SUN Weiling , CHEN Jianbing , LI Jie
2011, 39(10):1413-1419. DOI: 10.3969/j.issn.0253-374x.2011.10.001 CSTR:
Abstract:The stochastic harmonic function of the second kind is proposed for representations of stochastic processes.It is firstly proved that,as long as the random phase angles and random circular frequencies are independent and uniformly distributed whereas the amplitudes are related to the target power spectral density function in a specified way,the power spectral density of the process represented by the stochastic harmonic function of the second kind is identical to the target power spectral density.Then,it is demonstrated that the process represented by the stochastic harmonic function of the second kind is asymptotically Gaussian.The rate of approaching Gaussian distribution is further studied by obtaining the onedimensional distribution via Pearson distribution.The study reveals the similarities between the stochastic harmonic functions of the first kind and the second kind.However,the application of the stochastic harmonic function of the second kind is more convenient than that of the first kind because the random circular frequencies are uniformly distributed.Finally,linear and nonlinear responses of a multidegreeoffreedom system subjected to random ground motions are analyzed to exemplify the effectiveness and superiorities of the proposed approach.
ZHOU Jianming , WANG Tiao , CHEN Fei , ZHAO Yong
2011, 39(10):1420-1425. DOI: 10.3969/j.issn.0253-374x.2011.10.002 CSTR:
Abstract:A test of 14 flexural members reinforced with 500 MPa bars was carried out to investigate the cracking behavior of reinforced concrete beam with highstrength bars.The crack distribution along the beam height and width and the relationship between crack width and moment were explored.This experiment and other relevant experiments results show that the sub cracks between cracks limit the width of crack when the steel bars stress is high.Crack width calculated according to GB 50010—2002 was larger than the experimental value,which means that the crack width formula could not apply to the member with highstrength bars.A comparative study of the major factor of crackwidth of this experiment and other relevant experiments data,a new crack width formula was put forward.The results of the proposed formulas were in good agreement with the experiment results.
2011, 39(10):1426-1433. DOI: 10.3969/j.issn.0253-374x.2011.10.003 CSTR:
Abstract:The paper presents a kind of cross gusset plate used in steel tube towers.The advantages of this gusset plate are illustrated,the failure mode and design theory of the gusset plate are analyzed.In order to investigate the performance,failure pattern and ultimate capacity of the gusset plate,Monotonic axial loaded tests have been carried out on two largescale specimens used in Rongjiang steel tube tower.Nonlinear analysis simulating the static behavior is conducted by utilizing the general-purpose finite element(FE) package ANSYS.Both experimental and FE analytical results show that the gusset plate possesses excellent mechanical performance and can be used in engineering.Lastly,according to the results of tests and FE parameters analyses,the failure mode and design theory of the gusset plate are proposed,the formula of ultimate capacity are recommended.
GU Ming , YU Xianfeng , QUAN Yong
2011, 39(10):1434-1440. DOI: 10.3969/j.issn.0253-374x.2011.10.004 CSTR:
Abstract:The study progress of internal pressure governing equation is first summarized from theoretical analysis.Then several main factors that affect windinduced internal pressure including building flexibility,Helmholtz resonant effect,interferer effect and internal partitioning are reviewed,and a comprehensive survey is presented from the aspects of wind tunnel test,field measurement and computational fluid dynamics (CFD) numerical simulation.Description of internal pressure in wind load codes of several main countries is presented too.Finally some limitations in current researches are pointed out by analyzing the problems existed in internal pressure governing equations,influencing factors and research methods,and some recommendations are made for further researches on internal pressure.
2011, 39(10):1441-1446. DOI: 10.3969/j.issn.0253-374x.2011.10.005 CSTR:
Abstract:Wind tunnel tests were conducted to study the wind pressure on principal square building adjacent to another one in sidebyside arrangement at attack angle 0°.The interference effects on wind pressure of the principal building were analyzed with different heights and positions of the interfering building.The results show that with an increase in spacing ratio,associated with buildings of the same height,the maximum value of mean and fluctuating pressure coefficient interference factor decreases on the gap and outer side while slightly increases on the front and rear face.Notably,the fluctuating pressure coefficient interference factors on the gap side grow visibly,the maximum value is 2.2 on the top leading corner when the spacing ratio is 2.In addition,for effects on change of height ratio,the same index on the front side is affected little but increases on the other three sides with increasing height ratio,besides,the fluctuating pressure coefficient interference factors on the gap side increases apparently,its value even reaches 2.7.
CHEN Airong , TU Xi , MA Rujin
2011, 39(10):1447-1451. DOI: 10.3969/j.issn.0253-374x.2011.10.006 CSTR:
Abstract:This paper presents the application of digital photogrammetry in obtaining the vibration response of cables for full aeroelastic cablestayed bridge model in wind tunnel test.In the wind tunnel test,aeroelastic model for a cable stayed bridge with the span of 1 088 m was adopted and the vibration modes for cables during aerodynamic instable status were acquired by image capture and analysis,which clearly revealed the relationship between cable and girder of cable stayed bridge and provided essential data for future research on the mechanism of the flutter of cable stayed bridge with long span.Moreover,the measurement error was discussed and the countermeasures for improving precision were proposed.
JIAO Meiju , SUN Limin , LI Qingfu
2011, 39(10):1452-1457. DOI: 10.3969/j.issn.0253-374x.2011.10.007 CSTR:
Abstract:This study aimed at the reliability assessment based on the monitoring data.First,an analysis was made of the characteristic of the monitoring data. Then,a new method was proposed for data processing.A case study of 15monthmonitoring data collected about Donghai Bridge proved the feasibility of the proposed method.Assessment results were also discussed.
YE Weimin , ZHU Yueming , CHEN Bao , YE Bin
2011, 39(10):1458-1462. DOI: 10.3969/j.issn.0253-374x.2011.10.008 CSTR:
Abstract:Based on onedimensional compression tests,compressionreboundcompression curve and the compression index and rebound index of Shanghai soft soil were obtained.At the same time,the influences of suction on the strength of the unsaturated soil were analyzed.Then the test results were simulated with Alonso elasticplastic model,and the preconsolidation pressure versus suction (loadingcollapse curve) curve was fitted.Results show that the compressibility of the soil decreases while the matric suction increases.For certain suctions,elg p curve clearly step phases in elastic,elasticplastic and rebound recompressed phases.With compression of unsaturated soil,the preconsolidation pressure decreases with suction decreases.There is a surface among pore ration,suction and vertical stress.
GE Shiping , XIE Dongwu , DING Wenqi , YANG Hongjie
2011, 39(10):1463-1467. DOI: 10.3969/j.issn.0253-374x.2011.10.009 CSTR:
Abstract:A series of 3D numerical simulation about the shield tunnel undercrossing existing building was accomplished.Results show that important parameters include relative position of tunnel and existing building,weight and stiffness and geometric form of existing building have dominating influence on the pattern of surface settlement trough,especially in changing the maximum settlement and modifying the width and form of settlement trough.Based on the Shanghai Metro Line 11 undercrossing the historic buildingXujiahui Observatory,full threedimensional model about shield tunnel undercrossing Xujiahui Observatory was established to simulate construction process.Settlements of surface were forecasted.Measuring points were arranged to monitor surface settlements during undercrossing to verify simulation results.
CONG Haozhe , WANG Junhua , FANG Shouen , TONG Shixin
2011, 39(10):1468-1472. DOI: 10.3969/j.issn.0253-374x.2011.10.010 CSTR:
Abstract:Distribution model choice, parameters’ estimation and measures of goodness of fit were carried out, and the best distribution fitting for incident duration data was LogLogistic distribution. Accelerated failure time (AFT) modeling was employed based on survival analysis and LogLogistic distribution. Then stepwise by Akaike information criterion (AIC) was used to find the best group of factors for the prediction of freeway incident duration. The test result indicates that AFT model can represent actual incident duration and accept different distribution and missing data.
GONG Jinli , YANG Dongyuan , PENG Xianwu
2011, 39(10):1473-1478. DOI: 10.3969/j.issn.0253-374x.2011.10.011 CSTR:
Abstract:A research was made of the cell transmission models on city expressway.The Pattern cell transmission model (CTM) was proposed based on that the observability of traffic flows’ dynamic characteristic appeared to be different according the transmission methods of traffic information under different patterns of road traffic state.In Pattern CTM cell transmission model,the flow transmission model on mainroad was updated to be expressed as the form of piecewise function and the flow transmission model on offramp was constructed against the city expressway.Taking the real data on Shanghai NorthSouth Expressway as example,the performance of three CTMs were compared.The result shows that the Pattern CTM is the best of all.When the Pattern CTM is applied in large scales,the mean percent error (MPE) of density is around 20% and the MPE of flow is around 10%,which show that the simulation result is satisfactory.
YANG Fei , XIA Jun , CUI Yaping
2011, 39(10):1479-1484. DOI: 10.3969/j.issn.0253-374x.2011.10.012 CSTR:
Abstract:The mobile communication simulation experiment scenario is built and the simulation parameters are configured according to the real circumstance.The simulation tool,Matlab,is applied to analyzing the link travel speed error.First,the handover link is calibrated by handover test simulation to specify the average handover location and the handover link length.The experiment result shows the handover fluctuation complies with the normal distribution.Second,the handover sample data with handover cell sequence and time stamp is acquired by mobile communication network simulation.Thus,the handover link travel speed is calculated by means of the calibrated handover link length and time difference of the sample.Third,the speed error is obtained from the calculated link travel speed and the readily configured mobile phone speed.The influence of handover fluctuation on collected sample speed error is studied in terms of cell type and handover control rules.
HONG Ling , GAO Jia , XU Ruihua
2011, 39(10):1485-1489. DOI: 10.3969/j.issn.0253-374x.2011.10.013 CSTR:
Abstract:Some stations and intervals may suffer a temporary breakoff due to emergencies of urban mass transit network.The transitivity and diffusivity of train operation delay may lead to delay passenger flow,detour passenger flow and loss passenger flow in some stations.Based on the structure of urban mass transit network and graph theory,the evaluation method of partial interruption were built up.Adopting these models,the affected passenger flow volume,delay passenger flow volume,detour passenger flow volume,loss passenger flow volume,congested passenger flow volume and the lost time of passenger flow could be calculated out as time in different stations.Calculation and analysis of the local network of Shanghai rail transit proves the effectiveness of these models for emergency disposition.
LIN Xiaoping , LI Xinghua , LING Jianming , ZHOU Liang
2011, 39(10):1490-1494. DOI: 10.3969/j.issn.0253-374x.2011.10.014 CSTR:
Abstract:Several types of subgrade soil were sampled,and resilient modulus of subgrade soil with different moisture were measured using UTM dynamic triaxial test symtems.The effect of moisture on resilient modulus was analyzed and parameter calibration was executed on Witczak model of moisture adjustment factor for resilient modulus,furthermore,the model of moisture adjustment for resilient modulus applicable to coarse and fine grained soil in China was established.The results indicate that moisture adjustment factor varies linearly with moisture difference value which is in the range of -20%~20%,and moisture adjustment factor is not affected significantly by moisture difference value which exceeds 20%.Using the established model,the moisture adjustment factors for different types of subgrade soil are recommended,which can be used to predict field resilient modulus of subgrade soil with real moisture content combined with resilient modulus test in laboratory.
WU Jianliang , TANG Wen , SUN Lijun
2011, 39(10):1495-1499. DOI: 10.3969/j.issn.0253-374x.2011.10.015 CSTR:
Abstract:Pavement temperature field was abstracted as onedimensional transient heat conduction equation.Fourier series that compatibility with the equation was obtained by separation of variables.Then instantaneous temperature distribution of one dimensional layered body in terms of known interface temperature was derived based on Fourier series.The Newton method that backcalculation the thermal diffusivity of pavement material in related to measuring temperature distribution in field was presented.In cooling process as pavement temperature changes along the depth monotony,Fourier series with 50 items can attain the accuracy of 0.01℃.Results derived from measured data show that thermal diffusivity of top asphalt concrete layer is larger than that of bottom layer,with 0.002 4 m2·h-1 for AC16 and 0.001 6 m2·h-1 for AC25,which is lower than most of the laboratory measured values.
HUANG Hong , YIN Fang , WU Ying , YIN Daqiang
2011, 39(10):1500-1505. DOI: 10.3969/j.issn.0253-374x.2011.10.016 CSTR:
Abstract:Concentration of 14 polychlorinated biphenyls (PCBs) residues in sediments from Yangtze Estuary and nearshore of the East China Sea were determined by gas chromatographyelectron capture detector (GCECD).The concentration of PCBs in sediments were in the range of 18.66-87.31 ng·g-1.This paper will discuss PCB polluted sediments in the research area in terms of the distribution of PCBs,the pollution level,and the PCBs sources.According to component analysis,the types of PCBs found in the surface sediments were mainly 3 & 4 CB PCBs,accounting for 32.49%-96.43% of the total PCBs found.The principal factor analysis revealed that the PCBs in the sediments were mainly from industrial pollution.Correlation analysis revealed total organic carbon (TOC) content strongly influenced the distribution of OCPs in sediments.Compared with other regions around the world,the pollution level of PCBs was,in general,at a moderate level.The ecological risk assessment by the methods of calculating toxic equivalent quantity (TEQPCB) and comparing with interim sediment quality guideline (ISQG) and probable effect level (PEL ) values of risk evaluation,indicates the PCB contaminated sediments from Yangtze River estuary and its nearshore of the East China Sea will have a medium ecological risk.
ZHOU Yuwen , WENG Yaoyao , WANG Mingming
2011, 39(10):1506-1509. DOI: 10.3969/j.issn.0253-374x.2011.10.017 CSTR:
Abstract:Based on the Code for Design of Outdoor Wastewater Engineering,calculating storm sewer design flow (Q) with an attenuation coefficient (m) leads to a lower design flow than that of projects abroad,and reduces the capacity for disaster resistance of urban storm sewer system for the same design standard.This manuscript focuses on discussing the impacts of flow attenuation coefficient (m) on storm sewer system design.Based on appropriate assumptions,the mathematical expressions of the relationship between return periods with m=1 and m=2 were deduced,which lays the theoretical foundation for the analysis of the relationship among return periods.According to several examples,it is confirmed that the design flow rates defined by m=1,design return period at one year (P=1) and with same time intervals,could reach the same level as in the case with P=1.531 ~4.028 years when m=2 is taken.Reversely,when m=2 and P=1 year,the design flows are approximately equivalent to the values in situations with m=1 and P=0.69 ~0.393 years.In conclusion,the research suggests that the use of an attenuation coefficient would result in substantial reduction in storm sewer system design criteria and consequently increase the risk of waterlogging in urban regions in China.
DU Shoushuai , SONG Ting , MA Xingbo
2011, 39(10):1510-1516. DOI: 10.3969/j.issn.0253-374x.2011.10.018 CSTR:
Abstract:Based on a study of the Ueda Area of Oita in Japan,a multiagent system (MAS) was established.The change probability of each agent was calculated,and the distribution type of each agent was identified.Then, a simulation study was made of the land change of target areas and the results were verified.Based on this model,the change in future buildup area and green land was simulated and predicted.The suggestion and method to simulate land change in conjunction with population elements were proposed.
KAN Lili , SHI Huisheng , QU Guangfei , NING Ping
2011, 39(10):1517-1523. DOI: 10.3969/j.issn.0253-374x.2011.10.019 CSTR:
Abstract:The growth processes of selfhealing products on 15 μm,30 μm,and 50 μm cracks as well as on fiber surfaces were displayed by means of ESEM.The chemical characterizations of healing products were reported by applying many advanced research technologies such as EDS,TEM,XRD and FTIR.These results suggest that further hydration of cementitious materials and the formation of CSH gel and CaCO3 crystals are the main reasons for the selfhealing phenomena.CSH is the main selfhealing product for crack widths of 15 μm,and CSH and CaCO3are the main selfhealing products for crack widths of 30 μm.Selfhealing products couldn’t fill in the crack widths of 50 μm within observation period.At the microlevel,cracks below 30 μm in width can be almost totally healed.Meanwhile,PVA fibers with hydrophilic nature in ECC provide nucleation sites for healing products that may aid in the selfhealing of ECC.
XU Zijie , MA Chao , WANG Fei , LU Aihui
2011, 39(10):1524-1527. DOI: 10.3969/j.issn.0253-374x.2011.10.020 CSTR:
Abstract:Porous polycaprolactone(PCL)/hydroxyapatite(HAP) composites were synthesized by solgel process and vacuum drying technology.The morphology and component phases in hydroxyapatite (HAP) samples were investigated by scanning electron microscope(SEM),X-ray powder diffractometer(XRD) and laser Raman spectrometry(Raman) methods.The hydrogen bond interactions was found between HAP and PCL components,which decreased the phase separation.When the HAP content was below 40% in weightiness,no obvious phase separation was found in PCL/HAP samples.
SU Xing , ZHANG Xu , SUN Yongqiang
2011, 39(10):1528-1530. DOI: 10.3969/j.issn.0253-374x.2011.10.021 CSTR:
Abstract:Recovery rate should be taken into account when life cycle inventory of reproducible materials is analyzed.The existing problems of past algorithms are discussed.The recovery rate is separated into recovery capacity and recovery level,and a new algorithm contains these two factors for life cycle inventory analysis of reproducible materials is proposed.The difference between each algorithm is calculated with the steel plate,steel reinforcement,aluminum,glass and concrete for instance.It shows that new algorithm is more accurate than others.
2011, 39(10):1531-1536. DOI: 10.3969/j.issn.0253-374x.2011.10.022 CSTR:
Abstract:This paper presents an analysis of five decisive elements of the energy supply strategy for battery electric vehicles (BEVs),which include the characteristics of urban electric network,the technique of battery and charging,the usage pattern of BEVs,the effect of energy saving and emission reduction,and the constraint of urban land resources.With a consideration of these five decisive elements,this paper argues that the energy supply mode for BEVs should be different from that for traditional petrol vehicles.Energy supply of BEVs is proposed to be mainly dependent on charging at night during the low electric demand period.The modes of quickcharging in the daytime and batteryreplacing should act as supplementary methods.Then the service function and layout requirements of the slowcharging piles,fastcharging stations and battery swap stations are proposed based on the energy supply strategy.The study results are of great importance to the energy supply system and the upcoming rigorous construction of energy supply facilities.
LI Yong , ZUO Shuguang , LEI Lei , YANG Xianwu
2011, 39(10):1537-1542. DOI: 10.3969/j.issn.0253-374x.2011.10.023 CSTR:
Abstract:Considering the nonlinear characteristic of tire’s grounding friction,a dynamic model of tire’s lateralvertical force coupling is established based on LuGre friction model.According to selfexcitation theory,polygonal wear of tire is found to be related to lateral vibration of tire tread and the polygonal number is equivalent to the ratio of the lateral vibration frequency of tire tread to the rotational frequency of tire.The ranges of speed and toein angle which can motivate selfexcited vibration are given through simulation.The results show that this model can interpret the formation mechanism of the polygonal wear,and provide a theoretic foundation to reduce or eliminate the tire’s selfexcited vibration.
2011, 39(10):1543-1547. DOI: 10.3969/j.issn.0253-374x.2011.10.024 CSTR:
Abstract:The Ahmed model with 35°slant angle was tested in the model wind tunnel.The components of velocity were captured by using 3D CTA.By statistically analysis with the transient value of velocity,the contour spectrums of Reynolds stress components were presented.According to the spectrums,the feature of the flow structure is showed with drag vortex pair and ground effect extending to far field.The distribution characteristic of the stress components varies with the distance from model body.
WANG Hongyan , PAN Shuming , CAO Qingqing
2011, 39(10):1548-1551. DOI: 10.3969/j.issn.0253-374x.2011.10.025 CSTR:
Abstract:Accident reconstruction is an effective method to study the causes of child occupant injury in traffic accident.On the basis of “mean acceleration”,a typical traffic accident with child occupant is simulated by PCCrash and MADYMO.Child occupant movements and injury risks during the impact are well performed.A qualitative analysis on the causes of child occupant injuries in this accident is carried out and described.
WANG Wenbin , KANG Kang , ZHAO Honglun
2011, 39(10):1552-1556. DOI: 10.3969/j.issn.0253-374x.2011.10.026 CSTR:
Abstract:Based on nonlinear finite element and multibody dynamics,a simulation strategy is developed to solve the crashworthiness design problem for train sets.The relationship of nonlinear springs which describe characters of forcesdisplacements for energy absorbers during crash event is obtained by analyzing nonlinear FEA techniques.Then,a simulation was made for collision of two train sets with multibody dynamics.The results of impact force,deformation,velocity,acceleration and absorbed energy are analyzed to assess the passive safety of whole train set.Compared to the high velocity impact,the medium and low velocity impact can be absorbed a higher proportion energy by the interface between cab and the second vehicle.The results indicate that the joining simulation strategy is feasible and effective to simulate the whole process of train collision.
2011, 39(10):1557-1562. DOI: 10.3969/j.issn.0253-374x.2011.10.027 CSTR:
Abstract:Based on the GRIMech 3.0 mechanism,the premixed laminar combustion characteristics of methaneairdiluent mixtures were investigated by using PREMIXED Code.Several fundamental parameters,such as flame structure,laminar burning velocity,and flame thickness,were calculated at different equivalence ratios,initial pressures,and dilution ratios.It was found that increasing the dilution ratio in the mixture would lead to a decrease in laminar burning velocity and an increase of flame thickness.As a result,the hydrodynamic instability of methaneair laminar flame was suppressed with the addition of diluents,especially in the condition of CO2 dilution.When the initial pressure increased,the laminar burning velocity and flame thickness decreased accordingly.However,a further increase of the initial pressure did not have much effect on the flame thickness.
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