• Wind and Structures
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• v.14 no.5
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• pp.481-498
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• 2011

During the past decade, many electrical transmission tower structures have failed during downburst events. This study is a part of a research program aimed to understand the behaviour of transmission lines under such localized wind events. The present study focuses on assessing the behaviour of self supported transmission line towers under downburst loading. A parametric study is performed to determine the critical downburst configurations causing maximum axial forces for various members of a tower. The sensitivity of the internal forces developing in the tower's members to changes in the downburst size and location was studied. The structural behaviour associated with the critical downburst configurations is described and compared to the behaviour under 'normal' wind loads.

• Structural Engineering and Mechanics
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• v.12 no.2
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• pp.157-168
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• 2001

In this paper, experimental investigation into the behavior of reinforced concrete (RC) columns tested under large lateral displacement with four different types of loading arrangements is presented. Each loading arrangement has a different system for controlling the consistency of the loading condition. One of the loading arrangements used three units of link mechanism to control the parallelism of the top and bottom stub of column during testing, and the remaining employed eight hydraulic jacks for the same purpose. The loading systems condition used in this investigation were similar to the actual case in a moment-resisting frame where the tested column was displaced in a double curvature. Ten model column specimens, divided into four series were prepared. Two columns were tested monotonically until collapse, and unless failure took place at an earlier stage of loading, the remaining eight columns were tested under cyclic loading. Test results indicated that the proposed system to keep the top and bottom stubs parallel during testing performed well.

• Structural Engineering and Mechanics
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• v.30 no.6
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• pp.665-678
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• 2008

The beams components subjected to the loading such as axial, bending and cyclic thermal loads were studied in this research. The used constitutive equations are those of elasto-plasticity coupled to ductile and/or creep damage. The nonlinear kinematic hardening behavior was considered in elastoplasticity modeling. The unified damage law proposed for ductile failure and fatigue by the author of Sermage et al. (2000) and Kachanov's creep damage model applied to cyclic creep and low cycle fatigue of beams. Based on the results of the analysis, the shakedown limit loads were determined through the calculation of the residual strains developed in the beam analysis. The iterative technique determines the shakedown limit load in an iterative manner by performing a series of full coupled elastic-plastic and continuum damage cyclic loading modeling. The maximum load carrying capacity of the beam can withstand, were determined and imposed on the Bree's interaction diagram. Comparison between the shakedown diagrams generated by or without creep and/or ductile damage for the loading patterns was presented.

• Korean Journal of Biological Psychiatry
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• v.2 no.2
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• pp.157-168
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• 1995

The neuropsychiatric sequelae of traumatic brain unjury(TBI) are effects on complex aspect of behavior, cognition and emotional expression. They include psychiatric disorders such as depression, psychosis, personality change, dementia, and postconcussion syndrome. The damage is done not only to the cortex of the brain but also to subcortical and axial structures. The diffuse degeneration of cerebral white mailer is axonal damage that is caused by mechanical forces shearing the neuronal fiber at the moment of impact(diffuse axonal injury, DAI). The DAI and the changed receptor-agonist mechanism ore the most important mechanisms in genesis of neuropsychiatric sequalae by mild TBI. The most important instrument for diagnosis of neuropsychiatric sequalae of TBI is a physician or psychiatrist with experience and knowledge. The most effective therapeutic tool is a professional who understands the nature of the problem.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.35-42
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• 2000

Among the various models proposed for the description of semi-rigid connection behavior, Kinney's fixity facto. (=f) definition is adopted. If one follows this definition, f=1.0 signifies a completely fixed connection and f=0.0, the frictionless hinge. Kim's new slope-deflection equations based on the Kinney's fixity factors are the principal idea of this paper. Proposed finite element program also includes the effect of axial shortening of column, which is neglected in the stress analysis of frame leg conventional slope-deflection method. For the economic design, especially for the saving of beam weight in the high-rise office buildings or apartment houses, the proposed method can be applied.

• Computational Structural Engineering
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• v.6 no.3
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• pp.81-88
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• 1993

An efficient approach to the buckling analysis of stiffened cylindrical shells with rings and stringers under the axial and the lateral pressure loadings is presented. By this approach, the local buckling as well as overall buckling behavior has been investigated considering the discreteness of stiffeners and appropriate adoption of displacement functions. Some design criteria based on structural stability to determine optimum scantlings of stiffeners are also suggested. It is shown that the optimum scantlings of stiffeners can be designed from the condition of equal local and overall buckling strength.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.258-265
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• 2002

The recent earthquakes in worldwide have caused extensive damage to highway bridge structures. In particular, it has been demonstrated that concrete columns with inadequate lateral reinforcement contributed to the catastrophic collapse of many bridges. The poor detailing of the starter bars in these columns compounded the problem of seismic deficiency. Therefore, this study has been performed to verify the effect of lap spliced longitudinal steel and confinement steel type for the seismic behavior of reinforced concrete bridge piers. Eight concrete columns were constructed with existing scale as diameter, 1.2m and height, 4.8m. 4 confinement steel types were adopted for seismic performance evaluation. All specimens were rested under inelastic cyclic loading while simultaneously subjected to a constant axial load. The longitudinal steel lap-splice is highly effective in seismic performance deterioration of reinforced concrete bridge piers.

• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.43-54
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• 2017

In this study, the failure behavior of composite material in the biaxial and off-axis loading is studied based on a computational micromechanical model. The model is developed so that the combination of mechanical and thermal loading conditions can be considered in the analysis. The modified generalized plane strain assumption of the theory of elasticity is used for formulation of the micromechanical modeling of the problem. A truly meshless method is employed to solve the governing equation and predict the distribution of micro-stresses in the selected RVE of composite. The fiber matrix interface is assumed to be perfect until the interface failure occurs. The biaxial and off-axis loading of the SiC/Ti and Kevlar/Epoxy composite is studied. The failure envelopes of SiC/Ti and Kevlar/Epoxy composite in off-axis loading, biaxial transverse-transverse and axial-transverse loading are predicted based on the micromechanical approach. Various failure criteria are considered for fiber, matrix and fiber-matrix interface. Comparison of results with the available results in the litreture shows excellent agreement with experimental studies.

• Structural Engineering and Mechanics
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• v.60 no.3
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• pp.365-386
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• 2016

This paper describes a systematic numerical investigation into the nonlinear elastic behavior of conical shells, with various types of initial imperfections, subject to a uniformly distributed axial compression. Three different patterns of imperfections, including first axisymmetric linear bifurcation mode, first non-axisymmetric linear bifurcation mode, and weld depression are studied using geometrically nonlinear finite element analysis. Effects of each imperfection shape and tapering angle on imperfection sensitivity curves are investigated and the lower bound curve is determined. Finally, an empirical lower bound relation is proposed for hand calculation in the buckling design of conical shells.

• Journal of ILASS-Korea
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• v.20 no.2
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• pp.76-81
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• 2015

Swirl flow has an impact on the stabilization of the flame by the recirculation flow, improvement of the combustion efficiency. The swirl flow in the gun type burner is created by the spinner which is inside the airtube that guide the combustion air. Burner has generally the combustion device composed electronic spark plug, injection nozzle, combustion device adaptor, and spinner. These inner components change the air flow behavior passing through airtube. So, this study analyzed exhaust flow characteristics of the gun type burner according to the ratio of airtube diameter. Turbulence characteristics by the spinner was mean velocity, turbulence intensity, kinetic energy, shear stress and flattness factor of the air flow of axial direction and tangential direction from the exit of the airtube.