Advanced Materials Research Vols. 255-260

Abstract: In the conventional semi-analytical finite strip analysis of folded plates, the boundary conditions and the intermediate support conditions must be satisfied a priori. The admissible functions used as the longitudinal part of the displacement functions are sometimes difficult to find, and they are valid for specific conditions only. In this paper, a general semi-analytical finite strip is developed for the analysis of folded plate structures. The geometric constraints of the folded plates, such as the conditions at the end and intermediate supports, are modelled by very stiff translational and rotational springs, as appropriate. The complete Fourier series including the constant term are chosen as the longitudinal approximating functions for each of the displacements. As these displacement functions are more general in nature and independent of one another, they are capable of giving more accurate solutions. The potential problem of ill-conditioned matrices is investigated and the appropriate choice of the very stiff springs is also suggested. The formulation is done in such a way to obtain a unified approach, taking full advantage of the power of modern computers. Numerical examples are presented for comparison with numerical results from published solutions or solutions obtained from the finite element method. The results show that this kind of strips is versatile, efficient and accurate for the analysis of folded plates.

Abstract: Based on geologic condition of one tunnel surrounding rock mass, systematic numerical tests had been carried out to study the stability of surrounding rock mass with different distributions of weak intercalated rock by the FEM software ABAQUS and strength reduction finite element method. Some quantificational results about the stability of surrounding rock mass were summarized. And the safety factor and latent slip surface were worked out. The stability of surrounding rock mass was judged by strength reduction finite element method. According to the analysis above, it’s known that the discrepancy of two rules is small; the safety factor is the lowest when weak intercalated rock in vault, and when at bottom, it’s higher than that of in vault. The conclusion can be used to guide the procedure of construction and ensure the safety.

Abstract: Custom tooling is an effective method to improve surface roughness, geometrical accuracy, machining efficiency, and consequently the core competitiveness of the final products in very complicated freeform creation and micro/nano machining, such as the propeller, blisk and ductile-mode machining of hard and brittle materials. However, commercially available CAM systems have limitations in generating CNC programs for these customized tools due to considerations for special custom tool fabrication processes. Therefore unique CAM system is needed and consequently dedicated CAD sub-system is the prerequisite for such CAM system. In this paper, the dedicated CAD sub-system design is studied to extend the authors’ previous study. The characteristics of customized tools are summarized and analyzed. Then, the functions for the dedicated CAD sub-system are analyzed and defined. Finally, the system is designed and developed by using VC++, Open CASCADE, and ActiveX Data Object techniques.

Abstract: This study presents an improved finite beam element method developed to calculate lateral displacement of pile subjected to eccentric and inclined loads. The relationships between the moment and shear to the lateral displacements of pile are derived from the mechanical deferential equation of the pile by taking into account the P-Δ effect of the pile due to geometric nonlinearity, and the stiffness of the pile element discretized into the finite beam elements is obtained, followed by solving, lateral displacement of pile is deduced by the improved finite beam element equations. By comparing to results of a model test on piles under eccentric and inclined loads, it is shown that the improved finite beam element method accurately predicts the pile’s lateral displacements.

Abstract: Employing response surface method, the complicated implicit relationship between bridge structural static-load responses and structural parameters is approximately represented by the simple explicit function. Based on this response surface model (function), the structural finite element model parameters can be easily updated by selected optimization procedure. By a numerical example of a two-span continuous beam, the essential theory and implementation of structural static response surface based finite element model updating are presented in the paper.

Abstract: The bracing force of top horizontal braces supporting a row of columns under the only vertical load has been investigated in this paper. A large number of one-story longitudinal column-bracing systems were modeled and analyzed by second-order analysis using finite element method, in which the random combination of the initial imperfections between columns and braces was well considered by Monte Carlo method. According to the analysis results, three kinds of instability modes of one-story column-bracing system have been found, triple-normal probability density function of the top horizontal bracing forces is established based on probability statistics, and the design bracing forces are also obtained. A check method based on the vertical load analysis is supplied for the top horizontal bracing forces which are usually designed by the longitudinal horizontal load.

Abstract: In this study, expanded polystyrene (EPS) geofoam is placed between first lining and second lining of tunnels, serving as isolation buffer in earthquake. In order to investigate isolation effect of elastic modulus and thickness of EPS layer, ABAQUS script interface based on Python language is employed. The technological process of this parameterized analysis is elaborately designed. Parameterized modeling is realized by secondary development which controls the preprocessing process. Some technology such as infinite element boundary, definition of initial ground stress field, modification of input file and stress report in preprocessing is described. Python language is also used for secondary development of ABAQUS post-processing. Then the simulation results of different models under earthquake can be effectively computed from huge result data. The isolation effect with the change of elastic modulus and thickness of EPS can be presented clearly. That is, with the decreasing elastic modulus and increasing EPS layer thickness, the isolation effect is more obvious.

Abstract: A efficient 3D reinforced-concrete beam element based on the flexibility method and distributed nonlinearity theory is proposed, The sections of the beam element are divided into the plane isoparametric elements in this formulation, the section stiffness matrices are calculated through the integration of stress-strain relations of concrete including reinforcing steel effect in the section. The flexibility matrices of the sections are calculated by inverting the stiffness matrices, and the element flexibility matrix is formed through the force interpolation functions. The element stiffness matrix is evaluated through the element flexibility matrix. Finally, the buckling behaviors of a reinforced concrete beam under various eccentric loads are analyzed with the proposed formulation to illustrate its accuracy and computational efficiency.

Abstract: Three-vertical-line-element model and uniaxial spring model were adopted to simulate walls and beams. Based on the existing experiment data, numerical simulation is used to analysis the nonlinear behavior of reinforced concrete core walls. The analysis also considered the influence of relevant parameters on the elasto-plastic in core walls structure. Results from the simulation anlysis match well with those from the tests. It is shown that the higher axial compression ratio enhance the bearing capacity; the ratio of height to width has effect on the bearing capacity, deformation performance and the failure mode; the decrease of span-depth ratio of coupling beam reduce ductility and deformation ability of the core walls; the imposed horizontal angle has important effect on the overall space behavior of reinforced concrete core wall.

Abstract: This paper presents finite element analyses of a steel spiral staircase with multiple supports. The complex geometries were modeled using commercial finite element method (FEM) software. Linear elastic analyses were carried out to investigate its deformation and moment distribution. Besides these, mode analysis was also performed to explore its pedestrian comfort. Finally the reliability of the structure is proved.