• Title, Summary, Keyword: Equivalent strut model

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A Comparison Study of Equivalent Strut Models for Seismic Performance Evaluation of Masonry-Infilled Frame (조적채움벽 골조의 내진성능평가를 위한 등가 스트럿 모델의 비교연구)

  • Yu, EunJong;Kim, MinJae;Jung, DaeGye
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.2
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    • pp.79-87
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    • 2014
  • Masonry-infilled walls have been used in reinforced concrete(RC) frame structures as interior and exterior partition walls. Since these walls are considered as nonstructural elements, they were only considered as additional mass. However, infill walls tend to interact with the structure's overall strength, rigidity, and energy dissipation. Infill walls have been analyzed by finite element method or transposed as equivalent strut model. The equivalent strut model is a typical method to evaluate masonry-infilled structure to avoid the burden of complex finite element model. This study compares different strut models to identify their properties and applicability with regard to the characteristics of the structure and various material models.

Equivalent Strut Model for Seismic Design of Steel Moment Connections Reinforced with Ribs (리브로 보강된 철골 모멘트 접합부의 내진설계를 위한 등가 스트럿 모델)

  • 이철호
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.3
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    • pp.79-85
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    • 2001
  • This paper presents an equivalent strut model for seismic design of steel moment connections reinforced with ribs. It is shown from the finite element analysis results that the force transfer mechanism in the rib connections is completely different from that predicted by the classical beam theory and a clear strut action in the ribs does exist. By treating the rib as a strut, an equivalent strut model that could be used as the basis of a practical design procedure is proposed.

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Prediction of Ultimate Strength of Concrete Deep Beams with an Opening Using Strut-and-Tie Model (스트럿-타이 모델에 의한 개구부를 갖는 깊은 보의 극한강도 예측)

  • 지호석;송하원;변근주
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.189-194
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    • 2001
  • In this study, ultimate strength of concrete deep beams with an opening is predicted by using Strut-and-Tie Model with a new effective compressive strength. First crack occurs around an opening by stress concentration due to geometric discontinuity. This results in decreasing ultimate strength of deep beams with an opening compared with general deep beams. With fundamental notion that ultimate strength of deep beam with an opening decreases as a result of reduction in effective compressive strength of a concrete strut, an equivalent effective compressive strength formula is proposed in order to reflect ultimate strength reduction due to an opening located in a concrete strut. An equivalent effective compressive strength formula which can reflect opening size and position is added to a testified algorithm of predicting ultimate strength of concrete deep beams. Therefore, ultimate strength of concrete deep beam with an opening is predicted by using a simple and rational STM algorithm including an equivalent effective compressive strength formula, not by finite element analysis or a former complex Strut-and-Tie Model

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Design of Diaphragm of Prestressed Concrete Box Bridge by Strut-Tie Model (스트럿-타이 모델에 의한 프리스트레스트 콘크리트 박스교 격벽부의 상세 설계)

  • 선민호;김영훈;송하원;변근주
    • Proceedings of the KSR Conference
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    • pp.39-46
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    • 1998
  • This paper is about design for diaphragm of prestressed concrete box bridge using strut-tie model. In this paper, equivalent loads for the diaphragm are computed by considering loading conditions on continuous prestressed concrete box bridge and analyses for both longitudinal section and transverse section of the diaphragm an done by considering the equivalent loading and the prestressing. Based on principal stress trajectory obtained from the analyses, strut-tie model for each sections are constructed. By analyzing the constructed strut-tie model for each sections, the amounts and the locations of reinforcement for the diaphragm are obtained. The application of strut-tie model in this paper shows that the design by soul-tie model for the diaphragm of prestressed concrete box bridges can be rationally performed.

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Strut-tie model evaluation of behavior and strength of pre-tensioned concrete deep beams

  • Yun, Young Mook
    • Computers and Concrete
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    • v.2 no.4
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    • pp.267-291
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    • 2005
  • To date, many studies have been conducted for the analysis and design of reinforced concrete members with disturbed regions. However, prestressed concrete deep beams have not been the subject of many investigations. This paper presents an evaluation of the behavior and strength of three pre-tensioned concrete deep beams failed by shear and bond slip of prestressing strands using a nonlinear strut-tie model approach. In this approach, effective prestressing forces represented by equivalent external loads are gradually introduced along strand's transfer length in the nearest strut-tie model joints, the friction at the interface of main diagonal shear cracks is modeled by the aggregate interlock struts along the direction of the cracks in strut-tie model, and an algorithm considering the effect of bond slip of prestressing strands in the strut-tie model analysis and design of pre-tensioned concrete members is implemented. Through the strut-tie model analysis of pre-tensioned concrete deep beams, the nonlinear strut-tie model approach proved to present effective solutions for predicting the essential aspects of the behavior and strength of pre-tensioned concrete deep beams. The nonlinear strut-tie model approach is capable of predicting the strength and failure modes of pre-tensioned concrete deep beams including the anchorage failure of prestressing strands and, accordingly, can be employed in the practical and precise design of pre-tensioned concrete deep beams.

A new equivalent friction element for analysis of cable supported structures

  • Yan, Renzhang;Chen, Zhihua;Wang, Xiaodun;Liu, Hongbo;Xiao, Xiao
    • Steel and Composite Structures
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    • v.18 no.4
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    • pp.947-970
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    • 2015
  • An equivalent friction element is proposed to simulate the friction in cable-strut joints. Equivalent stiffness matrixes and load vectors of the friction element are derived and are unified into patterns for FEM by defining a virtual node specially to store internal forces. Three approaches are described to verify the rationality of the new equivalent friction element: applying the new element in a cable-roller model, and numerical solutions match well with experimental results; applying the element in a continuous sliding cable model, and theoretical values, numerical and experimental results are compared; and the last is applying it in truss string structures, whose results indicate that there would be a great error if the cable of cable supported structures is simulated with discontinuous cable model which is usually adopted in traditional finite element analysis, and that the prestress loss resulted from the friction in cable-strut joints would have adverse effect on the mechanical performance of cable supported structures.

Seismic Performance Evaluation of Masonry-Infilled Frame Structures using Equivalent Strut Models (등가 스트럿 모델을 이용한 조적조 채움벽 골조의 내진성능평가)

  • Park, Ji-Hun;Jeon, Seong-Ha;Kang, Kyung-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.1
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    • pp.47-59
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    • 2012
  • The seismic performance of masonry-infilled frame structures, typical in school buildings, is evaluated through equivalent strut models. A bare frame model, concentric strut models and eccentric strut models with various material characteristics available in the literature are analyzed. Displacements and damage states at the performance points obtained by the capacity spectrum method show great differences among the models. Infill walls act positively in concentric strut models and negatively in eccentric strut models at the performance points for a given seismic demand. In addition, the behavior at the ultimate displacements shows considerably different strengths, inter-story drifts, and numbers and locations of damaged members among various modeling methods and material strengths.

A Study on Fatigue Durability through the Structural Analysis of Strut Bar (스트럿 바의 구조 해석을 통한 피로 내구성에 관한 연구)

  • Han, Moonsik;Cho, Jaeung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.5
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    • pp.504-511
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    • 2016
  • This study investigates the durability of strut bar at car through structural and fatigue analyses. In this study, there are model 1 and model 2 as the analysis subjects. Model 1 is the existed one and model 2 is the improved one added with the reinforced part. Model 1 has the maximum equivalent stress of 165.11 MPa shown intensively at the welding part between the bracket and the bar. This stress is distributed over at the part of model 2 reinforced with this part. In case of fatigue analysis, there are three kinds of fatigue load as SAE bracket history, SAE transmission and sample history. The maximum fatigue life at SAE bracket history among three kinds of fatigue loads has the least value of $3.3693{\times}10^5$ cycles. The maximum fatigue life of model 2 becomes longer than that of model 1. As model 2 has the fatigue damage less than model 1, model 2 has the safety than model 1. As the fatigue durability about the configuration of strut bar is analyzed, it is thought to apply this study result into the real part effectively.

Seismic Design of Rib-Reinforced RBS (Reduced Beam Section) Steel Moment Connections Based on Equivalent Strut Model (등가 스트럿 모델에 의한 리브 보강 RBS 철골모멘트접합부의 내진설계)

  • Lee, Cheol Ho
    • Journal of Korean Society of Steel Construction
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    • v.13 no.5
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    • pp.493-502
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    • 2001
  • This paper describes a seismic design procedure for rib-reinforced RBS(Reduced Beam Section) steel moment connections. Engineers often use rib plates to enhance seismic performance of steel moment connections. thinking that the 2nd moment of inertia is increased so that the tensile stress in the beam flange groove weld is reduced However the force transfer mechanism in the rib connections is completely different from that as predicted by the classical beam theory ; a clear diagonal strut action is present in the rib. By treating the rib as a strut the writer has recently proposed an equivalent strut model that could be used as the basis of a practical design procedure. In this paper the proposed equivalent strut model is briefly presented first. A step-by-step design procedure is then recommended based on the proposed model.

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Infilled frames: developments in the evaluation of cyclic behaviour under lateral loads

  • Cavaleri, L.;Fossetti, M.;Papia, M.
    • Structural Engineering and Mechanics
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    • v.21 no.4
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    • pp.469-494
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    • 2005
  • In order to consider the modified seismic response of framed structures in the presence of masonry infills, proper models have to be formulated. Because of the complexity of the problem, a careful definition of an equivalent diagonal pin-jointed strut, able to represent the horizontal force-interstorey displacement cyclic law of the actual infill, may be a solution. In this connection the present paper, continuing a previous work in which a generalised criterion for the determination of the ideal cross-section of the equivalent strut was formulated, analizes some models known in literature for the prediction of the lateral cyclic behaviour discussing their field of validity. As a support of the discussion, the results of an experimental investigation involving single story-single bay infilled reinforced concrete. Frames under vertical and lateral loads with different kind of infill (actually not yet so much investigated) are presented. Finally, an improvement of a model known in the literature is proposed, taking the results of the experimental tests before mentioned into account.