Abstract:Five hundred and sixty eight test coupons taken from thirty coldformed thickwalled steel square and rectangular tubes with different sizes of sections, thickness of plates, grades of steel and different manufacturers were tested to investigate the effects of coldforming process on the material properties of different parts of sections. The test results indicate that the coldforming effects have obvious influence on the strength and ductility of coldformed thickwalled sections. The difference of material properties between two adjacent plates connected to the plate containing weld can be ignored. The yield and tensile strength of weld portion and corner parts are enhanced compared with the adjacent plates. The yield strength enhancement factors of corner parts increase with the increase of the ratio of the length of centerline to the inside diameter of corners, but the enhancement factors for tensile strength are independent on the respective parameters. Based on the investigation, distribution patterns of yield strength, tensile strength, tensile to yield ratio and percentage elongation of coldformed thickwalled steel rectangular hollow sections were proposed, which can be used for strength and stability analysis of corresponding beams and columns, while the coldforming effects are to be taken into account.

Abstract:A disasterresistance design method for bridge based on risk is developed by taking account the hazard model and the multilevel performance of bridge. Considering quantitative performance objects, fragility curves of every performance level are obtained through fragility analysis. The failure risk is determined by considering the failure probability, which is calculated by convolving the fragility curve with the hazard model and the damage ratio of every performance level. A tower of cablestayed bridge in seismic district is provided to illustrate the method.

Abstract:Acceleration responses of Sutong Bridge during typhoon Haikui were recorded by structural health monitoring system (SHMS). On the basis of recorded data, the modal parameter identification of the bridge was conducted with HilbertHuang transform (HHT) and wavelet transform (WT) methods, and the identified results were compared with each other. Then, the relationship between modal damping ratios and measured mean wind speed at the bridge site was studied. Results show that the identified modal frequencies based on the HHT method are almost the same with the WTbased modal frequencies. However, the difference between modal damping ratios is larger, which exhibits that the mean values of HHTbased damping ratios are larger than those WTbased results. Besides, the windspeedrelated varying trends of modal ratios identified by the HHT method are identical with those by the WT method.

Abstract:A Bayesian dynamic linear model (BDLM) is introduced, which includes state equation and observation equation of bridge monitoring stress, and the stress is monitored with Bayesian factors. Combining parameters prior information with the early stress monitored data containing noise, the monitored stress state parameters are deduced with Bayesian posterior probability. Optimal stress state estimation uses continuous probability forecastfixed recursion operator to predict the bridge stress. The prediction formula of bridge reliability is given based on BDLM of bridge stress. Finally, an actual example is provided to demonstrate the applicability and feasibility of the proposed model.

Abstract:In order to study the seismic performance of precast segmental bridge pier with grouted sleeve, two pier models with different sleevefixed positions and one castinplace benchmark were used to conduct pseudostatic tests. The damage area, damage development and failure mode of the models were observed. And their seismic performance was summarized by analyzing hysteresis curves, skeleton curves, stiffness, ductility and energy dissipation. The results show that two pier models with different sleevefixed positions share similar seismic performance in spite of difference in damage mode and plastichinge mechanism; the damage of precast pier models is slighter and focuses on the area of segmental interface; precast pier models are emulative considering various seismic performance parameters and their performance is able to meet seismic demand.

Abstract:Based on the fabrication length of main cable and hangers and the installation location of cable clamps, the lower end force matrix of hanger was established, and independent equilibrium equations of temporary system were established for each construction stage. Multisegment twoforce bars considering gravity and multistage spatial catenary were respectively employed to simulate bidirectional sag characteristics of spatial cables, and two analytical methods were proposed for construction processes during hoisting girder. The proposed methods can separately solve the physical effect of any construction stages, without depending on the effect of any previous stages. The example shows that the proposed methods can rapidly respond to the realtime changes of construction state, and are very suitable for the realtime monitoring of construction process and technical decision analysis.

Abstract:Based on reasonable assumptions and flow patterns, a blockage correction method for tall buildings was derived using the momentum principle and the continuity equation. The new method called wake area method (WAM) took the wake area ratio as the key parameter. Then, WAM was validated by wind tunnel test results. Finally, WAM was compared with Maskell’s method (MM). The results show that test data conform to the basic assumptions of WAM very well. Corrected mean pressure and mean drag coefficients by WAM are basically satisfactory. Corrected results by WAM and MM agree well at low blockage ratios (4.1% and 6.1%), while WAM is better than MM at high blockage ratios (8.4% and 10.1%).

Abstract:A joint probability density function of along wind direction and acrosswind direction on wind load effect was built based on the highfrequency force balance test and Copula Frank function. Then, the rule of stress was taken as a design basis and the combination coefficient with a certain assurance of wind load components was solved. Finally, the stress effects obtained from the proposed combination method were compared with the true stress effect and the stress effect obtained from other combination methods. The results show that the combination coefficients provided by the proposed method can make the combination stress effect close to the real stress effect while the traditional combination method tends to be conservative.

Abstract:The process of rock cutting was simulated by discrete element method software where the reasonable contact model for rock summarized from the micro bond contact experiment was implanted. The macroscopic and microscopic mechanism on the crack propagation of each stage during rock cutting was investigated. The results show that: the process of rock cutting can be divided into three stages, i.e. loading stage, unloading stage and residual leaping broken stage; failures of the bonds mainly exhibit tensile failure and sheartorsion failure. The crack under the tip is mainly caused by sheartorsion failures while oblique crack is mainly caused by tensile failures. Therefore, the tension failure theory was confirmed. The unloading stage is the critical stage of the overall process and the efficiency of rock fragmentation will be improved if the fragmentation behavior of unloading stage is efficiently used.

Abstract:From 60 689 km of naturalistic driving data, 1 613 carfollowing events were identified. Two major parameters of carfollowing behavior were analyzed—time headway and reaction time. The results show that forward collision warning(FCW) did not have a significant effect on time headway; while FCW resulted in a 0.13 s decrease of reaction time in daytime driving, and a 0.09 s decrease when a following vehicle had higher speed than the lead vehicle. Key words： forward collision warning(FCW); naturalistic driving study; carfollowing behavior; headway time; reaction time

Abstract:Based on the urban transportation demand of bus corridor, this paper studies the optimization design of multiple services with urban transit. For the operation characteristics of bus lines, the optimization model of minimum costs in terms of waiting time, invehicle travel time and operator cost is developed with genetic algorithm(GA). An application of the model to the case of No.737 bus line in Shanghai shows that the optimization model is practical and effective for satisfying the demand of passengers and improving the operating efficiency of bus transit system.

Abstract:A vehicletracktunnelsoilbuilding spatial coupling model was proposed to analyze influencing factors of vibration of integrated structure, which is composed of intercity railway tunnel and big public building. The results show as follows: the vertical vibration is dominated in the nearby area of vibration source, and the vertical vibration acceleration amplitude is about 1.6 times of transverse vibration. The vibration intensity is more easily changed when the structure constraint condition alters. Room size has an effect on the dominant vibration frequency. The vibration of building structure changes with the stiffness of tunnel foundation, mainly in 1~5 Hz.The sensitivity of vibration level to velocity is lower when the structure constraint becomes stronger. The vibration in the nearby area of vibration source can be attenuated by decreasing velocity.

Abstract:Solid wastebased composite geopolymer was prepared from high calcium fly ash and construction waste brick powder. The setting time and the rheological properties were also investigated. The results show that the initial setting time and final setting time of the solid wastebased composite geopolymer increased with the increase of the content of waste brick powder, shortened gradually along with the increase of the modulus of water glass, slightly increased with the increase of the content of water glass, and rapidly shortened with the increase of curing temperature. Rheological curve of the solid wastebased composite geopolymer was fitted by Matlab, and the results show that the measured data are in according with the HerschelBulkely fluid curve. With the increase of the content of waste brick powder, the yield stress and viscosity of geopolymer paste increases but the flow behavior index decreases.

Abstract:Quasistatic and dynamic tensile tests of Q235 steel were performed to study the dynamic tensile behaviors under different strain rates by INSTRON and HTM5020 testing machines. Experimental results show that Q235 steel is very sensitive to strain rates. Both the yield strength and the ultimate tensile strength of Q235 steel increase with the growth of strain rate. The hardening characteristics also vary evidently with the increasing strain rate. The dynamic increasing factors of both engineering yield stress and engineering ultimate stress can be expressed as the function of strain rates by using the CowperSymonds model. Based on the true stressstrain relationship before necking of Q235 steel, the JohnsonCook model is modified to take into account the coupled effect of strain hardening and strain rate.

Abstract:This paper presents an experimental study on very high strength steel S960 after cooling down from elevated temperatures and its postfire elastic modulus, yield strength, ultimate strength and stressstrain curves are obtained. The results show that the material properties of steels after fire are dependent on their grade and process of manufacture. Based on the experimental results, this paper proposes some unique predictive equations for evaluating the postfire mechanical properties of S960.

Abstract:An ant colony algorithm based cooperative optimization for machining scheme selection and operation sequencing of engine cylinder is proposed. Considering that features have alternative machining schemes, one machining scheme is chosen randomly for every feature in total iterations, and an operatingconstraint matrix is created automatically based on featureconstraint matrix and operation priority. Aiming at minimizing the transforming times of manufacturing resources that contain setups, tools and machine tools, a son optimal solution is found by the ant colony algorithm in the son iteration. In addition, a global optimal process line is ensured to be gotten through the usage of elitist preserving strategy in the total iteration. Finally, an engine cylinder case is illustrated to prove the validity of the proposed method.

Abstract:The planetary gearbox applied to the hoisting mechanism and the experimental scheme based on powerclosed platform were designed to evaluate the vibration and temperature rise performance of planetary gearbox. The vibration acceleration of planetary gearbox under different working conditions was obtained, and the dynamic characteristics of vibration were analyzed. Then the temperature test was accomplished to gain the temperature rise of critical positions and lubricating oil, and the oil’s temperature accorded with the standards. The experimental results show that the vibration and temperature rise performance of planetary gearbox applied to the hoisting mechanism reaches the requirements.

Abstract:A standard kε model was used to analyze the effect of row number and fin pitch on the flow and heat transfer performance of heat exchanger. The average heat transfer coefficients of each row of fin was given, and also the relationship between row number and j, f factors. It is found that the fin pitch is mainly related to air side pressure loss, and when the fin pitch is smaller than 2.5 mm, the air side pressure drop will be more sensitive to air velocity. The comprehensive performance of heat exchanger could be improved through the use of high thermal conductivity material in fins.

Abstract:Ground temperature and systematic parameters of running groundsource heatpump system were collected from a laboratory in Tongji University, and the change laws of the parameters were analyzed to evaluate its effect on the system. The following conclusion can be drawn: the ground temperature rises 0.64 ℃ in 44 d, the range of temperature variation decreases with depths, and the temperature will be a relative constant when depth is deeper than 120 m. The ground temperature recovery rate is 0.14 ℃?100 d-1, and with the increasing of soil temperature, the temperature gap of inlet and outlet water will decrease 0.87 ℃ and the system performance rate and heat transfer efficiency will decline.

Abstract:A concept model for compressed air energy storage system in aquifer (at a depth of 800 m and with a permeability of 0.5×10-12 m2) was designed and investigated through numerical simulations. The pressure variation, gas plume evolution and system cycle times during the formation of initial gas bubble and system daily cycle were analyzed. The modeling results show that there is a small change in pressure and gas saturation after each daily cycle. However, the total effective gas volume in gas bubble decreases with cycle continuing. Makeup gas should be injected into gas bubble during daily cycle or carry out another gas bubble injection after cycle is ceased. The comparisons of daily cycle and weekly cycle scenarios indicate that weekly cycle needs higher requirement for system. Aquifers as storage tank for compressed air energy storage is feasible and should be designed according to the specific geological conditions.

Abstract:By introducing granular computing into concept lattice, and integrating similarity measure model and structure information of concept lattice, the paper proposes an expanded concept lattice model based on granular computing. It can help to expand intent and extent of classical concept, and also can effectively reduce the scale of concepts to some extent. The model is not only a useful attempt and exploration for the fusion of these two theories, but also an effective means of expanding the classical concept lattice.

Abstract:After studying the computation rules in vector form intrinsic finite element(VFIFE) and the feature of spatial truss structure, a node distributing mechanism for parallel computing was proposed. According to the defined rules of decomposing, the model data of spatial truss structure were dynamically decomposed. Based on the results of decomposition, the data sets of nodes were dynamically decomposed, and the parallel computing was accomplished in the specific frame. The numerical experiments indicate that, the node distributing mechanism greatly improves the speed of spatial truss structure analysis, in contrast with those based on serial computing or classical finite element method.

Abstract:Drawing on the idea and mechanism of natural ecosystem resolving the optimization problem, the concept of “Urban Land Ecosystem” was proposed. Firstly, the structure and the selfevolvement mechanism of urban land ecosystem were defined. Then, the algorithm model of urban ecosystem’s selfevolvement process—Urban Land Ecosystem Evolutionary Algorithm called urban ecological algorithm for short was established. Lastly, the mathematical model of urban development land structure optimization was set up and could be resolved by the urban ecological algorithm. Shanghai’s urban development land structure optimization was selected as the application example. The experimental results show that the urban ecological algorithm could effectively solve the problem of structure optimization of urban development land.