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Young Bong Kwon - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of the Squash Loads of concrete-filled tubular section columns with local buckling
    Thin-walled Structures, 2020
    Co-Authors: Young Bong Kwon, Doo Won Kang
    Abstract:

    Abstract This paper describes a series of compression tests of circular hollow steel (CHS) sections and circular concrete-filled tubular (CFT) sections. The diameter to thickness ratios of the test specimens ranged 45–140. This range was set to investigate the effect of local buckling in the circular steel skin on the ultimate strength of CFT columns. The confining effect against filled-in concrete was also studied. A Squash Load formula for CFT stub columns is proposed to account for the post-local-buckling strength of steel skin. The ultimate strength of steel skin was predicted by a kind of Direct Strength Method (DSM). The proposed DSM does not require the computation of the effective area of the steel skin, but uses the gross area of the steel skin and the design strength formula based on various test results. The compressive strength formula of the filled-in concrete accounting for the strength ratio of steel skin to filled-in concrete is also proposed to consider the increase in compressive strength of the filled-in concrete, due to the confining effect of the steel skin. The design strengths of CFT columns were compared with the test results for verification.

  • resistance of circular concrete filled tubular sections to combined axial compression and bending
    Thin-walled Structures, 2017
    Co-Authors: Young Bong Kwon, Sung Woong Park
    Abstract:

    Abstract This paper describes strength formulae and simplified strength interaction curves for the direct strength method (DSM) for circular concrete-filled tubular (CFT) sections. A simple axial strength formula and a flexural strength formula for circular CFT sections are proposed to account for the post-local buckling strength of the circular steel skin and the increase in concrete compressive strength caused by confinement of the steel skin. The Squash Load predicted by the proposed strength formula is compared with test results in the literature, and those predicted by AISC specifications and Eurocode4. A simplified strength interaction curve for circular CFT members under combined axial compression and bending is proposed and compared with test results. The comparison confirms that the proposed axial and flexural strength formulae and simplified strength interaction curves can be used to conservatively predict the resistance of circular CFT columns to an axial Load, and combined axial compression and bending.

  • resistance of rectangular concrete filled tubular cft sections to the axial Load and combined axial compression and bending
    Thin-walled Structures, 2014
    Co-Authors: Young Bong Kwon, In-kyu Jeong
    Abstract:

    Abstract This paper describes the development of the direct strength method (DSM) for concrete-filled tubular (CFT) sections. The axial and flexural strength of CFT sections with local buckling are proposed based on previous test results. Although Eurocode4 does not allow the use of slender steel skins for CFT sections, the limit of the width-to-thickness ratio for the steel skin has recently been extended to slender sections in AISC specifications. A simple formula for the axial and flexural strength of CFT sections for the DSM is proposed to account for the local buckling of a thin steel skin and for the enhanced compressive strength of concrete from the confining effect of the steel skin. The Squash Load predicted by the proposed formula is compared with test results and those predicted by AISC specifications and Eurocode4. A formula for strength interactions of CFT members under combined compression and flexure is proposed and is compared with test results. The comparison confirmed that the formula for axial and flexural strength and that for strength interactions can conservatively predict the resistance of CFT columns to the axial Load and combined compression and bending.

  • The Ultimate Strength of the Concrete-Filled Tubular (CFT) Section Columns
    Applied Mechanics and Materials, 2012
    Co-Authors: Young Bong Kwon, In-kyu Jeong, In Kyu Kwon
    Abstract:

    This paper describes design strength of concrete-filled tubular (CFT) section columns accounting for local buckling of steel skin. The local buckling has a negative effect on the ultimate compression strength based on the yield stress of steel skin and nominal compressive strength of in-filled concrete. A Squash Load formula for CFT stub columns is proposed to account for the post-local-buckling strength of steel skin. A compressive strength formula for filled-in concrete accounting for the confining effect of steel skin and strength ratio between filled-in concrete and steel skin is also proposed. The Squash Loads predicted by the proposed strength formula for the direct strength method were compared with the AISC (2010) and Eurocode4 (2004). The comparison showed that the Squash Load formula proposed can predict conservatively the Squash Load of circular and rectangular CFT columns with local buckling

Faris Albermani - One of the best experts on this subject based on the ideXlab platform.

  • Buckling-restrained-lug connection for energy dissipation
    2020
    Co-Authors: Ricky W.k. Chan, Faris Albermani
    Abstract:

    A new energy dissipation device is presented in this paper. The device is referred to as Buckling-Restrained-Lug (BRL) which can be incorporated in structural joints. The device is composed of a short segment of a steel strut embedded inside a mortar filled jacket which makes the BRL's capacity governed by the Squash Load under axial tension or compression. The BRL dissipates energy through axial yielding of the steel strut. Analytical and experimental results of the proposed BRL are presented and compared. Implementation of the BRL in a beam-to-column connection that results in a dissipative partial-moment-resisting joint is proposed. Based on the obtained results, the paper advocates the consideration of the BRL as a viable, compact and low-cost passive energy dissipation device.

  • Buckling-Restrained-Lug Connection for Energy Dissipation:
    Advances in Structural Engineering, 2020
    Co-Authors: Ricky W.k. Chan, Faris Albermani
    Abstract:

    Under extreme Loading conditions such as an earthquake event considerable amount of energy is imparted to a structure. To protect the structure and to minimize damages, a method is to divert a portion of the input energy into designated energy dissipating devices. A new energy dissipation device is presented in this paper. The device is referred to as Buckling-Restrained-Lug (BRL) which can be incorporated in structural joints. The device is composed of a short segment of a steel strut embedded inside a mortar filled jacket which makes the BRL's capacity governed by the Squash Load under axial tension or compression. The BRL dissipates energy through axial yielding of the steel strut. Analytical, finite element modeling and experimental results of the proposed BRL are presented and compared. Implementation of the BRL in a beam-to-column connection that results in a dissipative partial-moment-resisting joint is proposed. Based on the obtained results, the paper advocates the consideration of the BRL as a viable, compact and low-cost passive energy dissipation device.

Hoyoung Park - One of the best experts on this subject based on the ideXlab platform.

  • strength and behavior of steel plate concrete wall structures using ordinary and eco oriented cement concrete under axial compression
    Thin-walled Structures, 2014
    Co-Authors: Byong-jeong Choi, Cheol-kyu Kang, Hoyoung Park
    Abstract:

    The main objectives of this study are to describe the compressive behavior and to determine the Squash Load of steel plate–concrete (SC) wall structures using ordinary and eco-oriented cement concrete. The major parameters in this research were the material of the concrete and width–thickness (B/t) ratio of surface steel plate. Six SC wall specimens were tested in compression in this test. In the three specimens, to reduce emissions of carbon dioxide (CO2), some of the cement in weight was replaced by the Hwangtho (red clay) which is traditional and environmental material. The failure behavior, buckling behavior of the surface steel plate, the effective buckling length factors and plate buckling coefficient are discussed. Based on the test results, simplified rule was suggested to evaluate the buckling stress for surface steel plate. Several comparisons were made to evaluate the predicted strengths and test results.

  • Strength and behavior of steel plate–concrete wall structures using ordinary and eco-oriented cement concrete under axial compression
    Thin-walled Structures, 2014
    Co-Authors: Byong-jeong Choi, Cheol-kyu Kang, Hoyoung Park
    Abstract:

    The main objectives of this study are to describe the compressive behavior and to determine the Squash Load of steel plate–concrete (SC) wall structures using ordinary and eco-oriented cement concrete. The major parameters in this research were the material of the concrete and width–thickness (B/t) ratio of surface steel plate. Six SC wall specimens were tested in compression in this test. In the three specimens, to reduce emissions of carbon dioxide (CO2), some of the cement in weight was replaced by the Hwangtho (red clay) which is traditional and environmental material. The failure behavior, buckling behavior of the surface steel plate, the effective buckling length factors and plate buckling coefficient are discussed. Based on the test results, simplified rule was suggested to evaluate the buckling stress for surface steel plate. Several comparisons were made to evaluate the predicted strengths and test results.

O. Ifayefunmi - One of the best experts on this subject based on the ideXlab platform.

  • Plastic buckling of axially compressed thick unstiffened steel cones
    Ocean Engineering, 2015
    Co-Authors: O. Ifayefunmi
    Abstract:

    The paper examines the effect of material modeling behavior on the elastic–plastic buckling of relatively thick unstiffened steel cones subjected to axial compression. Cones are assumed to be made from mild steel with radius-to-thickness ratio, (r2/t) of 34.3 and cone angle of 26.56°. Three material models were considered: (i) elastic-perfectly plastic, (ii) engineering stress–strain and (iii) true stress true strain. The accuracy of numerical predictions as compared to experimental results was seen to be strongly dependent on the material modeling strategy. Plastic mechanism design approach previously proposed for cones under axial compression was modified to widen the range of its applicability by catering for the effect of excessive plastic deformation. The proposed model utilizes the concept of true stress true strain nature of constitutive equation in determining the Squash Load. Predictions of collapse Load given by the modified constitutive model were compared with initial plastic mechanism design approach and available design codes (API, ECCS, and ASME code case 2286-2) for published experimental data on axially compressed unstiffened steel cones in the elastic–plastic range. Results indicate that the proposed model gives much better predictions of Load carrying capacity than both the initial design approach and the available design codes.

Yong Wang - One of the best experts on this subject based on the ideXlab platform.

  • A simple method for calculating the fire resistance of concrete-filled CHS columns
    Journal of Constructional Steel Research, 2000
    Co-Authors: Yong Wang
    Abstract:

    Abstract This paper is concerned with the development of a simple method for calculating the Squash Load and rigidity of concrete-filled Circular Hollow Steel (CHS) sections. These two values are sufficient for evaluating the Load bearing capacity of a column under fire conditions. Concrete-filled CHS columns are particularly suitable to be “fire engineered” to give reduction in construction cost. Although Eurocode 4 Part 1.2 has a method for calculating these values, it only gives general principles for temperature analysis and the structural calculation part is tedious to use. This complicated method may have deterred engineers from considering using the fire engineering approach. In this paper, a simple method is proposed for both unprotected and protected columns. Although the proposed method is based on Eurocode 4 Part 1.2, in the proposed simple method, it is no longer necessary to evaluate the non-uniform temperature distribution in the column and only a few linear interpolations are required to obtain the column Squash Load and rigidity. This paper gives the necessary information for using the proposed method for unprotected columns. For protected columns, this paper reports the results of a parametric study using the Eurocode 4 Part 1.2 method and uses these results to check the accuracy of the proposed method. Two examples, one for an unprotected column and one for a protected column, are then given to demonstrate the easiness of using the proposed method.

  • An approach for calculating the failure Loads of unprotected concrete filled steel columns exposed to fire
    Structural Engineering and Mechanics, 1999
    Co-Authors: Yong Wang, Venkatesh Kodur
    Abstract:

    This paper deals with the development of an approach for evaluating the Squash Load and rigidity of unprotected concrete filled steel columns at elevated temperatures. The current approach of evaluating these properties is reviewed. It is shown that with a non-uniform temperature distribution, over the composite cross-section, the calculations for the Squash Load and rigidity are tedious in the current method. A simplified approach is proposed to evaluate the temperature distribution, Squash Load, and rigidity of composite columns. This approach is based on the model in Eurocode 4 and can conveniently be used to calculate the resistance to axial compression of a concrete filled steel column for any fire resistance time. The accuracy of the proposed approach is assessed by comparing the predicted strengths against the results of fire tests on concrete filled circular and square steel columns. The applicability of the proposed approach to a design situation is illustrated through a numerical example.