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Explicit Analytical Solutions for the Shearingand Radial Stresses in Curved Beams

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Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 151-156页

作者： Aiming YU+ Xiangrong LI+++ (tongji university, shanghai 2.0092. china)++ (shanghai university, shanghai 200072, china) tongji university Shanghai 200092 China shanghai university Shanghai 200072 China

The shearing stresses in curved beams can be solved explicitly from anintegral equation, which is obtained by differentiation & integral manipulations. Twonovel formulae for shearing & radial stresses are also presented in the paper. The resultsof an example reveal that the shearing & radial stresses arrive at their maximum valuesslightly below the centroid of the section.

关键词： curved beam shearing stress radial stress integral equation

Macro-micromechanical approaches for non-coaxiality of coarse grained soils

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中国科学：技术科学英文版 2011年第S1期54卷 147-153页

作者： QIAN JianGu 1,2,HUANG MaoSong 1,2 & SUN HaiZhong 1,2 1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,shanghai 2.0092.china 2 Department of Geotechnical Engineering,tongji university,shanghai 2.0092.china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

For coarse grained soils,their principal stress directions may change when the water level of embankment dam varies *** this loading case,the principal directions of stress and strain rate will become *** an effort to model non-coaxial behavior,a modified three-dimensional non-coaxial model is developed in the context of vertex yield(tangent plasticity) *** Element Method(PFC) incorporating user-defined interparticle contact models is also employed to gain an insight into microscopic mechanism of *** analysis focuses on non-coaxial behaviors under simple shear *** has been shown that the proposed non-coaxial model gives good predictions for non-coaxiality with reference to microscopic observations while the classical coaxial model fails to simulate the non-coaxial *** general,non-coaxiality as a result of the rotation of principal stress,is large at a small shear strain,and inclined to become negligible with increasing shear *** coarse grained soils,their non-coaxiality tends to largely depend on the initial normal pressure,where a larger degree of non-coaxiality can be observed at a higher pressure.

关键词： coarse grained soils non-coaxiality particle flow code simple shear

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2 1. Department of Civil Engineering,shanghai university,shanghai 200072,china 2. School of Transportation Engineering,tongji university,shanghai 2.0092.china 1. Department of Civil Engineering Shanghai University Shanghai 200072 China 2. School of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,china

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Science china(Technological Sciences) 2011年第S1期54卷 192-198页

作者： WANG JianXiu 1,2,FENG Bo 2,HU LiSheng 2,TIAN PuZhuo 2,SUI DongChang 2,TANG YiQun 1,2 &YANG Ping 1,2 1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,shanghai 2.0092.china 2 Department of Geotechnical Engineering,tongji university,shanghai 2.0092.china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,china,is designed to study the effect of grout *** impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are *** results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure *** same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure *** the same water pressure,the smaller inflow of grout curtain,the less volume of water to be *** impact of hydraulic conductivity of grout curtain is more obvious than that of *** increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly *** proposed thickness of grout curtain for the diversion tunnels is 16 m.

关键词： tunnel grout curtain water pressure model test

THE INDUCED REPRESENTATION OF C^＊-GROUPOID DYNAMIC SYSTEMS

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Chinese Annals of Mathematics,Series B 1996年第1期17卷 103-114页

作者： FANG XIAOCHUN(Department of Mathematics, tongji university, shanghai 200029, china.) tongji UNIV DEPT MATHSHANGHAI 200029PEOPLES R CHINA

Let G be a second countable locally compact groupoid with Haar system {λu}, H be a closed subgroupoid containing Go with Haar system {λuH}. *** introduced the C*-Groupoid dynamic system (G, A, α) and its reduced crossed product Cr.d(G, A) in [2], where A is a C*-algebra, α is the homomorphism G→Aut(A). In this paper the author introduces the C*-groupoid dynamic systems (H, A, α|H) and (H\G2, A, α) induced by (G, A, α) and proves that C~*red(H, A) and C~*red(H\G2, A) are strongly Morita equivalent. Moreover the induced representation from C~*red(H, A) to C~*red(G, A) is got.

关键词： C~*-groupoid dynamic system Induced representation Haar system

STABILITY OF IMPULSIVE LINEAR HYBRID SYSTEMS WITH TIME DELAY

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Journal of Systems Science & Complexity 2010年第4期23卷 738-747页

作者： Yu ZHANG·Jitao SUN Department of Mathematics,tongji university,shanghai 2.0092.china. JitaoSUN Department of Mathematics Tongji University

This paper investigates the stability of impulsive linear hybrid systems with time *** a number of delay-independent/delay-dependent stability criteria are obtained by using Lyapunovfunctions or Lyapunov *** examples ... 详细信息

关键词： Impulsive linear hybrid system Lyapunov function Lyapunov functional time delay.

A geometrical and physical nonlinear finite element model for spatial thin-walled beams with arbitrary section

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Science china(Technological Sciences) 2010年第3期53卷 829-838页

作者： YANG QingShan 1 &WANG XiaoFeng 2 1 School of Civil Engineering,Beijing Jiaotong university,Beijing 100044,china 2 College of Civil Engineering,tongji university,shanghai 2.0092.china 1. School of Civil Engineering Beijing Jiaotong University Beijing 100044 China2. College of Civil Engineering Tongji University Shanghai 200092 China

Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all ***,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are *** plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of *** stiffness matrix is derived by numerical integration on the basis of the finite segment *** show that the developed model is feasible in analysis of thin-walled structures with high accuracy.

关键词： Spatial beams thin-walled structures geometrical and physical nonlinearity finite element arbitrary section

Homogenization-based multi-scale damage theory

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 690-698页

作者： LI Jie 1,2 & REN XiaoDan 1 1 School of Civil Engineering, tongji university, shanghai 2.0092. china 2 State Key Laboratory of Disaster Reduction in Civil Engineering, shanghai 2.0092. china 1. School of Civil Engineering Tongji University Shanghai 200092 China2. State Key Laboratory of Disaster Reduction in Civil Engineering Shanghai 200092 China

The research of modern mechanics reveals that the damage and failure of structures should be considered on different scales. The present paper is dedicated to establishing the multi-scale damage theory for the nonlinear structural analysis. Starting from the asymptotic expansion based homogenization theory, the multi-scale energy integration is proposed to bridge the gap between the micro and macro scales. By recalling the Helmholtz free energy based damage definition, the damage variable is represented by the multi-scale energy integration. Hence the damage evolution could be numerically simulated on the basis of the unit cell analysis rather than the experimental data identification. Finally the framework of the multi-scale damage theory is established by transforming the multi-scale damage evolution into the conventional continuum damage mechanics. The agree- ment between the simulated results and the benchmark results indicates the validity and effectiveness of the proposed theory.

关键词： Multi-scale damage representation asymptotic method constitutive model numerical simulation

Flexural and Impact Resistance of FRC/Bamboo Laminate

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Journal of Materials Science & Technology 2002年第4期18卷 369-371页

作者： Wu YAOState Key Laboratory of Concrete Materials Research, tongji university, shanghai 2.0092. china Lab. of Concrete Mat. Res. Tongji Univ. Shanghai 200092 China

The flexural and impact resistance of a newly developed FRC/bamboo laminate have been investigated. The laminate considered in this study was combined with reformed bamboo plate and extruded fiber reinforced cementitious (FRC) sheet. Innovated from the raw bamboo, reformed bamboo showed high tensile strength and high strength to weight ratio. It can not only remarkably strengthen the FRC sheet but also reduce the total weight of the laminate. Flexural and impact load, broken energy, deflection and duration were measured. Test results showed that the flexural strength value for the laminate can be improved to greater than 90 MPa, while the impact resistance is increased more than 10 times for the laminate when compared with the FRC sheet only.

关键词： Flexural strength Impact FRC/bamboo composite