Seismic Retrofitting of Steel Frames with Buckling Restrained and Ordinary Concentrically Bracing Systems with Various Strain Hardening and Slenderness Ratios

Authors

1 Faculty of Civil Engineering, Babol University of Technology, PO Box 4714871167, Shariati St., Babol 484, Iran

2 Civil Engineering Department, University of Shomal, Amol, Iran

Abstract

The present study assesses the seismic performance of steel moment resisting frames (SMFs) retrofitted with different bracing systems. Two structural configurations were utilized: ordinary concentrically braces (OCBFs), buckling-restrained braces (BRBFs). A 7-story and 18-story steel perimeter SMFs were designed with insufficient lateral stiffness to satisfy code drift limitations in high seismic hazard zone. The frames were then retrofitted with OCBFs with 30, 60, 90, 120 slenderness ratios and BRBFs. Inelastic time-history analyses have been carried out using OPENSEES software for strain hardening from 1 to 10 percent to assess the structural performance under earthquake ground motions. Inter story drifts were employed to compare the inelastic response of the retrofitted frames. It is shown that the distribution of maximum story drifts in the height of BRBFs is more uniform than OCBFs with various slenderness ratios and with increasing strain hardening, the inter story drift and P-∆ effects is decreased. In addition, normal buckling braces with low slenderness ratio behave similar to the BRBFs to control inter story drift, but the cycling behavior in dissipation the energy can’t be changed, and finally the suitable performance from BRBF can’t be obtained.

Keywords

References

[1] Di Sarno, L., Elnashai, A.S. and Nethercot, D.A, (2008), “Seismic response of stainless steel braced frames”. Journal of Constructional Steel Research, Vol. 64(7-8), pp. 914-925.
[2] Asgarian B, Shokrgozar HR. (2009), “BRBF response modification factor”. Journal of Constructional Steel Research, Vol. 65, pp. 290-298.
[3] Kim J, Seo Y. (2004), “Seismic design of low-rise steel frames with buckling-restrained braces”. Journal of Engineering Structures, Vol. 26(5), pp. 543-51.
[4] Kim J, Choi H. (2005), “Response modification factors of chevron-braced frames”. Journal of Engineering Structures, Vol. 27(2), pp. 285-300.
[5] Di Sarno L, Manfredi G, Acanfora M. (2007), “Design approach for the seismic strengthening of an existing RC building with buckling restrained braces”. In: Proceeding of ASSISi 10th world conference on seismic isolation, energy dissipation and active vibrations control of structures.
[6] Di Sarno, L. and Manfredi, G. (2010), “Seismic retrofitting with buckling restrained braces: Application to an existing non-ductile RC framed building”. Journal of soil dynamic and earthquake engineering, Vol. 30, pp. 1279-1297.
[7] Asgarian B, Amirhesari N. A. (2008), “Comparison of dynamic nonlinear behavior of ordinary and buckling restrained braced frames subjected to strong ground motion”. Journal of Structural Design of Tall and Special Buildings, Vol. 17, pp. 367-86.
[8] Rahai AR, Alinia MM. (2008), “Performance evaluation and strengthening of concrete structures with composite bracing members”. Journal of Construction & Building Materials, Vol. 22(10), pp. 2100-10.
[9] Chang H.Y, and Chiu C. K. (2011), “Performance Assessment of Buckling Restrained Braces”. Journal of Procedia Engineering, Vol. 14, pp. 2187–2195.
[10] BHRC, (2005), “Iranian code of practice for seismic resistance design of buildings: Standard no. 2800”. 3rd ed. Building and Housing Research Center.
[11] MHUD, (2009), “Iranian national building code (part 10): steel structure design”. Ministry of Housing and Urban Development, Tehran (Iran).
[12] AISC, (2005), “Seismic provisions for structural steel buildings”. American Institute of Steel Constructions, Chicago (IL).
[13] Sabelli R, Mahin S, Chang C. (2003), “Seismic demands on steel braced frame buildings with buckling-restrained braces”. Journal of Engineering Structures, Vol. 25(5), pp. 655-66.
[14] International Codes Council (1997), “'Uniform Building Code, UBC 1997”. International Conference of Building Officials, Whittier, CA.
[15] MPO. (2007), “Iranian Instruction for Seismic Rehabilitation of Existing Buildings”. Management and Planning Organization Office of Deputy for Technical Affairs, Technical Criteria Codification & Earthquake Risk Reduction Affairs Bureau, Tehran (Iran).
[16] FEMA 356, (2000), “Pre-standard and commentary for the seismic rehabilitation of building”. Federal Emergency Management Agency, Washington, DC.

Files

History

  • Receive Date: 23 June 2013
  • Revise Date: 30 September 2014
  • Accept Date: 22 October 2014

Share

How to cite

Statistics