Cyclic Seismic Performance of Weak-Axis RBS Welded Steel Moment Connections

  • Cheol-Ho LeeEmail author
  • Jong-Hyun Jung
  • Sung-Yong Kim


In this study, cyclic seismic performance of weak-axis reduced beam section (RBS) welded steel moment connections was experimentally investigated. Experimental results of this study again showed that the weak-axis RBS moment connection designed based on the procedure proposed by Gilton and Uang (J Struct Eng 122:1292–1299, 2002) performs well and developed an excellent seismic performance much better than 4% story drift with 80% of beam plastic capacity. However, it was also shown that the sharp corner of C-shaped fillet weld, used for attaching the beam web to the shear plate, can be the origin of crack propagation owing to stress concentration there. Slight trimming of the sharp corner is recommended to reduce notch effect. One specimen in this study eventually failed due to low cycle fatigue fracture as a result of cyclic flange local buckling that occurred at the butt joint between the beam flange and the horizontal continuity plate. The size of the weld access hole beneath the butt joint should be minimized if possible to suppress the occurrence of flange local buckling around the butt joint. The factors affecting the size of C-shaped fillet weld and the beam shear eccentricity for the weld design were also examined through a case study and simple analytical modeling. The sectional factor governing the beam shear eccentricity was shown to be the plastic section modulus ratio of beam section at RBS center to the beam flanges at welded joint. The elastic method neglecting the ductile behavior of the C-shaped fillet weld group was shown to be too conservative and should not be used in design in order to minimize welding heat affection to the thin beam web as well.


Welded steel moment connection Weak-axis connection RBS connection Seismic design Local buckling Fracture 



The Institute of Engineering Research at Seoul National University provided research facilities for this work.


  1. AISC. (2010a). Prequalified connections for special and intermediate steel moment frames for seismic applications. Chicago, IL: AISC.Google Scholar
  2. AISC. (2010b). Steel construction manual. Chicago, IL: AISC.Google Scholar
  3. AISC. (2010c). Seismic provisions for structural steel buildings. Chicago: AISC.Google Scholar
  4. Chen, S. J., Yeh, C. H., & Chu, J. M. (1996). Ductile steel beam-to-column connections for seismic resistance. Journal of Structural Engineering, 122, 1292–1299.CrossRefGoogle Scholar
  5. Chi, B., & Uang, C. M. (2002). Cyclic response and design recommendations of reduced beam section moment connections with deep columns. Journal of Structural Engineering, 128, 464–473.CrossRefGoogle Scholar
  6. Driscoll, G. C., & Beedle, L. S. (1982). Suggestions for avoiding beam-to-column web connection failure. Engineering Journal, 19, 16–19.Google Scholar
  7. Engelhardt, M. D. (1999). Design of reduced beam section moment connections. In Proceedings of 1999 North American steel construction conference. Chicago, IL: AISC.Google Scholar
  8. Engelhardt, M. D., Winneberger, T., Zekany, A. J., & Potyraj, T. J. (1998). Experimental investigations of dogbone moment connections. Engineering Journal, 35, 128–139.Google Scholar
  9. Gilton, C., & Uang, C. M. (2002). Cyclic response and design recommendations of weak-axis reduced beam section moment connections. Journal of Structural Engineering, 122, 1292–1299.Google Scholar
  10. Jones, S. L., Fry, G. T., & Engelhardt, M. D. (2002). Experimental evaluation of cyclically loaded reduced beam section moment connections. Journal of Structural Engineering, 128, 441–451.CrossRefGoogle Scholar
  11. Lee, C. H., Jeon, S. W., Kim, J. H., & Uang, C. M. (2005). Effects of panel zone strength and beam web connection method on seismic performance of reduced beam section steel moment connections. Journal of Structural Engineering, 131, 1854–1865.CrossRefGoogle Scholar
  12. Li, R., Samali, B., Tao, J, & Hassan, M. K. (2017). Cyclic behaviour of composite joints with reduced beam sections. Engineering Structures, 136, 329–344.CrossRefGoogle Scholar
  13. Plumier, A. (1997). The dogbone: Back to the future. Engineering Journal-American Institute of Steel Construction, 34, 61–67.Google Scholar
  14. Popov, E. P., & Tsai, K. C. (1989). Performance of large seismic steel moment connections under cyclic loads. Engineering Journal, 26, 51–60.Google Scholar
  15. Rentschler, G. P., Driscoll, G. C., & Chen, W. F. (1980). Tests of beam-to-column web moment connections. Journal of the Structural Division, 106, 1005–1022.Google Scholar

Copyright information

© Korean Society of Steel Construction 2019

Authors and Affiliations

  1. 1.Department of Architecture and Architectural EngineeringSeoul National UniversitySeoulKorea
  2. 2.School of ArchitectureKyungnam UniversityChangwonKorea
  3. 3.School of ArchitectureChangwon National UniversityChangwonKorea

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