Abstract:When faced with the threat of flutter instability, a reasonable and effective passive aerodynamic flutter control method is the best protection scheme for a long span bridge from wind induced collapse in its service life. The effects of several passive aerodynamic flutter control methods were investigated for three widely adopted main girders for long span bridges including closed box girder. It can be concluded that central slotting best suits closed box girder, fairings are able to improve the flutter performance of more bluff girder section significantly, and central stabilizer can be applied to all the three girder sections. In addition, adjusting the position of inspection rails can also achieve the flutter control goal, and a rational combination of different methods may have extra advantages. It should be noted that the flutter control effect of a method is largely influenced by its parameters, so the appropriate setting and optimization of detailed parameters for different flutter control measures are also investigated.

Abstract:A reinforced concrete (RC) non linear grid model method is established by inserting the calculation section into the structure to achieve the sectional stress redistribution analysis. It considers the flexure and shear mechanism respectively, and describes the behavior of RC slender and deep beams from the cracking to the failure. Thus, it realizes a unified analysis model for RC shallow and deep beams. Several examples illustrate the accuracy of the capacity calculation by the non linear grid model method. The grid model method can also reflect the mechanical behavior of RC beams and provide design parameters.

Abstract:In order to derive the load slip constitutive expression of headed stud connectors used widely in composite bridges, thirty five push out specimens were prepared and tested. Based on the tests results, the influences of stud diameter, stud height, stud ultimate tensile strength and compressive strength of concrete on the peak slip were investigated, and the expression for calculating the peak slip and the load slip constitutive expression with a consideration of the effect of peak slip were proposed. The results indicate that the peak slip increases with the increasing of stud diameter, but stud height and ultimate tensile strength decreases with the increasing of compressive strength of concrete. The proposed expression of peak slip considers more influence factors and fits better with the test results in comparison with the expression specified by the CEB FIP. The load slip constitutive expression by taking into consideration the effect of peak slip is able to reflect the influence of stud diameter, stud height, stud ultimate tensile strength and compressive strength and be employed to conduct the non linear numerical and analytical study of composite bridges.

Abstract:The shear bearing capacity of single stud obtained from single row stud push out test and that from multi row stud push out test are different to some degree. In order to clarify the effect of the stud row numbers on the ultimate strength of the stud, one single stud push out test and four multi row stud push out tests with different rows were carried out. The test results show that the number of stud rows affects the stud shear bearing capacity, and the average capacity of single stud connector decreases by increasing the number of stud rows, while the influence of the number of stud rows tends to be stable with the increasing of the number of row, also the influence value is within 15%. Combined with the push out test, the expression of the number of stud row affecting the shear bearing capacity of stud is given. In addition, based on the load slip curves of multi row stud, the expression of the load slip relation of multi row stud is proposed. Compared to testing results, the new expression has a better match with the experimental values.

Abstract:Bolted end plate connection was proposed as beam to column rigid connection between H beams with corrugated webs and common H columns. Based on rigid end plate model and T stud method on tensile performance of high strength bolts, a designing method for bolted end plate connections of H beams with corrugated webs was proposed. Then 2 static tests of beam to column bolted end plate connections of beams with corrugated webs were conducted, and finite element analyses(FEA) of the specimens were carried out with the commercial software ABAQUS. The maximum tension in bolts under designing moment from test results and FE analysis were presented, which proved the designing method for high strength bolts to be secure. A comparative study of designing moment with the end plate yielding moment proved the reliability of designing method for end plate.

Abstract:Taking the influence of thickness of joint plate, shear connector and loading scheme on the load bearing behavior of aluminum alloy gusset joint into consideration, experiments including 14 aluminum alloy gusset joint specimens were carried out. First, the experimental program was introduced in detail. Subsequently, the collapse phenomena of joint specimens are described. It is found that their failure modes mainly involve the block shear rupture of the top plate and the local buckling of the bottom plate. The joint plate is mainly subjected to hoop stress when the joint is under primary bending moment. The increase of thickness of joint plate can enhance the load bearing capacity of joint effectively. The shear connector C can improve the global behavior of joint efficiently.

Abstract:Sandwiched wedge splitting method and double K fracture model were used to study the fracture properties of concrete epoxy interface. Compared to the prototype specimens, the cracking load, ultimate load, double K fracture parameters and fracture energy of the sandwiched specimens formed by epoxy injection improve, while the cohesive fracture toughness shows no improvement. To specimens with rough interface, the cohesive fracture toughness value calculated with soften curve is identical with that of the test. And the cohesive fracture toughness value of specimens with smooth interface is lower than that of specimens with rough interface because of the wall effect. It is assumed that the epoxy injection technique helps postpone the developing of cracks in sandwiched specimens, which improves the initial fracture toughness. The initial fracture toughness is used to judge interface crack deflection, and the results agree well with the tests. It is recommended that the initial fracture toughness be used to characterize the fracture properties of concrete epoxy interface.

Abstract:Studying the diaphragm’s in plane stiffness and its capacity on transferring horizontal loads in elastic phase, the detail of pseudo static experiment was described about a one story two span timber steel hybrid structure with light wood steel diaphragm under concentrated horizontal force. In addition, for quantifying the influence of in plane stiffness on horizontal load distribution, horizontal load transfer ability factor β was defined and the relationship of it with α discussed, which was the ratio of diaphragm’s in plane stiffness to vertical resist element’s anti resistance stiffness. Moreover, rigid diaphragm was classified according to their value. The result shows that in the case of it lays only SPF (Spruce Pine Fir) dimension lumber upon and the vertical resisting element containing barely steel frame, the diaphragm is already capable of distributing horizontal load well and α in the range of 0.5~1.0 and β about 64.0%; When α increases over 3.0 and β rises to around 90.0%, structural spatial cooperation is perfect and the diaphragm is converted to be rigid after paving cement mortar coat on it; Ultimately the diaphragm is no longer be rigid as α reduces within 1.0~2.0 and β drops to 78.0% if the light frame shear walls are installed in the vertical steel frame.

Abstract:According to continuum mechanics and virtual work principle, incremental updated Lagrangian formulation (U.L.) was presented. The large displacement incremental stiffness matrix was considered in U.L., which was rectified to be symmetrical matrix. Based on U.L., three dimension general purpose three node triangular shell element was presented when the triangular shape function was employed, transverse shear stress was also considered. During the solution of incremental equilibrium equation, the pure nodal point incremental deformation was obtained when the rigid body rotation was removed from the nodal point incremental displacement by using co rotational procedure. Furthermore, by utilizing aforementioned theory, the nonlinear finite element program was developed. Several geometrically nonlinear numerical problems were presented to demonstrate the accuracy, effectiveness, and generality of the three dimensional three node shell element.

Abstract:Based on the theory of space syntax, this paper presents two correction methods of prediction model of pedestrian movement by introducing the distance and type of vertical transition. Two case studies of the multi level systems in the metro station area show that the pedestrian movement can be influenced by either the distance or the type of vertical transition to different degrees. Furthermore, both of the two correction methods significantly improve the ability of the prediction models of the pedestrian movement.

Abstract:A generalized travel cost based model is established to obtain the attraction area of an urban rail transit station according to the uniform accessibility principle. The detailed algorithm as well as a case study is also presented. Based on the fact that city center is not the only destination to all trips, accessible points are used to describe all the possible destinations whose weights are determined by the trip distribution of the whole city. Trip time value is refined by the actual population structure in every traffic zone around the urban rail transit stations. Access distance calculated on the basis of the actual road network becomes more practical. Therefore, a detailed algorithm is given and its method optimization is also discussed. At last, a case study based on the predicted passenger flow data of a city in Guangdong Province verifies the model. The results indicate that the attraction area of a station is related to the road network around, trip distribution and service levels of the competing traffic modes, not just a simple circular region. This model can provide a way to obtain the attraction area of an already existing or a planning station, which is the foundation of passenger flow prediction and facility configuration of all the access modes.

Abstract:Shape of ballast is complex. The irregular shape affects the dynamic characteristic of ballast bed significantly. In order to reveal the effects of simulation methods on railway ballast bed mechanical property, a program is compiled to generate cluster to model real ballast according to the characteristics of ballast irregular shape and interlock behavior. Based on discrete element method, the 3 dimenson models of ballast bed and sleeper are established by using sphere ballast and cluster ballast. The paper presents an analysis of the differences of two kinds of ballast bed model under cyclic load on contact force, coordination number, ballast bed stress and acceleration. The results indicate that the maximum contact force of cluster ballast is 769 N smaller than the sphere ballast and the average contact force is less than 10 N, which shows that magnitude contact force of cluster is smaller and its distribution is more uniform. The coordination number of sphere varies within 1.0~3.2 and that of cluster is between 5.3 and 6.1, which suggests that contact point of cluster is larger and its contact state is more stable. The acceleration of the cluster ballast bed top is 0.26g smaller than the sphere and the stress is less than 16 kPa, which proves that cluster can simulate the interlock behavior and maintain the ballast bed integrity.

Abstract:The conventional design method of airport asphalt pavement doesn’t take seasonal changes and decay characteristic into account, as a result, the linear cumulation based on the structure calculation with each structure layer using a single value of modulus is unreasonable. Therefore, the idea of time sharing cumulation is proposed to design asphalt pavements in different periods by taking the impacts of environmental factors, traffic loads and performance deteriorating on the design of airport asphalt pavement into consideration. Furthermore, based on the principle of time sharing cumulation, they are discussed as well, including modulus prediction models for different materials, design index and standard and performance prediction models to form a completely structural design method of asphalt concrete airport pavements based on time sharing cumulating which overcomes the shortcomings of the conventional method.

Abstract:A case study was made of the public bicycle system of Minhang District, Shanghai, by carring out a questionnaire survey to record the travel mode shift behavior after the introduction of the system. A discrete choice model was employed to explain the decision mechanism underlying the modal shift. It is found that the characteristics of public bicycle, travel time and the accessibility of the bicycle service stations are important factors for decision making. The application of the model reveals travel quality improvement, while the most aggregate quality improvement occurs for relatively utilitarian travel purposes. The modal shift from public transits improve travel quality the most, while the modal shift from private cars improves the least. It is estimated that the travel quality by electric bikes improves more than that by setting up denser service stations.

Abstract:Naturalistic driving data under real traffic conditions in Shanghai were firstly collected by video drive recorders and these data were screened and classified and then 152 risk cases involving pedal cyclists, including bicyclists, motorcyclists and moped cyclists, were obtained. A cluster analysis was made of the risk cases and the results were tested by Chi square test method and seven typical categories of risk scenarios involving pedal cyclists were obtained. These seven categories of risk scenarios were then modeled by PreScan and the risk scenario database involving pedal cyclists was finally established.

Abstract:A control strategy of Handling improvement was proposed for the distributed drive electric vehicle with electric motored wheels which featured the independent and accurate driving/braking of individual wheel. Considering the ideal assistant power character curve under different vehicle velocities, a control strategy of differential drive assist steering was developed, as well as the torque vectoring control strategy according to the optimized reference model of yaw rate. A joint control strategy which was a combination of the differential drive assisted steering strategy and torque vectoring control strategy was presented based on a longitudinal force distribution algorithm. The results of vehicle tests indicate that on the premise to guarantee the road feeling, with the joint control strategy the steering torque and angle are decreased markedly, which means the workload of driver is lowered. The yaw rate response is enhanced obviously, the accelerating understeer is restrained effectively and the handling of the distributed drive electric vehicle is improved significantly.

Abstract:Based on a platform of a high pressure air compressor, the transfer function matrix of the air supply subsystem for high pressure proton exchange membrane fuel cell (PEMFC) is identified and then the air flow and back pressure is decoupled via feed forward compensation decoupling control technique. Both the results of experiment and simulation show that the proposed controller can really achieve the decoupling control of air flow and back pressure, and it also has good robust performance in a large range of working condition.

Abstract:Vibration differential equation of a novel wheel drive system with a swing motor as dynamic damper was deduced, its three degree of freedom (DOF) vibration model was established both in MATLAB and ADAMS software, then body acceleration and wheel dynamic load power spectrum density (PSD) were simulated and analyzed, and accuracies of theoretical equation and simulation model were verified. Then its effect on improving vehicle comfort and wheel ground adhesion were compared with normal In wheel drive system (IWD) based on body acceleration and wheel dynamic load power spectrum density. The results show body acceleration and wheel dynamic load power spectrum density of this novel wheel drive system are lower, and vehicle ride comfort and ground wheel adhesion are improved apparently.

Abstract:Numerical simulation of flameless combustion of pulverized coal was carried out by species transport method. Realizable kε model was used to simulate gas phase turbulent. The solid phase was solved by particle stochastic trajectory model. Thermal volatilization was made by the CPD model. Turbulent chemical reaction was simulated via eddy dissipation model. Intrinsic model was used to simulate Particle of pulverized coal surface combustion. Radiation heat transfer simulation was carried out with P1 radiation model. The result shows that experimental data are accurately predicted by the numerical simulation. Flameless combustion takes place in whole furnace, the maximum temperature difference is about 200K and the temperature is well distributed in furnace. The flameless combustion is in low O2 concentration and low emission of NOx.

Abstract:This paper considers a control approach for a nonlinear system with mismatched disturbances via the estimation of system states and unknown inputs reconstruction. First, under the assumptions that both states and unknown disturbance are measurable, a new sliding mode controller is proposed to stabilize the output of the system. Then, by designing a kind of unknown input observer (UIO), a time varying unknown inputs reconstruction method is established. Meanwhile a set of high gain sliding mode observers are considered to obtain the derivative information of system outputs and the unknown disturbance in finite time, which will be further used in reconstructing the disturbance and designing control strategy. Subsequently, a new observer based controller is developed and its feasibility is proved. At last, a simulation example to a real model is given to verify the effectiveness of the proposed controller.

Abstract:For the sake of the security challenge to manage strange recommendations, a trusted recommendation control model (TRCM) for social network sites is established. TRCM describes four parts in social network site(SNS) recommendation formally including roles of individuals, recommendation routes, factors of trust and control rules. This model combines the belief among individuals and reputation to calculate three kinds of the recommended trust such as serial route recommendation, parallel route recommendation and overlapped route recommendation. Further, factors about the objective bias and confidence in TRCM are addressed to evaluate the reliability of the recommended trust computation. Meanwhile, TRCM defines a set of trust control rules to manage the recommendation in SNS. Experiment results verify the efficiency and feasibility of the model.

Abstract:Processing strategy of receiver clock error offset in least squares and Kalman filtering method for global navigation satellite system (GNSS) solution is mentioned. Disabled clock error offsets will be eliminated through matrix transformation. Due to the fact that Kalman filter algorithm is sensitive to computer foundoff, HouseHold transformation is put in GNSS parameter solution. According to the properties of its initial reflective matrix, this method is proved to be effectively. It is found that the computer roundoff can be eliminated, which is more elegant in theory. Plus, the solution using HouseHold transformation is more space saving and efficient.

Abstract:Rational Polynomial Coefficients (RPC) parameters and ephemeris parameters are two main types of orientation parameters which provide as auxiliary data for satellite images. This paper presents a conversation method for the orientation parameters so the data can be easily used in Earth Centered Earth Fixed (ECEF) coordinate system. We rebuild RPC and collineariy equation in ECEF and integrate the two geometric imaging equations to one positioning model by combining adjustment for multi source spaceborne optical imagery. Several tests for 4 sensor images are given, and the analyses for the model and its application are provided. The proposed model can be widely available for different cases where parameters of imagery orientation or sensor geometric calibration are different.

Abstract:With a consideration of the factors such as the public requirements, the financial status, the project characteristics, an evaluation index system was established based on the balanced scorecard(BSC) and fuzzy analytic network process(FANP) model available for governments at all levels. Furthermore, based on the model selection, a selection and decision process was proposed. Finally, a case study of the application of the method showed that it provided an effective guidance for rational selection of projects to improve the residents well being.

Abstract:According to the service dominant logic idea and value co creation theory, a model of the effect relationship among co creation user experience, user co created value and behavioral intention was established; empirical research of structural equation model was carried out. Meanwhile, the method of hierarchical regression analysis was adopted to analyze the mediated effect of user co created value on the relationship between co creation user experience and behavioral intention. The results show that the co creation user experience has significantly positive impact on user co created value; both of the pragmatic value and hedonic value have significantly positive impact on behavioral intention, and the effect of hedonic value is more significant; the user co created value partially mediates the relationship between co creation user experience and behavioral intention.