Advanced Steel Construction

Vol. 4, No. 2, pp. 134-146 (2008)



T. Sopha, T.B.N. Nguyen, S.P. Chiew 1,*, C.K. Lee and S.T. Lie

1 School of Civil and Environmental Engineering, Nanyang Technology University

50 Nanyang Avenue, Singapore 639798, Tel: (65) 6790 5294; Fax: (65) 6792 1650

*(Corresponding author: E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.)




View Article   Export Citation:Plain Text | RIS | Endnote


  This paper presents the experimental studies of two partially overlapped CHS   K-joints specimens (Specimens S1 and S2) with through brace subjected to basic and combined loads. The stress analysis of the joints revealed the maximum stress concentration factor (SCF) to be located on the brace side. Then, the maximum SCF was compared with existing Efthymiou’s formulae. It is observed that the Efthymiou’s formulae are over-conservative in in-plane bending load case (IPB), but in axial load case (AX) are not conservative. In addition, the fatigue life was also compared with existing S-N curves. The S-N curve was found to be marginally conservative for first specimen, but it was not conservative for other one.



Partially overlapped K-joints, stress concentration and stress intensity factor, fatigue failure, surface and through-thickness cracks



[1]      Tizani, W.M.K., Yusurf, K.O., Davies, G. and Smith, N.J., “A Knowledge Based System to Support Joint Fabrication Decision Making at the Design Stage- Case Study for CHS Trusses”, Proceeding of the 7th International Symposium of Tubular Structures, Hungary, 1996, pp. 483-489.

[2]      Wardenier, J., “Hollow Section Joints”, Delft University Press, Delft, The Netherlands, 1982.

[3]      Romeijn, A., Karamonus, S.A. and Wardenier, J., “Effects of Joint Flexibility on Fatigue Design of Welded Tubular Lattice Structures”, The Seventh International Offshore and Polar Engineering Conference, San Frncisco, USA, 1997, Vol. IV, pp 27-36.

[4]       Herion, S. and Puthli, R.S., “Fatigue Design and Secondary Bending Moments in RHS K-joints with Gap”, The Eighth International Symposium on Tubular Structures, Singapore, 1998, pp. 315-322.

[5]       Wydle, J.G.. and McDolald, A., “The Influence of Joint Dimensions on Fatigue Strength of Welded Tubular Joints”, Proceeding of 2nd International Conference, Behaviour of Offshore Structures, BHRA Fluid Engineering, Cranfield, U.K. 1979, paper 42, pp. 535-500.

[6]      Efthymiou, M. and Durkin, S., “Stress Concentrations in T/Y and Gap/Overlap K-joints”, Behavior of Offshore Structures, Elsevier, Amsterdam, Netherlands, 1985, pp. 429-440

[7]      Dover, W.D., Dharmavasan, S., Brenan, F.P. and Marsh, K.J., “Fatigue Crack Growth in Offshore Structures”, Engineering Materials Advisory Services (EMAS) Ltd., Chamelon Press, London, 1995.

[8]     Chiew, S.P., Lie, S.T., Lee, C.K. and Huang, Z.W., “Fatigue Performance of Cracked Tubular T- Joints under Combined Loads-Part I- Experimental”, Journal of Structural Engineering, American Society of Civil Engineers, ASCE, 2004, Vol. 130, No. 4, pp. 562-571.

[9]       Lee, C.K., Lie, S.T., Chiew, S.P. and Shao, Yongbo, “Numerical Models Verification of Cracked Tubular T, Y and K-Joints Under Combined Loads”, Engineering Fracture Mechanics (United States), 2005, Vol. 72, No. 7, pp. 983 - 1009.

[10]    Lie, S.T., Lee, C.K., Chiew, S.P. and Shao, Yongbo, “Validation of Surface Crack Stress Intensity Factors of a Tubular K-joint”, International Journal of Pressure Vessels and Piping (United Kingdom), 2005, Vol. 82, No. 8, pp 610 - 617.

[11]     Lie, S.T., Lee, C.K., Chiew, S.P. and Shao, Yongbo, “Mesh Modelling of Cracked Uni-planar Tubular K-joints”, Journal of Constructional Steel Research (United Kingdom), 2005, Vol. 61, No. 2, pp 235 - 264.

[12]    Zhao, X.L., Herion, S., Packer, J.A., Puthli, R., Sedlacek, G., Wardenier, J., Weynand, K., van Wingerde, A., and Yeomans, N., “Design Guide for Circular and Rectangular Hollow Section Joints under Fatigue Loading”, CIDECT Publication No. 8, TUV-Verlag, Germany, 2001.