• 제목/요약/키워드: semi-rigid frame

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Behavior of semi-rigid steel frames under near- and far-field earthquakes

  • Sharma, Vijay;Shrimali, Mahendra K.;Bharti, Shiv D.;Datta, Tushar K.
    • Steel and Composite Structures
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    • 제34권5호
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    • pp.625-641
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    • 2020
  • The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

Design optimization of semi-rigid space steel frames with semi-rigid bases using biogeography-based optimization and genetic algorithms

  • Shallan, Osman;Maaly, Hassan M.;Sagiroglu, Merve;Hamdy, Osman
    • Structural Engineering and Mechanics
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    • 제70권2호
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    • pp.221-231
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    • 2019
  • This paper performs for the first time a simultaneous optimization for members sections along with semi-rigid beam-to-column connections for space steel frames with fixed, semi-rigid, and hinged bases using a biogeography-based optimization algorithm (BBO) and a genetic algorithm (GA). Furthermore, a member's sections optimization for a fully fixed space frame is carried out. A real and accurate simulation of semi-rigid connection behavior is considered in this study, where the semi-rigid base connections are simulated using Kanvinde and Grilli (2012) nonlinear model, which considers deformations in different base connection components under the applied loads, while beam-to-column connections are modeled using the familiar Frye and Morris (1975) nonlinear polynomial model. Moreover, the $P-{\Delta}$ effect and geometric nonlinearity are considered. AISC-LRFD (2016) specification constraints of the stress and displacement are considered as well as section size fitting constraints. The optimization is applied to two benchmark space frame examples to inspect the effect of semi-rigidity on frame weight and drift using BBO and GA algorithms.

Genetic algorithm based optimum design of non-linear steel frames with semi-rigid connections

  • Hayalioglu, M.S.;Degertekin, S.O.
    • Steel and Composite Structures
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    • 제4권6호
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    • pp.453-469
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    • 2004
  • In this article, a genetic algorithm based optimum design method is presented for non-linear steel frames with semi-rigid connections. The design algorithm obtains the minimum weight frame by selecting suitable sections from a standard set of steel sections such as European wide flange beams (i.e., HE sections). A genetic algorithm is employed as optimization method which utilizes reproduction, crossover and mutation operators. Displacement and stress constraints of Turkish Building Code for Steel Structures (TS 648, 1980) are imposed on the frame. The algorithm requires a large number of non-linear analyses of frames. The analyses cover both the non-linear behaviour of beam-to-column connection and $P-{\Delta}$ effects of beam-column members. The Frye and Morris polynomial model is used for modelling of semi-rigid connections. Two design examples with various type of connections are presented to demonstrate the application of the algorithm. The semi-rigid connection modelling results in more economical solutions than rigid connection modelling, but it increases frame drift.

Effect of semi-rigid connections in improvement of seismic performance of steel moment-resisting frames

  • Feizi, M. Gholipour;Mojtahedi, A.;Nourani, V.
    • Steel and Composite Structures
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    • 제19권2호
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    • pp.467-484
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    • 2015
  • Seismic performances of dual steel moment-resisting frames with mixed use of rigid and semi-rigid connections were investigated to control of the base shear, story drifts and the ductility demand of the elements. To this end, nonlinear seismic responses of three groups of frames with three, eight and fifteen story were evaluated. These frames with rigid, semi-rigid and combined configuration of rigid and semi-rigid connections were analyzed under five earthquake records and their responses were compared in ultimate limit state of rigid frame. This study showed that in all frames, it could be found a state of semi-rigidity and connections configuration which behaved better than rigid frame, with consideration of the base shear and story drifts criterion. Finally, some criteria were suggested to locate the best place of the semi-rigid connections for improvement of the seismic performance of steel moment-resisting frames.

반강접 접합부를 갖는 평면 강골조의 거동에 관한 해석적 연구 (Analytical Study on Behaviour of Plane Steel Frame with Semi-Rigid Beam-to-Column Connection)

  • 김종성
    • 한국강구조학회 논문집
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    • 제21권5호
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    • pp.483-492
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    • 2009
  • 소성영역에서 부재의 강성감소, 휨효과 및 잔류응력의 영향을 고려하면서 극한 한계상태에서 강골조의 거동을 평가하기 위해 개선 소성 힌지법을 이용하여 평면강골조의 비선형해석을 실시하고, 강접 및 반강접 평면강골조의 다양한 모델에 대한 수치해석을 통하여 거동을 평가하는데 목적이 있다. 그리고 상용프로그램을 이용한 해석결과를 이용하여 반강접율의 변화에 따른 골조의 거동을 분석한다.

골조형(骨造型) 가구구조설계(家具構造設計)에의 유한요소해석 응용 (Finite Elements Analysis Application to the Structural Design of the Frame Type Furniture)

  • 정우양;카알 A. 에켈만
    • Journal of the Korean Wood Science and Technology
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    • 제23권3호
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    • pp.8-15
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    • 1995
  • This analytical study was carried out to make quality and productivity up in designing the frame-type furniture with semi-rigid joint by understanding the mechanical and structural behavior of the joint and by evaluating the validity of application of the time-saving Finite Element Method to its structural analysis. Slope deflection equation for rigid joint was modified to describe the moment-rotation behavior of semi-rigid joint and the joint stiffness factor(Z) could be calculated to lessen the experimental expense. It was proved that Finite Element Analysis with imaginary elements having equivalent MOE to the semi-rigid joint could be the alternative method for the structural analysis of the frame-type furniture, comparing the internal rotation of the 2-dimensional beam-to-column model with two-pin(wooden dowel) from the finite element method with other available theoretical and experimental rotation value.

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Practical and efficient approaches for semi-rigid design of composite frames

  • Gil, Beatriz;Bayo, Eduardo
    • Steel and Composite Structures
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    • 제7권2호
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    • pp.161-184
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    • 2007
  • The use of composite semi-rigid connections is not fully exploited, in spite of its great number of advantages. Composite semi-rigid connections may lead to an optimal moment distribution that will render lighter structures. Furthermore, using the appropriate semi-rigid connection design, the stability of the frames against lateral loads may entirely rely on the joint stiffness, thus avoiding bracing systems and permitting more diaphanous designs. Although modern codes, such as the Eurocode 4 (EC4), propose thorough methods of analysis they do not provide enough insight and simplicity from the design point of view. The purpose of this paper is to introduce practical and efficient methods of analysis that will facilitate the work of a structural analyst starting from the global analysis of the composite frame and ending on the final connection design. A key aspect is the definition of the stiffness and strength of the connections that will lead to an optimal moment distribution in the composite beams. Two examples are presented in order to clarify the application of the proposed methods and to demonstrate the advantages of the semi-rigid composite design with respect to the alternative pinned and rigid ones. The final aim of the paper is to stimulate and encourage the designer on the use of composite semi-rigid structures.

Sway of semi-rigid steel frames - Part 1: Regular frames

  • Ashraf, M.;Nethercot, D.A.;Ahmed, B.
    • Steel and Composite Structures
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    • 제4권5호
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    • pp.403-418
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    • 2004
  • Lateral sway is most likely to control the design of semi-rigid steel frames where the frame arrangements do not include any form of bracing. This paper investigates the sway behaviour of semi-rigid regular steel frames i.e., frames having the same arrangement of beam and column sections at all levels, and hence proposes some design charts for the prediction of sway that eliminate the need for doing any numerical modelling. Schueller's equation has also been modified to incorporate connection flexibility in addition to its original rigid frame considerations. All the proposed methods have been validated using results obtained from numerical analysis.

경량형강 시설물의 비선형 구조해석 모델개발(II) -반강결 뼈대구조물의 해석에 대하여- (Development of the Nonlinear Structural Analysis Model for the Light-Weight Framed Structures (II))

  • 김한중;이정재
    • 한국농공학회지
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    • 제40권1호
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    • pp.78-87
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    • 1998
  • In this study, semi-rigid light-weight framed structures analysis model (SERIFS) was developed by advancing the LEIFS model. This model enables us to analyze simultaneous effects of large deflection and semi-rigid connection by computing unbalanced load occurring in the process of repeated loading through equalization of bending moments and torsion. This model is also able to handle the effect of the semi-rigid connection and large deflection by modifying the elastic stiffness matrix using moment-rotation behavior of connection. Moment-rotation behavior of the semi-rigid connection was adopted from the experimental results of load-vertical displacement of frame element In conclusion, this model achieves to analyze the nonlinear and large deflection behavior on the semi-rigid and light-weight steel frame connection.

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Haringx의 전단변형 이론을 고려한 부분강절 뼈대구조의 비탄성 좌굴해석 (Inelastic Buckling Analysis of Semi-rigid Frames with Shear Deformations by Haringx's Theories)

  • 민병철
    • 한국안전학회지
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    • 제29권3호
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    • pp.64-71
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    • 2014
  • The generalized tangential stiffness matrix of semi-rigid frame element with shear deformations based on Haringx's shear theory is newly derived and compared with the previous study based on Engesser's shear theory. Also, linearized elastic and geometric stiffness matrices are newly presented from the exact tangential stiffness matrix. In oder to obtain the inelastic system buckling load of shear flexible semi-rigid frame structure, the Ef method by tangential modulus theory is adopted and the FE analysis programs are developed. Finally, the shear and semi-rigid effects of system bucking are investigated by two numerical examples.