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

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

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Effects of Reducing River Flow on Pulse Residence Time in Little Manatee River,usa

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Transactions of Tianjin university 2009年第2期15卷 95-100页

作者： HUANG Wenrui,LIU Xiaohai(department of civil engineering,Florida state university,Tallahassee,Florida 32310-6046,usa) department of civil engineering Florida State University Tallahassee Florida 32310-6046 USA

Residence time is an important indicator for river environmental *** this paper,a 3D hydrodynamic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence *** model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and *** model has been satisfactorily calibrated and verified by using two continuous data *** data sets consist of hourly observations of all forcing boundaries,including freshwater inputs,tides,winds,salinity and temperatures at bay boundary,and air temperatures for model *** data sets also consist of hourly observations of water levels,salinity,and temperature at several river *** calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee *** the minimum flow of 0.312 m3/s,the pulse residence time(PRT) is 108 *** simulations were also conducted for 17 flow *** regression equations have been satisfactorily derived to correlate PRT to freshwater *** coefficient R2 is 0.982 for PRT.

关键词： hydrodynamic modeling estuary residence time tidal river

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STEP-POOL MORPHOLOGY IN HIGH-GRADIENT STREAMS

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International Journal of Sediment Research 2001年第3期16卷 380-390页

作者： A.R. MAXWELL and A.N. PAPANICOLAOU Research Assistant, Dept. of civil and Envir. Engrg., washington state university, pullman, wa 99164-2910, Professor, Dept. of civil and Envir. Engrg., washington state university, pullman, wa 99164-2910, Dept. of civil and Envir. Engrg. Washington State University Pullman WA 99164-2910

The focus of this study is to examine bed stability and morphology in high-gradient gravel-bed streams, and thus to improve understanding of the various parameters governing the sediment flow characteristics in mountain streams. Ultimately, this knowledge can be used to design pseudo-natural channels, as in the stream simulation method of culvert design; with this in mind, prototype conditions are evaluated in a flume with slopes ranging from 3% to 7%, and particle relative submergence varying from 0.5 to 2.5 for three bed size distributions. These experiments are designed to satisfy the conditions of dynamic similarity for flow and sediment, and they are preferred over field measurements since they allow a high degree of control over testing conditions. It is found that step-pool bedforms are the most ubiquitous features along the gravel bed. A new formula is developed that correlates step height with the gravel-bed size distribution, relative submergence of the particles, and the Froude number. The step spacing is found to be related to step height and streambed longitudinal slope. Flow resistance is also examined, and a formula is developed which accounts for the resistance due to the bedforms (form resistance), as well as the individual sediment particles (grain resistance).

关键词： Mountain streams Step-pool bedforms Step height

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A NEW METHOD IN GROUNDwaTER FLOW MODELING

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Journal of Hydrodynamics 2009年第2期21卷 245-254页

作者： MA Xiu-yuan LI Shu-guang ZHU Wei-shen School of civil engineering Shandong University Jinan 250061 China department of civil and environmental engineering Michigan State University East Lansing Michigan 48834USA

One of the challenges in groundwater modeling is the prediction of hydraulic head related to local stress fluctuations with a regional scale model. Typical applications of numerical models require extensive field information for input data and for calibration If we can model the change directly, we may not have to know all the modeling parameters because sometimes the changes only depend on fewer parameters. In this article, we present an improved methodology for groundwater modeling related to local stress fluctuations using a perturbation approach. Our results demonstrate that this approach is capable of matching an exact solution for drawdown in both confined and unconfined aquifers. The results suggest that this perturbation method can provide an accurate representation of head in a large-scale hydrogeological system.

关键词： groundwater modeling local stress fluctuations perturbation method iteration scheme

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Effect of Limestone Powder and Fly Ash on Magnesium Sulfate Resistance of Mortar

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Journal of Wuhan university of Technology(Materials Science) 2010年第4期25卷 700-703页

作者：刘数华 state Key Laboratory of water Resources and Hydropower engineering Science Wuhan University

The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca（OH）2 and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.

关键词： limestone powder fly ash mortar magnesium sulfate resistance

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One-dimensional numerical models of higher-order Boussinesq equations with high dispersion accuracy

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Acta Oceanologica Sinica 2003年第2期22卷 287-300页

作者： ZouZhili wangTao ZhangXiaoli DarrenSpratt stateKeyLaboratoryofCoastalandOffshoreengineering DepartmentofCivilEngineeringDalianUniversityofTechnologyDalian116024China civilandenvironmentalengineering UniversityofIllinoisatUrbana-ChampaignChampaignUSA

Nonlinear water wave propagation passing a submerged shelf is studied experimentally and numerically. The applicability of the wave propagation model of higher-order Boussinesq equations derived by Zou (2000, Ocean engineering, 27, 557 - 575) is investigated. Physical experiments are conducted; three different front slopes (1:10, 1 = 5 and 1:2) of the shelf are set-up in the experiment and their effects on the wave propagation are investigated. Comparisons of the numerical results with test data are made and the higher-order Boussinesq equations agree well with the measurements since the dispersion of the model is of high accuracy. The numerical results show that the good results can also be obtained for the steep-slope cases although the mild-slope assumption is employed in the derivation of the higher-order terms in the higher-order Boussinesq equations.

关键词： water waves Boussinesq nonlinear dispersion

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QUALIFICATION OF UNCERTAINTY FOR SIMULATING SOLUTE TRANSPORT IN THE HETEROGENEOUS MEDIA WITH SPARSE GRID COLLOCATION METHOD

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Journal of Hydrodynamics 2009年第6期21卷 779-789页

作者： SHI Liang-sheng YANG Jin-zhong state Key Laboratory of water Resources and Hydropower engineering Science Wuhan University Wuhan 430072 China The Sonny Astani department of civil and environmental engineering University of Southern California Los Angeles CA 90089 USA

The sparse grid collocation method is discussed to qualify the uncertainty of solute transport. The Karhunen-Loeve （KL） expansion is employed to decompose the log transformed hydraulic conductivity. The head, velocity and concentration fields are represented by the Lagrange polynomial expansion. A sparse grid collocation method is then used to reduce the original stochastic partial differential equations to a set of deterministic equations which is collocated at selected interpolation （collocation） points. The collocation points are constructed by the Smolyak algorithm. The accuracy, efficiency and convergence property of sparse grid collocation method are investigated by numerical experiments. The analysis shows that stochastic collocation strategy helps to decouple stochastic computations, and all the numerical computation is possible to be implemented by existing deterministic finite element codes. The proposed method provides an efficient way to evaluate the uncertainty of the solute transport in the heterogeneous media.

关键词： stochastic partial differential equations collocation method solute transport uncertainty

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Analytical layer-element solutions for a multi-layered transversely isotropic elastic medium subjected to axisymmetric loading

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2012年第1期13卷 9-17页

作者： Zhi-yong AI Nai-rui CANG Jie HAN Key Laboratory of Geotechnical and Underground engineering of MOE Department of Geotechnical Engineering Tongji University Shanghai 200092 China department of Ciwl Environmental and Architectural Engineering The University of Kansas Lawrence KS 66045 USA

This paper presents an analytical layer-element method used to analyze the displacement of a multi-layered transversely isotropic elastic medium of arbitrary depth subjected to axisymmetric *** on the basic constitutive equations and the HU Hai-chang's solutions for transversely isotropic elastic media,the state vectors of a multi-layered transversely isotropic medium were *** the state vectors,an analytical layer element for a single layer(i.e.,a symmetric and exact stiffness matrix) was acquired in the Hankel transformed domain,which not only simplified the calculation but also improved the numerical efficiency and stability due to the absence of positive exponential *** global stiffness matrix was obtained by assembling the interrelated layer elements based on the principle of the finite layer *** solving the algebraic equations of the global stiffness matrix which satisfy the boundary conditions,the solutions for multi-layered transversely isotropic media in the Hankel transformed domain were *** actual solutions of this problem in the physical domain were acquired by inverting the Hankel *** paper presents numerical examples to verify the proposed solutions and investigate the influence of the properties of the multi-layered medium on the load-displacement response.

关键词： Transverse isotropy Analytical layer element Multi-layered elastic medium Axisymmetric loading Hankel transform

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Application analysis of empirical mode decomposition and phase space reconstruction in dam time-varying characteristic

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Science China(Technological Sciences) 2010年第6期53卷 1711-1716页

作者： ZHANG ZhiJun1,2,3,GU ChongShi1,2,BAO TengFei1,2,ZHANG Lan1,2 & YU Hong1,2 1 state Key Laboratory of Hydrology-water Resources and Hydraulic engineering,Hohai university,Nanjing 210098,China 2 National engineering Research Center of water Resources Efficient Utilization and engineering Safety,Hohai university,Nanjing 210098,China 3 department of civil,environmental and Geomatic engineering,Swiss Federal Institute of Technology,Zurich 8093,Switzerland 1. state Key Laboratory of Hydrology-water Resources and Hydraulic engineering Hohai University Nanjing 210098 China2. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China3. Department of Civil Environmental and Geomatic Engineering Swiss Federal Institute of Technology Zurich 8093 Switzerland

In view of some courses of the time-varying characteristics processing in the analysis of dam deformation,the paper proposes a new method to analyze the dam time-varying characteristic based on the empirical mode decomposition and phase space reconstruction *** of all,to reduce the influences on the traditional statistical model from human factors and assure the analysis accuracy,response variables of the time-varying characteristic are obtained by the way of the empirical mode decomposition;and then,a phase plane of those variables is reconstructed to investigate their processing *** methods have already been applied to an actual project and the results showed that data interpretation with the assists of empirical mode decomposition and phase space reconstruction is effective in analyzing the perturbations of response variables,explicit in reflecting the entire development process,and valid for obtaining the evolution rules of the time-varying *** methodology is a powerful technical support for people to further master the rules of dam operation.

关键词： dam safety monitoring dam time-varying characteristic empirical mode decomposition phase space reconstruction

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Cooling effect of ripped-stone embankments on Qing-Tibet railway under climatic warming

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Science Bulletin 2003年第6期48卷 598-604页

作者： LAI Yuanming1, ZHANG Luxin1 , ZHANG Shujuan1 & MI Long2 1. state Key Lab. of Frozen Soil engineering, Cold and Arid Regions environmental and engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. department of civil engineering, Northern Jiaotong university, Beijing 100044, China state Key Lab. of Frozen Soil engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China department of civil engineering Northern Jiaotong University Beijing China

The heat convection in ballast mass and ripped-stone mass in railway embankments is the problem of heat convection in porous media. In order to calculate the temperature distribution of Qing-Tibet railway embankment, from the governing equations used to study forced convec-tion for incompressible fluids porous media, the finite ele-ment formulae for heat convection in porous media are de-rived by using Galerkin抯 method. The temperature fields of the traditional ballast embankment and the ripped-stone mass embankment, constructed on July 15, have been ana-lyzed and compared under the case that the air temperature in Qinghai-Tibetan Plateau will be warmed up by 2.0℃ in the future 50 years. The calculated results indicate that, the permafrost 5 m below the traditional ballast embankment will be thawed in the regions in which the air yearly-average temperature is larger than -3.5℃ or the yearly-average temperature at the native surface is larger than -1℃. The embankment will cause large thawing settlement. The rail-way embankment will be damaged by permafrost degrada-tion. The ripped-stone mass embankment can not only resist the effect of climatic warm up on it but also provide cool energy for the permafrost under it. It can assure permafrost stability and not subjected to thawing. Therefore, it is highly recommended that the ripped-stone mass embankment be taken as the Qing-Tibet railway embankment structure in high-temperature permafrost regions so that permafrost embankment can be protected as possible as we could.

关键词： cooling effect ripped-stone embankment climatic warming.

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