Applied Mechanics and Materials Vols. 268-270

Abstract: The finite element formulations of steel-concrete composite (SCC) beams considering interlayer slip with end shear restraint is established. Elastic seismic response of SCC frame structures under different shear connection stiffness and slip boundary conditions are examined. The influences of the shear connection stiffness and the slip boundary condition on elastic seismic response are analyzed. With the shear connection stiffness increasing, the free vibration frequencies increase and the seismic responses decrease. The natural vibration properties of SCC frame structures and seismic responses are also significantly affected by the slip boundary condition, and it should be properly imposed on all composite beams in seismic response analysis.

Abstract: Due to collapses of tubings during well testing and completing in HPHT wells, it is required by Petrochina officially to calculate and analysis the collapse strength of down hole tubings with axial forces and corresponding bending moment being taken into considerations. Based on the 4th strength theorem, formulas were derived and method was present to analyze the collapse strength of down hole tubings loaded by compressive axial forces and bending moment to fulfill the official requirements, which could not be accomplished according to published standards and references. And, influences of axial tensile forces, compressive forces and bending loads on the collapse strengths of down hole tubings were studied. It is found that the collapse strength of down hole tubing loaded by compressive axial force is smaller with compressive axial force and buckling bending moment taking into considerations. The bigger the compressive axial forces, the smaller the collapse strengths.

Abstract: It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

Abstract: Historically, the guide cable system for installation of subsea oil production equipment has proven its efficiency. These cables extend from the rig to the wellhead, which are fixed to the guide base posts and will be subject to loads during the installation and operation of the production equipment. The majority of guide base designs have been calculated by analytical methods, although they allow obtaining exact answers in all infinite points of a structure, they are not applicable to all cases. This motivated the application of finite element analysis method (FEA) in this work, which from the development of approximate procedures can be applied regardless of the structure shape and loading conditions. This paper consists of a structural analysis of the guide base frame model, generated in Autodesk Inventor® software and analyzed in ANSYS® Workbench. The study brings a diagnostic research using a quantitative and exploratory approach. Different mathematical models were generated to obtain the results at the most critical points of the structure in order to determine its resistance to the loads applied during installation and operation, taking into account the criteria laid down in DNV 2.7-3, API 17D 1st Ed and von-Mises equivalent stress.

Abstract: By the method of plane charge on the tested beams, this paper studied 6 pieces of beams， dynamic performance by 4 time loadings, displayed the deflection waveform curves, measured the bearing ability of beams with different prestress degree, analyzed the effects of the deformed performance and the ductility of the test beams with the different prestress degree. The 6 pieces of PC（prestressed concrete）beams was divided into 2 groups.

Abstract: The study on anchorage characteristics of flexible pressurized anchor should be along with theoretical analysis, numerical simulation and test study. Through comparing three calculation results, it is concluded that the theoretical analysis and numerical simulation can authenticate the correctness of calculation process each other; After considering the situation that friction coefficient changed with different contact pressure stress, the deviation of calculation of theory derivation and numerical simulation with experimental results significantly reduced; Anchor was simplified for anisotropic composite material body, which should be able to better reduce deviation among test, theoretical derivation and numerical simulation calculation.

Abstract: The elastic stress and strain fields of plates containing one central hole and two auxiliary holes subjected to uniaxial tension are examined using finite element method. The interaction between holes and the thickness effect on stress and strain concentration factors are investigated. It is shown that the distributions of strain concentration factor and stress concentration factor are different in the region of stress concentration and both of them depend on the hole radii and the distance between central hole and auxiliary hole. For the finite thickness plates, the distributions of stress and strain concentration factors through thickness are not uniform in stress concentration regions. There is a strong disturbed region near the plate surface in the vicinity of central hole and auxiliary hole. The maximum values of stress and strain concentration factors and the corresponding locations depend on the r/R ratio, d/R ratio, Poisson’s ratio and thickness of plate.

Abstract: Abstract. The elastic stress and strain fields of plates containing one central hole and two auxiliary holes subjected to uniaxial tension are examined using finite element method. The interaction between holes and the thickness effect on stress and strain concentration factors are investigated. It is shown that the distributions of strain concentration factor and stress concentration factor are different near central hole and auxiliary hole, and both of them depend on the hole radii and the distance between central hole and auxiliary hole. There is a minimum value of K_ε/K_σ in stress concentration region and the quantity and location of this minimum value in plane stress state depend on the r/R ratio and d/R ratio of the plate. There are some specific distances between central hole and auxiliary hole corresponding to the radii of auxiliary hole to make the stress concentration factor in the plate minimum.

Abstract: Fractured reservoir development process are often faced with the angle wells flooded serious and side wells don’t get the effect of water injection. In order to increase the water flooding sweep efficiency. Profile control plugging is a measure that is frequently used. Traditional plugging program design does not take into account the fluid loss, Program design of the blocking agent dosage is always small, the result is not satisfactory. In this paper, the classic percolation theory is used, seepage equation of the fracture system and matrix system is established, the blocking agent Filtrate analytical solution that considers the different reservoir properties and different blocking agent performance is obtained, that can be used to guide the design of profile control water plugging program and can calculate the best blocking agent dosage. Through the actual implementation of the effect, the proposed method can be more substantial increase in the effect of plugging.

Abstract: At present, system research on performance of the physics, deformation, strength and other properties of light mixed soil already exists in China, but the study on permeability is just in the initial stage and the system study on permeability of EPS beads-mixed lightweight soil is lack of, therefore, it is necessary to study the permeability of EPS beads-mixed lightweight soil. This article draw some reliable conclusions which include the permeability of EPS beads-mixed lightweight soil decreases with the increasing of curing age and cement ratio, and decreasing of EPS beads ratio and particle size and the cement ratio has quadratic polynomial function relationship when EPS beads ratio has linear relationship, by analyzing the effects of curing age, cement ratio, EPS beads ratio and particle size. The paper proposes multiple linear regression equation, considering the relationship of lightweight soil permeability between EPS particles and cement ratio. These will do good to the application of the practice engineering.