Proposed development of a damage-resisting Eccentrically Braced Frame with rotational active links
DOI:
https://doi.org/10.5459/bnzsee.44.2.99-107Abstract
Eccentrically Braced Frames (EBFs) are widely used seismic-resisting systems, as they allow both strength and stiffness to be optimised while providing good ductility capacity. However, in theory they have a low damage threshold in severe earthquakes and post-earthquake repair of conventional EBFs will be difficult and expensive.
This paper presents the Numerical Integration Time-History (NITH) analysis of two ten storey EBF buildings; one with a conventional active link and the other with a new form of low damage active link based on rotational sliding bolted plates. The low damage active link can be designed to allow rotation only, or to allow both rotation and axial extension. The conventional active link response in terms of displacement, rotation and inelastic demand was well within the range of the rotational active links under the records considered. The analysis shows that average maximum displacement of the building and rotation of the link for both the rotational and the rotational+extension active links was almost identical. The extension of the rotational active link permitting axial extension was less than 1.5 mm. Axial load demands on the collector beams and braces were similar in the case all three active links.
It can be concluded from the analysis that the rotational active link with extension is not required, as the lateral extensions can be accommodated within the rotational plates with nominal clearances in the bolt holes to accommodate the lateral extension.
References
American Institute of Steel Construction, Inc. (AISC). Seismic Provisions for Structural Steel Buildings. ANSI/AISC 341-05. Chicago (IL, USA): AISC; 2005.
Bruneau, M., Clifton, G.C., MacRae, G., Leon, R. and Fussell, A. “Steel Building Damage From the Christchurch Earthquake of February 22, 2011, NZST”. New Zealand Society for Earthquake Engineering; www.eqclearinghouse.org. DOI: https://doi.org/10.1201/b11396-4
Carr, A.J. (2010), RUAUMOKO, “The Maori God of Volcanoes and Earthquakes”. Christchurch, The University of Canterbury.
Clifton, G.C. (2005), “Semi-rigid Joints for Moment-Resisting Steel Framed Seismic Resisting Systems”. PhD thesis University of Auckland, 2005.
Clifton, C., MacRae, G.A., Mackinven, H., Pampanin, S. and Butterworth, J.W. (2007), Sliding Hinge Joints and Sub-assemblies for Steel Moment Frames. NZSEE Conference Proceedings, March 2007.
Vera, C.O., McVerry, G. and Ingham, J. (2011), “Seismic Zonation and Default Suite of Ground-Motion Records for Time-History Analysis in the North Island of New Zealand”, Earthquake Spectra (Under review).
Feeney, M.J. & Clifton, G.C. (1995/2000). “Seismic Design Procedures for Steel Structures”, Manukau City, New Zealand, New Zealand HERA.
MacRae, G.A., Clifton, G.C., Mackinven, H., Mago, N., Butterworth, J. W. & Pampanin, S. (2010), “The sliding hinge joint moment connection”. Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 43, No 3. DOI: https://doi.org/10.5459/bnzsee.43.3.202-212
Khoo, H.H., Clifton, G.C., Butterworth, J. W & Mathieson, C.D. (2011), “Development of the Self-Centering Sliding Hinge Joint”. PCEE Conference Proceedings, April 2011.
Lai, Z. (2000), “Performance of Cross Braced Frames Incorporating Sliding Bolted Friction Dissipating Devices”. Master thesis, University of Auckland, 2000.
NZS 1170.5:2004, “Structural Design Actions Part 5: Earthquake Actions New Zealand”, Wellington, New Zealand, Standards New Zealand.
NZS 3404 (1997/2001/2007), “Steel Structures Standard, incorporating Amendments 1 and 2”, Wellington, New Zealand, Standards New Zealand.
Okazaki, T. & Engelhardt, M.D. (2007), “Cyclic Loading Behaviour of EBF Links Constructed of ASTM A992 Steel”, Journal of Constructional Steel Research 63, 751-765. DOI: https://doi.org/10.1016/j.jcsr.2006.08.004
Patel, C. and Lal, M. “Uniform Strength Eccentrically Braced Frames”. NZSEE Conference Proceedings, March 2010.
Richards, P. & Uang, C.M. (2003), “Development of Testing Protocol for Short Links in Eccentrically Braced Frames”, Technical Report SSRP-2003/08, University of California, San Diego.
