Experimental Study of Eccentricity and Width-to-Thickness Ratio Effects of Arched Steel Haunches on Cyclic Behavior

Document Type : Research Article


1 Department of Civil Engineering, Payame Noor University, Semnan, Iran

2 Associate Professor, Faculty of Civil Engineering, Semnan University, Iran


This paper introduces arched steel haunches (ASHs) as a novel technique in the seismic retrofitting of RC frames. In this regard, parameters such as ASH initial eccentricity and width-to-thickness ratio are evaluated as two factors affecting their cyclic behavior. A series of cyclic loading tests were performed on four specimens with single and double rectangular cross-sections and with the same nominal area and length, but with different eccentricities of 0.1 and 0.2 nominal length. Experimental results showed that the slenderness and width-to-thickness ratios play a significant role in the cyclic performance in compression and even tension, and by reducing the buckling potential and the cross-section reaching the fully plastic state, a more desirable hysteretic behavior is achieved. Therefore, with 50% reduction of these ratios simultaneously, the maximum compressive and tensile strength enhanced up to 59% and 27%, respectively, and the dissipated energy and the maximum viscosity damping ratio increased up to 152% and 14%, respectively. Also, the arched haunches showed different behavior in tension and compression for ultimate strength and plastic stiffness, which with decreasing the initial eccentricity, became more apparent. With increasing the initial eccentricity, the cross-sectional area effect on the increase of compressive strength and especially maximum tensile strength decreased. In addition, by reducing it by 50% and despite 59% reduction in cross-sectional area, the ultimate tensile plastic strength and stiffness increased up to 1.31 and 3.5 times, respectively. In addition, the obtained results will be used for further research on the experimental behavior of RC beam-column joints.


Main Subjects

[1] Q.S. Yu, C.M. Uang, J. Gross, Seismic rehabilitation design of steel moment connection with welded haunch, ASCE Journal of Structrual Engineering, 126(1) (2000) 69–78.
[2] T. Chen, Retrofit strategy of non-seismically designed frame systems based on a metallic haunch system, Master of engineering thesis. Christchurch (New Zealand): University of Canterbury, (2006).
[3] S. Pampanin, C. Christopoulos, T. Chen, Development and validation of a metallic haunch seismic retrofit solution for existing under-designed RC frame buildings. Earthquake Engineering and Structural Dynamics, 35(14) (2006) 1739–1766.
[4] M.K. Sharbatdar, A. Kheyroddin, E. Emami, Cyclic performance of retrofitted reinforced concrete beam-column joints using steel prop, Construction and Building Materials, 36 (Nov) (2012) 287–294.
[5]A. Kheyroddin, A. Khalili, E. Emami, M.K. Sharbatdar, An innovative experimental method to upgrade performance of external weak RC joints using fused steel prop plus sheets, Steel and Composite Structures, 21(2) (2016) 443–460.
[6] E. Emami, M.K. Sharbatdar, A. Kheyroddin, Experimental Investigation of the Cyclic Behaviour of RC Connections Strengthened with Steel Prop and Curb, Sharif Civil Engineering Journal, 30-2 (4.1) (2015) 45-55. (In Persian)
[7] B. Wang, S. Zhu, Y.L. Xu, H. Jiang, Seismic retrofitting of non-seismically designed RC beam–column joints using buckling restrained haunches: design and Analysis, Journal of Earthquake Engineering, 22(7) (2017) 1188–1208.
[8] A. Kanchanadevia, K. Ramanjaneyulua, Non-invasive hybrid retrofit for seismic damage mitigation of gravity load designed exterior beam–column sub-assemblage, Journal of Earthquake Engineering. (2019). https://doi.org/10.1080/13632469.2019.1592790.
[9] E. Emami, A. Kheyroddin, M.K. Sharbatdar, Investigation of steel prop effect on inelastic beahavior of RC frames using FE method, Modares Civil Engineering Journal, 14(3) (2015) 1-15. (In Persian)
[10] A. Sharma, G.R. Reddy, R. Eligehausen, G. Genesio, S. Pampanin, Seismic response of reinforced concrete frames with haunch retrofit solution. ACI Structural Journal 111(1–6) (2014) 1–12.
[11] J. Akbar, N. Ahmad, B. Alam, M. Ashraf, Seismic performance of RC frames retrofitted with haunch technique, Structural Engineering and Mechanics, 67(1) (2018) 1–8.
[12] N. Ahmad, J. Akbar, M. Rizwan, B. Alam, A.N. Khan, A. Lateef, Haunch retrofitting technique for seismic upgrading deficient RC frames, Bulletin of Earthquake Engineering, (2019). https://doi.org/10.1007/s10518-019-00638-9.
[13] J. Akbar, N. Ahmad, B. Alam, Seismic strengthening of deficient reinforced concrete frames using reinforced concrete haunch, ACI Structural  Journal, 116 (1) (2019) 225–235.
[14] A.S. Tasligedik, U. Akguzel, W.Y. Kam, S. Pampanin, Strength hierarchy at reinforced concrete beam-column joints and global capacity, Journal of Earthquake Engineering, (2016) 1–34.
[15] A. Zabihi, H.H. Tsang, E.F. Gad, J.L. Wilson, Seismic retrofit of exterior RC beam-column joint using diagonal haunch, Engineering Structure, 174 (2018) 753–767.
[16] S. Sasmal, S. Voggu, Strut-relieved single steel haunch bracing system for mitigating seismic damage of gravity load designed structures, ASCE Journal of Structural Engineering, (2018) 1-14. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002167.
[17] A. Kheyroddin, E. Emami, A. Khalili, RC beam–column connections retrofitted by steel prop: experimental and analytical studies, International Journal of Civil Engineering, 18 (2019)  501–518. https://doi.org/10.1007/s40999-019-00481-8.
[18] E. Emami, A. Kheyroddin, M.K. Sharbatdar, Experimental and analytical investigations of reinforced concrete beam-column joints retrofitted by single haunch, Advances in Structural Engineering, (2020) 1-14. DOI: 10.1177/1369433220922493 journals.sagepub.com/home/ase.
[19] H.L. Hsu, H. Halim, Improving seismic performance of framed structures with steel curved dampers, Engineering Structures, 130 (2017) 99–111.
[20] H.L. Hsu, H. Halim, Brace performance with steel curved dampers and amplified deformation
mechanisms, Engineering Structures, 175 (2018)  628–644.
[21] Z. Zhou, B. Ye, Y. Chen, Experimental investigation of curved steel knee braces with adjustable yield displacements, Journal of Constructional Steel Research, 161 (2019)  17–30.
[22] E. Emami, A. Kheyroddin, O. Rezaifar, Experimental and analytical investigation of arched steel haunches under cyclic loading, Engineering Structures, 246 (2021) 113041.
[23] ANSI/AISC 360-16, Specification for Structural Steel Buildings, American Institute of Steel Construction, Illinois, U.S.A, (2016).
[24] S.P. Timoshenko, J.M. Gere, Theory of elastic stability, International Student Edition, Second Edition, (1985).
[25] ATC-24, Guidelines for cyclic seismic testing of components of steel structures for buildings, Report No. ATC-24, Applied Technology Council, Redwood City, CA, (1992).
[26] A.K. Chopra, Dynamics of structures: theory and applications to earthquake engineering, 2nd ed, Englewood Cliffs: Prentice Hall, (2001).