• Steel and Composite Structures
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• v.13 no.5
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• pp.423-436
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• 2012

In this study total of six buckling-restrained braces (BRBs) were manufactured using a square steel rod as a load-resisting core member and a hollow steel tube as restrainer to prevent global buckling of the core. The gap between the core and the tube was filled with steel rods as filler material. The performances of the proposed BRB from uniaxial and subassemblage tests were compared with those of the specimens filled with mortar. The test results showed that the performance of the BRB with discontinuous steel rods as filler material was not satisfactory, whereas the BRBs with continuous steel rods as filler material showed good performance when the external tubes were strong enough against buckling. It was observed that the buckling strength of the external tube of the BRBs filled with steel rods needs to be at least twice as high as that of the BRBs filled with mortar to ensure high cumulative plastic deformation of the BRB.

• Structural Engineering and Mechanics
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• v.5 no.4
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• pp.369-383
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• 1997

The classical theory of thin-walled members is unable to reflect the shear lag phenomenon since it is based on the assumption of no shearing strains in the middle surface of the walls. In this paper, an energy equation for the lateral buckling of thin-walled members has been derived which includes the effects of torsion, warping and, especially, the shearing strains which reflect the shear lag phenomenon. A numerical analysis for the lateral buckling of thin-walled members with openings by using Galerkin's method of weighted residuals has been presented. The proposed numerical values and the predictions by experiment for the lateral buckling loads are to agree closely in the paper. The results from these comparisons show that the proposed method here is capable of predicting the lateral buckling of thin-walled members with openings. The fast convergence of the results indicates the numerical stability of the method. By the study, a very complex practical eigenvalue problem is transformed into a very simple one of solving only a linear equation with one variable.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.133-141
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• 2001

A tubular member holding an axially through-gusset connection is often used to transmit axial compression in a steel truss structures. The elastic buckling loads of the member is affected by the stiffness ratio($\beta$) and the length ratio(G) because of two elements with different properties. In current code, however, the strength is evaluated with an effective length factor k=0.9 without considering the above effect. Therefore this study analyzed a theoretical mechanism based on the elasticity theory and performed a finite element analysis to investigate the influence parameters on the elastic buckling strength of axially loaded member.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.12-17
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• 2015

In this study, the collapse characteristic of CFRP/Al compound square tube was investigated experimentally. The conclusions are as follows; The impact collapse characteristic of CFRP/Al compound square tube was found to be the most superior stacking conditions $[90^{\circ}]_8$. It showed that a very stable collapse mode was crushing. In the member with $[0_2{^{\circ}}/90_2{^{\circ}}]_s$ and $[90_2{^{\circ}}/0_2{^{\circ}}]_s$, stacking conditions, $0^{\circ}$ fibers were splayed to the external by laminar bending, while the $90^{\circ}$ fibers were held between the folds of the aluminum member by laminar bending, local buckling and transverse crack. In the member with $[45_2{^{\circ}}/45_2{^{\circ}}]_s$ stacking conditions, fibers were held between the folds of the aluminum member by local buckling and transverse crack.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.76-83
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• 2015

This paper aims at developing an environmentally friendly modular dome structure system with highly filled extrusion wood-plastic composite (WPC) member, and manufacturing a real-size specimen by modularizing members and nodes. The member used in the model is the WPC member with 70% wooden fiber contests, which is higher then previous WPC one. Its members and nodes are modularized by analyzing geometric characteristics of icosahedral-based geodetic dome. Applicapability of the 6ea prototype nodes and 3ea prototype members to the modular dome is examined with the results of the modulaization and the making process for the real-size specimen. Besides, from the analysis results, the lowest buckling mode is expected to be a nodal buckling on a node near the boundary.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.357-365
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• 2011

The current trends in steel construction intend to use tapered sections to minimize as much as possible the use of excess material. This can be done by choosing the cross-sections to be as economical as possible, leaving the classical approach of using prismatic members. In addition, it is important to predict the buckling behavior of tapered member with large depth-to-thickness ratio in order to prevent the collapse of PEB system subjected to overloads. An experimental investigation of buckling behavior of tapered beam was presented. The primary test parameter was depth-to-thickness ratio and taper ratio. Using initial stiffness and load-carrying capacity proposed by current provision, the simple plastic hinge method using modified Yoda's model and finite element analysis, the prediction of a moment-rotation curve of linearly tapered member was presented. Moreover, comparisons between analytical and experimental data for moment-rotation curves were accomplished.

• Structural Engineering and Mechanics
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• v.72 no.5
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• pp.569-583
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• 2019

Tubular steel sections are widespread all over the world because of their strength and aesthetic appearance. Tubular steel members may exhibit local buckling such as elephant foot or overall buckling under extreme compression load. Recently, external bonding of fiber reinforced polymers (FRP) sheets for strengthening these members has been explored through experimental research. This paper presents three-dimensional nonlinear finite element analysis (FEA) to investigate the structural behavior of strengthening tubular steel members with FRP against local and overall buckling phenomena. Out-of-roundness and out-of-straightness imperfections were introduced to the numerical models to simulate the elephant foot and overall buckling, respectively. The nonlinear analysis preferences such as the integration scheme of the shell elements, the algorithm for solution of nonlinear equations, the loading procedure, the bisection limits for the load increments, and the convergence criteria were set, appropriately enough, to successfully track the sophisticated buckling deformations. The agreement between the results of both the presented FEA and the experimental research was evident. The FEA results demonstrated the power of the presented rigorous FEA in monitoring the plastic strain distribution and the buckling phenomena (initiation and propagation). Consequently, the buckling process was interpreted for each mode (elephant foot and overall) into three sequential stages. Furthermore, the influence of FRP layers on the nonlinear analysis preferences and the results was presented.

• Structural Engineering and Mechanics
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• v.6 no.2
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• pp.185-200
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• 1998

Space truss design usually involves two main assumptions: that truss members are pin-ended, and compression members possess brittle post-buckling characteristics. The validity of these assumptions in the design of a new group of space trusses with continuous chords and eccentric joints is questionable. With chord member continuity and the consequent improvement in compression member behaviour, current design practice might be too conservative. In this paper, it is shown that substantial improvements in overall truss strength have resulted when the true member end conditions are considered, thus indicating potential savings in truss weight with considerable magnitudes.

• Structural Engineering and Mechanics
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• v.2 no.3
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• pp.269-284
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• 1994

The analysis and tests of thin-walled channel frames including nonlinear flexible or semi-rigid connection behaviour is presented. The semi-rigid connection behaviour is modelled using a mathematical approximation of the connection flexibility-moment relationship. Local instability such as local buckling and torsional flexural buckling of the member are included in the analysis. The full response of the frame, up to the collapse load, can be predicted. Experimental investigation was carried out on a series of simple double storey symmetrical frames with the purpose of verifying the accuracy and validity of the analysis. Agreement between the theoretical and experimental results is acceptable. The investigation also shows that connection flexibility and local instability such as local buckling and torsional flexural buckling can affect the behaviour and strength of thin-walled frames significantly. The results can also provide further insight into the advanced study of practical structures where interaction between flexible connections and phenomenon associated with thin-walled members are present.

• Structural Engineering and Mechanics
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• v.24 no.3
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.