Investigation of seismic behavior of drilled flange connection with inclined arrangement of holes

Document Type : Research Article

Authors

1 Civil engineering department,Islamic azad university, science and research branch, Tehran, Iran

2 IIEES,Tehran,Iran

3 Faculty of Niroo Research Institute (NRI)

Abstract

Since unreinforced welded connections were brittle and prematurely fractured in the connections of ​​the beam-to-column penetration welds in the 1994 Northridge earthquake, the researchers proposed radius-cut flange reduction connections to improve the seismic behavior of rigid connections. The brittle failure of the weld in the beam-to-column connection and the lateral buckling of the beam flange in the reduced sections of the beam flange led to propose the modified forms of this type of connection. The new type of connection includes drilled flange connection with parallel rows of holes. In order to improve the performance of these drilled flange connections, in this study, beam flange drilling arrangements were used with an inclined arrangement of holes with different hole diameters. The study showed that in the inclined arrangement of a hole, the amount of plastic rotation is 0.059 radians, which is 7.3% more than the plastic rotation of the same radius-cut flange reduction connection. Also, in the best connection sample with the most suitable oblique drilling arrangement, the equivalent plastic strain index in the center and corner of the complete joint penetration weld line decreased to 92.3% and 87.7%, respectively, compared to conventional radius-cut flange reduction connections. Mises index in this connection in the center and corner of the complete joint penetration weld line decreased to 45.5% and 39.9% compared to radius-cut flange reduction connections, respectively. This indicates better performance and less sensitivity of this type of connection to the problems of the complete joint penetration weld line of ​​the beam-to-column connection compared with conventional radius-cut flange reduction connections and these drilled flange connections with the parallel arrangement.

Keywords

Main Subjects


[1] N.F. Youssef, D. Bonowitz, J.L. Gross, A survey of steel moment-resisting frame buildings affected by the 1994 Northridge earthquake, US National Institute of Standards and Technology, 1995.
[2] E.P. Popov, T.-S. Yang, S.-P. Chang, Design of steel MRF connections before and after 1994 Northridge earthquake, Engineering Structures, 20(12) (1998) 1030-1038.
[3] S.W. Han, G.U. Kwon, K.H. Moon, Cyclic behaviour of post-Northridge WUF-B connections, Journal of Constructional Steel Research, 63(3) (2007) 365-374.
[4] Tzong-Shuoh Yang, E.P. Popov, experimental and analytical studies steel connections and energy dissipators, Earthquake Engineering Research Center College of Engineering University of California at Berkeley, Report No. UCB/EERC-95/13 (1995).
[5] H. Farrokhi, F. Danesh, S. Eshghi, A modified moment resisting connection for ductile steel frames (Numerical and experimental investigation), Journal of Constructional Steel Research, 65(10-11) (2009) 2040-2049.
[6] M. Vetr, A. Haddad, Study of drilled flange connection in moment resisting frames, in:  Report No. 3732, International Institute of Earthquake Engineering and Seismology Tehran; Iran, 2010.
[7] M. Vetr, M. Miri, A. Haddad, Seismic behavior of a new reduced beam section connection by drilled holes arrangement (RBS_DHA) on the beam flanges through experimental studies, in:  15th world conference of earthquake engineering, Lisbon, Portugal, 2012.
[8] S.J. Lee, S.E. Han, S.Y. Noh, S.-W. Shin, Deformation capacity of reduced beam section moment connection by staggered holes, in:  International conference on sustainable building, Seoul, Korea, 2007.
[9] A. Atashzaban, I. Hajirasouliha, R.A. Jazany, M. Izadinia, Optimum drilled flange moment resisting connections for seismic regions, Journal of Constructional Steel Research, 112 (2015) 325-338.
[10] R. Rahnavard, A. Hassanipour, N. Siahpolo, Analytical study on new types of reduced beam section moment connections affecting cyclic behavior, Case Studies in Structural Engineering, 3 (2015) 33-51.
[11] R.A. Jazany, Improved design of drilled flange (DF) moment resisting connection for seismic regions, Bulletin of Earthquake Engineering, 16(5) (2018) 1987-2020.
[12] P.S. Heidari, A. Aziminejad, A. Moghadam, M.A. Jafari, Evaluation of drilled flange connections with combined arrangements of holes and notches, Bulletin of Earthquake Engineering, 18(14) (2020) 6487-6532.
[13] J. Hancock, A. Mackenzie, On the mechanisms of ductile failure in high-strength steels subjected to multi-axial stress-states, Journal of the Mechanics and Physics of Solids, 24(2-3) (1976) 147-160.
[14] A. Kanvinde, G. Deierlein, Continuum based micro-models for ultra low cycle fatigue crack initiation in steel structures, in:  Structures Congress 2005: Metropolis and Beyond, 2005, pp. 1-11.
[15] A. Kanvinde, G. Deierlein, Cyclic void growth model to assess ductile fracture initiation in structural steels due to ultra low cycle fatigue, Journal of engineering mechanics, 133(6) (2007) 701-712.
[16] AISC360-16, Specification for structural steel buildings, American Institute of Steel Construction, Chicago, IL,  (2016).
[17] N.B. Regulations, Design and implementation of steel buildings, (2013), (in Persian). .
[18] AISC341-16, Seismic provisions for structural steel buildings, American Institute of Steel Construction,  (2016).
[19] C. Roeder, State of the art report on connection performance, Federal Emergency Management Agency (FEMA) Bulletin, (355D) (2000).
[20] AISC358-16, Prequalified connections for special and intermediate steel moment frames for seismic applications, in, American National Standard and American Institute of Steel Construction, 2016.
[21] A.S.f. Testing, Materials, ASTM A370: standard test methods and definitions for mechanical testing of steel products, in, ASTM West Conshohocken, 2014.
[22] A. Guide, Ansys Meshing User’s Guide, Últim accés Maig, 28 (2016).
[23] S. El-Tawil, T. Mikesell, E. Vidarsson, S.K. Kunnath, Strength and ductility of FR welded-bolted connections, SAC Report,  (1998) 98-01.