GU Ming , ZHAO Mingwei , QUAN Yong
Abstract:The paper presents a comprehensive review of worldwide research efforts in typhoon risk assessment of structures during recent decades,which covers the following topics such as typhoon hazards analysis,exposure study,structural vulnerability assessment,loss estimation,assessment of mitigation measures,modeling changes in typhoon risk over time,uncertainty analysis and sensitivity analysis.The typhoon hazards comprise strong wind,rainfall,and induced ocean effects including storm surge and wave.The methods of structural vulnerability assessment are grouped into qualitative and quantitative methods,and the latter are further classified into empirical methods,methods based on logical hypotheses,methods using structural reliability analysis,and methods utilizing artificial intelligence techniques.Some limitations in current research are pointed out and recommendations for future research are given.
GAO Wanyang , HU Kexu , LU Zhoudao
Abstract:Based on the reliable models of mechanical properties degradation of concrete,steel reinforement steel and carbon fiber reinforced polymer (CFRP) materials with increasing temperature being taken into account,the paper presents a numerical model of insulated CFRP strengthened reinforced concrete beams and a nonlinear finite element method (FEM) program (named NFACCB) of strengthened beams under exposure of fire event with the generalpurpose code ANSYS.Moreover,the coupled thermomechanical is analyzed.The simulated results show that although CFRPs are sensitive to elevated temperature,satisfactory fire performance behaviour can be achieved by providing reasonably supplemental fire insulation.Fire insulation thickness and fire load ratio have a significant effect on fire performance of strengthened beams;while the influence of longitudinal bar reinforcement,the amount of CFRP strengthening,the thermal conductivity of insulation materials and sectional dimension are moderate;the influence of the midspan deformations with thermal specific heat and density is the least.
Abstract:The paper presents a new hexahedral generalized conforming element with coarsemesh high accuracy to avoid resorting to a large number of elements in the 3D finite element analysis of thinwalled structures.The element is developed on the basis of the 12node hexahedral isoparametric elements.By introducing different unconforming displacement functions into the different coordinate directions, the element maintains good performance even if the element is coarse meshed.The unconforming displacement field satisfies the generalized conforming condition so that the element is convergent.Numerical examples indicate that the element yields good results even if one of the three dimensions is much longer than the other two.
Abstract:Pseudo static tests are conducted on the same four fourstory 1∶3 scaled shortleg shear wall specimens with dual binding beams in a bid to investigate how concrete stochastic characteristic affects the structural responses.Structure design,material preparation,specimen construction and loading system are fabricated strictly so as to eliminate other uncertain factors.Loaddisplacement curves,strain curves and partial relative displacement curves are obtained.Moreover,the bearing capacity,stiffness,and ductility are discussed.Strains variability,displacements variability and redistributed inner forces behavior of three typical crosssections are studied.Finally,failure characteristic of different specimens is contrasted.It is concluded that coupling of concrete randomicity and nonlinearity has notable effects on structural responses.
Abstract:With the finite software ANSYS,a formula is simulated on the basis of the analysis results of 80 samples with a consideration of geometry nonlinear,material nonlinear and contact nonlinear.The results from the formula agree well with those specified in Chinese Code Steel Reinforced Concrete Composite Structure Specification.The formula can provide a reference for the engineering design.
YAN Zijian , XIA Caichu , WANG Xiaodong , ZHANG Chunsheng
Abstract:Shear rheology tests were carried out to study the elasticviscoplastic behaviour of marble rock joints from the Jinping Hydraulic Power Station.The variation law of shear displacement of rock joints with time is analyzed and the effect of normal stress on rheological properties of joints is studied.A rheological model with consideration of normal stress is built according to the aging theory and the genetic creep theory.Based on the result of tests on rock joints, the proposed model is identified and the parameters in the model are determined.Comparison between the model and test results shows that the proposed rheological model is reasonable.
LIU Zheng , SHEN Jianwen , SHI Shuzong , YU Zhan
Abstract:Based on the earthquake acceleration records at deep alluvium sites and rock sites in the Western United States,the attenuation laws of peak ground acceleration at deep alluvium sites and rock sites are obtained respectively,and amplification effects of deep alluvium sites are discussed.The results show that the amplification effects for Site Class D and E are overestimated in the 2003 NEHRP.
JIA Mincai , WANG Lei , ZHOU Jian
Abstract:Numerical simulations of macromeso mechanical behaviour of an excavation process supported by deep mixing piles were performed by secondary exploitation using the Particle Flow Code in 2 Dimensions(PFC2D code),which was developed based on the assemblies of particlular materials.The PFC2D model of a real pit was established according to similarity theory,and the mesoscale parameters of soils in the model were determined through a series of calibration biaxial tests in order to link the change of mesoscale fabric to macroscale response.Deformations of ground surface were analysized for all excavation steps,including heaves of pit bottom and horizontal displacements of mixing piles.The study verifies that PFC2D can be used to visualize the evolution of excavation process.Comparison between simulation results and the measured data proves the feasibility to explore the interaction mechanism of retaining structure and soils around from the prospect of the mesomechanics.
HOU Qingzhi , REN Jianting , GU Ming
Abstract:Considering soilstructure interaction (SSI) and fluidstructure interaction (FSI), the axial vibration of a buried pipeline is analyzed with traveling wave method.The effectiveness of the algorithm is verified by an experiment.The influence of Poisson coupling, junction coupling and soil properties is studied in a numerical example.The numerical results show that amplitudes of vibration increase remarkably at some low frequencies when Poisson coupling is considered.If the fluid being ignored or just being regarded as a rigid filler,the characteristic of the system cannot be reflected,which may result in system risk under some lowfrequency dynamic actions.Due to the change of boundary conditions, junction coupling reduces the natural frequencies of the system.The natural frequencies of the system increase when the shear stiffness of soil increases.Soil damping reduces the amplitudes notably, but has little effect on the frequency of the system.
Abstract:Based on the test of the micro and macroperformances of Shell 60-80 asphalt after two aging processes,an exponential relation is found between residual viscosity ratio, dispersion degree and colloid instability index and aging time.A linear relationship is also found between the micro and macroindexes of asphalt,therefore,microindexes or macroindexes of asphalt can be used to characterize the asphalts’ aging regulation.The decline amplitude in the second aging process is larger than that of the first one,which verifies a correlation between antiaging of asphalt and aging frequency.
YUN Meiping , LIU Bin , YANG Xiaoguang
Abstract:Drivers’ reading and reaction process was analyzed and divided into four stages,including sensory,perception,judgment and execution.An analysis was also made of the necessary time and distance for lane change under uninterrupted traffic flow on expressway,and a method was proposed to determine visual disappearing site of traffic sign.Critical crossing time gap in lane change was established with a consideration of weaving safety.By introducing success probability of lane change,minimum driving distance for lane change was formulated.Then a theoretical model was established to describe minimum required frontal distance in traffic sign installation.The outputs of the model show that the weaving distance becomes longer when traffic volume is larger.The minimum frontal distance of traffic sign increases evidently as traffic volume becomes larger.The proposed model was tested in a section of TongSan freeway in the city of Yantai to verify its rationality.Finally,the paper presents the minimum frontal distance of traffic sign under different sucess probabilities of lane change.
Abstract:As a case study,three wellknown onramp metering algorithms,including fixedtime,Alinea and Flow,were evaluated via traffic simulation on Shenzhen Chunfeng expressway on various traffic demand levels,the parameters calibrations were also expatiated. Simulation results show that onramp metering can effectively improve mainline traffic when traffic demand is higher than a certain level.Both Alinea and Flow perform better than fixedtime metering,but increase ramp delay and queue obviously. Flow outperforms Alinea in this case study because the traffic bottleneck is closely related to its upstream onramps traffic.Finally,the scenarios of adding queue adjustment into Alinea and Flow were simulated.Results show that the distance of queue detectors to ramp entrance plays a key role to tradeoff between the mainline congestion and onramp queue.
LIU Tangzhi , TANG Boming , SHAO Dong
Abstract:An ideal milledin rumble strip is recommanded for China expressway on the basis of the illustration of the principle of rumble strips,the characteristics and conditions of the four types of rumble strips used in foreign countries.In addition,the best design dimensions and layout are proposed by testing five design dimensions of milledin rumble strips and evaluating the alert effect to the fatigue drivers.
YANG Xin’an , LIAO Lijian , LING Baolin , YE Peixu
Abstract:Based on the wavelet transform method,the primitive Ground Penetrating Radar(GPR) data were transformed into the signal whose principal constituent was only the sudden changes of the interface information.An interfacetest algorithm strategy is designed according to the characteristic of reflection echo from interfaces.By extracting the information of individual points of the interfaces from all traced data,an interface classification principle is proposed to distinguish the rupture,fluctuation,branching and intersection of the interface,so that the interfaces are intelligently traced.The actual testing shows that the method can be used to plot the graph of railroad trackbed interfaces swiftly,reflect the actual conditions of railroad substructures,and process a mass of data.The engineering technicians are released from the burden of the image interpretation.
LU Zhibo , DENG Dehan , CHEN Qiaoyan , ZHAO Limin
Abstract:A study is made of the physiological and ecological changes of earthworms treating biofilm sludge with different kinds of food,moisture contents and temperatures,and factors influencing sludge treatment as well.The results show that earthworms grow up quickly as they enjoy biofilm sludge with an average increase about 2.51%~3.9% in the weight per day.In the biofilm sludge with quartz sand medium,the ideal moisture content is 12%~18%,and temperature 15~25 ℃.The trend of changes of earthworms’ respiratory rate is basically consistent with that of the average gained weight.The temperature is an important factor to earthworms’ respiratory rate.When food is sufficient,earthworms’ respiratory rate in 25 ℃ is higher than that in 15 ℃,earthworms can not breathe normally when temperature is low (5 ℃),or high (35 ℃).
ZHANG Guangyi , NIE Fahui , NING Jing , LI Tian
Abstract:Probability analysis method is put forword to estimate the longterm operation efficiency of urban concavedown greenbelt which stores and infiltrates rainfall runoff.Case study was also carried out for proper design of the concavedown greenbelt based on the 20year statistical data of the hourly rainfall characteristic parameters in Shanghai area.The results show that this method can ensure the safety of the engineering design of urban concavedown greenbelt,and that the optimal practical concave depth was 80~160 mm,under which the storageinfiltration efficiency could reach up to above 90%.
SHI Huisheng , GUO Xiaolu , LIU Hongyan
Abstract:An investigation is made into the effect of flue gas desulphurization (FGD) gypsum used in slag concrete on the gas permeability and chloride ion penetration property of the concrete.The results show that the strength of slag concrete can be enhanced if adding FGD gypsum.The coefficient of gas permeability of concrete declines and the chloride ion penetration resistance improves as well.FGD gypsum used as a useful composition of admixture in slag concrete can improve the penetration resistance of the slag concrete and enhance the durability.Therefore,two sorts of byproduct can be recycled.
Abstract:Based on the continuum mechanical theory and Eshelby’s inclusion theory,a representative volume element model under uniaxial tension was built.The contribution of each constitute phases and their interaction to the overall strain hardenability of TRIP steels was analyzed in detail with the method of regarding ferrites the matrix and the other constitute phases the inclusions.With the volume fraction of retained austenites as a variable,a micromechanical model calculating strainhardening exponent considering transformation induced plasticity effect was proposed.Comparison between calculated strain hardening exponent with experimental result and published data shows the proposed model can predict the strainhardening exponent of transformation induced plasticity(TRIP)steels and strainhardening exponent can change with the plastic strain and fluctuates along a parabolic path instead of constant during the whole deformation.
JIN Lijun , LIAO Liming , AN Shichao , MEI Jian
Abstract:The paper presents a brief introduction to the characteristic of the traction power system.In view of the timesharing and high empty loading rate of the traction power systems,a special mechanical switch capacitor and thyristor control reactor static var compensator is designed.The effect of harmonic filtering in different types of loads and corresponding switch scheme is emulated in PSCAD.The study provides a reference for ensuring the power quality of the traction power system.
GUO Qiyi , ZHOU Guifa , MAO Zhongya
Abstract:90 MW DC arc furnace uses the current 2transformer rectifier bridge thyristor controlled by adjusting the angle trigger to compose 24 pulse wave rectifier circuit.The 24 pulse wave rectifier circuit generates harmonics mainly about 11,13,23 and 25 times harmonic,these highfrequency harmonics do great harm to arc furnace on the effectiveness of the current regulation.A variety of wavelet is employed in thresholding 90 MW DC arc furnace power system harmonic signal noise,and the optimal choice from the noise threshold optimize the signal processing correspondingly.The simulation results show that 90 MW DC arc furnace system harmonic signal wavelet denoises the optimal threshold for sqrt (2log (length (X))) threshold,and the harmonic components reduce obviously,as a result,the operation of the 90 MW DC arc furnace is ensured.
HAO Yongtao , XIAO Wensheng , HU Yajun
Abstract:This paper presents a feature recognition algorithm for discrete cloud points based on dimension information and a detailed wavelet decomposition method for 2D and 3D discrete cloud points.128 discrete points are adopted to analyze the algorithm,and it is found the result of this example meet the requirement for discrete cloud wavelet decomposition.The discrete cloud points are decomposed and different features are extracted according to its dimension information,and these decomposed data can be further processed to meet different visualization display requirement.
DU Junwei , XU Zhongwei , YU Gang
Abstract:A Generic framework of component composition with algebraic Petri nets,which was presented by Padberg J and Ehrig H on the basis of the graph transformation rule,provides a powerful support for dynamic and static component assembly in different fields.However,this framework is not flexible enough in practice due to the disjunction among import interfaces in each reduction step.The framework is extended by presenting a unique condition of composition.Based on the condition,the structure uniqueness and content compatibleness are proved,and the conventional synthesis of Petri nets in this framework is also discussed.Finally,the interlocking logic based on this framework is illustrated.
ZHANG Xue , TONG Xiaohua , LIU Miaolong
Abstract:Change and transformation of land cover types in suburban area are studied with an extended pixel comparison change detection method based on remote sensing classification.The extended method supports change detection of diverse land cover types synchronously. According to the characteristic that different land cover type is denoted by different gray value or RGB color in imagery, the changes of land cover types and transformation between them were statistically computed on the basis of overlapping land cover imageries of gray or RGB color to land cover change imageries.Taking Jiading District of Shanghai as an example,the change information of various land cover area and transformation processes between land cover types were first detected in the threeyear intervals of 1989—1995,1995—2001 and 2001—2006 by extended change detection method based on the land cover classification for four typical Landsat TM imageries in 1989,1995, 2001 and 2006, and the practicability and applicability of the extended change detection method are accordingly verified.
Abstract:In view of interrelations and constraints of the result of selecting matching area and the information of reference image,the paper presents a method for selecting suitable scene matching area by using support vector machine.First,intensitybased and featurebased measure parameters of reference image were selected to represent the reference image’s information accurately and effectively.Then the measured parameters were coded as input feature vectors of training set and matching results were gained as output of training set by normalized crosscorrelation algorithm.Finally,after the training with appropriate radial basis kernel function and corresponding optimal parameters,decision function which could separate suitable and unsuitable matching area class was obtained.Thus,matching area can be extracted from random reference image by decision function.The experimental results show that this method holds the capability of flexibility and jamming resistance as well as proper guide to selection of suitable matching area from complex reference image.
Abstract:The paper presents an investigation and a study of the condition of apssing per dwelling house implementation in some domestic cities.A passing per dwelling house measurement index system is established on the apparent quality and the function,and also a model of performance appraisal for contractor based on analysis hierarchy process(AHP) is set up.The sum of all the products of the composite weight coefficients and the corresponding qualified rate of the finished items is adopted as the standard for contractor performance ordering and contractor stimulation.The proposed model is an effective method for performance appraisal and stimulation for contractors during passing per dwelling house.
Abstract:This paper sets up a multiindex department integration decision model with time feature based on synergetics theory.And the synergetic measurement decision matrix between department and government system can be calculated from the standardized treatment of the benefit and cost index.The leastsquares method multiindex optimized model was set up based on the weight vectors of each index and each time slots and the closedegree of each integration proposal to the positivenegative ideal proposal.According to the research this decision model can offer theory support for the optimal synergetic government system department integration decision and improve the synergetic degree of government system.
YU Haimiao , ZHOU Haizhu , PEI Xiaomei
Abstract:The paper presents a study of the environmental value of China’s wind power and an assessment of its economy.A comparative study is conducted between the wind power and coal power with the prevention price based on China’s pollution charge schedule (PCS) and US environmental value schedule(EVS) as the environmental cost.The pollutant emission rate of coal power and the pollutant environmental value schedule were calculated.Results show that the environmental value of wind power is 0.087 3 yuan·kWh-1 in comparison with coal power,and the cost of wind power and coal power are 0.354 0 yuan·kWh-1 and 0.299 3 yuan·kWh-1 respectively.However,if taking environmental value into account,the cost of the coal power is 0.386 6 yuan·kWh-1,which is higher than that of the wind power.It’s concluded that the wind power is promising in future due to its economy and environmental value.
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