Seismic behaviour assessment of eccentrically split-X braced frames

Document Type : Article

Authors

Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran

Abstract

Eccentrically braced frames (EBF) are lateral resisting systems with appropriate ductility and strength against earthquakes. An important kind of arranging such systems, recommended by Popov and also presented in AISC, is eccentrically split-X bracing. The axial force applied to the beam outside link beam is reduced causing the improvement of the behaviour of this type of bracing. In this research, for the first time, ductility factor, overstrength factor and response modification factor of eccentrically split-X braces are investigated through nonlinear static and incremental dynamic analyses and fragility curves are presented for different ratios of link beam length to span length. For this purpose, three buildings, 2-, 6- and 10-storey structures with the ratios of link beam length to span length (e/L) of 0.05, 0.1, 0.15 and 0.2 are considered. Ductility factor of Rš›=3.55, overstrength factor of Rs = 2.31 and response modification factor of RLRFD =8.06 are calculated under 10 earthquake records. It is concluded that the most appropriate values of e/L ratio in the eccentrically split-X bracing are 0.1 for tall structures and 0.05 for small ones. According to the log-normal distribution, the fragility curves are also plotted considering collapse prevention (CP) and immediate occupancy (IO) performance levels.

Keywords

Main Subjects


References
1. Roeder, C.W. and Popov, E.P. \Inelastic behaviour
of eccentrically braced steel frames under cyclic loadings",
Report no. UCB/EERC-77/18, Berkeley (CA):
Earthquake Engineering Research Center (1977).
2. Hjelmstad, K.D. and Popov, E.P. \Seismic behaviour
of active beam links in eccentrically braced frames",
Report no. UCB/EERC-83/15, Berkeley (CA): Earthquake
Engineering Research Institute (1983).
3. Malley, J.O. and Popov, E.P. \Design considerations
for shear links in eccentrically braced frames", Report
no. UCB/EERC-83/24, Berkeley (CA): Earthquake
Engineering Research Institute (1983).
4. Kasai, K. and Popov, E.P. \A study of seismically
resistant eccentrically braced frame systems", Report
no. UCB/EERC-86/01, Berkeley (CA): Earthquake
Engineering Research Institute (1986).
5. Ricles, J.M. and Popov, E.P. \Experiments on eccentrically
braced frames with composite
oors", Report
no. UCB/EERC-87/06, Berkeley (CA): Earthquake
Engineering Research Institute (1987).
6. Engelhardt, M.D. and Popov, E.P. \Behaviour of
long links in eccentrically braced frames", Report
no. UCB/EERC-89/01, Berkeley (CA): Earthquake
Engineering Research Institute (1989).
7. Foutch, D.A., Goel, S., and Roeder, C.W. \Seismic
testing of full-scale steel building, part I", Journal
of Structural Engineering, ASCE, 113(11), pp. 2111{
2129 (1987).
8. Roeder, C.W., Foutch, D.A., and Goel, S.C. \Seismic
testing of full-scale steel building, part II", Journal
of Structural Engineering, ASCE, 113(11), p. 21936
(1987).
9. Whittaker, A.S., Uang, C.M., and Bertero, V.V.
\Earthquake simulation tests and associated studies
of a 0.3-scale model of a six-story eccentrically
braced steel structure", Report no. UCB/EERC-
87/02, Berkeley (CA): Earthquake Engineering Research
Center, University of California (1987).
10. Itani, A.M. \Cyclic behaviour of Richmond-San Rafael
tower links", Report no. CCEER 97-4. Reno (NV):
Center for Civil Engineering Earthquake Research,
University of Nevada at Reno (1997)
11. Dusicka, P. \Built-up shear links as energy dissipators
for seismic protection of bridges", Ph.D. Dissertation.
Reno (NV): Department of Civil and Environmental
Engineering, University of Nevada (2004).
12. McDaniel, C.C. , Uang, C.M., and Seible, F., Cyclic
Testing of Suspension Tower Shear Links of the San
Francisco (CA), Department of Structural Engineering,
University of California (2002).
13. Arce, G. \Impact of higher strength steels on local
buckling and overstrength of links in eccentrically
braced frames", M.S. Thesis, Austin (TX): Department
of Civil, Architectural and Environmental Engineering,
The University of Texas at Austin (2002).
14. Galvez, P. \Investigation of factors a ecting web
fractures in shear links", M.S. Thesis, Austin (TX):
Department of Civil, Architectural and Environmental
Engineering, The University of Texas at Austin (2004).
15. Ryu, H.C. \E ects of loading history on the behaviour
of links in seismic-resistant eccentrically
braced frames", M.S. Thesis, Austin (TX): Department
of Civil, Architectural and Environmental Engineering,
The University of Texas at Austin (2005).
16. Okazaki, T. \Seismic performance of link-to-column
connections in steel eccentrically braced frames",
Ph.D. Dissertation. Austin (TX): Department of Civil,
Architectural and Environmental Engineering, The
University of Texas at Austin (2004).
17. Okazaki, T., Arec, G., Ryu, H.C., and Engelhardt,
M.D. \Experimental study of local buckling, overstrength
and fracture of links in eccentrically braced
frames", Journal of Structural Engineering, 131(10),
pp. 1526{1535 (2005).
18. Chao, S.H., Khandelwal, K., and Sherif, E.T. \Ductile
web fracture initiation in steel shear links", Journal of
Structural Engineering, 132(8), pp. 1192{1200 (2006).
19. Rossi, P.P. and Lombardo, A. \In
uence of link overstrength
factor on seismic behaviour of eccentrically
braced frame", Journal of Structural Engineering,
63(11), pp. 1529{1545 (2007).
20. Ozhendekci, D. and Ozhendekci, N. \E ects of the
frame geometry on the weight and inelastic behaviour
of eccentrically braced chevron steel frames", Journal
of Constructional Steel Research, 64(3), pp. 326{343
(2008).
21. Chegeni, B. and Mohebkhah, A. \Rotation capacity
improvement of long link beams in eccentrically braced
frames", Scientia Iranica, 21(3), pp. 516{524 (2014).
22. Kurdi, K., Budiono, B., Moestopo, M., Kusumastuti,
D., and Refai Muslih, M. \Residual stress e ect on
link element of eccentrically braced frame", Journal
of Constructional Steel Research, 128(1), pp. 397{404
(2017).
84 R. Sheikhi Garjan and N. Fanaie/Scientia Iranica, Transactions A: Civil Engineering 28 (2021) 65{84
23. Ming, L. and Mingzhou, S. \Seismic performance
of high-strength steel fabricated eccentrically braced
frame with vertical shear link", Journal of Constructional
Steel Research, 137(10), pp. 262{285 (2017).
24. Tian, X., Su, M., Lian, M., Wang, F., and Li, S.
\Seismic behavior of K-shaped eccentrically braced
frames with high-strength steel, Shaking table testing
and FEM analysis", Journal of Constructional Steel
Research, 143(4), pp. 250{263 (2018).
25. Bosco, M. and Rossi, P.P. \Seismic behaviour of
eccentrically braced frames", Engineering Structures,
31(3), pp. 664{674 (2008).
26. Brunesi, E., Nascimbene, R., and Casagrande, L.
\Seismic analysis of high-rise mega-braced frame-core
buildings", Engineering Structures, 115, pp. 1{17
(2016).
27. Bosco, M., Marino, E.M., and Rossi, P.P. \In
uence of
modelling of steel link beams on the seismic response
of EBFs", Engineering Structures, 127, pp. 459{474
(2016).
28. AISC, Seismic Provisions for Structural Steel Buildings
(ANSI/AISC 341-05) Chicago (IL): American
Institute of Steel Construction, Inc (2005).
29. Vamvatsikos, D. and Cornell, C.A. \The incremental
dynamic analysis and its application to performancebased
earthquake engineering", 12th European Conference
on Earthquake Engineering, p. 479 (2002).
30. Uang, C.M. \Establishing R (or Rw) and Cd factor
for building seismic provision", Journal of Structure
Engineering, 117(1), pp. 19{28 (1991).
31. Zahrai, S.M. and Jalali, M. \Experimental and analytical
investigations on seismic behavior of ductile steel
knee braced frames", Steel and Composite Structures,
Journal, 16(1), pp. 1{21 (2014).
32. Mwafy, A.M. and Elnashai, A.S. \Calibration of force
reduction factors of RC buildings", Journal of Earthquake
Engineering, 6(22), pp. 239{273 (2002).
33. Vamvatsikos, D. and Cornell, C.A. \Incremental dynamic
analysis", Earthquake Engineering and Structural
Dynamics, 31(3), pp. 491{514 (2003).
34. ASCE/SEI 7-10, Minimum Design Loads for Buildings
and Other Structures, Reston, Virginia: American
Society of Civil Engineers (ASCE) (2010).
35. OpenSees, Command Language, Incremental Dynamic
Analysis, Earthquake Engineering, http://opensees.
berkeley.edu/ (2003).
36. Rozon, J., Koboevic, S., and Tremblay, R. \Study of
behaviour of eccentrically braced frames in response to
seismic loads", The 14th World Conference on Earthquake
Engineering, October 12{17, Beijing, China
(2008).
37. Gulec, C.K., Gibbons, B., Chen, A., and Whittaker,
A.S. \Damage states and fragility functions for link
beams in eccentrically braced frames", Journal of
Constructional Steel Research, 67(9), pp. 1299{1309
(2011).
38. Jalayer, F. and Cornell, C.A. \A technical framework
for probability-based demand and capacity factor design",
Paci c Earthquake Engineering Research Center
PEER Rep. 2003/8, PEER Berkeley, Calif. (2003)
39. Ellingwood, B.R. and Tekie, P.B. \Seismic fragility
assessment of concrete gravity dams", Earthquake Engineering
and Structural Dynamics, 32(14), pp. 2221{
2240 (2003).
40. Wen, Y.K., Ellingwood, B.R., and Bracci, J. \Vulnerability
function framework for consequence-based
engineering", MAE Center Project DS-4 Report, April
28, 44. (2004).
41. ASCE, American Society of Civil Engineers, Seismic
Rehabilitation of Existing Buildings, ASCE/SEI 41-06
(2007).

Volume 28, Issue 1
Transactions on Civil Engineering (A)
January and February 2021
Pages 65-84
  • Receive Date: 26 April 2018
  • Revise Date: 24 October 2018
  • Accept Date: 09 March 2019