• Title/Summary/Keyword: Collapse mode

Search Result 191, Processing Time 0.029 seconds

Influence of Spot Weld Pitches on Collapse Characteristics of SCPI Vehicle Members (차체구조용 SCPI 강도부재의 점용접간격이 압궤특성에 미치는 영향)

  • 차천석;박제웅;양인영
    • Journal of Welding and Joining
    • /
    • v.20 no.6
    • /
    • pp.78-78
    • /
    • 2002
  • Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

Influence of Spot Weld Pitches on Collapse Characteristics for SCP1 Vehicle Members (차체구조용 SCP1 강도부재의 점용접간격이 압궤특성에 미치는 영향)

  • 차천석;박제웅;양인영
    • Journal of Welding and Joining
    • /
    • v.20 no.6
    • /
    • pp.802-808
    • /
    • 2002
  • Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

Evaluation of Progressive Collapse Resisting Capacity of Special Concentrically Braced Frames (특수 중심가새골조의 연쇄붕괴 저항능력 평가)

  • Lee, Young-Ho;Kim, Jin-Koo;Choi, Hyun-Hoon
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2008.04a
    • /
    • pp.319-324
    • /
    • 2008
  • In this study the progressive collapse potential of special concentrically braced frames were investigated using the nonlinear static. All of seven different brace types were considered. According to the pushdown analysis results, most braced frames designed according to current design codes satisfied the design guidelines for progressive collapse initiated by loss of a first story mid-column; however most model structures showed brittle failure mode. This was caused by buckling of columns after compressive braces buckled. Among the braced frames considered, the inverted-V type braced frames showed superior ductile behavior during progressive collapse.

  • PDF

Closed-Form Plastic Collapse Loads of Pipe Bends Under Combined Pressure and In-Plane Bending (압력과 모멘트의 복합하중을 받는 곡관의 소성 붕괴하중 예측식 개발)

  • Oh Chang-Sik;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.30 no.8 s.251
    • /
    • pp.1008-1015
    • /
    • 2006
  • Based on three-dimensional (3-D) FE limit analyses, this paper provides plastic limit, collapse and instability load solutions for pipe bends under combined pressure and in-plane bending. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly plastic materials using the small geometry change option, and the FE limit analyses using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method) and instability loads. For the bending mode, both closing bending and opening bending are considered, and a wide range of parameters related to the bend geometry is considered. Based on the FE results, closed-form approximations of plastic limit and collapse load solutions for pipe bends under combined pressure and bending are proposed.

Effect of Wall Thinning Defect on the Collapse Moment of Elbow (엘보우의 붕괴모멘트에 미치는 감육결함의 영향)

  • Kim, Jin-Won;Kim, Tea-Soon;Park, Chi-Yong
    • Proceedings of the KSME Conference
    • /
    • 2003.04a
    • /
    • pp.622-628
    • /
    • 2003
  • The purpose of this study is to evaluate the effect of local wall thinning on the collapse of elbow subjected to internal pressure and bending moment. Thus, the nonlinear 3D finite element analyses were performed to obtained collapse moment of elbow containing various wall thinning defects under two loading; modes (closing and opening modes) and defect locations (intrados and extrados). From the results of analyses, the influence of wall thinning defect on the global moment-rotation behavior of elbow was discussed, and the dependance of collapse moment of elbow on wall thinning depth, length, and circumferential angle was investigated under different loading mode and defect location.

  • PDF

Effect of Local Wall Thinning Defect on the Collapse Moment of Elbow (엘보우의 붕괴모멘트에 미치는 국부 감육결함의 영향)

  • Kim, Jin-Weon;Kim, Tae-Soon;Park, Chi-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.28 no.4
    • /
    • pp.402-409
    • /
    • 2004
  • The purpose of this study is to investigate the effect of local wall thinning on the collapse of elbow subjected to internal pressure and bending moment. Thus, the nonlinear three-dimensional finite element analyses were performed to obtain the collapse moment of elbow containing various wall thinning defects located at intrados and extrados under two loading modes (closing and opening modes) with internal pressure. From the results of analysis, the effect of wall thinning defect on the global moment-rotation behavior of elbow was discussed, and the dependence of collapse moment of elbow on wall thinning depth, length, and circumferential angle was investigated under different loading mode and defect location.

Progressive Collapse of Steel High-Rise Buildings Exposed to Fire: Current State of Research

  • Jiang, Jian;Li, Guo-Qiang
    • International Journal of High-Rise Buildings
    • /
    • v.7 no.4
    • /
    • pp.375-387
    • /
    • 2018
  • This paper presents a review on progressive collapse mechanism of steel framed buildings exposed to fire. The influence of load ratios, strength of structural members (beam, column, slab, connection), fire scenarios, bracing systems, fire protections on the collapse mode and collapse time of structures is comprehensively reviewed. It is found that the key influencing factors include load ratio, fire scenario, bracing layout and fire protection. The application of strong beams, high load ratios, multi-compartment fires will lead to global downward collapse which is undesirable. The catenary action in beams and tensile membrane action in slabs contribute to the enhancement of structural collapse resistance, leading to a ductile collapse mechanism. It is recommended to increase the reinforcement ratio in the sagging and hogging region of slabs to not only enhance the tensile membrane action in the slab, but to prevent the failure of beam-to-column connections. It is also found that a frame may collapse in the cooling phase of compartment fires or under travelling fires. This is because that the steel members may experience maximum temperatures and maximum displacements under these two fire scenarios. An edge bay fire is more prone to induce the collapse of structures than a central bay fire. The progressive collapse of buildings can be effectively prevented by using bracing systems and fire protections. A combination of horizontal and vertical bracing systems as well as increasing the strength and stiffness of bracing members is recommended to enhance the collapse resistance. A protected frame dose not collapse immediately after the local failure but experiences a relatively long withstanding period of at least 60 mins. It is suggested to use three-dimensional models for accurate predictions of whether, when and how a structure collapses under various fire scenarios.

An Experimental Study on Deep Collapse of Steel Tubes under Pure Bending (순수 굽힘 시험기를 이용한 연강 사각관의 굽힘 붕괴에 관한 실험적 연구)

  • KiM, C.S.;Chung, T.E.;Kang, S.Y.
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.14 no.9
    • /
    • pp.37-44
    • /
    • 1997
  • In this paper the bending collapse characteristics of square and rectangular steel tubes were studied with the pure bending test machine which apply pure bending moment without imposing shear and tensile forces. Under pure bending moment, delayed buckling modes occur and depend on test length and shape of section. For delayed mode, the endrgy of bending moment is absorbed by strain hardening energy. The pre- dictions of maximum moment and moment-rotation angle curve from those concepts are in good agreement with experimental observations.

  • PDF

Crashworthiness Design Concepts for the Improved Energy Absorbing Performance of an Aluminum Lightweight Vehicle Body (알루미늄 경량 차체의 충돌에너지 흡수 성능 향상을 위한 설계 개선 연구)

  • 김범진;허승진
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.11 no.3
    • /
    • pp.155-160
    • /
    • 2003
  • For the weight reduction of vehicle body up to 20∼30% compared to the conventional monocoque steel body·.in-white, most automotive manufacturers have attempted to develop the aluminum intensive body-in-white using an aluminum space frame. In this paper, the crush tests and simulations for the aluminum extrusions filled with the structural from are performed to evaluate the collapse characteristics of that light weighted material. From these studies. the effectiveness of structural for is evaluated in improving automotive crashworthiness. In order to improve the improve energy absorption capability of the aluminum space frame body, safety design modifications are performed and analyzed based on the suggested collapse initiator concepts and on the application of the aluminum extrusions filled with structural foam. The effectiveness of these design concepts on the frontal and side impact characteristics of the aluminum intensive vehicle structure is investigated and summarized.

Test and Analysis for Axial and Bending Collapse Characteristics Evaluation of Aluminum Extruded Beams (알루미늄 압출재의 압괴 및 굽힘붕괴 특성규명을 위한 시험 및 해석)

  • 김범진;허승진;구정서;송달호
    • Journal of the Korean Society for Railway
    • /
    • v.4 no.3
    • /
    • pp.110-115
    • /
    • 2001
  • Recently, many engineers actively participate in research and development w.r.t the weight reduction and the safety increase of vehicle body structure to meet the requirement of fuel economy and regulations. However, vehicle design concept related with weight reduction and safety increase is reduced to the design conflict problem. In the paper, the axial and bending collapse test of aluminum extruded beams are performed and the collapse characteristics are investigated. The analysis method to verify the fracture characteristics of aluminum extruded beam is presented and discussed.

  • PDF