Advanced Materials Research Vols. 446-449

Abstract: The slump test is a very important industrial test for evaluation of workability of fresh granular-cement paste material, especially concrete. The test method is used as a generic tool for classification of a wide range of mixtures and can deal with a wide range of workabilities. The current paper presents a numerical approach, based on Discrete Element Method (DEM), with the aim to study the effect of the mix composition on the rheological behavior of a mixture after demolding, i.e. lifting the slump cone. The research approach is based on a conceptual idea, where the particle-paste interaction is explicitly modelled as an interactive two phase “paste –particle” system. Each mixture is considered to consist of these elements with the rheological behaviour characterized by the “excess paste” model. Simulations and experimental laboratory test results show good agreement.

Abstract: As an important building material, concrete is widely used in military and civil areas for its superiorities, such as civil engineering, hydraulic engineering, protection engineering and so on. It is necessary to research its dynamic mechanical properties under strong shock loading. The concrete is considered as a composite material which is made of aggregate particles and cement paste from micromechanical angle. This paper uses random function to establish random particle model and simulates dynamic mechanical responses of concrete under strong shock loading based on random particle model using ANSYS/LS-DYNA.

Abstract: Change order is a frequent phenomenon in most construction projects. However, these changes can be controlled when their causes are known. This report is set to find out the various techniques through which this phenomenon can be controlled most especially in the roadway construction projects in south of Iran. In order to reduce this occurrence to the minimum, certain mechanisms have been identified as being very effective and these are clearly the project objectives and scope of change order of work, provision of complete documentation, finalize the design during the design phase. The outcomes of this study would provide necessary information that may be used by employers and contractors to minimize cases of change orders in construction projects. Moreover, it is anticipated that the results of this study will assist greatly in reducing the total cost of construction works and the time of completion of the project hence increase the efficiency of the work.

Abstract: Investment projects of the civil engineering have many characteristics,such as large scale of construction,tremendous investment cost,long payback period of investment, and bad risk. For investors, the investment payback period of construction projects is an important index that evaluate and measure economic effect of project investment. The investment capital can be recovered in the operation of actual projects by the influence of random factors, it is difficult that the investment payback period of construction projects is calculated generally using analytic method. Combined with restaurant project in this paper, set up the mathematical model of the payback period of investment, find out random factors that influence its cash flow of restaurant project, to research and measure the data of random factors on existing similar projects, to determine the probability distribution of random parameters,and Statistical data processing, make use of the computer simulation, set up the simulation model of the payback period of investment, to forecast the static and dynamic payback period of construction projects,provided decision-making with scientific base and meaningful reference.

Abstract: The information of boundary condition in the contact interface reflected complex properties of visco-elastic material with various contact conditions. Numerical results and the asymptotic estimates were calculated. It is presented by the software which are consistent with the boundary-layer analysis in our previous papers. In this paper, the application of computer simulating and related numerical result on the contact boundary-layer has been discussed. Numerical results were calculated (by using HPC platform, NAG toolbox for Matlab) and shown by use of the software i.e. LS-DYNA. The numerical scheme yields the convergent finite element analysis (FEA) solution and stable semi-discrete Galerkin-ADI (G-ADI) iteration.

Abstract: According to the features of reinforced layer of steel wire wound reinforced high-pressure hose (hereinafter referred to as SRH), 9 classical models for predicting the engineering elastic modulus of reinforced layer of continuous filament reinforced composite material were contrastively analyzed. As a result, Chinese engineering empirical formula should be conformable for predicting the engineering elastic constants of SRH reinforced layer in material normal coordinates. Based on composite microscopic theory and tensor theory, constitutive equation of SRH reinforced layer in structural cylindrical coordinates in three-dimensional case was obtained.

Abstract: Hyper-spectral remote sensing as new science and technology, is gradually applied to various fields. The technology has the technical advantages which are the high spectral resolution and non-destructive detection. These provide a new perspective for the research and protection of cultural relics. This paper firstly described the basic principles of hyper-spectral technology and its advantages, then stated the main applications of the technology in the conservation work, and at last, briefly summarized its limitations and potential applications.

Abstract: The common approach to describe the rheological behavior of a granular-paste material relies on a description of the motion within the frame of continuum mechanics. However, since a granular-paste system cannot be considered as a homogeneous continuous fluid its behavior should not be estimated by common fluid models, such as Bingham or Herschell Bulkley models. Therefore, a continuum approach is not considered the best option to study the phase effects of a multi-phase material and its corresponding rheological behavior. In this particular case analytical techniques based on the multi-phase models are required. A more appropriate approach is to consider a granular-paste material as a two phase model that accounts for the effect of the gradually decreasing the volume fraction of the pasty phase until getting to zero value on the rheological behavior of the material. In this investigation, a cone test is used to evaluate the rheological behavior of a granular mix where a discrete element method (DEM) is considered as a basis of the numerical simulation.

Abstract: Numerical specimens with single-hole is established by particle flow code PFC2D and uniaxial compression tests are conducted. Studies have shown that uniaxial compressive strength of specimen with single hole is less than complete specimens. As the holes move to the end of specimen, the uniaxial compressive strength first increases and then tends to decrease.

Abstract: In order to ensure the highway design and construction turnkey project smooth implementation, it is necessary to proactively consider risks produced by highway design and construction turnkey model, and to input specific risk prevention and corresponding risk control measures. This paper firstly discusses risk control measures for highway design and construction turnkey model. Then, risk is reasonably contributed both the owners and general contractors. The risk range has also be defined between the owner and general contractor. In the ending of this article, there are some recommendations about risk prevention and control measures for highway design and construction turnkey project.