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Yutaka Toi - One of the best experts on this subject based on the ideXlab platform.

  • adaptively shifted integration technique for finite element Collapse Analysis of framed structures
    International Journal for Numerical Methods in Engineering, 1993
    Co-Authors: Yutaka Toi, Daigoro Isobe
    Abstract:

    The present study is concerned with the improvement of the previously proposed ‘shifted integration technique’ for the plastic Collapse Analysis of framed structures using the linear Timoshenko beam element or the cubic beam element based on the Bernoulli-Euler hypothesis. In the newly proposed ‘adaptively shifted integration technique’, the numerical integration points for the evaluation of the stiffness matrices are automatically shifted immediately after. the occurrence of plastic hinges according to the previously established relations between the locations of numerical integration points and those of plastic hinges. By using the adaptively shifted integration technique, sufficiently accurate solutions can be obtained in the non-linear frame Analysis by two-linear-element or only one-cubic-element idealization for each structural member. The present technique can easily be implemented in the existing finite element codes utilizing the linear or the cubic beam element.

  • shifted integration technique in one dimensional plastic Collapse Analysis using linear and cubic finite elements
    International Journal for Numerical Methods in Engineering, 1991
    Co-Authors: Yutaka Toi
    Abstract:

    The present study is concerned with the physical explanations of the linear and the cubic finite elements for beams and axisymmetric shells through comparisons of their strain energy approximations with those of the Rigid Bodies-Spring Models which are discrete elements suitable for plastic Collapse Analysis using the concepts of plastic hinges and hinge lines. The established conditions for the equivalence between these two modellings, which are given as the relations between the locations of the numerical integration points and those of the occurrence of plastic hinges, can be conveniently used in the economical plastic Collapse Analysis of framed structures and axisymmetric shells where the locations of plastic hinge formations are controlled by the movement of numerical integration points. Some numerical results are shown in order to prove numerically the obtained relations and to verify the validity of the proposed shifting technique of numerical integration points, which is identified as ‘the shifted integration technique’ in the present paper.

  • Shifted integration technique in one‐dimensional plastic Collapse Analysis using linear and cubic finite elements
    International Journal for Numerical Methods in Engineering, 1991
    Co-Authors: Yutaka Toi
    Abstract:

    The present study is concerned with the physical explanations of the linear and the cubic finite elements for beams and axisymmetric shells through comparisons of their strain energy approximations with those of the Rigid Bodies-Spring Models which are discrete elements suitable for plastic Collapse Analysis using the concepts of plastic hinges and hinge lines. The established conditions for the equivalence between these two modellings, which are given as the relations between the locations of the numerical integration points and those of the occurrence of plastic hinges, can be conveniently used in the economical plastic Collapse Analysis of framed structures and axisymmetric shells where the locations of plastic hinge formations are controlled by the movement of numerical integration points. Some numerical results are shown in order to prove numerically the obtained relations and to verify the validity of the proposed shifting technique of numerical integration points, which is identified as ‘the shifted integration technique’ in the present paper.

Daigoro Isobe - One of the best experts on this subject based on the ideXlab platform.

  • Chapter Ten – Seismic Collapse Analysis of the CTV Building
    Progressive Collapse Analysis of Structures, 2018
    Co-Authors: Daigoro Isobe
    Abstract:

    This chapter describes the investigation of the factors that caused the Collapse of the Canterbury Television (CTV) building during the Lyttelton aftershock on February 22, 2011, in New Zealand. The building Collapsed during the earthquake with the exception of the north-wall complex left standing. A numerical model of the building was constructed based on the actual structural drawing, and a static pushover Analysis was conducted. The result showed its unbalanced strengths in the EW and NS directions because of a biased distribution of anti-seismic walls. Furthermore, the Collapse behavior with a clear twist mode vibration around the north-wall complex was observed by carrying out a seismic Collapse Analysis. The period of the twist mode vibration at the southeast corner of the building coincidentally matched the predominant period of the seismic wave in EW direction, which might had led to the deterioration of the columns at the location.

  • Seismic Collapse Analysis of Reinforced Concrete Framed Structures Using the Finite Element Method
    Earthquake Engineering & Structural Dynamics, 2003
    Co-Authors: Daigoro Isobe, Michihiro Tsuda
    Abstract:

    A new finite element code using the Adaptively Shifted Integration (ASI) technique with a linear Timoshenko beam element is applied to the seismic Collapse Analysis of reinforced concrete (RC) framed structures. This technique can express member fracture as a plastic hinge located at either end of an element with simultaneous release of the resultant forces in the element. Contact between members is also considered in order to obtain results that agree more closely with actual behavior, such as intermediate-layer failure. By using the proposed code, sufficiently reliable solutions have been obtained, and the results reveal that this code can be used in the numerical estimation of the seismic design of RC framed structures. Copyright © 2003 John Wiley & Sons, Ltd.

  • adaptively shifted integration technique for finite element Collapse Analysis of framed structures
    International Journal for Numerical Methods in Engineering, 1993
    Co-Authors: Yutaka Toi, Daigoro Isobe
    Abstract:

    The present study is concerned with the improvement of the previously proposed ‘shifted integration technique’ for the plastic Collapse Analysis of framed structures using the linear Timoshenko beam element or the cubic beam element based on the Bernoulli-Euler hypothesis. In the newly proposed ‘adaptively shifted integration technique’, the numerical integration points for the evaluation of the stiffness matrices are automatically shifted immediately after. the occurrence of plastic hinges according to the previously established relations between the locations of numerical integration points and those of plastic hinges. By using the adaptively shifted integration technique, sufficiently accurate solutions can be obtained in the non-linear frame Analysis by two-linear-element or only one-cubic-element idealization for each structural member. The present technique can easily be implemented in the existing finite element codes utilizing the linear or the cubic beam element.

Masahiko Fujikubo - One of the best experts on this subject based on the ideXlab platform.

  • Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model: Part 2
    Volume 2B: Structures Safety and Reliability, 2020
    Co-Authors: Akira Tatsumi, Kazuhiro Iijima, Masahiko Fujikubo
    Abstract:

    Abstract In Part 1 study, a time-domain Collapse Analysis method of ship hull girder was developed and named FE-Smith method. Hull girder was treated as elastoplastic beam model and Smith’s method was used for Collapse Analysis of cross sections. A concept of average stress-average plastic strain relationship was introduced so that nonlinear Collapse behavior of members can be treated as pseudo strain-hardening/softening behavior. Fluid-structure interaction effects were considered. Uniform cross-section beam was assumed as a most fundamental study. In this Part 2, a container ship is taken as subject model. Not only FE-Smith Analysis but also non-linear FE analyses using shell model for Collapse parts are performed for comparison purpose. Two types of average stress-average strain curves are considered for FE-Smith Analysis, i.e. obtained by Gordo-Soares formulae and by shell FEM. Applicability of FE-Smith method is examined comparing with more precise but time-consuming methods. Some parametric studies are also performed. Wave response will be reported in the next papers.

  • Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model
    Volume 11B: Honoring Symposium for Professor Carlos Guedes Soares on Marine Technology and Ocean Engineering, 2018
    Co-Authors: Akira Tatsumi, Kazuhiro Iijima, Masahiko Fujikubo
    Abstract:

    A method of time-domain Collapse Analysis of ship hull girder considering the interaction between elastoplastic deformation and hydrostatic/dynamic forces is developed. Ship hull girder is longitudinally divided by conventional beam elements, and progressive Collapse behavior of cross sections is simulated by Smith method considering material yielding, buckling and post-buckling of structural elements. Average stress–average strain relationship of structural elements is transformed to average stress–average plastic strain relationship so that it can be treated as pseudo strain-hardening/softening effects. Strip method is used for the calculation of hydrodynamic forces on the hull girder. Hydrodynamic coefficients for cross-sections are calculated by 2D-BEM. In-house Analysis code is developed and applied to the Collapse Analysis of a uniform hull-girder model under impulsive bending loads. The effects of load duration time on the dynamic Collapse behavior of the hull girder are discussed.

  • Collapse Analysis of Ship Hull Girder in Waves Using Idealized Structural Unit Method
    Volume 9: Prof. Norman Jones Honoring Symposium on Impact Engineering; Prof. Yukio Ueda Honoring Symposium on Idealized Nonlinear Mechanics for Weldin, 2016
    Co-Authors: Masahiko Fujikubo, Kazuhiro Iijima, Zhiyong Pei
    Abstract:

    Recent progress in the development and application of the ISUM plate element is highlighted with a particular focus on its application to the progressive Collapse Analysis of a ship hull structure. The plate element is characterized by idealized shape functions for defection based on buckling Collapse mode and a simple procedure for element formulation similar to that for standard displacement-based finite elements. The formulation of the plate element under in-plane loads is presented, and then the plate element and the plate-stiffener combination model are applied to the progressive Collapse Analysis of a hull-girder cross section and double bottom structure. The development of a total system for motion/Collapse Analysis of a whole ship in waves is also presented. The effectiveness of these ISUM models is demonstrated.

  • Application of Idealized Structural Unit Method to Progressive Collapse Analysis of Ship¿s Hull Girder Under Longitudinal Bending
    2005
    Co-Authors: Zhiyong Pei, Masahiko Fujikubo
    Abstract:

    New ISUM stiffened plate model that consists of large plate elements for local plate panels and beam-column elements for stiffeners is applied to the progressive Collapse Analysis of a ship’s hull girder under longitudinal bending. The employed ISUM model is characterized by the shape functions for deflection of local plate panels based on the Collapse modes and the ability to consider the localization of plastic deformation. High computational efficiency and sufficient accuracy of the new ISUM stiffened plate model are demonstrated through a series of ultimate strength analyses of continuous stiffened plates and a progressive Collapse Analysis of a 1/3-scale welded steel frigate model under longitudinal bending.

  • New simplified approach to Collapse Analysis of stiffened plates
    Marine Structures, 2002
    Co-Authors: Masahiko Fujikubo, Patrick Kaeding
    Abstract:

    Abstract A new simplified model for Collapse Analysis of stiffened plates is developed in the framework of the idealized structural unit method (ISUM). By idealizing material and geometrical nonlinearities, larger structural units are defined as an element in ISUM than in conventional finite element Analysis (FEA). The proposed stiffened plate model consists of ISUM plate elements and beam-column elements. The formulation of the plate element is performed by introducing accurate shape functions to simulate the buckling/plastic Collapse behaviour of plate panels. Combining plate and beam-column elements allows for both local buckling of the plate panel and overall buckling of the stiffener. Fundamental Collapse modes of plate panels and stiffened plates are investigated by conventional FEA. According to the observed characteristics, the new simplified model is formulated. Comparisons with FEA demonstrate the accuracy of the simplified model and its high applicability to typical stiffened plates in marine structures.

Seonwoong Kim - One of the best experts on this subject based on the ideXlab platform.

  • Simplified nonlinear progressive Collapse Analysis of steel moment frames considering floor slab effects
    2016
    Co-Authors: Seonwoong Kim
    Abstract:

    An energy-based simplified nonliear static progressive Collapse Analysis method of steel moment frames considering the contribution of the composite floor slab is proposed in this study. To this end, the behavior of the double-span composite floor slab is first investigated through the material and geometric nonlinear finite element Analysis. The polynomial for calculating the contribution of the doble-span composite floor slab is derived from the deformed shape of the double-span composite floor slab obtained from the numerical results. The application of the proposed simplified model can be utilized in conducting more precise energy-based progressive Collapse Analysis of steel moment frames.

  • Parallel Axial-Flexural Hinge Model for Nonlinear Dynamic Progressive Collapse Analysis of Welded Steel Moment Frames
    Journal of Structural Engineering, 2010
    Co-Authors: Cheol-ho Lee, Seonwoong Kim, Kyungkoo Lee
    Abstract:

    In this study, a parallel axial-flexural hinge model capable of representing postyield flexural behavior and considering interaction effects of axial force and moment is proposed for a simplified nonlinear progressive Collapse Analysis of welded steel moment frames. To this end, the load-resisting mechanism of the column-removed double-span beams was investigated based on the material and geometric nonlinear parametric finite-element Analysis. A multilinear parallel point hinge model which captures the moment-axial tension interaction was then proposed. The emphasis was to develop a reliable and computationally efficient macromodel for practical progressive Collapse Analysis. The application of the proposed hinge model to nonlinear dynamic progressive Collapse Analysis was illustrated by using OpenSEES program. The accuracy as well as the efficiency of the proposed model was verified based on inelastic dynamic finite-element Analysis results. The importance of including catenary action effects for proper progressive Collapse resistant Analysis and design was also emphasized.

  • Simplified nonlinear progressive Collapse Analysis of welded steel moment frames
    Journal of Constructional Steel Research, 2009
    Co-Authors: Cheol-ho Lee, Seonwoong Kim, Kyu-hong Han, Kyungkoo Lee
    Abstract:

    Abstract In this study, two nonlinear Analysis methods are proposed that can be used for a simplified but accurate evaluation of progressive Collapse potential in welded steel moment frames. To this end, the load-resisting mechanism of the column-removed double-span beams in welded steel moment frames was first investigated based on material and geometric nonlinear parametric finite element Analysis. A simplified tri-linear model for the vertical resistance versus chord rotation relationship of the double-span beams was developed. The application of the developed model to energy-based nonlinear static progressive Collapse Analysis was then proposed. The relationship between the gravity loading and the maximum dynamic chord rotation or the concept of Collapse spectrum was also established for a quick assessment of the maximum deformation demands.

Kyungkoo Lee - One of the best experts on this subject based on the ideXlab platform.

  • Parallel Axial-Flexural Hinge Model for Nonlinear Dynamic Progressive Collapse Analysis of Welded Steel Moment Frames
    Journal of Structural Engineering, 2010
    Co-Authors: Cheol-ho Lee, Seonwoong Kim, Kyungkoo Lee
    Abstract:

    In this study, a parallel axial-flexural hinge model capable of representing postyield flexural behavior and considering interaction effects of axial force and moment is proposed for a simplified nonlinear progressive Collapse Analysis of welded steel moment frames. To this end, the load-resisting mechanism of the column-removed double-span beams was investigated based on the material and geometric nonlinear parametric finite-element Analysis. A multilinear parallel point hinge model which captures the moment-axial tension interaction was then proposed. The emphasis was to develop a reliable and computationally efficient macromodel for practical progressive Collapse Analysis. The application of the proposed hinge model to nonlinear dynamic progressive Collapse Analysis was illustrated by using OpenSEES program. The accuracy as well as the efficiency of the proposed model was verified based on inelastic dynamic finite-element Analysis results. The importance of including catenary action effects for proper progressive Collapse resistant Analysis and design was also emphasized.

  • Simplified nonlinear progressive Collapse Analysis of welded steel moment frames
    Journal of Constructional Steel Research, 2009
    Co-Authors: Cheol-ho Lee, Seonwoong Kim, Kyu-hong Han, Kyungkoo Lee
    Abstract:

    Abstract In this study, two nonlinear Analysis methods are proposed that can be used for a simplified but accurate evaluation of progressive Collapse potential in welded steel moment frames. To this end, the load-resisting mechanism of the column-removed double-span beams in welded steel moment frames was first investigated based on material and geometric nonlinear parametric finite element Analysis. A simplified tri-linear model for the vertical resistance versus chord rotation relationship of the double-span beams was developed. The application of the developed model to energy-based nonlinear static progressive Collapse Analysis was then proposed. The relationship between the gravity loading and the maximum dynamic chord rotation or the concept of Collapse spectrum was also established for a quick assessment of the maximum deformation demands.