Numerical Study of High-strength Steel CHS X-joints Including Effects of Chord Stresses

주관응력효과를 고려한 고강도강 X형 원형강관접합부의 수치해석 연구

  • Kim, Seon Hu (Dept. of Architecture & Architectural Engineering, Seoul National University) ;
  • Lee, Cheol Ho (Dept. of Architecture & Architectural Engineering, Seoul National University)
  • Received : 2018.02.10
  • Accepted : 2018.03.30
  • Published : 2018.04.27


Internationally representative steel design standards have forbidden or limited the application of high-strength steels to tubular joints, partly because of concerns about their unique material characteristics such as high yield ratio. Most of design standards stipulate that for steels whose yield strengths exceed 355 or 360 MPa, the strength equations cannot be utilized or strength reduction factor below 1.0 should be multiplied. However, the mechanical background behind these limitations is not clear. Experimental testing of high-strength steel CHS (circular hollow section) X-joints recently conducted by the authors also clearly indicated that the current limitations might be unduly conservative. As a continuing work, extensive, test-validated numerical analyses were made to investigate the behavior of high-strength steel CHS X-joint under axial compression. Three steel grades covering ordinary to very high strength steels were considered in the analysis. Again it was found that the high strength penalty to the joint strength in current standards is too severe and needs to be relaxed. The high-strength steel joints under the effects of chord stress generally showed higher strength than the ordinary steel joints and their strengths were conservatively predicted by current standards. It is also emphasized that current format of the CHS X-joint strength equation does not reflect observed behavior and needs to be recast.


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