third and last, the asphalt mixture with a void ratio of approximately 8% exhibited minimum resistance to water damage. These phenomena revealed that the method can be used to evaluate the resistance of asphalt concrete to water damage.

The combination of Rayleigh's energy method and Southwell's frequency composition method denoted the fundamental vibration frequencies of the freestanding pylon of suspension bridges as the composition of several subsystem frequencies. The subsystems consisted of deformation and inertia components. Thus, the algorithm for calculating the fundamental vibration frequency of the freestanding pylon of suspension bridges was derived through the rational selection of the deflection function. Take the middle steel pylon of Taizhou Bridge as a calculation example. The impact of top additional mass ratio, structure shear deformation, and vibration of the bearing platform on fundamental vibration frequency was analyzed. The numerical calculation and real bridge field vibration test show that (1) the fundamental vibration frequency of the pylon decreases as top additional mass ratio increases, and (2) the vibration of the bearing platform should not be ignored even if ignoring shear deformation only has a slight impact on the calculation results. The algorithm is not only suitable for pylons with a fixed base or additional mass at the top but also for other high buildings, chimneys, and structures with complicated sections.

Cracking is a typical kind of defect present in cement concrete bridges. Image-based bridge crack detection is a new technology for the lossless digital detection of bridge defects. An image-based method is proposed for recognizing and extracting the characteristic parameters of cracks on the bridge surface. Three main processes are aimed at resolving the interference of construction joints, sunlight, defacements, and vibration. First, the characteristics of cracks found in the acquired and de-noised bridge images are analyzed. Second, suspicious cracks are extracted using pixel gray-value comparison. Finally, false cracks are removed through the computed measurement of the connected domain, whereas true cracks are maintained. The qualities of the images are tested, and the results show that the proposed method exhibits robustness and efficiency in detecting bridge cracks.

Kelvin contact element was used to simulate the collision between expansion joints at the pier and the abutment. The purpose was to investigate the pounding responses of the expansion joint in a curved ramp bridge under earthquake conditions. With a multilayer interchange system project, a space dynamic model of a single curved ramp bridge was established, which includes the pier, the beam, the bearing, and the expansion joint. Nonlinear time-history analysis helped compare the different pounding responses between expansion joints at the pier and the abutment in a curved ramp bridge. Two theoretical models were used under eight types of seismic conditions. Results indicate that a curved ramp bridge without an abutment expansion joint is a favorable structure for seismic design.

The Baling River Bridge is a long-span bridge located in a special mountainous area. The site has a very complicated wind field that is representative of many cases in west China. A terrain model that simulates the practical status of the wind field in the bridge site was tested in a wind tunnel to confirm the design of basic wind speed. Other characteristic wind parameters were also determined to provide a reference for similar bridge designation in the future. The test method was researched to identify its correctness and reliability, and the Von Karman pulse wind speed PSD was used. The wind speed evidently increased at the height of the middle span girder because of the effect of narrowing. Furthermore, the wind profile distribution was not uniform. The average attack angle range was -4.7° to+4.7°, obviously larger than the Wind resistant design specifications of highway bridges required (±3°). The Power spectral density function(PSD) of lateral and vertical wind speed was close to that listed in the criteria at the high-frequency part of the bridge; no clear differences at the low-frequency part were observed.

This study discusses the objectives of state-level and enterprise-level positions of decision makers in bridge engineering decision problems and their hierarchical structures. Based on the aforementioned factors, cost classification method is established according to economic evaluation techniques, undertakers, and decision makers' objectives. Social, enterprise, and ecology discount rates are discussed for national economic evaluation, financial evaluation, and environmental cost calculation, respectively. Computation period of cost analysis is discussed for national economic evaluation and financial evaluation. Residual life value of people and compensation are analyzed in order to facilitate the cost calculation related to bridge defect-incurred accidents. Finally, cost and parameter analysis in national economic evaluation and financial evaluation for wind-shielding screen schemes of a particular project is used as an example to illustrate the proposed cost composition and parameter analysis.

A method is proposed to identify bridge collapse patterns based on the limit analysis theorem. The Erchong Floodway single-pylon cable-stayed bridge in Taiwan and the Kap Shui Mun twin-pylon cable-stayed bridge in Hong Kong were taken as examples. The bridge collapse patterns were identified, and the results were verified using nonlinear finite element analysis method. The simplified calculation method can correctly identify the damaged components that caused the total or partial collapse of the bridges. The calculation errors of the ultimate load-bearing capacity of the two bridges were less than 1.1% and 1.3%, respectively. Considering that the simplified method is accurate and computationally efficient, it can be used to study bridge collapse mechanisms to identify critical components and provide scientific foundation for bridge collapse-resistance design and reinforcement.

Field measurements were performed by closely tracking the invert construction states of the Liuyanghe tunnel. Based on measurement data, the mechanical effect of the invert construction was analyzed for the shallow embedded underwater highway tunnel. The research results reveal that (1) to the different parts of the upper-arch, invert excavation causes the increase or decrease of local contact pressure between the initial lining and surrounding rock; (2) the closure of the whole initial lining layer can restrict the development of vault settlement and horizontal convergence of the upper-arch initial lining; (3) the steel frame stress at the invert bottom increases remarkably after digging out the temporary fill on the initial lining; (4) the water pressure behind the initial lining of the invert is increased after concrete pouring; (5) the invert concrete can share the surrounding rock pressure and can be used as safety reserve; and (6) it is reasonable that the distance between the end of the invert concrete and the invert excavation face ranges from 25 m to 35 m.

We examined the selection of emergency evacuation routes in an urban traffic network with dynamic information. A method of selecting emergency evacuation routes was proposed based on the uncertainty characteristics of urban traffic networks and the demand of urban disaster emergency management for an evacuation route selection and given the developments in advanced traveler information subsystems. The approach involves planning evacuation route schemes in an offline module and updating them in an online module with real-time traffic information. In the offline module, a model of evacuation route planning based on time-dependent networks was established by using prior knowledge of traffic network statistics. A synthetic algorithm using the successive shortest path flow and shortest path in the non-first-in-first-out time-dependent network was adopted in the concrete optimization course to obtain a solution. In the online module, an emergency evacuation route model based on real-time traffic information was established with forecast road impedance by nonparametric regression. The Floyd algorithm was adopted in the concrete optimization course, and an updated scheme of evacuation routes was implemented. The results, which were analyzed by simulation, indicate that the principle and method are correct and feasible.

To avoid traffic congestion, improve transport efficiency, and meet the requirements of users and traffic flow equilibrium, the fusion framework of urban traffic control and route guidance was studied. The characteristics of an urban traffic control and route guidance system and a cyber-physical system (CPS) were analyzed, and the relationship between such systems was examined. The technical requirements of the application of CPS theory to an urban traffic control and route guidance system were discussed. Based on the components of a dynamic urban traffic flow guidance system (UTFGS) and urban traffic control system (UTCS), considering the man-machine system characteristics of CPS, and in the light of relevance, conflict, and solution method of both systems, a fusion framework for urban traffic control and route guidance based on the CPS was proposed. This framework involves computation, communication, control, and physical components that facilitate the enhancement of the fusion degree of the UTFGS and the UTCS. The proposed framework focuses on the technical analysis of the feasibility of the depth fusion of both systems and provides a theoretical basis for the implementation of urban traffic control and route guidance fusion in intelligent traffic systems.

A bi-level programming model for optimization of multi-vehicle-type freeway continuous equilibrium network design problem is presented to set up a scientific method for road section reconstruction or extension in freeway network which integrates their positions, capacities and the corresponding network toll rates into one optimal decision-making process. The upper level program model takes the road manager (government) as the leader of the decision-making, and regards the operators' financial goals and upper limit of investment as the constraints to achieve optimum system. The low level program builds multi-vehicle-type multi-criteria user equilibrium model considering the differences in route choice behaviors between different vehicle type users and the effects of road volume extension on the traffic distribution. Finally, a numerical example is presented to illustrate the benefit of this model. Result shows that the proposed model is efficient to make decisions on freeway reconstruction or extension project.

Hydrodynamic pressure is the major cause of vehicle hydroplaning in wet weather. By establishing a finite element model of the tire with longitudinal and transverse pattern, hydrodynamic pressure of the tire under different driving conditions and distributing pattern of water velocity in different parts of the tire were obtained through Fluent. The relations of hydrodynamic pressure with vehicle velocity, water film thickness, and tire pattern depth were gained based on data regression. The results show that (1) hydrodynamic pressure of the tire depends on water film thickness, tread pattern depth, and vehicle speed; (2) as water film thickness increases, the relation between hydrodynamic pressure and vehicle speed gradually shifts from non-linear to linear; and (3) influence of vehicle speed on hydrodynamic pressure is the most obvious, and changing the tread pattern depth alone cannot completely avoid hydroplaning.

The body-in-white finite element model of a type of domestic car was established.The effectiveness and the reliability of the numerical simulation model were verified by comparing the results of prototype vehicle's stiffness,modal test and finite element analysis.On this basis,considered the static and dynamic mechanical property of the body comprehensively,combined lightweight research with manufacture,mass distribution of the thicknesses of body parts was optimized,and dynamic mechanical property was essentially kept.The total mass of the optimized body reduced by 7.84%,the torsional stiffness increased by 1.54% and the bending rigidity increased by 30%. A practical analyzing method of optimizing body structure was provided.