Abstract:The simulation of random traffic load is the foundation and crux of load assessment and performance evaluation of bridges. The current traffic simulation based on the Monte Carlo method is inappropriate for describing the dynamic evolution of traffic on microscopic scales within a relatively long span, while the singlecell method based on cellular automaton (CA) remains to be improved concerning precision. In the singlecell method, a car is simulated by a single cell, which could not consider the influence of axle load and exerts a limit on enhancement of simulation precision. In this paper, based on the current CA, a model is proposed to simulate an axle by a cell and to simulate a car by a number of consecutive cells, which is defined as multicell cellular automaton (MCA). It verifies the mathematical model with realistic traffic and its load data. It is demonstrated that the parameters of traffic flow and traffic load, such as traffic volume, time headway, velocity and weight of simulated traffic are reproduced accurately by the multicell method. With the distribution load, bearing shear and midspan moment in a simply supported girder with a length of 1 000 meters set as indexes respectively, the statistics analysis of the load response characteristics of simulated and realistic data is conducted. The result indicates that the relative errors of simulated data of the MCA model to realistic data are within 5%. When MCA is applied, the precision of load response can be increased from the correlated error of less than 17% in the traditional singlecell method to a relatively high precision.

Abstract:To investigate the effect of the concrete shear keys at abutment on transverse seismic reaction of a short and medium span continuous girder bridge, a finite element model was built based a continuous girder bridge. The effects of peak strength of the concrete shear keys at abutment on transverse seismic reaction of a continuous girder bridge were analyzed using the nonlinear time history method. The results show that when the peak strength of the concrete shear key at abutment increases, the shear demand of the top of abutment increases while the displacement demand of bearing at pier decreases, but the decrease amplitude declined to zero. A reasonable selection of the peak strength of the concrete shear key at abutment can effectively reduce the displacement demand of bearing at the pier, and avoid the severe seismic damage on the abutment.

Abstract:Utilizing the powerful matrix calculating function from Matlab and the opensource characteristics from OpenSEES, this paper proposes a substructure testing system based on MatlabOpenSEES by adopting mixed programming. It introduces three basic components, which are the Matlab module, the OpenSEES numerical substructure simulation module and the interface function between Matlab and OpenSEES, and the principle of the proposed substructure system. The Matlab module is used to realize the function of solving motion equation, the loading control, and data acquisition of experimental substructure. The OpenSEES numerical substructure simulation module, which is a submodule called by Matlab module, is used to realize the numerical simulation analysis of numerical substructure. The interface is used to realize the data transmission between Matlab and OpenSEES by the text or Socket communication variables. The proposed system can be programmed on an external computer connected with the hardware I/O channel of the MTS electrohydraulic servo control system through the data acquisition card. In this way, the system can not only avoid the complex underlying programming technology of the electrohydraulic servo control system, but also reduce the requirement of system itself and finally reduce the test difficulty and cost. The test results of three largescale structure test models verify the feasibility of the proposed substructure testing system.

Abstract:In this paper, the monotonic directshear tests composed of eleven C80 and four C40 concrete pushoff specimens were conducted. The failure patterns of specimens, loadslip relation curves, and loadrebar strain relation curves were obtained. The experimental results were analyzed in terms of concrete strength, interface shear rebar strength, and interface types. Afterwards, 32 sets abroad results of interface shear capacity were compared with calculated values using relevant standards at home and abroad. It is found that two failure patterns occur, specifically the interface shear failure and concrete punch failure. The load of C80 specimens with rough interfaces at their first peaks are lower than those of C40 specimens. Moreover, the load values of specimens with shear keys are larger than those with rough interfaces, and the load increases with interface rebar strength. The ratio of capacity calculated by JGJ 1 and test results is between 0.33 and 0.72. Compared with MC2010, ACI318 and EN1992, JGJ 1 is more conservative. Based on the test results, regression analysis was finished and a modification suggestion calculation formula aimed at interface between high strength concretes was presented.

Abstract:A field monitoring program was performed to measure the steel strain in segments of a shield tunnel deeply buried with high pore water pressure of Nanjing Metro Line 3 project. Concerning the nonlinear properties of concrete and segment joint of tunnel, an improved algorithm was proposed to compute the internal forces of deeply buried shield tunnels under high water pressures based on three existing reverse calculation methods, and the results were compared to the ones computed in structural design. The results show that the improved algorithm can reflect the actual stress state of segments, especially the lining of shield tunnels deeply buried with high pore pressure; the distribution of internal forces calculated in design is almost equal to the one computed by the improved algorithm, but there are some quantitative discrepancies; the axial forces of segments and joints calculated in structural design are approximately half of the backcalculation results; the bending moments of segments calculated by the proposed algorithm are close to the results of the modified routine method at the bottom of the tunnel while approximate the results of the beamspring model at the roof and haunch of the tunnel, and the bending moments of segment joints are greater than the results of the beamspring model. The insights provided from this study can contribute to the improvement of largesection shield lining design.

Abstract:In this paper, flume model test on local scour around piles embedded in composite sand was performed, and comparisons and discussions of such predictions of local scour depth in current China and America were also made. The test results show that the scoring progress is slow because the main scoured parts are coarse sand in the early stage. However, in the later stage, as the fine sand becomes the main scoured parts, the progress is faster. The upperlayer coarse sand can help to keep the lowerlayer fine sand from being scoured, and the thicker the coarse sand layer was slower than the fine sand will be scoured. The present design codes of China and USA both work well, but these codes often lead to a much exaggerated results. Therefore, to reflect the effects of the coarse sand on the fine sand, the scour depth should be reduced.

Abstract:Contact forces acted on representative pentagons were achieved through fringe analysis based on the photoelastic experiment of pentagons subject to loading and unloading. The evolution of contact forces reveal that residual contact force lies remarkably in contacts between deepburied pentagons while barely in contacts between superficial pentagons during unloading. Photoelastic experiment was reproduced via discrete element simulation, and the comparison of both interparticle contact force between photoelastic test and numerical test demonstrates that the numerical model is reasonable. Besides, the stress evolution of pentagon packings during loading and unloading was studied. The results indicate that the spatial distributions of stress and force chain, residual stress and residual contact force are consistent.

Abstract:For the quantitative analysis of the speech articulation in highspeed train compartment under strong noise environment, the speech articulation was achieved in different positions of highspeed train compartments under different speeds and speech levels by using the relationship between Chinese speech articulation and the speech transmission index (STI) according to IEC 6026816(2011). The results show that the interior location below the pantograph is the weakest position for speech articulation. In addition, at this position speech articulation changes with speed linearly rule and with speech level quadratic nonlinearly. Then, by using multivariate nonlinear regression analysis, the relational expression of interior speech articulation, speed and speech level was established. The standard deviation between the test results and the curve was 1.75% and the coefficient of determination R2 was 0.963, which indicates that the expression can well simulate the relationship among them. Compared with the evaluation method based on speech transmission index, the objective parameter of this evaluation method is simpler and this method has more application values.

Abstract:A refined etype fastener model based on its real size was established and nonlinear contact and restraints were used to deal with the interaction between the components of the fastener. The modal shapes and harmonic response characters of the fastener, in both unrestraint and service status, were analyzed using the timefrequency responses analytical method. Besides, the main cause for fastener fracture was revealed and compared with the field test results. This research shows that the first and second resonance frequencies of fasteners in unrestraint and service status (808 Hz~812 Hz, 869 Hz and 410 Hz~420 Hz, 530 Hz) agree with the test section corrugation frequencies, which is the main cause leading to fasteners fracture. An effective way to reduce or avoid fastener fracture is to change the running speed of the train. To avoid the resonant response, it is recommended to control the traveling speed under 80 km?h-1 after calculation.

Abstract:Taking the roller system of the heavy equipment telescopic boom as the research object, the overloading contact tests of the rolller system and the supporting plate was conducted to investigate the wear mechanism of friction specimens, in order to improve the wear resistance and the life span of the mechanical parts. By using scanning metallography, SEM and EDS techniques, the surface morphologies, chemical composition and plastic deformation of the worn test specimens were analyzed. The results show that under heavyduty conditions and with the increase of wear times, the wear mechanism of the supporting plate is both abrasive and adhesive. However, the wear of the roller is less serious than that of the supporting plate because of its higher hardness. The wear mechanism of the roller is both abrasive and mild adhesive. A study of the worn roller layer microstructure indicates that lamellar pearlite has dislocation movement and microstructure damage in the local area, which shows that the plastic deformation of the roller has happened under overloading contact.

Abstract:A mathematical equation system was derived based on the Lagrange method for wind vane electric double inertia vibrator fatigue loading system, and thus a electromechanical coupling equation of the system was built. Using the small parameter cycle average method, the approximate analytic system vibration was derived for coupling process synchronization stability conditions. The influencing factors on the motor load torque in the process of system operation were obtained, and the mechanism of system coupling was revealed. On this basis, a simulation model was established to numerically simulate system frequency characteristic, and the vibration characteristics of blade under different loading frequencies were obtained. Experimental study on system frequency characteristics, main resonance electromechanical coupling characteristics, and control synchronization verifies the correctness of the mathematical model and simulation model and the feasibility of the control, providing reference for engineering application of fatigue loading system and test.

Abstract:The realizable k –ε method was used for steady simulation of external airflow of Ahmed model with different rear slant angles, and the large eddy simulation (LES) method was employed for transient simulation. Based on the pressure and velocity fluctuation distribution, Ahmed body surface pressure fluctuation level distribution and aerodynamic noise characteristics in the far field were studied. Furthermore, the relationship between wind noise radiated in the far field and aerodynamic drag was studied. The results show that there is a significant difference between model rear pressure and velocity fluctuation distribution of Ahmed model at different rear slant angles due to different flow separation pattern, which influences the noise power radiated to the far field and its distribution. Additionally, there exists a certain relationshape between noise power and aerodynamic drag. Therefore, optimizing rear slant angle is very important for rear wind noise control.

Abstract:Based on a retrofitted twocylinder diesel engine, combined with a selfdesigned intake and direct high temperature water injection system, the knock condition existed in internal combustion rankine cycle engine have been investigated at a high compression ratio and high oxygen fraction. The results show that compared with air intake, the knock occurred results in a high oxygen faction and the knock intensity (KIA) calculated from incylinder pressure Fourier transfer and bandpass filtering reaches 0.26 MPa. The knock frequency is controlled by utilizing a suitable direct water injection strategy and the combustion stability is sustained. Meanwhile, the injected high temperature and pressure water evaporate after heat absorption, which improves system thermal efficiency effectively.

Abstract:Based on the reference relation between piston velocity and piston position in the stable operation stage of the linear engine/generator system, a trajectory tracking control strategy based on PI controller was proposed. A system Simulink model was established which was verified to be accurate by experiment. Simulation results show that when fuel injection quantity fluctuates or misfire happens, the proposed control strategy makes the piston trajectory go back to the reference trajectory within one cycle, realizing an effective and prompt control over piston motion.

Abstract:The hydraulic antikink system is an important component equipped in lowfloor trams to improve the riding quality, stability and curving behavior of the vehicles. The system has two functions in antikink and lateral damping. A mathematical model for damping properties was established based on the operating mechanisms of the system. Furthermore, the influence of throttle valve and pressure limiting valve on the damping characteristics of the system was investigated by simulation. The calculating curve of the damping characteristics coincides with the experimental curve, which proves the correctness of the damping mathematical model.

Abstract:In the electropneumatic breaking system, the dynamic performance of the electropneumatic brake solenoid valve directly determines the train safety. To improve the sensitivity and reliability, the solenoid valve armature clearance, coil turns, spring preload and other major structural parameters were adjusted based on the law of electromagnetic wave energy flow fluctuation and its influence on the dynamic characteristics of valve during action process. The dynamic electromagnetic field range of changes was controlled, and the performance parameters were optimized. It is found that the electromagnetic field energy output was reduced and the operating temperature rising velocity was decreased.

Abstract:A simplified model of envelope HAVC load prediction for individual building was proposed, in which the number of input parameters was reduced to six, and prediction accuracy guaranteed. This building thermal dynamic model was established with the open source library of Buildings Modelica Library developed by Lawrence Berkeley National Laboratory. The linear aggregation method was used to reduce the order of simplified model, in order to accelerate calculation. This simplified model makes possible the fast calculation of HVAC load for each individual building, and hence provides the method basis to expand to the regional scale simulation. Finally, discussion was conducted to expand the method in regional dynamic load prediction in the future.

Abstract:A field measurement was conducted on to a real building for temperature distribution at its faade and louver blinds in this paper. Halfhourly surface temperature distribution of louver blinds, louvered faade and unlouvered faade were performed by this measurement. From this data, a conclusion on maximum temperature difference (about 10 ℃) between louver blinds and louvered faade was reached. Besides, the surface temperature at louvered facade was compared with that at an unlouvered one. Based on the measurement above, the effect of louver blinds on convective and longwave radiative heat transfer at building faade was briefly analyzed, and the importance to correctly describe these two process was pointed out.

Abstract:The relationships between vehicles, such as position, velocity and distance, are the main cantonments of microtraffic flow parameters. These parameters are important to unmanned driving, intelligent traffic, etc. A novel method was proposed for microtraffic flow extraction from mobile laser scanning data. Based on the mobile sectional laser scanning data, a threshold was selected to segment and classify the original point cloud into different vehicles. Then, the quadratic polynomial weighting method was used to extract the feature point from vehicle’s point cloud. The distance and velocity parameters were then computed from adjacent vehicles or adjacent sections. Finally, an experiment was conducted in Shanghai Yan’an elevated road to verify the traffic flow parameter extraction method from mobile laser scanning data. The results show that such parameters could be easily and accurately calculated. The average distance error of directly front or behind car is about 0.058 m and its average velocity error is about 1.62 km?h-1. The average distance error of sideward car is merely 0.100 m, and its average velocity error is about 1.29 km?h-1.

Abstract:BeiDou navigation satellite system (BDS) integrates legacy PNT and authorized differential service, where differential service is provided by the satellitebased augmentation system (SBAS). The latest progress of the BDS SBAS development were introduced and the performance of pseudorange based and carrier phase based user differential positioning was evaluated. Observations of 10 stations in Chinese mainland were used. The results show that the coordinate accuracy of the pseudorange differential positioning (SBAS SPP) reaches 0.4 m, 0.3 m and 0.8 m in the North, East and Up directions respectively, which shows an improvement of 53% over the legacy SPP. For the evaluation of carrier phase based positioning, kinematic precise point positioing (SBAS PPP) was performed and compared to the kinematic PPP results based on post processing precise satellite orbits and clocks (POST PPP). The results show that the SBAS PPP kinematic coordinate estimates converge to 1 meter in 7 mins on average and the coordinate accuracy reaches 0.1 meter in horizontal and 0.2 meter in vertical component after convergence. Compared to the results of POST PPP, SBAS PPP shows better accuracy and shorter converge time, which indicates that the accuracy of BDS satellite orbits has been increased and clocks still have to be improved.

Abstract:Based on property rights, enterprises are divided into stateowned ones and non stateowned ones. Considering the lag of impact, a bidirectional model was designed for an empirical research on the stagecrossing interaction between CSR (corporate social responsibility) and FP (financial performance), with the data of Ashare listed companies in Jiangsu, Zhejiang provinces and Shanghai municipality in 20102014. The results show that, the higher current CSR is, the better current FP will be; the positive effect by current FP on nextstage CSR is greater than that on current one; the nature of stateowned enterprises impairs this reciprocity. Enterprises should recognize the significance of CSR and make it a driving force for sustainable development.

Abstract:A controllingactivity based model was proposed to estimate the construction duration of terminal megaprojects from the consulting achievements of project timecontrolling for more than ten airport megaprojects in China (2000—2016). First, typical construction sequences of controlling activities for each possible critical path were determined, and the distributions of nonoverlapping time between controlling activities were fitted. After that, based on fitting the duration distributions of four possible critical paths, a model for predicting the duration of terminal building was proposed and applied to three completed terminals. The results show that the proposed model reasonably predicts the construction duration for the case projects. Compared to traditional risk planning methods, the model proposed simplifies the complex work.