The analytical solution for the ultimate bearing capacity of a circular shallow foundation is studied. The characteristics of existing assumptions, the calculation method, and the yield criterion of the calculation method for the ultimate bearing capacity of a shallow circular foundation are examined. With the assumption that the global shearing deformation surface of the foundation obeys the sliding surface of Prandtl-Reissner's classic theory, the destruction soil under the foundation is an indeformable rigid-plastic body, and the failure surface obeys the Mohr-Coulomb yield criterion. Based on the static equilibrium condition of the rigid-plastic body and considering the frictional resistance part σ tan φ of the failure surface, the theoretical solution for the ultimate bearing capacity of a shallow circular foundation is derived and compared with those of Vesic's semi-empirical equation and other existing analytic equations. Comparison results show that the bearing capacity coefficients N_c and N_q can be increased if the frictional resistance part σ tan φ of the failure surface is considered, but the variation of bearing capacity coefficient with the internal friction angle of soil are different. Furthermore, the presented theoretical solution, which is a revised calculation method for the ultimate bearing capacity of a shallow circular foundation, is similar to those of Vesic's semi-empirical equation and other analytic equations.

The modified Burgers model was considered as the series connection between a Van Der Pool model and a nonlinear dashpot to draw a conclusion that the process of damage evolution only results in a decrease in dashpot viscosity, whereas the other three elements are undamaged. A damage evolution equation was established from a statistical perspective with the distribution of the inner flaw of asphalt described by the Weibull function. The equation was then incorporated into the modified Burgers model to obtain a new viscoelastic damage model of the asphalt mixture. The creep strain, rate, and acceleration were obtained. These parameters exhibited good agreement with the three-phase creep character of the asphalt mixture. Finally, the proposed model was verified through two experimental examples. Results showed that the model considering the dashpot damage was not only simpler than the previous models, but also exhibited good agreement with the experimental result. Moreover, this method was based on a reasonable theory.

To develop a purely inorganic fire-retardant-modified asphalt, we selected highly fire-retardant materials that have low-carbon content, non-polluting properties, and are inexpensive as fire retarder of asphalt. The optimal preparation technique for inorganic fire-retardant-modified asphalt is determined on the basis of three indexes of modified asphalts. First, limiting oxygen index and smoke density tests are conducted to investigate the influencing regularity of the dosage and type of inorganic fire retarder on fire and smoke retardant properties of inorganic fire-retardant-modified asphalt. Second, the TG test is used to explore the fire-retardant mechanism of inorganic fire-retardant-modified asphalt. Third, by testing the viscosity, anti-aging property, and adhesion of the inorganic fire-retardant-modified asphalt, the influencing regularity of inorganic fire-retardant dosage on the road performance of the modified asphalt is studied. Finally, the economic benefits of the inorganic fire-retardant-modified asphalt are analyzed. Results showed the following: (1) the inorganic fire retarder has good fire and smoke retardant properties and can meet the requirements of the corresponding national specifications; (2) the fire-retardant property of the inorganic fire-retardant-modified asphalt can be increased significantly by increasing the dosage of the fire retarder, and the smoke retarder can improve the fire-retardant property with its functions (these properties overcome the contradictory shortcomings between fire and smoke retardant properties); (3) the effect of the fire retardant mainly depends on the decomposition and release of water from the inorganic fire retarders, and the absorption effect of the layered metal oxide; (4) with the increasing dosage of the inorganic fire retarder, the degree of penetration and ductility of the inorganic fire-retardant-modified asphalt decreases, the softening point and viscosity increase, and the penetration ratio and viscosity become larger; (5) the addition of the inorganic fire retarder does not affect the adhesion of SBS-modified asphalt. The inorganic fire-retarder has excellent economic benefits and is suitable for promotion and application in fire-retardant asphalt mixtures for pavements.

Given the unique pattern of butterfly-shaped arch bridges, the nonlinear behavior rules of the main girders are difficult to determined compared with those of ordinary arch bridges. The traditional design method that does not fully consider nonlinear influences is unsuitable for such investigation. The nonlinear behavior of the main girders was analyzed by considering various nonlinear factors using a self-compiled program. The influences and rules of different design parameters such as depression angle, rise/span ratio, steel ratio, and so on, were studied. The following results were obtained. (1) The beam-column effect of arch rib elements has unfavorable influences on the main beam moment, but the beam-column effect of the main beam elements can effectively prevent such unfavorable effects. (2) The nonlinear behavior rules of the main beam moment are more complicated than the rules of deformation. (3) The distance of the eccentric load has a significant effect on the influence coefficients of the boundary beams at the unloading side. (4) The influence coefficients of the mid-span deformation and moment increase as the depression angle increases. (5) The influence of the steel ratio and the angle between the cable plane and the arch plane on the nonlinear behavior of the main beams can be neglected.

With Wanzhou Yangtze River Bridge as an engineering example, FEM is applied to simulate the whole bridge construction process to optimize the truss member assembling sequences and determine the critical member bars that should be monitored. Real-time or fixed time data on stress and deflection are collected through a wireless integrated test system. Thus, the status of stress and deflection for the cantilever structure is under good control to ensure safety and stability. Measurements and theoretical computations of temperature effects are valuable for closure time selection and temperature deformation adjustment. The middle span is closed under the conditions of "zero error and zero additional stress". A successful construction of this bridge provides experience and guidance for other similar bridges.

The arch rib, tie beam, and rod of the tied arch are considered common forces. According to the characteristics of these forces, the calculation equation of the moment augment factor of the tied arch is derived. The equation is based on the energy variational principle. The calculated results of the derived equation and the current bridge code are compared with the project example. For examples 1 and 2, the difference in calculation results between the derived practical equations and naked-arch simplified equivalent straight bar under the existing bridge specification is 12.9% to 24.3% before simplification. After simplification, the calculation results of the derived equation deviates by about 1%. The derived equation is comparatively economic and practical because the current bridge code is calculated according to the nude arch. The moment-amplified factor increases with increasing axial force and is related to the constraint and load form. The moment augment factor of the eccentric compress bar and arch rib in the arch structure exhibits substantial difference.

Calculating the collapse probability of large and complex bridges during ship collisions by using reliability theory is an inevitable trend in the development of risk assessment for ship-bridge collisions. On the basis of reliability theory and by combining VC++ with ANSYS general finite element software, we develop a program for computing the reliability of bridges during ship collisions by the ANSYS and response surface method. The collapse probability and reliability sensitivity index of the Jialing River Huanghuayuan Bridge during ship collisions are calculated by the program. Results show the following: (1) the pier collapse probability with ship collisions is greater when the water level of the bridge area is at the normal level of 174 m; (2) the density, ship-collision velocity, ship-collision angle, and concrete compressive strength are the main factors that affect bridge collapse probability during ship collisions.

The main channel girder of Jiaxing-Shaoxing Bridge is the first six-tower, separate-deck, space four-cable-plane cable-stayed bridge in the world. The main bridge has seven closures, and the closure scheme is complex. Considering the problems in traditional temperature closure, this study introduced a new closure process called geometric closure based on geometric construction control. Then, this study introduced a closure attitude adjustment calculation method and enumerated the considerations in selecting geometric closure for the main channel bridge. Finally, the operating details that implement geometric closure for Jiaxing-Shaoxing Bridge was introduced. Geometric closure can eliminate the additional effect of temperature and ensure the established closure time. The measurement data show that the profile of the main girder of Jiaxing-Shaoxing Bridge is smooth and that the error is small with geometric closure. As a result, the construction control work achieves satisfactory results.

Most research on travel time reliability (TTR) is from the perspective of the road managers. Therefore, dynamic TTR from the view of road users is proposed. The concept considers the influence of random road network variations on road users. Two dimensions of travel time distribution and its temporal-spatial characteristic are analyzed. Based on daily variation reliability and assumptions of normal distribution of travel time and given threshold value, the influencing factors are studied according to its probability density distribution function. A TTR index is then proposed. Link and route TTRs are computed with the index, and the dynamic TTR of urban road networks is calculated and investigated. Three methods are adopted separately to compute the route TTR on a test road network. The traditional method is flawed, whereas the presented reliability index method and Monte Carlo method can obtain comparable results. Therefore, the validity of the reliability index method is verified.

Strategies for inputting coordinated control signals in a freeway system are studied. Based on the symmetric, two-lane Nagel-Schreckenberg (STNS) model, a cellular automaton model of a coordinated control section on a freeway with only one on-ramp segment and a mainline segment is established with access to real-time traffic information from an intelligent transportation system (ITS). The characteristics of traffic flow obtained by inputting coordinated control signals in the controlled section are discussed based on the results of simulations conducted using different control strategies. The effects of various traffic states, mainline upstream traffic volumes, and ramp demands on actual road capacity and traffic flow are analyzed by inputting no control signal, only on-ramp control signal, only variable speed limits signal, and speed limits, and ramp-metering signal. The simulation results indicate the following: the applicability of coordinated control as a main traffic management tool is better than that of other control methods; (2) the goal of decreasing the vehicle passing time, suppressing traffic jams, and enhancing road actual traffic volume can be realized by using the strategy of inputting different control signals under different traffic demands.

A speed-flow graph is used to calibrate Wiedemann 74 model parameters. A parameter calibration platform integrating VISSIM, Matlab, and ExceLVBA is built, which minimizes the differences between the measured values and the simulated values of the speed-flow graph. The optimization methods adopt the relevant knowledge in image recognition and a genetic algorithm. This platform achieves automatic parameter optimization by iteration. The proposed parameter calibration platform calibrates the driver behavior threshold based on a speed-flow graph, provides an automated technique for parameter calibration using detector data, and provides an effective method for studying driver behavior. This platform soLÜes the low precision problem of default parameters, which is not suitable for Chinese traffic conditions. We collect traffic flow data at the south second ring road of Changsha city using a roadside laser detector. We first calibrate Wiedemann's model using collected data and the proposed parameter calibration platform. Then, we fit the driver behavior threshold curve. Finally, we analyze driver behavior passing Changsha south second ring road.

Traffic incidents decrease the capacity of road segments and disturb normal traffic flow. Analyzing the evolution of traffic incident effects by building a simulation model for traffic incidents not only helps in better understanding traffic flow characteristics in abnormal conditions, but also provides a theoretical basis for traffic control strategies. Considering the characteristics of driver behavior, this study proposes an improved model of traditional symmetric two-lane cellular automaton (STCA) based on lane-changing rules. Velocity is used to build a traffic simulation cellular automaton model for traffic incident conditions. The improved model simulated traffic flow better than the traditional STCA model.

Driving behavior is closely related to several aspects of traffic research. Individual difference is an important factor that degrades the accuracy of driving behavior research. The individual characteristics of driving behavior were considered to study individual differences further. 22 participants' driving behavior data in curve road were collected through simulated driving. The data characteristics confirmed the existence of individual differences in driving behavior. With the use of a correlation analysis method, 12 indicators of driving behavior were analyzed to evaluate individual characteristics and differences. Results show that the mean and standard deviation of acceleration, standard deviation of steering wheel angle, and mean of throttle can explain individual characteristics and differences. These four indicators are thus important in studying individual characteristics and differences. Furthermore, the mean of steering wheel angle, mean of speed, and mean and standard deviation of brake can be used to analyze individual characteristics. The conclusions provide the foundation for accurate studies of driving behavior.

The structure and working principle of an electro-hydraulic hybrid brake system for electric vehicles were introduced simply. The regenerative braking control strategy of the conventional friction brake system and the influence of the electro-hydraulic brake (EHB) system on the braking energy recovery capability of electric vehicles were discussed. Through characteristics that enable the EHB system to precisely control the braking process of electric vehicles, a theoretical conclusion that friction braking force is distributed to a non-drive shaft to maximize regenerative braking was established. A regenerative braking control strategy based on this conclusion was designed. A simulation research, which verified the effectiveness of the regenerative braking control strategy, was conducted in ADVISOR2002. Result shows that the control strategy can improve the rates of braking energy recovery and effective energy recovery in electric vehicles compared with the traditional parallel brake distribution control strategy.