Skip to main content
Log in

Seismic strengthening of weak bolted end plate connections using welded haunches

International Journal of Steel Structures Aims and scope Submit manuscript


Bolted steel connections have been frequently used after Northridge earthquake. Among the concerns regarding the poor performance of weak connections is the ability to effectively and economically rehabilitate steel moment connections in existing buildings. Strengthening of these connections without the need for changing or replacing their components is a problem that has been recently considered by engineers. This study develops and experimentally validates an innovative technique for enhancing the seismic performance of steel beam to column moment connections. The use of haunch as a way to rehabilitate end plate bolted connections with weak end plate or bolts is studied constructing 6 experimental specimens of corner connections under SAC (Structural Engineers Association of California) cyclic loading protocol. The results of the study show that this strengthening method improves the cyclic behavior of the weak connections. Besides, it provides specimens with better performance than that of the reference connection designed according to AISC. The moment capacity, initial rotational stiffness and energy dissipation of the rehabilitated connections are averagely higher than those of the reference connection by 25, 10 and 12 percent respectively. Moreover, the failure potential in the connection is reduced because the plastic hinge is kept away from connection region and is transferred to the haunch end. It should be noted that this strengthening method is more efficient for cyclic behavior of a bolted connections with weak end-plate than a bolted connection with weak bolts, since the moment capacity is more increased.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions


  • AISC Design Guide 04. (2004). “Extended End-Plate Moment Connections: Seismic and Wind Applications”-2nd Edition.

  • Asada H, Tanaka T, Yamada S, Matoba H. (2014). “Proposal for seismic retrofit of beam-to-column connection by the addition of H-section haunches to beams using bolt connection.” International Journal of Steel Structures. 14(4), pp. 865–871. DOI: 10.1007/s13296-014-1217-8.

    Article  Google Scholar 

  • Chi B, Uang CM, Chen A. (2006). “Seismic rehabilitation of pre-Northridge steel moment connections: A case study.” Journal of Constructional Steel Research. DOI:10.1016/j.jcsr.2005.11.001.

  • Federal Emergency Management Agency (FEMA). (2000). “FEMA-350: Recommended seismic design criteria for new steel moment frame buildings” California Universities for Research in Earthquake Engineering.

  • Grande E, Rasulo A. (2015). “A simple approach for seismic retrofit of low-rise concentric X-braced steel frames.” Journal of Constructional Steel Research. Vol. 107, pp. 162–172. DOI:10.1016/j.jcsr.2015.01.017.

    Article  Google Scholar 

  • Kim YJ, Oh SH, Moon TS. (2004). “Seismic behavior and retrofit of steel moment connections considering slab effects.” Journal of Engineering Structure, 26(13), November 2004, Pages 1993–2005. DOI: 10.1016/j.engstruct.2004.07.017.

    Article  Google Scholar 

  • Lee CH, Uang CM. (2001). “Analytical modeling and seismic design of steel moment connections with welded straight haunch.” Journal of Structural Engineering. DOI:10.1061/(ASCE)0733-9445(2001)127:9(1028).

  • Md Tahir M, Hong Yong L, Mohammad S, Poi Ngian S. (2011). “Finite element analysis of flush end-plate connections connected to column web.” International Journal of Steel Structures. 11(3), pp. 247–258. DOI: 10.1007/s13296-011-3001-3.

    Article  Google Scholar 

  • Ng YH, Shanmugam NE, Richard Lie YJ. (2012). “Experimental studies on composite haunch beams.” Journal of Constructional Steel Research. Vol. 75, pp. 160–168. DOI:10.1016/j.jcsr.2012.03.016.

    Article  Google Scholar 

  • Qiang X, Jiang X, Bijlaard FSK, Kolstein H, Luo Y. (2015). “Post-fire behaviour of high strength steel endplate connections-Part 1: Experimental study.” Journal of Constructional Steel Research. Vol. 108, pp. 82–93. DOI: 10.1016/j.jcsr.2014.10.028.

    Article  Google Scholar 

  • Park R. State-of-the Art Report. (1988). “Ductility Evaluation from Laboratory and Analytical Testing”. Proceedings of Ninth World Conference on Earthquake Engineering Vol. VIII. Tokyo-Kyoto, Japan.

  • Saberi H, Kheyroddin A, Gerami M. (2014). “Comparison of bolted end plate and T-stub connections sensitivity to bolt diameter on cyclic behavior.” International Journal of Steel Structures. 14(3), pp. 633–647. DOI: 10.1007/s13296-014-3021-x.

    Article  Google Scholar 

  • Saberi V, Gerami M, Kheyroddin A. (2014). “Comparison of bolted end plate and T-stub connection sensitivity to component thickness.” Journal of Constructional Steel Research. DOI: 10.1016/j.jcsr.2014.02.012.

    Google Scholar 

  • Shakib H, Dardaei Joghan S, Pirizadeh M, Moghaddasi Musavi A. (2011). “Seismic rehabilitation of semi-rigid steel framed buildings-A case study.” Journal of Constructional Steel Research. 67(6), pp. 1042–1049. DOI: 10.1016/j.jcsr.2011.01.002.

    Article  Google Scholar 

  • Yang JG, Lee HD. (2015). “Method for increasing the energy dissipation capacity of T-stub connections.” International Journal of Steel Structures. 15(3), pp. 595–603. DOI: 10.1007/s13296-015-9007-5.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Hamid Saberi.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Saberi, H., Kheyroddin, A. & Gerami, M. Seismic strengthening of weak bolted end plate connections using welded haunches. Int J Steel Struct 17, 743–755 (2017).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: