• Title/Summary/Keyword: Member buckling

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Seismic Performance Assessment of a Modular System with Composite Section (합성단면을 적용한 모듈러 시스템의 내진 성능평가)

  • Choi, Young-Hoo;Lee, Ho-Chan;Kim, Jin-Koo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.69-77
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    • 2017
  • By producing pre-engineered modular system in the factory, It is enable to expedite construction and can be distinguished from two types by the method resisting load. One is the open-sided modular system composed of beams and columns. The other is enclosed modular system composed of panels and studs. Of the modular systems, the open-sided modular system buildings the connection between modules are difficult due to closed member sections, and the overall strength is reduced as a result of local buckling. In this study, in order to solve these problems, a modular system with folded steel members filled with concrete are proposed. The capacity spectrum method presented in ATC 40 is used for seismic performance assessment of the proposed model structure and the structure with conventional steel members. The analysis results show that at the performance point of each model the number and rotation of plastic hinge formed in the proposed modular system are smaller than those in the conventional system. Based on this observation it is concluded that the proposed system with composite sections has superior seismic capacity compared with conventional system.

A Study on the Load Carrying Capacity and Deformation Capacity of the Internal Anchors Welded Cold Formed Concrete Filled Columns (내부앵커형 콘크리트 충전 기둥의 내력 및 변형능력에 관한 연구)

  • Kim, Sun Hee;Yom, Kong Soo;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.25 no.4
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    • pp.347-357
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    • 2013
  • Recently, In recognition of outstanding structural performance the use of Concrete Filled steel Tube(CFT) columns has been increased. Research is ongoing that effective use of cross-sectional because steel strength development and rising prices. In this Lab, suggests new shape by Thin steel plates bent to be L-channel welded to form square steel tube to maximize efficiency of the cross section. In addition, since the rib placed at the center of the tube width acts as an anchor; higher load capacity of buckling is acceptable. we have developed New shape welded built-up square tube for broader usability which were bent to be L-shaped and thin Plate each unit member were welded. In order to apply the new shape built-up square columns, we predicted structure behavior, stress distribution with parameter Width thickness ratio. The experimental results presented in standards and even exceed the b/t of the rib anchors installed in the role due to exert enough strength and deformation to improve performance was favorable.

Optimum Design of Plane Steel Frame Structures Using Refined Plastic Hinge Analysis and SUMT (개선소성힌지해석과 SUMT를 이용한 평면 강골조의 연속최적설계)

  • Yun, Young Mook;Kang, Moon Myoung;Lee, Mal Suk
    • Journal of Korean Society of Steel Construction
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    • v.16 no.1 s.68
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    • pp.21-32
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    • 2004
  • In this study, a continuous optimum design model with its application program for plane steel frame structures developed. In the model, the sequential unconstrained minimization technique (SUMT) transforming the nonlinear optimization problem with multidesign variables and constraints into an unconstrained minimization problem and the refined plastic hinge analysis method as one of the most effective second-order inelastic analysis methods for steel frame structures were implemented. The total weight of a steel frame structure was taken as the objective function, and the AISC-LRFD code requirements for the local and member buckling, flexural strength, shear strength, axial strength and size of the cross-sectional shapes of members were used for the derivation of constraint equations. To verify the appropriateness of the present model, the optimum designs of serveral plane steel frame structures subject to vertical and horizontal loads were conducted.

Experimental Study on Structural Behavior of Tapered non-compact Frame with Snug-tightened Conditions (밀착조임 볼트체결에 따른 판폭두께비가 큰 변단면 프레임의 구조성능에 관한 실험적 연구)

  • Chung, Kyung-Soo;Jeon, Bae-Ho;Park, Man-Woo;Do, Byung-Ho
    • Journal of Korean Society of Steel Construction
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    • v.24 no.3
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    • pp.257-265
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    • 2012
  • Current trends in steel construction include using tapered, non-compact sections to minimize the use of excess material as much as possible by choosing the cross-sections instead of the classical approach of using prismatic members. In addition, snug conditions, especially the end-plate type, have the advantage of incurring less construction costs and shorter assembly times as opposed to full pre-tensioned conditions. On the other hand, it is important to predict the collapse of the PEB system due to over-loading. Large-scale tests of tapered steel portal frames with non-compact sections were conducted. The primary test parameters included the bolt connection method and the loading condition (vertical and horizontal load). The test results on initial stiffness and load capacity were investigated. Furthermore, comparisons between the analytical and experimental data for load-displacement curves were initiated. In addition, we evaluated the applicability of a snug bolt for the PEB frame in the field.

A Procedure for a Strength Assessment of Permanent Means of Access Structure (Permanent Means of Access 강도 평가 방법에 대한 연구)

  • Jang, Beom-Seon;Chung, Sung-Wook;Ko, Dae-En;Chun, Min-Sung;Kim, Ji-Young
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.1
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    • pp.31-42
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    • 2009
  • Common structural rule (CSR) doesn' t provide any other specific regulations for permanent means of access (PMA) platform structure in a cargo oil tank. The PMA platform is recommended to comply with scantling requirement of local support member. However, it leads to too conservative scantlings compared with actual loads imposed on the platform. This paper proposes a strength assessment procedure for the PMA structure based on a nonlinear ultimate strength. The ultimate strength is evaluated in a sufficiently conservative way. The first linear buckling mode is used as an initial imperfection shape and its magnitude is determined using the definitions of DNV PULS. Since the same imperfection mode as the failure mode of the ultimate limit state is assumed, it can accelerate the failure. Au ultimate strength capacity curve obtained from a series of nonlinear FE analysis is compared with actual stresses calculated by CSR cargo hold analysis.

A Study on the Compression Strength of Structural Steel Tube Applied in Spatial Structure (공간구조에 적용되는 일반구조용 강관의 압축내력에 관한 연구)

  • Baek, Ki-Youl
    • Journal of Korean Association for Spatial Structures
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    • v.8 no.5
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    • pp.83-93
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    • 2008
  • Space truss is a rational system which forming large span in spatial structure and the steel tube is used well as a structure member in truss system. This study includes coupon test and Stub-column compression test on the structural steel tube. The compression test of Stub-column was performed to characterize and quantify the material characteristic and strength of column. In this study, we also researched the matter of compatibility, in which we compared the experiment formula and the abstract formula by the application of the LSD standard formula, SSRC and ECCS multiple column curve.

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Comparison of Limit Strength of Steel Cable-Stayed Bridges using Nonlinear Inelastic Displacement and Buckling Analyses (비선헝 비탄성 유한변위 해석 및 좌굴해석에 의한 강사장교의 극한강도 비교)

  • Kim Sung-Eock;Choi Dong-Ho;Ma Sang-Soo;Song Weon-Keun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.3
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    • pp.277-289
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    • 2005
  • The study examines the limit strength for steel cable-stayed bridges. A case studies have been performed in order to evaluate the limit strength lot steel cable-stayed bridges using nonlinear inelastic analysis approach and bifurcation point instability analysis approach, effective tangent modulus $(E_f)$ method. To realize it, a practical nonlinear inelastic analysis condoling the initial shape is developed. In the initial shape analysis, updated structural configuration is introduced instead of initial member forces for beam-column members at every iterative step. Geometric and material nonlinearities of beam-column members are accounted by using stability function, and by using CRC tangent modulus and parabolic function, respectively Besides, geometric nonlinearity of cable members is accounted by using secant value of equivalent modulus of elasticity. The load-displacement relationships obtained by the proposed method are compared well with those given by other approaches. The limit strengths evaluated by the proposed nonlinear inelastic analysis for the proposed cable-stayed bridges with tee dimensional configuration compared with those by the inelastic bifurcation point instability analyses.

The Structural Reinforcing of PCC-Deck with Cantilever (캔틸레버를 갖는 PCC-Deck의 구조보강)

  • Lho, Byeong-Cheol;Kim, Chang-Kyo;Park, Jong-Hyeon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.21-30
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    • 2013
  • LB-Deck is one of the widely used member in interior part of girders as a permanent formwork in structures, but it is not easy to apply to the exterior part of girder due to the overturning and excessive deflection. Considering allowable deflection and safety of the exterior part, Precast Concrete Cantilever Deck (PCC-Deck) is proposed with normal LB-Deck in inner part and extended bars of LB-Deck in outer part. Both numerical analyses and experimental tests were compared to check the safety and allowable deflection for 6 types of PCC-Deck, and D-type (with 16 mm top bar, 6 mm lattice bar, 12 mm bottom bar) is suggested as an optimal structural reinforcement to the 28 kN of maximum load and 27.49 mm of final deflection. The load resisting ratio of D-type under working load of 10 kN was about 2.8 times and 77.5% of improvement was observed.

Analysis on Flexural Behavior of Spiral Steel Pipe Considering Residual Stress Developed by Pipe Manufacturing (조관에 의한 잔류 응력을 고려한 스파이럴 강관의 휨 거동 분석)

  • Kim, Kyuwon;Kim, Jeongsoo;Kang, Dongyoon;Kim, Moon Kyum
    • Journal of the Korean Institute of Gas
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    • v.23 no.4
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    • pp.65-73
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    • 2019
  • A spiral steel pipe has been more used widely as a structural member as well as transport pipeline because the pipe can be manufactured continuously, consequently more economical than the conventional UOE pipe. As improved pipe manufacture technology makes spiral pipes to have high strength and to have larger diameters, the spiral pipes have been recently used as long distance transport pipeline with a large diameter and strain-based design is thus required to keep structural integrity and cost effectiveness of the spiral pipe. However, design codes of spiral pipe have not been completely established yet, and structural behaviors of a spiral pipe are not clearly understood for strain-based design. In this paper, the effects of residual stresses due to the spiral pipe manufacture process are investigated on the flexural behavior of the spiral pipe. Finite element analyses were conducted to estimate residual stresses due to the manufacturing process for the pipes which have different forming angle, thickness, and strength, respectively. After that, the results were used as initial conditions for flexural analysis of the pipe to numerically investigate its flexural behaviors.

The Optimal Configuration of Arch Structures Using Force Approximate Method (부재력(部材力) 근사해법(近似解法)을 이용(利用)한 아치구조물(構造物)의 형상최적화(形狀最適化)에 관한 연구(研究))

  • Lee, Gyu Won;Ro, Min Lae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.2
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    • pp.95-109
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    • 1993
  • In this study, the optimal configuration of arch structure has been tested by a decomposition technique. The object of this study is to provide the method of optimizing the shapes of both two hinged and fixed arches. The problem of optimal configuration of arch structures includes the interaction formulas, the working stress, and the buckling stress constraints on the assumption that arch ribs can be approximated by a finite number of straight members. On the first level, buckling loads are calculated from the relation of the stiffness matrix and the geometric stiffness matrix by using Rayleigh-Ritz method, and the number of the structural analyses can be decreased by approximating member forces through sensitivity analysis using the design space approach. The objective function is formulated as the total weight of the structures, and the constraints are derived by including the working stress, the buckling stress, and the side limit. On the second level, the nodal point coordinates of the arch structures are used as design variables and the objective function has been taken as the weight function. By treating the nodal point coordinates as design variable, the problem of optimization can be reduced to unconstrained optimal design problem which is easy to solve. Numerical comparisons with results which are obtained from numerical tests for several arch structures with various shapes and constraints show that convergence rate is very fast regardless of constraint types and configuration of arch structures. And the optimal configuration or the arch structures obtained in this study is almost the identical one from other results. The total weight could be decreased by 17.7%-91.7% when an optimal configuration is accomplished.

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