Table of Content

25 March 2019, Volume 47 Issue 3

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Power & Electrical Engineering

Air Conditioning Load Optimization Dispatching Model Considering Users' Comfort Compensation

ZHANG Yongjun HAO Jinbao

2019, 47(3):  1-8.  doi:10.12141/j.issn.1000-565X.180496

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Through the dispatching of demand side response resources，the adverse effects of distributed power output fluctuation on grid operation can be alleviated，and the consumption of renewable energy can be promoted． Firstly，based on the operation framework of the load aggregator，the cost and benefit of the load aggregator were analyzed． In the component of the load aggregator cost，the demand response compensation strategy based on users' comfort was proposed． Secondly，the temperature variation model of air conditioning load was established． Finally， the air conditioning load optimization dispatching model was proposed． The objective function of the model is the maximum total revenue of the air conditioning load aggregator，taking into account the air conditioning temperature，wind power fluctuation and aggregator revenue constraints． The simulation results show that the proposed model has good economic benefits and improves the smoothing effect on distributed wind power fluctuations．

Optimal Energy Scheduling of Photovoltaic Natural Gas，Cooling， Heating and Power Co-supply Park Micro-network

LIN Shunjiang YANG Zhibin LU Yuan LIU Mingbo HE Sen JIANG Hao

2019, 47(3):  9-19.  doi:10.12141/j.issn.1000-565X.180245

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Natural gas，cooling，heating and power co-supply park micro-network provides cooling，heating， power and natural gas supply functions，and has the advantage of energy cascade utilization． It can effectively improve the energy utilization rate and reduce the emission of pollutants． Aiming at the energy optimal dispatch problem of natural gas，cooling，heating and power co-supply park micro-network，and taking the minimum operating cost as the objective function，a multi-period dynamic optimal scheduling model of the natural gas，cooling，heating and power co-supply park micro-network was established． It considered both the network operation characteristics of the cooling network，heating network，power supply network and natural gas supply network，and the influence of multiple energy storage devices including electricity storage，cooling storage and heating storage on the microgrid dispatch． Based on the scenario method，an optimal energy dispatching model of co-supply park micro-network considering the stochastic fluctuation of photovoltaic output was established，and the uncertain fluctuation of PV output was balanced by rapidly adjusting the stored power of the energy storage device． Taking a natural gas， cooling，heating and power co-supply park micro-network as an example，the correctness and effectiveness of the proposed optimal scheduling model were verified． The optimization results show that the proposed operation scheduling scheme of micro-network can effectively save the energy consumption and reduce its operating cost; the coordinated operation of multiple energy storage devices can more effectively reduce the operating cost of the micro-network and help to stabilize the uncertain fluctuations of PV power generation

Numerical Simulation of the Gas-Liquid Two Phases Flow and Evaporative Cooling Process in the Desulphurization Absorption Tower at Different Spraying Layers Operation Modes

LIN Yu, CHEN Dezhen

2019, 47(3):  20-29.  doi:10.12141/j.issn.1000-565X.170572

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The operation modes of spraying layers in the large scale desulphurization tower with four spraying layers were investigated by computational fluid dynamics numerical simulation． The Euler-Lagrange approach was adopted and the inter-exchanges of momentum，mass and energy between the gas and liquid phase were fully studied; the effect of instantaneous turbulent velocity fluctuations on the particle trajectories was also taken into account through the use of stochastic methods． The simulation results were also validated via actual on-site data． The main results are as follow: ( 1) for all spraying modes，the area-weighted mean total velocity and its horizontal component of the gas phase on the horizontal cross-sections reach to their peak values inside the height of the flue gas inlet and then decline quickly，the horizontal component almost decreases to 0 when the flue gas comes to the bottom spraying layer． Meanwhile，the curves of area-weighted mean vertical velocity components of all spraying modes almost overlap completely along the absorption tower，and inside the height of the flue gas inlet，they show perfect monotonous linear increase． ( 2) Among all spraying modes，the most non-uniformity in the temperature field and water vapor field of the flue gas occurs when only bottom spraying layer operating． In addition，in such spraying mode， the area-weighted mean temperature on the flue gas outlet is much higher than the other spraying modes，and the area-weighted mean humidity on the flue gas outlet is not saturated． Whereas，the above-mentioned non-uniformity is alleviated obviously when only top spraying layer operating． ( 3) For all spraying modes except only bottom spraying layer operating，the curve extremums of area-weighted mean temperature and humidity of the gas phase on the horizontal cross-sections along the absorption tower are all located within the lower quarter height of the flue gas inlet． With the increase of spraying layers，the maximum values of the above-mentioned temperature curves decrease，while the minimum values of the humidity curves increase． ( 4) When only bottom spraying layer operates， the evaporation water quantity accounts for four fifths the value when all the four spraying layers operating． There is no significant difference in evaporation water quantity between only top spraying layer mode and other multiple layers modes． Among all the spraying modes，the highest evaporation ratio is found when only top spraying layer adopted．

State Analysis of Induction Motor Based on CF-SOM-MQE Under Unbalanced Sample Condition

WANG Lei LIU Yongqiang

2019, 47(3):  30-36，92.  doi:10.12141/j.issn.1000-565X.180228

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To improve the accuracy of induction motor state evaluation，a model based on correlation algorithm ( CF) and self-organizing map minimum quantization error ( SOM-MQE) was proposed to solve the problem of fundamental current signal interference and lack of fault data． Firstly，the autocorrelation algorithm and cross-correlation algorithm theory were briefly introduced． The characteristic harmonic components in the stator current were analyzed and input into the SOM neural network as performance degradation indicators． Based on this，the minimum quantization error ( MQE) value was calculated． MQE was used as a measure of condition monitoring of induction motors． The example shows that the proposed model can accurately estimate the health status of induction motors，so it has strong engineering application value and versatility．

Mechanical Engineering

Theoretical and Experimental Research on Elastohydrodynamic Lubrication of Non-Newtonian Fluids in Point Contact

HUANG Ping YUAN Jiafu

2019, 47(3):  37-43.  doi:10.12141/j.issn.1000-565X.180252

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In order to study the elastohydrodynamic lubrication characteristics of power function non-Newtonian fluids under isothermal conditions，based on the Ostwald constitutive model，the non-Newtonian fluid lubrication problem was solved with the universal fluid lubrication equation． The effects of parameters such as rheological index，load，and entrainment velocity on the point contact EHL under isothermal and steady state conditions were discussed． A comparison between the non-Newtonian fluid and the Newtonian fluid was made． Then，the film thickness was measured by elastohydrodynamic lubrication experiment with a certain rheological index，and the effect of the entrainment velocity and the load on the film thickness was analyzed． The results show that when the non-Newtonian properties of the lubricant are more significant，the lubricant film will become less thick，and the pressure distribution will be closer to the Hertz contact stress distribution，and the influence of the load and the entrainment velocity on the lubricant film thickness pressure distribution of non-Newtonian fluids will be smaller than that on the Newtonian fluids． Under the same conditions，the film thickness of non-Newtonian fluid is smaller than that of the Newtonian fluid． From the comparison of the experimental measurement results with the numerical calculation results，it can be concluded that the effect of the entrainment velocity and load on the film thickness is basically consistent

Analysis of the Mechanical Properties of Head /Disk Interface in Air-Helium Gas Mixtures

TANG Zhengqiang ZHOU Dongdong JIA Tong ZHANG Chuanwei

2019, 47(3):  44-52.  doi:10.12141/j.issn.1000-565X.180244

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Helium can improve storage density and reduce power consumption of hard disk drives． In air-helium gas mixtures，the percentage of helium will affect the air bearing force of a slider and the air shearing force of a disk surface，which leads to lubricant transfer at the head /disk interface． In this research，the finite element method was used to solve the modified Ｒeynolds equation． The air bearing force of the slider and the air shearing force of the disk surface in air-helium gas mixture were calculated． The effect of flying gesture，disk velocity，and environmental temperature on the mechanical properties of the slider and the disk were investigated． The results show that，in air-helium gas mixtures，the air bearing force of the slider and the air shearing force of the disk surface decrease with an increase in flying height． The air bearing force and the shearing force increase with an increase in disk velocity and temperature． With an increase in pitch angle and roll angle，the flying height decreases，which leads to an increase in the air bearing force． However，the effect of the pitch angle and the roll angle on the air shearing force of the disk surface in air-helium gas mixtures is negligible．

Stability Analysis of Automotive Brake Systems Based on Evidence Theory

Lǚ Hui SHANGGUAN Wenbin YU Dejie

2019, 47(3):  53-60.  doi:10.12141/j.issn.1000-565X.180096

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An evidence theory-based approach for the stability analysis of disc brakes was proposed to deal with the incomplete or conflicting information which may exist in automotive brake systems． In the proposed approach，parametric uncertainty was taken into account for the stability analysis of a disc brake． The evidence variables were employed to deal with the uncertain parameters whose information was incomplete or even conflicting，and the uncertain parameters with large intervals． Subsequently，the stability analysis model of uncertain disc brake system was established based on evidence theory，and the belief function and plausibility function related to the negative damping ratio of system unstable eigenvalue were used to evaluate system stability． Meanwhile，the detailed procedure of the proposed approach was presented． Finally，the influence of uncertain system parameters on brake stability was explored，based on the probability interval analysis of system stability meeting design requirement． The proposed approach has potential guidance and application in the field of automotive brake noise control．

Dynamic Measurement Method for Vehicle Contour Dimensions Based on Laser Point Cloud

ZHANG Libin WU Dao SHAN Hongying LIU Qifeng

2019, 47(3):  61-69.  doi:10.12141/j.issn.1000-565X.180323

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A dynamic measurement method based on laser point cloud was proposed in order to solve the problem of low measurement accuracy，poor repeatability and poor reconstruction quality of three-dimensional ( 3D) contour in the measurement of vehicle contour dimension． Firstly，the method was based on the measuring principle of vehicle contour dimension，and the system measurement scheme was designed． Then，in order to remove the noise and redundant data generated by lidar during data collection，the topology of the point cloud was established based on kd-tree and the neighborhood averaging method was used to denoise the point cloud data，and the point cloud data were simplified by using the least square method to judge the local curvature features，and the boundary features were protected by the boundary point recognition algorithm． Finally，the proposed method was verified by the real vehicle test，and the reflector filter and the curve correction model were designed to further optimize the test result． The test results show that the indicating errors of four types of vehicles are all less than 1% ，with a maximum repeatability of 0. 48% ，which has higher accuracy and better stability to meet the national standard requirements． According to the 3D contour reconstruction model of vehicle，it can locate out-of-gauge position quickly．

Fusion Assessment on the Credibility of Cloud Nondestructive Testing for Large-Scale Steel Structures

HONG Xiaobin ZI Wenjiang YU Rong LUO Zongqiang HE Zhenwei

2019, 47(3):  70-77.  doi:10.12141/j.issn.1000-565X.180383

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For the problem that single testing method is difficult to achieve comprehensive assessment of the object，the comprehensive testing using a variety of nondestructive testing methods is suggested to be effective，in which the credibility assessment of comprehensive test results is critical． In the investigation，firstly，the cloud nondestructive testing system architecture for large-scale steel structures was designed based on Hadoop，and the information flow of large-scale steel structures cloud nondestructive testing Hadoop architecture was analyzed． Then，the D-S evidence theory joint operator of credibility fusion of large-scale steel structures cloud nondestructive testing data was defined，and the multi-source data credibility MapＲeduce fusion algorithm based on D-S evidence theory was proposed． Finally，a large steel tube tower structure testing experimental platform was established，and the credibility of visual endoscopic inspection，eddy current testing and conventional ultrasonic inspection multisource data was tested by fusion evaluation． The results show that the detection rate of defects in each single testing method is improved by the MapReduce fusion algorithm for the credibility of cloud testing data． It meets the cloud nondestructive testing requirements of large-scale steel structures

Food Science & Technology

On the Preparation of Esterified Soybean Polysaccharides and Its Dispersion Stability

QI Junru ZHAO Ruxia LIU Qianru ZENG Weiqi YANG Xiaoquan

2019, 47(3):  78-84.  doi:10.12141/j.issn.1000-565X.180036

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A simple and eco-friendly procedure was developed to prepare high-molecular-weight octenyl succinic esters of SSPS ( OSA-SSPS) via the esterification between soybean soluble polysaccharides ( SSPS) and octenyl succinic anhydride ( OSA) and then the ultrafiltration membrance of certain molecular weight cut-off ( MWCO) was selected for separating OSA-SSPS． The infrared spectra，particle size，Zeta potential and viscosity of SSPS and OSA-SSPS were compared． The results show that there is an obvious absorption peak of OSA-SSPS at 1733cm － 1 ， indicating that the esterification reaction between SSPS and OSA generated OSA-SSPS; the particle size and absolute potential of OSA-SSPS are higher than that of SSPS; the viscosity of OSA-SSPS is higher than that of SSPS． The stability and morphology analysis of acid milk beverage shows that OSA-SSPS has better protein dispersion stability and uniform distribution of microdroplets than SSPS． The results show that in the esterification reaction between SSPS and OSA，the side chain of SSPS increased，the potential changed and the steric resistance increased．

Influences of Soybean Protein Isolate Hydrolysate on the Quality of Laboratory Prepared Yoghurt

ZHAO Qiangzhong HUANG Lihua CHEN Bifen CAI Yongjian DENG Xinlun ZHAO Mouming

2019, 47(3):  85-92.  doi:10.12141/j.issn.1000-565X.180324

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Soybean protein isolate hydrolysate ( SPIH) obtained at different enzymatic hydrolysis times ( 3，12 and 24 h) were added to homemade yoghurt． The effects of SPIH on the fermentation and storage quality of yoghurt were studied by measuring the enzymatic hydrolysis characteristics，fermentation characteristics and storage quality of SPIH ( SPIH-A3，SPIH-A12 and SPIH-A24) ． The results show that the longer the enzymatic hydrolysis time，the higher the degree of SPIH hydrolysis． All SPIH can promote yoghurt fermentation，inhibit post-acidification during yoghurt storage，reduce whey precipitation，and reduce the number of viable bacteria． Ultrafiltration separation was carried out on SPIH-A12，which has the most significant effect of promoting fermentation． It was found that the SPIH-A24 component below 4 ku had more hydrophobic amino acids and uncharged hydrophilic amino acids，which could improve the number of live bacteria and the apparent viscosity of yoghourt coccus and reduce the whey precipitation rate． Appropriate enzymatic hydrolysis of SPIH can effectively promote yoghurt fermentation，improve yoghurt storage quality． In the meantime，small molecular fraction obtained by ultrafiltration demonstrated a more pronounced effect．

Analysis on the Characteristics of Soybean Protein Isolate Gel Fermented by Lactobacillus plantarum

LI Liang YANG Xiaoyu WANG Yan SU Yue JIANG Lianzhou

2019, 47(3):  93-100.  doi:10.12141/j.issn.1000-565X.180477

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Soybean protein isolate ( SPI) as the raw material，protein gels were prepared by Lactobacillus plantarum fermentation． Both the gel process and the properties of the aggregation were analyzed． The experimental results show that: the optimal quantity of Lactobacillus plantarum is 3% ，the fermentation time is 5 h，and fermentation temperature is 37 ℃，initial pH value is 6. 5． Under this conditions，the water holding capacity of the gel is 46. 00% ，and the gel strength is 23. 67g． It finds that the Lactobacillus plantarum fermentation has a significant influence on protein turbidity，Zeta-potential and the average particle size． The experimental results are useful for clarifying the influence of Lactobacillus fermentation treatment on soy protein gel，and further provide a theoretical guidance for the application of probiotic Lactobacillus in soy products．

Antioxidant and Antitumor Activities of Myricetin In Vitro

SU Jianyu HU Han WU Ping MENG Xiaofeng XU Zhenbo ZHENG Huade

2019, 47(3):  101-108,152.  doi:10.12141/j.issn.1000-565X.180234

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Antioxidant assay and ESEM observation were carried out to investigate the antioxidant and anti-bladder cancer activities of myricetin． The results show that myricetin can effectively inhibit the AAPH-induced hemolysis of erythrocytes in a dose-dependent manner． The hemolysis inhibition rate of myricetin increases to ( 93. 67 ± 0. 01) % at a concentration of 80 μmol /L． A further experiment confirms that SOD and GPx antioxidant enzyme activities are enhanced to control ＲOS and MDA generation when erythrocytes are preconditioned by myricetin． Moreover，MTT tests indicate that myricetin could suppress the EJ and T24 bladder cancer cells proliferation in a dose-related manner with the half-maximal inhibitory concentration ( IC50 ) of ( 39. 8 ± 1. 0) μmol /L and ( 49. 0 ± 0. 9) μmol /L，as well as a lower cytotoxicity on normal bladder cell SV-HUC-1 with the IC50 of ( 75. 9 ± 1. 8) μmol /L． In addition， myricetin exhibits higher antitumor activity in EJ cell than that in T24 cells due to higher intracellular uptake amount of myricetin in EJ cells． Further flow cytometric studies of EJ cell cycle distribution show that myricetin inhibits the proliferation of EJ cancer cells mainly through induction of apoptosis and S cycle arrest．

Simultaneous Determination of Ergosterol and VD2 Content in Lentinus edodes Based on LC-MS /MS Method

XU Mingfang LI Ming SHEN Linyan CHEN Gengnan WANG Yangyang

2019, 47(3):  109-118.  doi:10.12141/j.issn.1000-565X.180304

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Liquid chromatography coupled with tandem mass spectrometry ( LC-MS /MS) method was established for simultaneous determination of ergosterol and vitamin D2 content in Lentinus edodes． Ergosterol and vitamin D2 were extracted by saponification reflux combined in ultrasonic auxiliary and purified through C8 chromatographic column with optimizing the chromatographic conditions at 25 ℃ of column temperature，270 nm of detection wavelength and 1. 5 mL /min of the flow rate of methanol aqueous solution in the gradient elution methods． The prepared samples were tested by mass spectrometry with electrospray ionization positive ion ( ESI + ) mode and multi-reaction ( MＲM) monitoring mode． Ion source injection voltage ( IS) at 5500V，ionic source temperature ( TEM) at 500℃ and ion source spray velocity at 5 L /min were applied as mass spectrometer conditions when the set pressure of air curtain gas ( CUＲ) ，atomization gas ( GS1 ) and auxiliary gas ( GS2 ) were controlled at 137. 9，310. 3 and 413. 7 kPa， respectively． Ｒesults show that the retention time of ergosterol and vitamin D2 chromatographic peaks are at 4. 49 and 4. 26 min，respectively，the content of ergosterol ( 0. 40 ～ 3. 60 mg /L) and vitamin D2 ( 0. 22 ～ 2. 20 mg /L) within a certain content range of peak area presents a good linear relationship． The average recovery rate of ergosterol and vitamin D2 are within 86. 7% ～ 102. 4% ，and the relative standard deviation are within 1. 02% ～ 4. 13% ，respectively，according to methodological validation． The collection samples were detected by LC-MS / MS established in this experiment and HPLC recommended by the national standard． The detecting results suggest that no significant difference ( P ＞ 0. 05) is found by two methods utilized for samples analysis． Compared with the peak area quantification by HPLC chromatography，LC-MS /MS method has the advantages of shorter detection time，lower detection limit and more sensitive detection． The simultaneous determination of ergosterol and vitamin D2 in Lentinus edodes by liquid chromatography-tandem mass spectrometry established in this study lays a foundation for the establishment of new product quality standards and product quality testing standards for edible fungi，and provides theoretical basis for the simultaneous detection and research of isomers．

Architecture & Civil Engineering

Experimental Research on the Effect of Using Calcium Chloride and Electroosmosis to Reinforce Silt Clay

ZHANG Heng MA Qinguo HU He NIU Fujun

2019, 47(3):  119-125.  doi:10.12141/j.issn.1000-565X.180300

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A series of laboratory experiments were performed in a customized apparatus to investigate the effect of using electroosmosis and calcium chloride with percentages of 0，5% ，10% and 15% on reinforcing Wuhan silt clay． During the process of electrochemical treatment，the temporal evolution of electric current and drainage were monitored periodically． Also，the differences in moisture content，soil shear strength and microstructure before and after treatment were studied to assess the synchronous effect of electroosmosis and calcium chloride solution． The following conclusions can be drawn: injecting calcium chloride solution into anodic reservoir can significantly improve the efficiency of electroosmosis by shorting consolidation time and compacting soil microstructure，thus strengthening the properties of silt clay． Further，with injecting calcium chloride solution，the shear strength of cathodic soil increased by approximately 368. 6% ． However，there is a threshold value exists in the reinforcement effect，and the positive influence on reinforcing silt clay was negligible once the concentration of calcium chloride exceed 10% ． Adding calcium chloride solution would induce severe electrode corrosion，simultaneously．

Effect of Dry-Wet Cycles on the Deterioration of Sandstone with Various Initial Dry Densities

ZHU Jianghong HAN Shuxian TONG Yanmei LI Yan YU Rongguang ZHANG Huyuan

2019, 47(3):  126-134.  doi:10.12141/j.issn.1000-565X.180361

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Ｒevealing the deterioration law of sandstone strength under dry-wet cycles is highly significant for preventing and controlling unstable rocky slope of road engineering． Taking sandstone of a rocky slope in Lanzhou city as the research object，the effects of dry-wet cycles on the deterioration of sandstone with various initial dry densities were analyzed by uniaxial compressive test，tensile test and SEM observation． The results show that the uniaxial compressive strength，elastic modulus，uniaxial tensile strength and their deterioration rate of sandstone are negatively correlated with cycle number． The uniaxial compressive strength，elastic modulus and uniaxial tensile strength are respectively in good exponential correlation with cycle number． Among the same strength parameters， the difference in strength values of sandstone for various initial dry densities decreases with the increase of cycle number． The uniaxial compressive strength，elastic modulus，uniaxial tensile and their total deterioration degree gradually increase with the increase of initial dry density when cycle number is the same． During the increase of cycle number，the microstructure of sandstone changes significantly，and the microstructure difference between sandstone with various initial dry densities decreases gradually． Hence，the effects of dry-wet cycles on sandstone strength are related to cycle number and initial dry density closely

Accumulative Deformation of Subgrade Under CRTS Ⅲ Slab Track

LI Yangbo ZHANG Jiasheng ZHU Zhihui WANG Xuan SHI Xion

2019, 47(3):  135-142.  doi:10.12141/j.issn.1000-565X.180229

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An experimental scheme for the accumulative deformation of subgrade was proposed to study the accumulative deformation law of the subgrade under CＲTS Ⅲ slab track during the design service life． A full-scale CＲTS Ⅲ slab track-subgrade system was introduced，and a 100 million cyclic loading experiment was carried out on the test platform． Test results show that the number of cyclic loading has small influence on dynamic stress of the subgrade; with the increase of cyclic loading times，subgrade accumulative deformation grows fast in the initial stage，and after that the rate of growth gradually decreases; when the cyclic loading reaches 3. 5 million times，it tends to be stable，and after 100 million loading，the final stability value reaches 3. 38 mm． The accumulative deformation of the surface layer of subgrade，bottom layer of subgrade and foundation respectively accounts for 68. 93% ，16. 86% ，8. 88% ，5. 33% of the total accumulative deformation of the subgrade． Finally，an accumulative deformation prediction model was proposed based on the test result，which can provide reference for the establishment of a practical calculation method for the acumulative deformation of high-speed railway subgrade under long-term repeated train loads．

Homogeneous Generalized Yield Function and Ultimate Bearing Capacity Evaluation of Rectangular Steel Frame

YANG Lufeng HUANG Zilin XIE Weiwei

2019, 47(3):  143-152.  doi:10.12141/j.issn.1000-565X.180319

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In order to solve the problems in the ultimate bearing capacity analysis of steel frames with rectangular sections，an appropriate generalized yield function of rectangular cross-section was selected through the control internal force analysis，and then the elastic modulus reduction method for the analysis of the ultimate bearing capacity of rectangular cross-section rigid frame structure was established through the homogenization． Firstly，the equivalent homogeneous generalized yield function was established based on regression analysis and fitting error analysis． Secondly，the element bearing ratio were defined based on the homogeneous generalized yield function，then，the elastic modulus reduction method was proposed for determining the ultimate bearing capacity of steel frame by strategically reducing the elastic modulus of the highly stressed elements to simulate the structural stiffness damage． Finally，the key internal forces of the plane and space steel frames were investigated by means of determining the internal force ratios，further，an exact homogeneous generalized yield function was determined，and the accuracy and efficiency of the proposed method was verified． The results show that the proposed method as a linear elastic iterative method has high accuracy and overcomes the limitations of the traditional nonlinear iterative method，which can achieve higher computational efficiency．