• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.963-968
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• 2006

The main purpose of this paper is to investigate the stability of water tower with a relatively small footing. The water tower is modeled that the column carrying a container is supported by a rotational spring at the base and is of constant cross-section, with a weight per unit length of column axis. The column model is based on the Bernoulli-Euler beam theory. The Runge-Kutta method and Determinant Search method are used to perform the integration of the governing differential equation and to determine the critical values(critical own weight. and critical buckling load), respectively. The critical buckling loads are calculated over a range of system parameters: the rotational stiffness parameter, the dimensionless radius of container and the own weight parameter of the column. The relation between the rotational stiffness parameter and the critical own weight parameter of the column is analyzed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.369-374
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• 2001

This paper deals with the buckling loads of column with rotation end restricted by rotational spring. The ordinary differential equations governing the buckling loads of such column is derived as nondimensional forms, and also its boundary conditions are derived. The buckled column model is based on the classical Bemoulli-Euler beam theory. The Runge-Kutta method and Regula-Falsi method are used to perform the integration of the differential equations and to determine the eigenvalue. The numerical methods developed herein for the buckling loads of the such column are found to be efficient and reliable. It is expected that the results obtained herein can be practically utilized in the structural engineering field.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.169-179
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• 2005

An improved method for evaluating effective buckling lengths of beam-column members in plane frames is newly proposed based on system inelastic buckling analysis. To this end, the tangent stiffness matrix of be am-column elements is first calculated using stability functions and then the inelastic buckling analysis method is presented. The scheme for determining effective length of individual members is also addressed. Design examples and numerical results ?uc presented to show the validity of the proposed method.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.27-37
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• 2012

The construction of a moment connection for a rectangular hollow section (RHS) column and a H-shaped beam is difficult because the RHS is a closed section. When a inner diaphragm is used for such a connection, in general, it is installed after cutting the HSS columns, which results in increased construction work. This paper suggests a new fabrication method to overcome such problems: An inner diaphragm is welded to inside a C-shaped section first, and then a column is fabricated by welding two C-shaped sections. This fabrication method is superior to a classic method in terms of constructibility. An experimental and a numerical study using Ansys 9.0 were performed in order to compare the strength of connections with respect to the presence of concrete, the corner shape of diaphragm, and the axis of loading. The experimental results including initial stiffness and ultimate loads are reported and the analytical results including load transfer mechanism, degree of stress concentration, and strain distribution are also reported.

• Computers and Concrete
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• v.20 no.3
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• pp.361-368
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• 2017

Seismic response of the concrete column covered by nanofiber reinforced polymer (NFRP) layer is investigated. The concrete column is studied in this paper. The column is modeled using sinusoidal shear deformation beam theory (SSDT). Mori-Tanaka model is used for obtaining the effective material properties of the NFRP layer considering agglomeration effects. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle, the motion equations are derived. Harmonic differential quadrature method (HDQM) along with Newmark method is utilized to obtain the dynamic response of the structure. The effects of different parameters such as NFRP layer, geometrical parameters of column, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure are shown. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure. In addition, using nanofibersas reinforcement leads a reduction in the maximum dynamic displacement of the structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.139-150
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• 2005

Finite element method is applied to the determinations of the two eigenvalues(the elastic critical load and the natural frequence of lateral vibrations) of single story-3 equal bay rectangular frame. The analysis parameters are taper parameter ${\alpha}$ for column, and beam span to column height ratio, ${\beta}$ and second moment area ratio of beam to column, ${\Upsilon}$. Support condition at the column base and sway condition at the column top are also considered in the stability analysis of frame. The changes in the coefficient of eigenvalue are represented by algebraic function of analysis parameter. The coefficients estimated by the proposed algebraic function show good agreement with those determined by finite element method, which suggest the design aid role of the proposed function. By increasing the column axial forces step by step, the corresponding frequencies are also determined, which makes one examine or confirm the relationship suggested by other studies.

• International Journal of Concrete Structures and Materials
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• v.5 no.1
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• pp.57-64
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• 2011

An extensive database has been constructed of reinforced concrete (RC) beam-column connection tests subjected to cyclic lateral loading. All cases within the database experienced joint shear failure, either in conjunction with or without yielding of longitudinal beam reinforcement. Using the experimental database, envelope curves of joint shear stress vs. joint shear strain behavior have been created by connecting key points such as cracking, yielding, and peak loading. Various prediction approaches for RC joint shear behavior are discussed using the constructed experimental database. RC joint shear strength and deformation models are first presented using the database in conjunction with a Bayesian parameter estimation method, and then a complete model applicable to the full range of RC joint shear behavior is suggested. An RC joint shear prediction model following a U.S. standard is next summarized and evaluated. Finally, a particular joint shear prediction model using basic joint shear resistance mechanisms is described and for the first time critically assessed.

• Structural Engineering and Mechanics
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• v.32 no.5
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• pp.649-665
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• 2009

This paper reports part of a comprehensive research study conducted at the University of Queensland on the ability of CFRP web-bonded systems in strengthening an exterior beam-column joint subjected to monotonic loads. One 1/2.2 scaled plain and four CFRP repaired/retrofitted joints subjected to monotonic loads were analysed using the nonlinear finite-element program ANSYS and the results were calibrated against experiments. The ANSYS model was employed in order to account for tension stiffening in concrete after cracking and a modified version of the Hognestad's model was used to model the concrete compressive strength. The stress-strain properties of main steel bars were modelled using multilinear isotropic hardening model and the FRPs were modelled as anisotropic materials. A perfect bond was assumed as nodes were shared between adjacent elements irrespective of their type. Good agreement between the numerical predictions and the experimental observation of the failure mechanisms for all specimens were observed. Closeness of these results proved that the numerical analysis can be used by design engineers for the analysis of web-bonded FRP strengthened beam-column joints with confidence.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.361-374
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• 2020

Recently, small and medium-sized rahmen-type bridges have been developed as a technology that ensures the stability of structural behavior and the safety of use at the same time by using efficient and economical materials that make up the convergence section of reinforced bar, structural steel and concrete. This study is about a rahmen-type structure applied with the installation and dismantling of the strut. It improves the serviceability of the structure by forming multi-points and efficiently applies the convergence section of structural steel and concrete materials to the structural system changes to induce the displacement improvement effect additionally. By constructing mock-up models for the beam-column joint, the displacement was calculated and compared, and this was compared and analyzed by numerical analysis. The final displacement showed an improvement effect of 13.46% to 36.28% based on the vertical displacement of the existing structure without struts through the experiment of the mock-up models. As a result of analysis by numerical analysis method, the displacement improvement effect of 42.89% could be derived.

• Earthquakes and Structures
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• v.15 no.2
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• pp.145-153
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• 2018

Extensive reinforced concrete interior beam-column joints with beams of different depths have been used in large industrial buildings and tall building structures under the demand of craft or function. The seismic behavior of the joint, particularly the relationship between deformation and strength in the core region of these eccentric reinforced concrete beam-column joints, has rarely been investigated. This paper performed a theoretical study on the effects of geometric features on the shear strength of the reinforced concrete interior beam-column joints with beams of different depths, which was critical factor in seismic behavior. A new model was developed to analyze the relationship between the shear strength and deformation based on the Equivalent Strut Mechanism (ESM), which combined the truss model and the diagonal strut model. Additionally, this paper developed a simplified calculation method to estimate the shear strength of these type eccentric joints. The accuracy of the model was verified as the modifying analysis data fitted to the test results, which was a loading test of 6 eccentric joints conducted previously.