• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.1
• /
• pp.101-110
• /
• 2015

Recently, nine $1397{\times}1397{\times}178mm$ RC panels were tested under in-plane pure-shear monotonic loading condition using the Panel Element Tester by Hsu (1997, ACI). By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, Modern Truss Model (MCFT, RA-STM) are capable of producing the nonlinear analysis of RC membrane panel through the complicated trial-and-error method with double loop. In this paper, an efficient algorithm with one loop is proposed for the refined Mohr compatibility Method based on the strut-tie failure criteria. This algorithm can be speedy calculated to analyze the shear history of RC membrane element using the results of Hsu test. The results indicate that the response of shear deformation energy at Big Bang of shear strain significantly influenced by the principal compressive stress-strain (crushing failure).

• Computational Structural Engineering
• /
• v.3 no.3
• /
• pp.113-123
• /
• 1990

The paper is concerned with the elasto-plastic and geometrically nonlinear analysis of shell structures using an improved degenerated shell element. In the formulation of the element stiffness, the combined use of three different techniques was made. They are; 1) an enhanced interpolation of transverse shear strains in the natural coordinate system to overcome the shear locking problem ; 2) the reduced integration technique in in-plane strains to avoid the membrane locking behavior ; and 3) selective addition of the nonconforming displacement modes to improve the element performances. This element is free of serious shear/membrane locking problems and undesirable compatible/commutable spurious kinematic deformation modes. In the formulation for plastic deformation, the concept of a layered element model is used and the material is assumed von Mises yield criterion. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements and rotations. The resulting non-linear equilibrium equations are solved by the Netwon-Raphson method combined with load or displacement increment. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.2
• /
• pp.33-42
• /
• 2014

The shear strength and deformation characteristics of granular soils at low confining stresses differ from those with high confining stresses. Thus, the clear understanding of geotechnical problems related to the low confining stress state such as the stability of shallow foundations, embankments, slope failure, debris flow characteristics and liquefaction as well as the various laboratory model tests is needed. In this study, drained triaxial compression tests with the cell pressures from 5 kPa to 300 kPa were performed on dry Jumunjin sand. The results show that the internal friction angle and deformation modulus are dependent on the confining stress. Also, the correlations between them on the dense and loose sand were established.

• Earthquakes and Structures
• /
• v.14 no.1
• /
• pp.85-94
• /
• 2018

The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

• Journal of Korean Association for Spatial Structures
• /
• v.5 no.2 s.16
• /
• pp.47-55
• /
• 2005

The method to form the space of the pneumatic structures by internal pressure is classified greatly as the dual type with the nlty type. The shape of the pneumatic structures consists of the curved surface under uniform tension not greatly to be deformed by the design load and stress must not be concentrated also. Therefore, In this study, we have done the structural analysis of the unity typed pneumatic structures by the NASS which is the program for nonlinear analysis. The analytic model is a rectangular pneumatic membrane structures which have four side fixed edges. And we have done the nonlinear incremental analysis considering the orthotropic material.

• Structural Engineering and Mechanics
• /
• v.55 no.2
• /
• pp.435-459
• /
• 2015

Parametric resonance of shear deformable composite skew plates subjected to non-uniform (parabolic) and linearly varying periodic edge loading is studied for different boundary conditions. The skew plate structural model is based on higher order shear deformation theory (HSDT), which accurately predicts the numerical results for thick skew plate. The total energy functional is derived for the skew plates from total potential energy and kinetic energy of the plate. The strain energy which is the part of total potential energy contains membrane energy, bending energy, additional bending energy due to additional change in curvature and shear energy due to shear deformation, respectively. The total energy functional is solved using Rayleigh-Ritz method in conjunction with boundary characteristics orthonormal polynomials (BCOPs) functions. The orthonormal polynomials are generated for unit square domain using Gram-Schmidt orthogonalization process. Bolotin method is followed to obtain the boundaries of parametric resonance region with higher order approximation. These boundaries are traced by the periodic solution of Mathieu-Hill equations with period T and 2T. Effect of various parameters like skew angle, span-to-thickness ratio, aspect ratio, boundary conditions, static load factor on parametric resonance of skew plate have been investigated. The investigation also includes influence of different types of linearly varying loading and parabolically varying bi-axial loading.

• Steel and Composite Structures
• /
• v.21 no.2
• /
• pp.373-394
• /
• 2016

The postbuckling behavior of laminated composite plates and shells, subjected to various shear loadings, is presented, using a modified 8-ANS method. The finite element, based on a modified first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the various location and number of enhanced membrane and shear interpolation. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. The effects of various types of lay-ups, materials and number of layers on initial buckling and postbuckling response of the laminated composite plates and shells for various shear loading have been discussed. In addition, the effect of direction of shear load on the postbuckling behavior is studied. Numerical results and comparisons of the present results with those found in the literature for typical benchmark problems involving symmetric cross-ply laminated composites are found to be excellent and show the validity of the developed finite element model. The study is relevant to the simulation of barrels, pipes, wing surfaces, aircrafts, rockets and missile structures subjected to intense complex loading.

• Aerospace Engineering and Technology
• /
• v.2 no.2
• /
• pp.133-141
• /
• 2003

When superplastic forming process is employed in manufacturing spherical pressure vessel, the thickness and spherical profile are not constant and varies during the forming process. In the current study, theoretical analysis for the prediction of thickness change was carried out under the consideration of membrane theory which has been employed in Kuglov et. al.'s study. Then the thickness of initial blank to obtain the required thickness at the final forming step, the time vs. pressure profile which yields uniform deformation in blank, and the thickness distribution according to the position at each forming step have been determined. The employed model and the developed analytical code were verified throughout comparing the theoretical predictions at each forming stage with the experimental results shown in literature.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.912-917
• /
• 2003

In this paper a new truss modeling technique for describing the beam shear resistance mechanism is proposed based on the reinterpretation of the well-known relationship between shear and the rate of change of bending moment in a reinforced concrete beam subjected to combined shear and moment loads. The core of the model is that a new perspective on the shear resistance can be gained by viewing the internal stress filed in terms of the superposition of two base components of shear resistance; arch action and beam action. The arch action can be described as a simple tied-arch which is consisted of a curved compression chord and a tension tie of the longitudinal steel, while the beam action between the two chords can be modeled as a membrane shearing element with forming a smeared truss action. The compatibility of deformation associated to the two action is taken into account by employing an experimental factor or internal state force factor a. Then the base equation of V=dM/dx is numerically duplicated. The new model was examined by the 362 experimental results. The shear strength predicted by the internal force state factor a show better correlation with the tested values than the present shear design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.1
• /
• pp.23-31
• /
• 2011

An analysis has been conducted of the flow characteristics and pumping performance of a thermopneumatic micropump with electrically conducting fluid. In the present study, considered is a thermopneumatic micropump for electrically conducting fluids with electromagnetic resistance alternately exerted at the inlet and outlet by alternately applied magnetic fields. A model of Prescribed Deformation is used for the motion of the membrane. Here, the pumping performance of the micropump and flow characteristics of the electrically conducting fluid are investigated in the range of Hartmann number less than 30. The current numerical study shows that the net flow rate through the micropump is almost proportional to the strength of the applied magnetic field.