Performance Assessment of Steel Moment Connections Retrofitted with Various Reduced Section Patterns

Abstract

It is of high importance in seismic retrofitting of lateral load-bearing systems to increase the connections performance. The crucial point in the steel frame retrofitting process is to create plastic hinges in these types of frames. The formation of plastic hinges in beams and near columns generates large strains on column flanges as well as welding metal and heated surroundings, which can lead to brittle failure. The connection should be designed in such a way as to allow plastic hinge formation at certain points of the beam. One such method suggested for retrofit connections is to reduce the beam section locally away from the connection zone. There are various patterns available to locally reduce the beam section, such as circular, elliptical, and symmetric/asymmetric. In recent years, different proposals have been presented to design these connections which vary from older instructions. For this study, radiused cuts in the flange and slotted holes in the web of connection beams were selected for retrofitting analysis. Cyclic behavior, energy damping levels, and ductility of these connections were studied and compared before and after the retrofit by using nonlinear dynamic analysis. The results showed that the symmetrical circular hole pattern in the beam flanges demonstrated reliable performance.

If the inline PDF is not rendering correctly, you can download the PDF file here.

  • 1. AISC, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications. Chicago, Illinois, ANSI/AISC 358, 2016.

  • 2. AISC, Specification for Structural Steel Buildings, Chicago, Illinois: ANSI/AISC 360, 2016.

  • 3. ANSYS. Multiphysics 12.1. Canonsber: Ansys Inc, 2010.

  • 4. ASCE 7-10, Minimum Design Loads for Buildings and Other Structures. American Society of Civil Engineers, Reston, Virginia, 2010.

  • 5. ATC 24, Guidelines for Cyclic Seismic Testing of Components of Steel Structures, Applied Technology Council, 1992.

  • 6. Bogdanovic, A, Rakicevic, Z, and Noroozinejad Farsangi, E 2019. Shake table tests and numerical investigation of a resilient damping device for seismic response control of building structures. Structural Control and Health Monitoring, 26(11), e2443.

  • 7. Chi, B, Uang, CM and Chen, A 2006. Seismic rehabilitation of pre-Northridge steel moment connections: A case study. Journal of Constructional Steel Research, 62,783-792.

  • 8. Fanaie, N, Faegh, SS and Partovi, F 2019. An improved and innovative formulation for calculating amplified elastic story drift induced by RBS connections in steel moment frames. Journal of Constructional Steel Research, 160, 510-527.

  • 9. Farsangi, EN, Yang, TY and Tasnimi, AA 2016. Influence of concurrent horizontal and vertical ground excitations on the collapse margins of non-ductile RC frame buildings. Structural Engineering and Mechanics, 59(4), pp.653-669.

  • 10. Farsangi, EN, Tasnimi, AA, Yang, TY, Takewaki, I and Mohammadhasani, M 2018. Seismic performance of a resilient low-damage base isolation system under combined vertical and horizontal excitations. Smart Structures and Systems, 22(4), pp.383-397.

  • 11. FEMA-350, Recommended Seismic Design Criteria for New Steel Moment Frame Buildings, FEMA 350. Washington, DC: Federal Emergency Management Agency, 2000.

  • 12. Gerami, M, Sharbati, Y and Sivandi-Pour, A 2013. Nonlinear seismic vulnerability evaluation of irregular steel buildings with cumulative damage indices. International Journal of Advanced Structural Engineering, 5, p.9.

  • 13. Han, SW, Moon, KH and Stojadinovic, B 2009. Design equations for moment strength of RBS-B connections. Journal of Constructional Steel Research, 65, 1087-1095.

  • 14. Hedayat, AA and Celikag, M 2009. Post-Northridge connection with modified beam end configuration to enhance strength and ductility. Journal of Constructional Steel Research, 65, 1413-1430.

  • 15. Jones, SL, Fry, GT and Engelhardt, MD 2002. Experimental evaluation of cyclically loaded reduced beam section moment connections. Journal of Structural Engineering, 128(4), pp.441-451.

  • 16. Lee, CH, Jeon, SW, Kim, JH and Uang, CM 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(12), pp.1854-1865.

  • 17. Montuori, R and Sagarese, V 2018. The use of steel rbs to increase ductility of wooden beams. Engineering Structures, 169, pp.154-161.

  • 18. Rong, B, Liu, S, Yan, JB and Zhang, R 2018. Shear behaviour of panel zone in through-diaphragm connections to steel tubular columns. Thin-Walled Structures, 122, 286-299.

  • 19. SAC joint venture. Recommended seismic design criteria for new steel moment-frame buildings; FEMA-350. Richmond, Calif, 2000.

  • 20. Sivandi-Pour, A, Gerami, M and Kheyroddin, A 2015. Determination of modal damping ratios for non-classically damped rehabilitated steel structures. Iranian Journal of Science and Technology. Transactions of Civil Engineering, 39, p.81.

  • 21. Sivandi-Pour, A, Gerami, M and Khodayarnezhad, D 2014. Equivalent modal damping ratios for non-classically damped hybrid steel concrete buildings with transitional storey. Structural Engineering and Mechanics, 50, pp.383-401.

  • 22. Tuna, M and Topkaya, C 2015. Panel zone deformation demands in steel moment resisting frames. Journal of Constructional Steel Research, 110, 65-75.

  • 23. Yang, Q, Li, B and Yang, N 2009. Aseismic behaviors of steel moment resisting frames with opening in beam web. Journal of Constructional Steel Research, 65,1323-1336.

  • 24. Zhang, X, Zheng, S and Zhao, X 2019. Seismic performance of steel beam-to-column moment connections with different structural forms. Journal of Constructional Steel Research, 158, 130-142.

OPEN ACCESS

Journal + Issues

Search