• 제목/요약/키워드: Constant Axial Load

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Buckling and stability analysis of sandwich beams subjected to varying axial loads

  • Eltaher, Mohamed A.;Mohamed, Salwa A
    • Steel and Composite Structures
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    • 제34권2호
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    • pp.241-260
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    • 2020
  • This article presented a comprehensive model to study static buckling stability and associated mode-shapes of higher shear deformation theories of sandwich laminated composite beam under the compression of varying axial load function. Four higher order shear deformation beam theories are considered in formulation and analysis. So, the model can consider the influence of both thick and thin beams without needing to shear correction factor. The compression force can be described through axial direction by uniform constant, linear and parabolic distribution functions. The Hamilton's principle is exploited to derive equilibrium governing equations of unified sandwich laminated beams. The governing equilibrium differential equations are transformed to algebraic system of equations by using numerical differential quadrature method (DQM). The system of equations is solved as an eigenvalue problem to get critical buckling loads and their corresponding mode-shapes. The stability of DQM in determining of buckling loads of sandwich structure is performed. The validation studies are achieved and the obtained results are matched with those. Parametric studies are presented to figure out effects of in-plane load type, sandwich thickness, fiber orientation and boundary conditions on buckling loads and mode-shapes. The present model is important in designing process of aircraft, naval structural components, and naval structural when non-uniform in-plane compressive loading is dominated.

에너지 흡수요소로서의 주름관(bellows)의 최적설계에 관한 연구 (Study on the Optimal Design of Bellows as an Energy Absorbing Element)

  • 김행겸;김권희
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 추계학술대회논문집
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    • pp.121-129
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    • 1997
  • Bellows are suggested as energy absorbing elements for automotive steering systems. A metallic bellows has nearly constant axial collapse load which is desirable as an energy absorbing element for a steering column. Axial collapsability and bending flexibility of bellows can be utilized to reduce upward tilting and backward displacement of steering columns in the early stage of high speed crash. Since bending flexibility of bellows has negative effects on the vibration characteristics of steering columns it is necessary to maximize the first natural frequency of a bellows while maintaining its plastic bending flexibility and axial collapse load. An effort is made to attain optimum design of bellows based upon the Taguchi method. A general guideline for design of bellows is suggested.

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Experimental behaviours of steel tube confined concrete (STCC) columns

  • Han, Lin-Hai;Yao, Guo-Huang;Chen, Zhi-Bo;Yu, Qing
    • Steel and Composite Structures
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    • 제5권6호
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    • pp.459-484
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    • 2005
  • In recent years, the use of steel tube confined concrete (STCC) columns has been the interests of many structural engineers. The present study is an attempt to study the monotonic and cyclic behaviours of STCC columns. For the monotonic behaviours, a series of tests on STCC stub columns (twenty one), and beam-columns (twenty) were carried out. The main parameters varied in the tests are: (1) column section types, circular and square; (2) tube diameter (or width) to thickness ratio, from 40 to 162, and (3) load eccentricity ratio (e/r), from 0 to 0.5. For the cyclic behaviours, the test parameters included the sectional types and the axial load level (n). Twelve STCC column specimens, including 6 specimens with circular sections and 6 specimens with square sections were tested under constant axial load and cyclically increasing flexural loading. Comparisons are made with predicted column strengths and flexural stiffness using the existing codes. It was found that STCC columns exhibit very high levels of energy dissipation and ductility, particularly when subjected to high axial loads. Generally, the energy dissipation ability of the columns with circular sections was much higher than those of the specimens with square sections. Comparisons are made with predicted column strengths and flexural stiffness using the existing codes such as AIJ-1997, AISCLRFD- 1994, BS5400-1979 and EC4-1994.

Influence of axial load and loading path on the performance of R.C. bridge piers

  • Kehila, Fouad;Bechtoula, Hakim;Benaouar, Djillali
    • Computers and Concrete
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    • 제15권4호
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    • pp.563-588
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    • 2015
  • Piers are the most vulnerable part of a bridge structure during an earthquake event. During Kobe earthquake in 1995, several bridge piers of the Hanshin Expressway collapsed for more than 600m of the bridge length. In this paper, the most important results of an experimental and analytical investigation of ten reinforced concrete bridge piers specimens with the same cross section subjected to constant axial (or variable) load and reversed (or one direction) cycling loading are presented. The objective was to investigate the main parameters influencing the seismic performance of reinforced concrete bridge piers. It was found that loading history and axial load intensity had a great influence on the performance of piers, especially concerning strength and stiffness degradation as well as the energy dissipation. Controlling these parameters is one of the keys for an ideal seismic performance for a given structure during an eventual seismic event. Numerical models for the tested specimens were developed and analyzed using SeismoStruct software. The analytical results show reasonable agreement with the experimental ones. The analysis not only correctly predicted the stiffness, load, and deformation at the peak, but also captured the post-peak softening as well. The analytical results showed that, in all cases, the ratio, experimental peak strength to the analytical one, was greater than 0.95.

일정체적 고정-회전 기둥의 동적안정 해석 (Dynamic Stability Analysis of Clamped-Hinged Columns with Constant Volume)

  • 김석기;이병구
    • 한국소음진동공학회논문집
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    • 제16권10호
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    • pp.1074-1081
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    • 2006
  • This paper deals with the dynamic stability analysis of clamped-hinged columns with constant volume. Numerical methods are developed for solving natural frequencies and buckling loads of such columns, subjected to an axial compressive load. The parabolic taper with the regular polygon cross-section is considered, whose material volume and column length are always held constant. Differential equations governing both free vibrations and buckled shapes of such columns are derived. The Runge-Kutta method is used to integrate the differential equations, and the Regula-Falsi method is used to determine natural frequencies and buckling loads, respectively. The numerical methods developed herein for computing natural frequencies and buckling loads are found to be efficient and robust. From the numerical results, dynamic stability regions, dynamic optimal shapes and configurations of strongest columns are reported in figures and tables.

Axial compression ratio limit values for steel reinforced concrete (SRC) special shaped columns

  • Chen, Zongping;Xu, Jinjun;Chen, Yuliang;Xue, Jianyang
    • Steel and Composite Structures
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    • 제20권2호
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    • pp.295-316
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    • 2016
  • This paper presents the results of experimental investigation, numerical calculation and theoretical analysis on axial compression ratio limit values for steel reinforced concrete (SRC) special shaped columns. 17 specimens were firstly intensively carried out to investigate the hysteretic behavior of SRC special shaped columns subjected to a constant axial load and cyclic reversed loads. Two theories were used to calculate the limits of axial compression ratio for all the specimens, including the balanced failure theory and superposition theory. It was found that the results of balanced failure theory by numerical integration method cannot conform the reality of test results, while the calculation results by employing the superposition theory can agree well with the test results. On the basis of superposition theory, the design limit values of axial compression ratio under different seismic grades were proposed for SRC special shaped columns.

Seismic Performance of High-Strength Concrete Columns

  • 황선경;윤현도;한병찬;박완신;김선우;한민기
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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    • pp.41-44
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    • 2004
  • This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete (HSC). The columns were subjected to a constant axial load corresponding to 30 per cent of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement, tie configuration and tie yield strength. Columns with 42 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. Relationships between the calculated damage index and the observed damage such as initial crack, spalling of concrete, buckling of longitudinal bar, and crushing of concrete are propose.

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Characteristic Behavior of High-Strength Concrete Columns under Simulated Seismic Loading

  • Hwang, Sun-Kyoung
    • International Journal of Concrete Structures and Materials
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    • 제18권2E호
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    • pp.79-87
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    • 2006
  • The main objective of this research is to examine the behavior of high-strength concrete(HSC) columns. Eight test columns in one-third scale were tested under the conditions of cyclic lateral force and a constant axial load equal to 30% of the column axial load capacity. The $200{\times}200mm$ square columns were reinforced with eight DB bars constituting a longitudinal steel ratio of 2.54% of the column cross-sectional area. The main experimental parameters were volumetric ratio of transverse reinforcement(${\rho}_s$=1.58, 2.25 percent), tie configuration(Type H, Type C, Type D) and tie yield strength($f_{yh}$=548.8 and 779.1 MPa). It was found that the hysteretic behaviour and ultimate deformability of HSC columns were influenced by the amount and details of transverse reinforcement in the potential plastic hinge regions. Columns of transverse reinforcement in the amount 42 percent higher than that required by seismic provisions of ACI 318-02 showed ductile behavior. At 30% of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 548.8 MPa. Correlations between the calculated damage index and the damage progress are proposed.

Experimental study on seismic behavior of frame structures composed of concrete encased columns with L-shaped steel section and steel beams

  • Zeng, Lei;Ren, Wenting;Zou, Zhengtao;Chen, Yiguang;Xie, Wei;Li, Xianjie
    • Earthquakes and Structures
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    • 제16권1호
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    • pp.97-107
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    • 2019
  • The frame structures investigated in this paper is composed of Concrete encased columns with L-shaped steel section and steel beams. The seismic behavior of this structural system is studied through experimental and numerical studies. A 2-bay, 3-story and 1/3 scaled frame specimen is tested under constant axial loading and cyclic lateral loading applied on the column top. The load-displacement hysteretic loops, ductility, energy dissipation, stiffness and strength degradation are investigated. A typical failure mode is observed in the test, and the experimental results show that this type of framed structure exhibit a high strength with good ductility and energy dissipation capacity. Furthermore, finite element analysis software Perform-3D was conducted to simulate the behavior of the frame. The calculating results agreed with the test ones well. Further analysis is conducted to investigate the effects of parameters including concrete strength, column axial compressive force and steel ratio on the seismic performance indexes, such as the elastic stiffness, the maximum strength, the ductility coefficient, the strength and stiffness degradation, and the equivalent viscous damping ratio. It can be concluded that with the axial compression ratio increasing, the load carrying capacity and ductility decreased. The load carrying capacity and ductility increased when increasing the steel ratio. Increasing the concrete grade can improve the ultimate bearing capacity of the structure, but the ductility of structure decreases slightly.

횡보강근에 따른 고강도 콘크리트 기둥의 휨강도와 연성 (Effects of Transverse Reinforcement on Flexural Strength and Ductility of High-Strength Concrete Columns)

  • 황선경;윤현도;정수영
    • 콘크리트학회논문집
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    • 제14권3호
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    • pp.365-372
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    • 2002
  • 본 연구는 700kgf/$\textrm{cm}^2$ 고강도 콘크리트에서 횡보강근 형태, 체적비 그리고 횡보강근 항복강도에 따른 고강도 콘크리트기둥의 거동을 규명하기 위한 실험연구이다. 기둥은 중심축내력의 30%에 해당하는 일정축력과 수평방향의 반복 휨모멘트를 받는다. 본 연구에서 사용된 변수는 횡보강근 체적비(Ps=1.58, 2.25%), 횡보강근 형태(hoop-type, cross-type, diagonal-type) 그리고 횡보강근 항복강도(fy=5,600, 7,950 kgf/$\textrm{cm}^2$)이다. 실험결과로 모든 기둥의 휨강도는 현행규준의 등가응력블럭에 근거하여 산정된 휨강도보다 낮게 나타났다. 횡보강근을 ACI 규준 요구량보다 42%증가시킨 기둥 시험체는 연성적인 거동을 보였다. 그리고, 본 연구에서 적용한 축력비 0.3 P/PO하에서 고강도급 횡보강근을 사용한 시험체의 연성이 저강도급 횡보강근을 사용한 시험체의 경우보다 같거나 다소 큰 경향을 보이고 있었다.