• Structural Engineering and Mechanics
• /
• v.66 no.6
• /
• pp.783-792
• /
• 2018

This paper presents a detailed theoretical study of the sleeved compression members based on a mechanical model. In the mechanical model, the core protrusion above sleeve and the contact force between the core and sleeve are specially taken into account. Via the theoretical analyses, load-displacement relationships of the sleeved compression members are obtained and verified by the experimental results. On the basis of the core moment distribution changing with the increase of the applied axial load, failure mechanism of the sleeved compression members is assumed and proved to be consistent with the experimental results in terms of the failure modes and the ultimate bearing capacities. A parametric study is conducted to quantify how essential factors including the core protrusion length above sleeve, stiffness ratio of the core to sleeve, core slenderness ratio and gap between the core and sleeve affect the mechanical behaviors of the sleeved compression members, and it is concluded that the constrained effect of the sleeve is overestimated neglecting the core protrusion; the improvement of ultimate bearing capacity for the sleeved compression member is considered to be decreasing with the decrease of the core slenderness ratio and for the sleeved compression member with core of small slenderness ratio, small gap and small stiffness ratio are preferred to obtain larger ultimate bearing capacity and stiffness.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.11a
• /
• pp.83-86
• /
• 2005

The front-end side members of automobiles, such as the hat-shaped section member, absorb most of the energy during the front-end collision. The side members absorb more energy in collision if they have higher strength and stiffness, and stable folding capacity (local buckling). Using the above characteristics on energy absorption, vehicle should be designed light-weight to improve fuel combustion ratio and reduce exhaust gas. Because of their specific strength and stiffness, CFRP are currently being considered for many structural (aerospace vehicle, automobiles, trains and ships) applications due to their potential for reducing structural weight. Although CFRP members exhibit collapse modes that are significantly different from the collapse modes of metallic materials, numerous studies have shown that CFRP members can be efficient energy absorbing materials. In this study, the CFRP side members were manufactured using a uni-directional prepreg sheet of carbon/Epoxy and axial static collapse tests were performed for the members. The collapse mode and the energy absorption capability of the members were analyzed under the static load.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.627-636
• /
• 2005

The analysis and design procedure of intermediate support strut for the innovative prestressed scaffolding (IPS) system was presented in this paper. The stability check of intermediate support strut is required as the behavior of the strut system is similar to that of the built-up column. The computer analysis model of the support strut was constructed for in-plane and out-of-plane buckling analysis, and the design of the support strut was performed. Using the eigenvalue for the buckling load and the member forces of support strut under design earth pressure, the effective buckling length was estimated. The allowable axial and bending stresses were calculated considering the effective buckling length. The combined stresses due to these axial forces and bending moment were estimated to be satisfied the safety condition of the intermediate support strut.

• Computational Structural Engineering
• /
• v.8 no.4
• /
• pp.149-158
• /
• 1995

When hot-rolled wide flanges are used as vertical compressive or bending member, opening web are often to take a space for equipments of pipe or duct. The Web of hot-rolled wide flange steel with opening may be analyzed as a rectangular plate, subjected to in plane force, and the buckling load is governed by the ultimate force of web. The result of the theory showed close agreement with the result of the finite element analysis. It was also shown that the buckling loads of stiffened opening plates could be larger than those of the plate. The stiffened opening plates for the 4-side simply supported case showed more stiffening effect than the Two Opposite Elastic Supports and Two Other Opposite Simply Supports case. In this study, we proposed the effective opening sizes that buckling loads of stiffened opening plate could be greater than those of the plates.

• Computational Structural Engineering
• /
• v.10 no.4
• /
• pp.205-216
• /
• 1997

In order to trace the lateral post-buckling behaviors of thin-wafled space frames, a geometrically nonlinear finite element formulation is presented by applying incremental equilibrium equations based on the updated Lagrangian formulation and introducing Vlasov's assumption. The improved displacement field for symmetric thin-walled cross sections is introduced based on inclusion of second order terms of finite rotations, and the potential energy corresponding to the semitangential rotations and moments is consistently derived. For finite element analysis, tangent stiffness matrices of the thinwalled space frame element with 7 degrees of freedom including the restrained warping for each node are derived by using the Hermition polynomials as shape functions. A co-rotational formulation in order to evaluate the unbalanced loads is presented by separating the rigid body rotations and pure deformations from incremental displacements and evaluating the updated direction cosines of the frame element due to rigid body rotations and incremental member forces from pure deformations. Finite element solutions for the spatial buckling and post-buckling analysis of thin-walled space frames are presented and compared with available solutions and other researcher's results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.1
• /
• pp.83-88
• /
• 2013

Progressive collapse is a chain reaction of failures propagating throughout a portion of a structure that is disproportionate to the original local failure. When column members are subjected to unexpected load (compression load), they will buckle if the applied load is greater than the critical load that induces buckling. The post-buckling strength of the columns will decrease rapidly, but if there is enough residual strength, the members will absorb the potential energy generated by the impact load to prevent progressive collapse. Thus, it is necessary to identify the relationship of the load-deformation of a column member in the progressive collapse of a structure up to final collapse. In this study, we carried out nonlinear FEM analysis and based on deflection theory, we investigated the load-deformation relationship of H-section steel columns when both ends were fixed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.3
• /
• pp.331-337
• /
• 2012

In this study, the front side member is optimized using a topography optimization technique. Optimization of a simple beam is conducted before optimization of the front side member. The objective function is set to minimize the first buckling factor in the longitudinal direction. The design variable corresponds to the perturbation of nodes normal to the shell's mid-plane space. The crash analysis is conducted on a simple beam, which is optimized by Response Surface Method and the topography optimization technique. In order to verify the topography optimization technique, the results of the RSM and topography optimization model are compared. Consequently, we confirm the satisfactory performance of the topography optimization technique, and apply this topography optimization to the front side member. Thus, the front side member is optimized and its crashworthiness is increased.

• Advances in nano research
• /
• v.8 no.4
• /
• pp.323-333
• /
• 2020

In recent years, there has been an upsurge for the usage of buckling restrained braces (BRB) rather than ordinary braces, as they have evidently performed better. If the overall brace buckling is ignored, BRBs are proven to have higher energy absorption capacity and flexibility. This article aims to deliberate an economically efficient yet adequate type of all-steel BRB, comprised of the main components as in traditional ones, such as : (1) a steel core that holds all axial forces and (2) a steel restrainer tube that hinders buckling to occurr in the core; there is a more practical detailing in the BRB system due to the elimination of a filling mortar. An investigation has been conducted for the proposed rectangular-tube core BRB and it is hysteric behavioral results have been compared to previous researches conducted on a structure containing a similar plate core profile that has the same cross-sectional area in its core. A loss of strength is known to occur in the BRB when the limiting condition of local buckling is not satisfied, thus causing instability. This typically occurs when the thickness of the restrainer tube's wall is smaller than the cross-sectional area of the core plate or its width. In this study, a parametric investigation for BRBs with different formations has been performed to verify the effect of the design parameters such as different core section profiles, restraining member width to thickness ratio and relative cross-sectional area of the core to restrainer, on buckling load evaluation. The proposed BRB investigation results have also been presented and compared to past BRB researches with a plate profile as the core section, and the advantages and disadvantages of this configuration have been discussed, and it is concluded that BRBs with tubular core section exhibit a better seismic performance than the ones with a plate core profile.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.1
• /
• pp.77-85
• /
• 2015

This paper describes the development of force limiting device(FLD). The FLD could induce compressive yield before occurring elastic buckling for slender member under compressive load. Therefore, it might prevent reduction of load carrying capacity by elastic buckling and the structures with the devices would behave stable. A new type of FLD reduced cross area is proposed in this study different to existing studies like as out of plane type, slit type and folded plate type. The parameters of specimens are depth, width and number of cutting. The structural capacity and characteristics of proposed types were verified by experiment and FEM analysis. The FLD of cutting type is efficient in compressive member.

• International Journal of High-Rise Buildings
• /
• v.3 no.1
• /
• pp.21-33
• /
• 2014

The tied braced frame (TBF) system was developed to achieve uniform seismic inelastic demand along the height of multi-storey eccentrically braced steel frames. A modular tied braced frame (M-TBF) configuration has been recently proposed to reach the same objective while reducing the large axial force demand imposed on the vertical tie members connecting the link beams together in TBFs. M-TBFs may however experience variations in storey drifts at levels where the ties have been removed to form the modules. In this paper, the possibility of reducing the discontinuity in displacement response of a 16-storey M-TBF structure by introducing energy dissipating (ED) devices between the modules is examined. Two M-TBF configurations are investigated: an M-TBF with two 8-storey modules and an M-TBF with four 4-storey modules. Three types of ED devices are studied: friction dampers (FD), buckling restrained bracing (BRB) members and self-centering energy dissipative (SCED) members. The ED devices were sized such that no additional force demand was imposed on the discontinuous tie members. Nonlinear response history analysis showed that all three ED systems can be used to reduce discontinuities in storey drifts of M-TBFs. The BRB members experienced the smallest peak deformations whereas minimum residual deformations were obtained with the SCED devices.