• Advances in Computational Design
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• v.8 no.1
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• pp.61-76
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• 2023

Fiber reinforced polymer (FRP) columns are increasingly being used in various engineering fields due to its high strength to weight ratio and corrosion resistance. Being a thin-walled structure, their designs are often governed by buckling.Buckling strength depends on state of stress of elements which is greatly influence by stacking sequence and various inaccuracies such as geometric imperfections and imperfections due to eccentricity of compressive load and non-uniform boundary conditions. In the present work, influence of load eccentricity on buckling strength of FRP column has been investigated by conducting parametric study. Numerical analyses were carried out by using finite element software ABAQUS. The finite element (FE) model was validated using experimental results from the literature, which demonstrated good agreement in terms of failure loads and deformed shapes.The influence of load eccentricity on buckling behavior is discussed with the help of developed graphs.

• Steel and Composite Structures
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• v.1 no.2
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• pp.171-185
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• 2001

The design of tall buildings has recently provided many challenges to structural engineers. One such challenge is to minimise the cross-sectional dimensions of columns to ensure greater floor space in a building is attainable. This has both an economic and aesthetics benefit in buildings, which require structural engineering solutions. The use of high strength steel in tall buildings has the ability to achieve these benefits as the material provides a higher strength to cross-section ratio. However as the strength of the steel is increased the buckling characteristics become more dominant with slenderness limits for both local and global buckling becoming more significant. To arrest the problems associated with buckling of high strength steel, concrete filling and encasement can be utilised as it has the affect of changing the buckling mode, which increases the strength and stiffness of the member. This paper describes an experimental program undertaken for both encased and concrete filled composite columns, which were designed to be stocky in nature and thus fail by strength alone. The columns were designed to consider the strength in axial compression and were fabricated from high strength steel plate. In addition to the encased and concrete filled columns, unencased columns and hollow columns were also fabricated and tested to act as calibration specimens. A model for the axial strength was suggested and this is shown to compare well with the test results. Finally aspects of further research are addressed in this paper which include considering the effects of slender columns which may fail by global instabilities.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.210-224
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• 2010

The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.11 no.1
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• pp.1-10
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• 2005

Paper angle, environment friendly packaging material, has been mainly used as an edge protector. But, we have perceived its application to package design of heavy product such as strength reinforcement or unit load system (ULS) in the future. Above all, understanding of buckling behavior for angle itself and compression strength and quality standard have to be accomplished for the paper angle to be used for this purpose. The purpose of this study was to elucidate the buckling behavior through theoretical and finite element analysis, and to develop compression strength model by compression test for symetric and asymetric paper angle. Based on the result of theoretical and finite element analysis, increasing rate of buckling of asymmetric paper angle was higher as applied load level was bigger and/or the length of angle was longer than that of symmetric paper angle. Decreasing rate of minimum principal moment of inertia was remarkably increased as the extent of asymmetric angle is bigger, and buckling orientation of angle was open direction near the small web. Increasing rate of maximum compression strength (MCS) for thickness of angle was smaller as the web size was bigger in symmetric angle. MCS of asymmetric angle of $43{\times}57$ and $33{\times}67$ was decreased $15{\sim}18%$ and $65{\sim}78%$, and change of buckling was increased $12{\sim}13%$ and $62{\sim}66%$, respectively.

• Interaction and multiscale mechanics
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• v.5 no.2
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• pp.91-104
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• 2012

There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multiscale numerical model for simulating the interaction local and global buckling behavior of high strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the M$\ddot{u}$ller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale level. Performance indices are proposed to quantify the performance of CFST slender beam-columns. The accuracy of the multiscale numerical model is examined by comparisons of computer solutions with existing experimental results. The numerical model is utilized to investigate the effects of concrete compressive strength, depth-to-thickness ratio, loading eccentricity ratio and column slenderness ratio on the performance indices. The multiscale numerical model is shown to be accurate and efficient for predicting the interaction buckling behavior of high strength thin-walled CFST slender beam-columns.

• Steel and Composite Structures
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• v.51 no.3
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• pp.225-241
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• 2024

For several reasons, cold-formed steel (CFS) beams are often manufactured with holes. Nevertheless, because of holes, the reduction in the web area causes a decrease in the bending strength. Edge stiffeners are presently added around the holes to improve the bending strength of flexural members. Therefore, this research studies CFSZ-beams with stiffened holes and investigates how edge stiffener affects bending strength and failure modes. Nonlinear analysis was carried out using ABAQUS software and the developed finite element (FE) model was verified against tests from previous studies. Using the verified FE model, a parametric study of 104 FE models was conducted to investigate the influence of key parameters on bending strength of Z- sections. The results indicated that the effect of holes is less noticeable in very thin Z-sections. Moreover, adding edge stiffeners around the holes improves the flexural capacity of Z-beams and sometimes restores the original bending capacity. Because the computational techniques used to solve the CFS buckling mode with stiffened holes are still unclear, a numerical method using constrained and unconstrained finite strip method (CUFSM) software was proposed to predict the elastic distortional buckling moment for a wide variety of CFSZ-sections with stiffened holes. A numerical method with two procedures was applied and validated. Upon comparison, the numerical method accurately predicted the distortional buckling moment of CFS Z-sections with stiffened holes.

• International Journal of High-Rise Buildings
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• v.6 no.3
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• pp.249-259
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• 2017

The use of high-strength steels in construction of highrise and mega building structures can bring about many technological advantages from fabrication to erection. However, key design criteria such as local and lateral stability in current steel design specifications were developed based on tests of ordinary steels which have stress-strain characteristics very different from that of high strength steels. A series of tests on 800 MPa tensile strength steel (HSA800) members are summarized in this paper which were conducted to investigate the appropriateness of extrapolating current ordinary-steel based design criteria to high strength steels. 800 MPa I-shape beam specimens designed according to flange local buckling (FLB) criteria of the AISC Specification developed a sufficient strength for elastic design and a marginal rotation capacity for plastic design. It is shown that, without introducing distinct and significant yield plateau to the stress-strain property of high-strength steel, it is inherently difficult to achieve a high rotation capacity even if all the current stability limits are met. 800 MPa I-shape beam specimens with both low and high warping rigidity exhibited sufficient lateral torsional buckling (LTB) strength. HSA800 short-column specimens with various edge restraint exhibited sufficient local buckling strength under uniform compression and generally outperformed ordinary steel specimens. The experimental P-M strength was much higher than the AISC nominal P-M strength. The measured residual stresses indicated that the impact of residual stress on inelastic buckling of high-strength steel is less. Cyclic seismic test results showed that HSA800 members have the potential to be used as non-ductile members or members with limited ductility demand in seismic load resisting systems. Finally, recent applications of 800 MPa high strength steel to highrise and mega building structures in Korea are briefly presented.

• Journal of Korean Association for Spatial Structures
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• v.2 no.1 s.3
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• pp.85-92
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• 2002

Two way grid single-layer domes are of great advantage in fabrication and construction because of the simple fact that they have only four members at each junction. But, from a point of view of mechanics, the rectangular latticed pattern gives rise to a nonuniform rigidity-distribution in the circumferential direction. If the equivalent rigidity is considered in the axial direction of members, the in-plane equivalent shearing rigidity depends only on the in-plane bending rigidity of members and its value is very small in comparison to that of the in-plane equivalent stretching rigidity. It has a tendency to decrease buckling -strength of dome considerably by external force. But it is possible to increase buckling strength by the use of roofing covering materials connected to framework. In a case like this, shearing rigidity of roofing material increases buckling strength of the overall structure and can be designed economically from the viewpoint of practice. Therefore, the purpose of this paper, in Lamella dome and rectangular latticed dome that are a set of 2-way grid dome, is to clarify the effects of roofing covering materials for increasing of buckling strength of overall dome. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems. The conclusion were given as follows: 1. In case of Lamella domes which have nearly equal rigidity in the direction of circumference, the rigidity of roofing covering materials does not have a great influence on buckling-strength, but in rectangular latticed domes that has a clear periodicity of rigidity, the value of its buckling strength has a tendency to increase considerably with increasing rigidity of roofing covering materials 2. In case of rectangular latticed domes, as rise-span-ratio increases, models which is subjected to pressure -type-uniform loading than vertical-type-uniform loading are higher in the aspects of the increasing rate of buckling- strength according to the rate of shear reinforcement rigidity, but in case of Lamella dome, the condition of loading and rise-span-ratio do not have a great influence on the increasing rate of buckling strength according to the rate of shear reinforcement rigidity.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.427-436
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• 2006

The classical buckling theory assumes that prebuckling behavior is linear and that the effect of prebuckling deformations on buckling can be ignored. However, when the rise to span ratio decreases, prebuckling deformation cannot be ignored and the symetrical buckling strength can be smaler than the asymetrical buckling strength. Finally, arches can fail due to snap-through buckling. This paper investigates the non-linear behavior and strength of pin-ended parabolic shallow arches using the non-linear governing differential equation of shallow arches. These results were compared with the solution for the symmetrical buckling load of pin-ended parabolic shallow arches was suggested.

• Journal of Korean Society of Steel Construction
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• v.23 no.6
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• pp.647-657
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• 2011

This paper describes the moment capacity of flexural members with local buckling based on a series of FE and experiment results. Thin-walled flexural members undergo local, lateral-torsional, or interactive buckling according to the section geometries and lateral boundary conditions. Flexural members with large width-to-thickness ratios in the flanges or the web may undergo local buckling before lateral-torsional buckling. Local buckling has a negative effect on the flexural strength based on the lateral-torsional buckling of flexural members. This phenomenon should be considered in the estimation of the flexural strength of thin-walled sections. Flexural members with various width-to-thickness ratios in their flanges and web were analyzed. Initial imperfections in the local buckling mode, and residual stresses, were included in the FE analyses. Simple bending moment formulae for flexural members were proposed based on the FE and test results to account for local and lateral-torsional buckling. The proposed bending moment formulae for the thin-walled flexural members in the Direct Strength Method use the empirical strength formula and the grosssection modulus. The ultimate flexural strengths predicted by the proposed moment formulae were compared with the AISC (2005), Eurocode3 (2003), and Korean Highway Bridge Design Specifications (2010). The comparison showed that the proposed bending moment formulae can reasonably predict the ultimate moment capacity of thin-walled flexural members.