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Damage and progressive failure of concrete structures using non-local peridynamic modeling

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Science china(Technological Sciences) 2011年第3期54卷 591-596页

作者： HUANG Dan1,2, ZHANG Qing1,2 & QIAO PiZhong1,3 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering, hohai university, nanjing 210098, china 2 department of engineering mechanics, hohai university, nanjing 210098, china 3 department of Civil and Environmental engineering, Washington State university, Pullman, WA 99164-2910, USA 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing 210098 China2. Department of Engineering Mechanics Hohai University Nanjing 210098 China3. Department of Civil and Environmental Engineering Washington State University Pullman WA 99164-2910 USA

Peridynamics (PD), a recently developed theory of solid mechanics, which employs a non-local model of force interaction and makes use of integral formulation rather than the spatial partial differential equations used in the classical continuum mechanics theory, has shown effectiveness and promise in solving discontinuous problems at both macro and micro scales. In this paper, the peridynamics theory is used to analyze damage and progressive failure of concrete structures. A non-local peridynamic model for a rectangular concrete plate is developed, and a central pairwise force function is introduced to describe the interior interactions between particles within some definite distance. Damage initiation, evolution and crack propagation in the concrete model subject to in-plane uni-axial tension, in-plane uni-axial compression and out-of-plane impact load are investigated respectively. The numerical results show that discontinuities appear and grow spontaneously as part of the solution to the peridynamic equations of motion, and no special failure criteria or re-meshing techniques are required, which proves the potential of peridynamic modeling as a promising technique for analyzing the progressive failure of concrete materials and structures.

关键词： concrete damage progressive failure peridynamic model discontinuities

Effects of shear keys on nonlinear seismic responses of an arch-gravity dam

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Science china(Technological Sciences) 2011年第S1期54卷 18-27页

作者： JIANG ShouYan 1,DU ChengBin 1 &YUAN JuWei 2 1 department of engineering mechanics,hohai university,nanjing 210098,china 2 Jiangsu Hongji Science and Technology Company.,Ltd.,nanjing 210008,china 1. department of engineering mechanics Hohai University Nanjing 210098 China2. Jiangsu Hongji Science and Technology Company. Ltd. Nanjing 210008 China

In the paper,the added tangential nonlinear springs are introduced to represent the effects of one-way and two-way shear keys. The added tangential stiffness coefficient is relative to the joint opening and the relative tangential movement and determined numerically by using a refined model of shear *** user subroutine of nonlinear spring elements has been implemented into ABAQUS *** seismic responses of an arch-gravity dam are mainly *** is shown by the results that a significant increase of about 17%-30%in joint opening can be observed for the dam with one-way shear keys;the two-way shear keys are beneficial to restrain the sliding displacement along both the radial and vertical directions,whereas the one-way shear keys mainly restrain the displacement along the radial direction;for the dam with shear keys,the maximum arch stress is increased,the cantilever stress is reduced,and the location of the maximum cantilever stress is also moved from the dam heel to the midheight of the cantilever.

关键词： seismic responses arch-gravity dam contraction joints shear keys nonlinear spring elements

A macro-meso constitutive law for concrete having imperfect interface and nonlinear matrix

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中国科学:技术科学 2010年第3期 330-330页

作者： ZHANG Qing1 & XIA XiaoZhou1,2 1 department of engineering mechanics,hohai university,nanjing 210098,china 2 Institute of Construct,Guangdong university of Technology,Guangzhou 510006,china

The overall behavior of concrete depends on its meso structures such as aggregate shape,interface status,and mortar matrix *** two key meso structure characters of concrete,bond status of interface and nonlinear property of matrix,are considered in *** variational structure principle is adopted to establish the macro-meso constitutive law of ***,a linear reference composite material is selected to make its effective behavior approach the nonlinear overall behavior of *** the overall property of linear reference composite can be estimated by classical estimation method such as self-consistent estimates method and Mori-Tanaka *** variational structure method involves an optimum problem ***,the macro-meso constitutive law of concrete is established by optimizing the shear modulus of matrix of the linear reference *** analyzing the constitutive relation of concrete established,we find that the brittleness of concrete stems from the imperfect interface and the shear dilation property of concrete comes from the micro holes contained in concrete.

关键词： imperfect interface matrix nonlinear property variational structure principle macro-meso constitutive law concrete

Theory and methods of global stability analysis for high arch dam

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Science china(Technological Sciences) 2011年第S1期54卷 9-17页

作者： REN QingWen 1,LI Qiang 1,JIANG YaZhou 2 & JIANG XiaoLan 3 1 department of engineering mechanics,hohai university,nanjing 210098,china 2 College of Water Conservation and Hydropower engineering,hohai university,nanjing 210098,china 3 Changjiang Academy of Sciences,Wuhan 430010,china 1. department of engineering mechanics Hohai University Nanjing 210098 China2. College of Water Conservation and Hydropower Engineering Hohai University Nanjing 210098 China3. Changjiang Academy of Sciences Wuhan 430010 China

The global stability of high arch dam is one of the key problems in the safety study of arch dams,but no feasible method with theoretical basis is *** this paper,based on the stability theory of mechanical system,it is demonstrated that the global failure of high arch dams belongs to a physical instability starting from local strength failure,which is the extreme point instability according to the characteristics of load-displacement curve obtained from the failure process of dam-foundation system. So the global failure of dam-foundation system should be studied with the stability theory of mechanical *** is also pointed out that the current stability analysis methods used in engineering are consistent with the stability theory,but not established according to the mechanical system stability theory directly.A perfect method can be obtained through the study of physical disturbance equations.

关键词： high arch dam global stability physical instability extreme point instability

EFFECTS OF SUBMERGED MACROPHYTES ON SEDIMENT SUSPENSION AND NH_4-N RELEASE UNDER HYDRODYNAMIC CONDITIONS

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Journal of Hydrodynamics 2010年第6期22卷 810-815页

作者： WANG Chao WANG Cun WANG Ze Key Laboratory of Integrated Regulation and Resource department on Shallow Lakes Ministry of EducationHohai University Nanjing 210098 China State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing210098 China College of mechanics and Materials Hohai University Nanjing 210098 China

Aquatic vegetation affects sediment suspension and nutrient release by changing the flow structure. Experiments on the influence of submerged vegetation on flow structure, sediment suspension, and NH4-N release were carried in a flume with natural submerged vegetation. Turbulence characteristics in the vegetation section were measured using a three-dimensional acoustic Doppler velocimeter. The effects of submerged vegetation on bed shear stress （ τb ）, sediment suspension, and NH4-N release were analyzed. Results show that with vegetation, bed shear stress is reduced by about 20% - 80%, which, in turn, reduces sediment suspension. The impact of submerged vegetation on sediment suspension and NH4-N release should be considered along with flow intensity. When the flow Reynolds number is relatively small, the submerged vegetation is quite capable of inhibiting sediment suspension and reducing NH4-N release, but when the Reynolds number reaches a certain value, the presence of aquatic plants exacerbates sediment suspension and promotes NH4-N release. Results also reveal that a highly significant positive correlation exists between NH4-N concentration and water turbidity in both vegetated and non-vegetated channels.

关键词： sediment suspension submerged macrophytes turbulence behavior bed shear stress turbidity

COMPOSITE MODELING APPROACH AND EXPERIMENTAL STUDY FOR SUBSURFACE TRANSPORT OF CONTAMINANTS FROM LAND-DISPOSAL SITES

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Journal of Hydrodynamics 2003年第4期15卷 1-9页

作者： Wang Chao, Wang Pei-fang, Li Yong department of Environmental engineering, hohai university, nanjing 210098, china Dept. of Environ. Eng. Hohai Univ. Nanjing 210098 China

A composite modeling approach was presented for simulating thethree-dimensional (3-D) subsurface transport of dissolved contaminants with transformation *** approach was based on vertical infiltration and contaminant transport in the unsaturated zoneand 3-D groundwater flow and contaminant migration in the saturated zone. Moisture movement andgroundwater flow were considered to be steady, but contaminant transport was treated as continuousand transient. The transformed unsaturated zone and saturated zone transport equations were solvednumerically with different techniques. The model contains a 3-D solution to flow and transport inthe saturated zone, as well as two-dimensional solutions to vertical cross-sectional and arealscenarios. In order to verify the composite modeling, extensive experiments were conducted in twolarge-scale variable-slope soil tanks of 1200cm in length, 150cm in width and 150cm in height. Sandsoil was filled in the tank as the porous media. The solutions of KBr or NH_4C1 were introduced intoeach soil tank from 80 X 37cm^2 area sources located on the top of the porous medium. Results fromnumerical simulations were compared with the data from tests. Predicted results are in goodagreement with the experimental data.

关键词： composite modeling groundater flow finite element model experiment

A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils

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Science china(Technological Sciences) 2010年第8期53卷 2152-2159页

作者： LIU HanLong 1,2 ,XIAO Yang 1,2 ,LIU JinYuan 3 &LI GuoYing 4 1 Key Laboratory of Ministry of Education for Geomechanics and Embankment engineering,hohai university, nanjing 210098,china 2 Geotechnical Research Institute,hohai university,nanjing 210098,china 3department of Civil engineering,Ryerson university,Toronto,Canada 4 department of Geotechnical engineering,nanjing Hydraulic Research Institute,nanjing 210014,china 1. Key Laboratory of Ministry of Education for Geomechanics and Embankment engineering Hohai University Nanjing 210098 China2. Geotechnical Research Institute Hohai University Nanjing 210098 China3. Department of Civil Engineering Ryerson University Toronto Canada4. Department of Geotechnical Engineering Nanjing Hydraulic Research Institute Nanjing 210014 China

An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria,including the Mohr-Coulomb criterion,the Lade criterion and the Matsuoka-Nakai criterion,cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too *** new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more *** original elliptic-parabolic yield surface model can capture both soil contraction and dilation ***,it normally over-predicts the soil strength due to its application of the Extended Mises criterion.A new elliptic-parabolic yield surface mode is presented in this paper,which introduces the adaptive criterion in three-dimensional principal stress *** new model can well model the stress-strain behavior of soils under general stress *** to the original model which can only simulate soil behavior under triaxial compression conditions,the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions.

关键词： principal stress space intermediate principal stress yield surface failure criterion constitutive model

Game model of safety monitoring for arch dam deformation

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Science china(Technological Sciences) 2008年第S2期51卷 76-81页

作者： SU HuaiZhi1,2,WU ZhongRu1,2,GU YanChang1,2,HU Jiang1 & WEN ZhiPing3 1 College of Water Conservancy and Hydropower engineering,hohai university,nanjing 210098,china 2 National engineering Research Center of Water Resources Efficient Utilization and engineering Safety,nanjing 210098,china 3 department of Computer engineering,nanjing Institute of Technology,nanjing 210013,china College of Water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China National engineering Research Center of Water Resources Efficient Utilization and engineering Safety Nanjing 210098 China department of Computer engineering Nanjing Institute of Technology Nanjing 210013 China

Arch dam deformation is comprehensively affected by water pressure,temperature,dam's structural behavior and material properties as well as other *** them the water pressure and temperature are external factors(source factors) that cause dam deformation,and dam's structural behavior and material properties are the internal factors of deformation(resistance factors).The dam deformation is the result of the mutual game playing between source factors and resistance ***,resistance factors of structure and materials that reflect resistance character of arch dam structure are introduced into the traditional model,where structure factor is embodied by the flexibility coefficient of dam body and the maximum dam height,and material property is embodied by the elastic modulus of *** the basis of analyzing the correlation between dam deformation and resistance factors,the game model of safety monitoring for arch dam deformation is put forward.

关键词： arch dam deformation monitoring model flexibility coefficient game theory

Fabrication and Photoluminescence Property of CdS Nanowire Array by Template Eiectrodeposition

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Journal of Wuhan university of Technology(Materials Science) 2008年第1期23卷 118-120页

作者：徐金霞 department of Materials Science and engineering Hohai University

CdS nanowire arrays were synthesized by altering current（AC） electrodeposition in the porous anodic alumina film prepared by aluminium anodizing in oxalic acid. These nanowires have a uniform diameter of about 45 nm corresponding to the pore size of the films used and length up to several microns. The X-ray diffraction（XRD） pattern indicates that the CdS nanowires crystallize in an hcp structure. Besides, photoluminescences（PL） of CdS nanowire arrays, characterized by spectrophotometer show that CdS nanowries embedded in porous alumina template increases the light-emitting intensity and induces a red shift of PL band.

关键词： CdS nanowire army alumina template photoluminescence red shift