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• 지관과 주관의 폭이 동일한 각형강관 X형 접합부의 압축강도에 대한 해석적 연구(Analytical Study of Compressive Strength of Equal-Width RHS X-Joint)

• 저자: 김정현, 이철호, 한규홍, 김선후

• Abstract: The equal-width RHS (rectangular hollow section) X-joint, of which the widths of the chord and the brace are identical, is one of the most frequently used uniplanar tubular joints. However, the compressive strength of this joint has been specified very conservatively by most representative international design standards. In this study, a more accurate strength formula of equal-width RHS X-joint is proposed by extending the plate buckling model recently proposed by Becque and Cheng. From the eigenvalue analysis results of the test-backed numerical joint models, the more appropriate shape function for chord sidewall buckling is first obtained. The elastic buckling strength and the non-dimensional slenderness of the chord sidewall are then derived based on the classical energy method. It is finally shown that, when the newly proposed non-dimensional sidewall slenderness is used in combination with the column curve ‘c’ of EC3, it gives more accurate and consistent prediction on joint strength compared to existing method.

• 저자: 김정현, 이철호, 김선후, 한규홍

• Abstract: The use of high-strength steels for tubular structures has been forbidden or permitted with some joint-strength reduction in most representative international standards. Six rectangular hollow section (RHS) X-joint specimens were tested under axial compression to investigate inelastic joint behavior. The key test parameters included brace-to-chord width ratio and grade of steels. All high-strength steel specimens exhibited sufficient strength compared with current European standards’ strength criteria; their strengths were even higher than the standard’s prescribed unreduced nominal strength. Significantly different postyielding behavior was observed depending upon the brace-tochord width ratio and the grade of steels. It was also observed that the formulation of sidewall buckling strength in the current European standard tends to predict overly conservative results and requires further examination. A new design formula for RHS X-joints subjected to sidewall buckling was proposed in this paper based on a more realistic buckling shape. When the normalized plate slenderness ratio newly defined in this study is used in conjunction with the column curve c of the European standard, both accuracy and consistency of strength predictions were significantly improved compared with those of the strength formulas currently available.

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• 지관 압축을 받는 고강도강 X형 각형강관접합부의 구조적 성능에 대한 실험적 연구(Experimental Study of High-strength Steel RHS X-joints under Axial Compression)

• 저자: 김정현, 이철호, 한규홍, 김선후

• Abstract: The application of high-strength steel to RHS joints can bring many benefits for structures, but it is forbidden or permitted with high-strength penalty in KBC 2016 and most representative international standards. To examine the appropriateness of these limitations, especially the strength reduction penalty imposed on high-strength steels, six RHS X-joint specimens were tested under axial compression. The key parameters of the test are brace to chord width ratios and grades of steels. All high-strength steel specimens exhibited sufficient strength compared to the EC3 strength criteria; their strengths were even higher than the EC3 unreduced nominal strength. It was also found that the formulation of sidewall buckling strength in current EC3 is inaccurate (too conservative) and needs to be improved.