Journal of Structural and Construction Engineering

Journal of Structural and Construction Engineering

Ductility Evaluation of inverted V-bracing and concentrically bracing systems

Document Type : Original Article

Author
Abazar Asghari
Assistant Professor, Urmia University of Technology, Urmia, Iran
10.22065/jsce.2018.109599.1402
Abstract
The current design philosophy for buildings located in zones with high seismic risks is that the buildings must have sufficient strength and stiffness to remain elastic and serviceable under moderate but frequently occurring earthquakes and to have sufficient ductility to prevent collapse under extreme earthquakes. Conventional structural steel framing systems such as moment resisting frames (MRFs), concentrically braced frames (CBFs), and eccentrically braced frames (EBFs) I extensively used in seismically active areas. Each of the previously mentioned structural systems has different advantages and disadvantages.
In this study, response modification factor of ordinary inverted V-braced frames and specially inverted V-braced frames are evaluated, result confirm that the proposed height for buildings with ordinary inverted braced frames in the ASCE7,can be increased up to 10.7 meter. also results indicate that by using ordinary inverted V-bracing systems in buildings .their height can be increased up to 6 story or 20 meter. Using special inverted V-braced systems can have saving about 0 to 30 percent on used materials for frames from 1 story to 16 stories. According to the results of this study, response modification factor proposed by Iranian seismic design code (2800 standard fourth edition),(R=5.5), is more logical than the one which is proposed by ASCE7, (R=6). Unfortunately, in special inverted V-braced frames, and when the story of the frames increases up to 12 stories, ductility demand can't be achieved .So as a result for frames which are more than 12 stories tall, lower response modification factor should be used. In addition, frames taller than 12 story height don’t experience specified target displacement and collapse before getting to preferred mechanism. This phenomenon shows the necessity of using different response modification factor for frames taller than 12 stories.
Keywords
Ductility
ductility reduction factor
concentrically V-braced frame
Pushover analysis
target displacement

Subjects

[1] Uriz, P., Filippou, F.C. and Mahin, S. A. (2008), Model for cyclic inelastic buckling of steel braces, J. Struct. Eng., 134(4): 619–628.
[2] Uriz, P. and Mahin, S.A. (2008), Toward earthquake-resistant design of concentrically braced steel-frame structures. PEER-2008/08, Pacific Earthquake Engineering Research Center (PEER), Univ. of California, Berkeley, Berkeley, CA; 2008.
[3] Uang, C.M. and Nakashima, M. (2004), Steel buckling-restrained frames. Earthquake engineering: From engineering seismology to performance-based engineering, Y. Bozorgnia and V.V. Bertero, eds, CRC Press, Boca Raton, FL.
[4] Mofid, M., Lotfollahi, M. (2006), on the characteristics of new ductile knee bracing systems. Journal of Constructional Steel Research, 62:271–281.
[5] MHUD. Iranian National Building Code, Part 10, (2013), Steel Structure Design. Tehran (Iran): Ministry of Housing and Urban Development.
[6] American Institute of steel construction (AISC341), (2010), Seismic Provisions for Structural Steel Buildings.
[7] American Society of Civil Engineers (ASCE7), (2010), Minimum Design Loads for Buildings and Other Structures, pp.7.
[8] BHRC. Iranian Code of Practice for seismic Resistant Design of Buildings: Standard No. 2800 (3rd Edition), (2005), Building and Housing Research Center.
[9] ETABS, (1995), Integrated building design software, nonlinear version 9.7.3, Berkeley; (California), USA: Inc.
[10] American Institute of steel construction (AISC360-2010), Specification for structural steel buildings.
[11] Balendra, T. and Huang, X. (2003), Overstrength and Ductility Factors for Steel Frames Designed According to BS 5950, Journal of Structural Engineering, ASCE, Vol. 129, No.8.
[12] Newmark, N.M. and Hall, W.J., (1973), Seismic Design Criteria for Nuclear Reactor Facilities, Rep. No. 46, Building Practices for Disaster Mitigation, National Bureau of Standards, U.S. Department of Commerce.
[13] Newmark N.M. and Hall W.J., (1982), EERI Monograph Series, Earthquake Spectra and Design, Earthquake Engineering Research Institute, Oakland, California.
[14] Miranda, E., (1993), Site-Dependent Strength Reduction Factors, Journal of Structural Engineering, ASCE, Vol. 119, No.12.
[15] Miranda E. and Bertero V.V., (1994), Evaluation of Strength Reduction Factors for Earthquake-Resistant Design, Earthquake Spectra, Vol. 10, No.2.
[16] Federal Emergency Management Agency (FEMA), (2000), Prestandard and Commentary for the Seismic Rehabilitation of Buildings, (FEMA 356), Washington, DC.
[17] Prinz, G.S., (2010), using buckling-restrained braces in eccentric configurations, Brigham Young University.

  • Receive Date 06 December 2017
  • Revise Date 07 March 2018
  • Accept Date 11 April 2018