Table of Content

25 July 2007, Volume 35 Issue 7

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Mechanics

Analysis of Interfacial Stresses for RC Beams Strengthened with Prestressed FRP

Guo Xin-yan Huang Pei-yan Yang Yi Zheng Xiao-hong

2007, 35(7):  1-5. 

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Bonding prestressed fiber-reinforced polymer (FRP) plate to strengthen and repair civil engineering structures improves the working efficiency and the force conditions of structures. In this paper , formulae of the shears and normal stresses on the interfacial layer between the prestressed FRPs and the concrete members of strengthened reinforced concrete (RC) beams were deduced based on theoretical analyses , and the distributions of the interfacial stresses were analyzed. Then , by means of finite element method (FEM) , numerical experimer山were carried out to reveal the effects of initial prestress and CFL thickness on the interfacial stresses. It is shown from theoretical analyses and FEM results that there may arise the debonding of CFL from the concrete members when the initial prestress is 20% of the tensile strength and is loaded on the CFL without anchorage at the two ends.

Nonlinear Finite Element Analysis of RC Beams Strengthened with CFS/ AFS

Guo Yong-chang Li Li-juan Deng lun Liu Feng

2007, 35(7):  6-9,36. 

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This paper aims at the mechanical characteristics of the reinforced concrete (RC) beams strengthened with carbon fiber sheet/ aramid fiber sheet (CFS/ AFS) , a new hybrid strengthening method. In the investigation ,the nonlinear finite element analyses of the single-layer and double-layer strengthening models for the RC beams are made by establishing the constitutive equations of different materials. Then , the effects of the fibre sheet type and the sheet length on the bending stiffness , initial cracking loads and failure loads of the beams are analyzed. Moreover, a comparative analysis is performed , finding that the calculated results are consistent with the experimental ones. It is indicated that the hybrid strengthening by using CFS and AFS may result in a good hybrid effect and may sufficiently bring the high strength of CFS into play.

Theoretical and Experimental Study on Interfacial Stresses of Steel Beam Strengthened with CFRP Plates

Deng Jun Huang Pei-yan

2007, 35(7):  10-14. 

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In order to overcome the carhon fiher-reinforced polymer (CFRP) plate dehonding from the CFRPstrengthened steel heam due to the stress concentrations at the two ends of the plate , the interfacial stresses in the strengthened heam under mechanical loads were formulated , and the hearing capahilities and stiffness of 8 specimens with different plate lengths , thickness and loading cases under static loads were tested. Theoretical and experimental results show that dehonding is the main failure mode of the strengthened heam , that the increase of plate length does not affect the hearing capacity and stiffness of the strengthened heam hut decrease the stress concentration, that the increase of plate thickness not only improves the hearing capahility and stiffness hut also increases the stress concentration , and that a11 the theoretical maximum interfacial stresses of the specimens under the dehonding loads are very close.

Traffic & Transportation Engineering

Visual Adaptation Index for Driving Safety at Entrance and Exit of Highway Tunnel

Du Zhi-gang Pan Xiao-dong Guo Xue-bin

2007, 35(7):  15-19. 

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The sha.rp variation of luminance at the entrance and exit of highway tunnel will cause the difficulty in visual adaptation of the driver , and even lead to traffic accidents. In order to solve this prohlem , hy using the EMR-8B eye tracker system , the pupillary change of the driver at the entrance and exit of highway tunnel is experimentally investigated. Experiment results indicate that , within the range of 50 m away from the entrance and the exit , the logarithmic illuminance of the retinal is positively linear to the logarithmic luminance of the road. Moreover , an index to evaluate the driving safety is presented hased on the pupil area and its variation velocity , that is , when the variation velocity of pupil area transcends the critical velocity with a duration time of more than0. 2 s , the driving is unsafe , otherwise , the driving is safe. The paper also elicits a visual adaptation-hased transition slope of rational illuminance in the end.

Detection of Trans-Line Vehicles ßased on Inductive Loop

Liang Jun-bin Xu Jian-min

2007, 35(7):  20-24. 

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Loop detector is one of the instruments that have been widely applied to vehicle detection. However , its accuracy is greatly affected because it fails to judge trans-line vehicles. In order to avoid the trouble , this paper analyzes the detection theory of loop detector and reveals the influence of the tested frequency on the collected data accordirig to the eddy current effect , and then deduces the data conversion formula for the tested frequencies on adjacent lanes , according to which a valuable detection method to detect trans-line vehicles is proposed based on the segmented time series pattern matching. It is proved that the presented method can effectively detect trans-line vehicles and greatly improve the accuracy and reliability of vehicle detectors.

Simulated Analysis of Coordinated Control System for Ramp on Freeway

Xu Lun-hui Lu Wang-yi Zhou Jing

2007, 35(7):  25-30. 

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Based on the macroscopical stable continuous-flow traffic mode and the occupancy adjustment strategy , this paper proposes a coordinated control system of ramp on freeway by using Visual Basic software. The proposed system is then used to simulate the dynamic operation mode of freeway , and the corresponding operation and calculation effectiveness are finally verified by data simulation. The results show that the proposed control system is of good dynamic performance , and possesses the advantages of eliminating traffic jams , maintaining traffic-flow stability and ensuring efficient and safe drive.

Chemistry & Chemical Engineering

Fatigue Properties of Large-Sample Asphalt Mixture Under the Same Conditions

Wu Kuang-hua Zhang Xiao-ning

2007, 35(7):  31-36. 

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Experimental investigation into the strain -controlled fatigue properties of large-sample asphalt mixture under the same conditions was carried out , and the distributions as well as the correlativity of three parameters including the fatigue life , the initial modulus and the cumulative dissipated energy were analyzed. Moreover , the relationships between the air void ratio in asphalt mixture and the three above-mentioned parameters were analyzed. The results indicate that the strain-controlled fatigue life is greatly discrete , that the fatigue life , the cumulative dissipated energy and the initial modulus all follow the simple and the logarithmic three-parameter Weibull distributions , revealing the feasibility of applying the simple three parameter Weibull distribution to the analysis of the fatigue test data , and that , under the same conditions , there are negative and logarithmic negative linear relationships between the fatigue life and the initial modulus , a strong positive linear relationship between the cumulative dissipated
energy and the fatigue life , a negative linear relationship between the air void ratio and the logarithmic cumulative dissipated energy as well as the logarithmic fatigue life , and a weak correlativity between the initial modulus and the air void ratio. All these above-mentioned statements demonstrate the laws of strain-controlled fatigue of asphalt mlxture.

Dynamic Mechanical Properties of SBS-Modified AsphaIt

Chen Hua-xin Wang Bing-gang

2007, 35(7):  37-40,51. 

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According to the tested results via dynamic shear rheometer for 13 types of SBS-modified asphalts composed of one base-asphalt and 4 styrene-butadiene-styrene (SBS) polymers , the temperature spectra of the original asphalt and the aged asphalt after the rolling thin-film oven test (RTFOT) were compared , and the variation mechanism of the dynamic mechanical properties for the modified asphalts was discussed. Furthermore , the effects of modifier type and dosage on the dynamic mechanical properties were investigated. The results show that the lowternperature dynamic mechanical properties of the modified asphalts depend on the property of the base asphalt , while the high-temperature properties rely on the property of SBS polymers , and that , during the RTFOT aging , there occurs the deterioration and degradation of SBS polymers , which may result in the loss of elastic components of the SBS-modified asphalts and the performance variation of the SBS-modified asphalt like the base asphalt.

Backcalculation of Elastic Moduli of Asphalt Surface Course Based on Asphalt Surface Curvature Index

Yang Guo-liang Wang Duan-yi Zhang Xiao-ning

2007, 35(7):  41-45. 

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Based on the theory of layered elastic system , first , the moduli of asphalt surface course were backcalculated according to the surficial deflection responses of pavement structure. Next , a database of the structural parameters and the corresponding surface deflections was established according to the offsets of geophones set on the falling weight deflectometer to the center of load plate. Then , the critical influencing thickness of asphalt surface course was brought up after analyzing the database. Finally , regressive models were developed according to the corresponding critical influencing thickness. It is shown , from the comparative analyses of theoretical and measured deflection basins , that the proposed method is practical and effective in rapidly evaluating pavement bearing capacity with high accuracy and good reliability.

Preparation and Characterization of Microencapsulated Phase-Change Materials

Yuan Wen-hui Liu Du-shu Li Li

2007, 35(7):  46-51. 

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Microencapsulated phase-change materials (MPCMs) were prepared by means of in-situ polymerization , with melamine-formaldehyde as the shell and n-octadecane as the core. The properties of the products were then analyzed and characterized by using optic microscope , SEM and DSC , and the effects of the emulsifier sort , the emulsifierdosage and the isocyanate addition on the properties of the prepared microcapsules were investigated. Experimental results show that the microcapsules prepared with nonionic emulsifier and anionic emulsifier are of better performances than those prepared only with one anionic emulsifier， that the addition of isocyanate greatly improves the latent heat of. MPCMs , and that the MPCMs with an average particle size of 4. 0 μm and a latent heat up to 176. 5 J/ g are of smooth morphologies , hundred-percent wrap and homogeneous size.

Cooling Technology of Electronic Device ßased on Phase-Change Material with Rapid Thermal Response

Yin Hui-bin Gao Xue-nong Ding Jing Zhang Zheng-guo

2007, 35(7):  52-56,104. 

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A kind of composite phase-change material (PCM) possessing rapid thermal response was prepared , with paraffin as the phase-change material and with porous expanded graphite of high thermal conductivity as the supporting material. The product with a thermal conductivity up to 4. 676 W / ( m . K) was then applied to the heat sinks of electronic devices. The results show that the apparent heat transfer coefficients of the PCM-based testing system at different heating powers are 1. 36 - 2. 98 times that of the traditional cooling system , meaning that the PCMbased testing system is of better cooling performances and is capable of effectively improving the resistance to highloading heat shock. Thus , the operation reliability and stability of electronic devices can be effectively ensured.

Effect of Ionic Strength on Ion-Exchange Equilibrium of Taurine

Song Feng Li Zhong Xia Qi-bin Sun Hui-li

2007, 35(7):  57-61. 

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In this paper , the effects of ionic strength of solution on the ion-exchange equilibria of taurine/OH ^- system on anion exchange resin D290 were investigated by means of static adsorption , and the equilibrium uptake isotherms of taurine on the alkali anion exchange resin were measured at different ionic strengths. The results show that , with the increase in ionic strength , the adsorbed amount of taurine on the resin D290 , the distribution coefficient λ_Tau and the fraction of zwitterion Tau^±all decrease , while the pH value of the solution at the equilibrium and the content of anionic taurine Tau ^- increase. Moreover , it is found that , at a certain taurine concentration , the increase in ionic strength may improve the selectivity of the anion resin for taurine.

Optimized Design of Recovery Process of Light Hydrocarbons from LNG

Xiong Yong-qiang Li ya-jun Hua Ben

2007, 35(7):  62-66. 

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According to the characteristics of the cold energy of liquefied natural gas (LNG) , a new recovery process of light hydrocarbons from liquefied natural gas was presented based on the gradient utilization of cold energy.The proposed recovery process was performed without using any gas compressor , and the cold energy of LNG was used to re-liquefy the methane-rich residual gas and to re-condense and store the methane in tanks in low-pressure liquid phase , the process was of the function of peak shaving , and the recovered light hydrocarbons in low-pressure liquid phase were easy to store and sell. Then , a case study of applying the process was carried out for the imported3.7 X 10⁶ t/a LNG from Australia by Shenzhen. The results indicate that , as compared with the conventional technologies, the proposed process can reduce the power consumption by 47.3% and decrease the heat load by 27.3% ,that approximately 20% of the methane-rich residual gas is re-condensed and stored in tanks in low-pressure liquid phase for the peak shaving of natural gas downstream system by vaporizing it ， that the C₂^＋ hydrocarbons recovered from LNG can be used as a substitution for naphtha and the feed of ethylene unit , with the advantages in decreasing the investment and saving the energy consumption and the cost.

Preparation and Antibacterial Properties of Zinc-Doped Hydroxyapatite Nanoparticles

Lin Ying-guang Yang Zhuo-ru Cheng Jiang

2007, 35(7):  67-71. 

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Hydroxyapatite (HAP) nanoparticles and zinc-doped hydroxyapatite (ZnHAP) nanoparticles with a Zn/ [ Ca + ZnJ molar ratio γof 0 - O. 2 were prepared hy means of sol-gel-supercritical fluid drying. Then , FTIR ,XRD and TEM , XRD were adopted to reveal the effects of zinc doping on the structure , crystal shape and crystallinity of the prepared nanoparticles. Moreover , the hacterial inhihition zone and antihacterial ratio were tested to investigate the antihacterial properties of HAP and ZnHAP nanoparticles to Escherichia coli , Stα'Phylococcus aureus and Lactobαcillus. The results are as follows. The sol-gel-supercritical fluid dηing is an effective method to prepare HAP and ZnHAP nanoparticles; zinc can he partially doped in HAP as the suhstitute of Ca to form ZnHAP; after the doping of zinc , the vihration frequencies of IR honds in ZnHAP increase , the transmittance and the crystallinity decrease with the γvalue increasing , and the morphology of the nanoparticles changes from short rod shape to needle shape; both the HAP nanoparticles and the ZnHAP nanoparticles with a γvalue of less than 0. 04 possess antihacterial properties only in dynamical forcible contact with tested bacteria at a nanoparticles content of 0. 1 glmL; the ZnHAP nanoparticles with a γvalue of more than O. 08 possess an antibacterial ability which increases with γ value at the same content no matter whether it is in static or dynamic contact with the tested bacteria. All of the results indicate that the antibacterial property is improved after the zinc doping.

Coating Mechanism and Dispersion Stability of Polyaniline-Coated Short Carbon Fibers

Yu Dong-xiu Chen Ming-tao Wen Xiu-fang Cheng Jiang Yang Zhuo-ru

2007, 35(7):  72-77. 

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In order to improve the dispersion stahilities and physico-mechanical properties of short carbon fibers ( SCFs) in coatings , the methods of nitric acid oxidation and in -situ polyaniline (P ANI) coating were adopted to modify the surface properties of SCFs. Then , by means of XPS , SEM , UV -Vis , four-point probe measurement and coaxial cable method , the activated functional groups on the modified SCF surface , the microstructure and dispersion
stability of the modified SCFs and the coating mechanism of PANI on the SFC surface were investigated. The results indicate that the nitric acid oxidation helps to increase the oxygen-containing functional groups , that the oxidation combined with the PANI coating on the SCF surface via chemical bonds helps to improve the dispersion stability of SCF in the coating , and that , as compared with the coating with the original SCFs , the coating with PANIcoated oxidized SCFs is of a sheet square resistance decreasing from 17. 1 Ω to 5. 3 Ω.

Improvement of Synthesis Procedure of Imiquimod

Zhang Yi-wei Chen Hai-quan He Wei-biao Liu Qiong

2007, 35(7):  78-81. 

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Imiquimod was synthesized from raw material 2 ,4-dihydroxyquinoline via 7 reaction steps including nitration, chlorination , amination , reduction of nitro group , cyclization , henzylamination and dehenzylation. The average yield of 2 ，4-dihydroxy-3-nintroquinoline (Ⅱ reached 99% by reusing the mother liquid of nitration for 7 times. 4-(2-methylpropylamino) -2-chloro-3-nitroquinoline (Ⅳ) was reduced to 4-( 2-methylpropylamino) -3-amino-
2-chloroquinoline ( V) hy iron powder and hydrochloric acid in 95%ethanol ， anhydrous K₂ CO₃ with proper quantity was added to the reaction mixture to make the hyproduct ferric oxide easy to filtrate off from the solution of V , the yield of V was 76%. With the improved synthesis procedure , the intermediates ohtained from the nitration , the amination , the reduction of nitro group , the cyclization and the henzylamination were pure enough to he directly used in the next reaction without further purification , thus simplifying the synthesis procedure with an overall imiquimod yield of more than 45%.

Dynamic Surface Tension and Adsorption Kinetics of Aqueous ELENIMOL JS-2 Solution

Yao Zhi-gang Hu Ai-xi Li Xiao-wu Li Gan-zuo

2007, 35(7):  82-87. 

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This paper first put forth a measurement of the dynamic surface tension (DST) of the reactive surfactant sodium dodecyl allyl sulfosuccinate (ELENIMOL JS-2) by means of the maximum bubble-pressure method. Next ,the effects of the ELENIMOL JS-2 concentration , the temperature and the electrolyte on the DST were investigated.Then , the parameters describing the DST were calculated. Finally , according to Word-Tordai equation , the adsorption kinetics of aqueous ELENIMOL JS-2 solution was presented. The results show that the adsorption process fol-lows a pure diffusion step at the beginning of the adsorption , obeys the mixed diffusion-kinetic adsorption mechanism during the adsorption process , and is finally controlled by a pseudo-diffusion step.

Influences of Inlet and Outlet Drying Temperatures on Re-Dispersible EV A Polymer Powders

Xie De-long Zhang Xin-ya Yang Bo Chen Huan-qin

2007, 35(7):  88-92. 

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Re-dispersible ethene-vinylacetate (EV A) polymer powders were prepared by means of spray drying , with polyvinyl alcohol (PV A) as the protective colloid and silica sol and inorganic powders as the anti -agglomerating agents. Then , the influence of the inlet and outlet temperatures on the performances of the prepared powders was investigated. Experimental results show that the inlet and outlet temperatures greatly influence the appearance ,water content , fluidity , stacking density , re-dispersibility , film performance and storage stability of the polymer powders , and that the water content and the stacking density decrease while the fluidity improves when increasing the inlet and outlet temperatures. It is also found that the appropriate inlet and outlet temperatures for spray drying are respectively 150 - 180℃ and 75 - 80 ℃, and that giving higher inlet temperature may result in the structure change of the powders. Moreover , the FfIR spectrum indicates that the mo1ecu1ar structure of the polymer powders after the spηdrying keeps unchanged at an inlet temperature of 180 ℃ .

Kinetics of Non-Isothermal Degradation of Polyethylene-Octene Elastomer / Starch Blends

Shαng Xiao-ya Fu Xiong Yang Lian-sheng He Xiao-wei Wen Ren-gui

2007, 35(7):  93-98. 

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The non-isothermal degradation of polyethylene-octene elastomer (POE) / gelatinized waxy com starch ( GWCS) blends with different compositions was first carried out in an inert atmosphere , and the corresponding degradation behaviors and kinetics were investigated by means of the thermogravimetric (TG) method. Then , the mechanism of the thermal degradation was discussed. The results indicate that , with the increase of starch content ,the TG curves of POE/GWCS blends shift to the low-temperature range and the onset temperatures of epitaxial grow decrease , meaning that the addition of starch results in the decrease in thermal stability of the blend. Moreover , it is shown that the maximum degradation rate and the corresponding temperature increase with the heating rate , and that the values of kinetic parameter E/logA calculated by Kissinger and Flynn--Wall-Ozawa methods decrease with the increase in starch content , revealing an obvious effect of starch content on the thermal stability of the blends.

Synthesis and Application of Phenolic Resin Internally Toughened by Chain Extension Polymer of Epoxidized Soybean Oil

Situ Yue Hu Jian-feng Huang Hong Fu He-qing Zeng Han-wei Chen Huan-qin

2007, 35(7):  99-104. 

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In this paper , first , a novel phenolic resin internally toughened by epoxidized soybean oil (ESO) with good toughness and thermal stability was prepared as the matrix resin of copper clad laminate (CCL). Next , IT-IR was adopted to characterize the molecular structure of the modified phenolic resin and SEM was used to observe the micro morphology of the resin intersections with impact. Then , the properties of CCLs prepared with the modified phenolic resin were studied to determine the optimal processing conditions. Finally , the corresponding toughening mechanism was investigated. It is demonstrated that the toughening relies mainly on the triethanolamine-catalyzed etherification reaction between phenol hydroxyl and ESO and the chain extension polymerization between ESO and multi-amine , which presents long-chain ESO epoxy grafting on the phenolic resin prepolymer. Moreover , it is foundthat the ESO-toughened phenolic resin possesses optimal performance at an ESO content of 30% and a curing agent content of 7 % , and that the flexible ESO epoxy possessing significant toughening effect can crosslink with the phenolic resin to form an internally toughened network for improving the solderleaching resistance of the CCL prepared with the modified phenolic resin.

Architecture & Civil Engineering

Optimized Algorithm of Wave Superposition Method to Simulate Stochastic Wind Field

Luo Jun-jie Han Da-jian

2007, 35(7):  105-109. 

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In order to improve the efficiency of the conventional wave superposition method in simulating the multivariable stochastic wind fields , an optimized recursive algorithm is employed to conduct the Cholesky factorization by blocking the cross-spectral density function matrix into several sub-matrices , and a matrix multiplication algorithm is introduced to replace the harrnonic superposition process of the conventional method. Thus , the number of
the elements for the factorization in the cross-spectral density matrix is reduced and the Cholesky factorization and the wind field synthesis are speeded up. The engineering practice indicates that the proposed optimized algorithm remarkably saves the simulation time and improves the simulation efficiency.

Fire Resistance of Reinforced Concrete Column with L-Shaped Cross Section

Xu Yu-ye Wu Bo

2007, 35(7):  110-115,130. 

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Analyzed in this paper were the influences of several parameters , such as the load ratio , the effective column length , the sectional dimensions , the load eccentricity ratio , the reinforcement ratio and the loading angle on the fire resistance of reinforced concrete columns with L-shaped cross section exposed to the IS0834 standard fire , and 5400 columns subjected to fire in all sides were used to caπY out the fire response analyses , with the above- mentioned parameters being the variables. Based on the analytical results , a practical method to calculate the fire resistance of the column with L-shaped cross section was presented. The results show that the loading angle has significant and complicated effect on the fire resistance of the column , and that reducing the load ratio is an effective method to improve the fire resistance.

Improvement of LocalMechanical Properties of Concrete Segment by Stee-l Fiber Reinforcement

Mo Hai-hong Chen Jun-sheng Liang Song Yang Yi-bo Su Yi

2007, 35(7):  116-121. 

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In order to revea l the effect of steel-fiber reinforcement on the local mechan ica l properties of concrete segmen ts used in sh ield tunne ls, a general 3D finite element code, ADINA, was used to numerica lly analyze the cracking loads, stress distributions and crack distributions of the steel fiber-re inforced concrete ( SFRC ) segment under the jacking force or in a regular service stage. The results indicate that the addition of steel fibers can effec- tively improve the local mechanical properties of segment surface, hand holes and bolt holes, greatly enhance the anti-crack performance of SFRC segment, and make the first-crack load 13. 3% ~ 22. 7% greater than that of the origina l reinforced concrete segm en.t

Experimental Investigation into In-Plane Bearing Capability of Single-Layer Glass Panels with Overlapped Connectors

Shi Yong-jiu Deng Xiao-wei wang Yuan-qing Luo Yi Xu Yue

2007, 35(7):  122-126. 

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In recent years , overlap-connected glass curtain walls have been widely used in the field of modem architecture, but the corresponding theoretical researches lag behind the engineering application. In order to solve this problem , the mechanical behavior and the corresponding mechanism , as well as the stress and displacement distributions of glass panels restrained by different types of overlapped connectors under in-plane shear were investigated by experimental tests and finite element method (FEM). Furthermore , the validity of FEM is experimentally verified. It is concluded that the displacement and stress of the glass panel linearly increase with the shear load in the loading process , and that the panel exhibits significant characteristic of brittle failure. Moreover , the stress mechanism of in-plane shearing is different from that of out-of-plane bending , the former being the compressive failure in contact boundary while the latter being the tensile failure in the joint region.

Reliability of Coupling of Strength and Stiffness in Structure System

Li Yi Zhao Wen Liang Lei Li Shen-gang Yun-qi

2007, 35(7):  127-130. 

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According to the concept of computational structural mechanics , a method to analyze the coupling reliability of strength and stiffness in the frame structure is presented to continuously generate the intemal force and limitstate function of the structure. The proposed method is then combined with the branch-and-bound method to evaluate the total failure probability of the system. As the proposed method simplifies the global stiffness matrÏx operation, the continuous analysis of reliability for the variational structure can be realized , and a new criterion of the degenerating from the structure into the mechanism can be obtained. Thus , the searching speed of systemic failure modes and the efficiency of reliability analysis are both improved.

Experimental Investigation into PHC Pipe Piles Under Lateral Load in Deep Soft Soil Foundation

Zhou Wan-qing Cai Jian Lin Yi-xi Huang Liang-ji

2007, 35(7):  131-136. 

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Based on the experimental results of prestressed high-strength concrete (PHC) pipe piles subjected to lateral loads in the deep soft soil foundation of Zhuhai free trade zone , the lateral bearing behaviors of the piles are discussed. The results show that the piles with high slendemess ratio can effectively bear the lateral loads , that the underside of the long elastic pile can be considered as a socking into the soil without rotation , the crescent resistance moment and the lateral soil pressure bearing the crescent lateral load , that the bearing capacity of the long elastic pile is mainly affected by the upside soil , and that the calculated proportional coefficient m describing the lateral resistance of foundation can be used as a reference for the design of the similar engineering. Moreover , according to the simulated results of the lateral bearing capability of PHC pipe piles via the finite element code ABAQUS , the high accuracy of the proposed method is finally revealed.

Design Methods for Piled Raft Foundations Based on the Economic Concept

Pan Jian wang Xing-bin Liu Li-yan Gu Tai-hua

2007, 35(7):  137-142. 

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In this paper , first , the soil under a piled raft foundation was simulated via the linear extended DruckerPrager elastic-plastic model. Next , behaviors of the piled raft foundation system were revealed by using a 3D finite element model based on the ABAQUS program. Then , the dimensional eight-node solid element , the four-node thick plate element and the 3 D finite element coupling interface element were adopted to respectively simulate piles and the soil in the model , the piled raft and the raft-soil system , thus obtaining the operation characteristics of the piled raft foundation. Moreover , the design method of composite pile foundation was investigated and an improved method based on a "three-stage" concept was presented according to the criterion of "Code for Design of Building Foundation". The two methods were finally applied to a practical engineering. Results show that , as compared with the conventional design method , the two above-mentioned methods are more feasible , practical and economical.