Seismic ratings for degrading structural systems
DOI:
https://doi.org/10.5459/bnzsee.34.3.214-236Abstract
A new method has been proposed for rating the seismic resistance of degrading bracing elements used in buildings constructed to NZS 3604. Most of these bracing elements are formed from thin cladding panels nailed or screwed to light timber frames, but the rating method is also used for bracing elements constructed from other materials. A new analytical model was developed as part of this study to accurately model the load-displacement responses of these bracing elements. A continuous pseudo-dynamic test method was developed to assess the accuracy of the analytical model in the BRANZ structural laboratory. The analytical model accurately predicted the time-displacement responses of three, pseudo-dynamically tested, 5.4 m long, light timber framed wall specimens, providing confidence in its use.
The new rating method has shown that P21 rating procedure, used since 1979, was dangerously unconservative for the tested specimens. Factors that led to this discrepancy are briefly described. A simple modification to the current P21 rating procedure is proposed to re-rate specimens from existing test results, but this needs to be verified for a wider range of specimen responses than the three described herein.
References
Standards New Zealand (SNZ) (1990). "Code of Practice for Light Timber Framed Buildings not Requiring Specific Design". Standards New Zealand, NZS 3604, Wellington.
Herbert, P.D. & King A.B. (1998). "Racking Resistance of Bracing Walls in Low-rise Buildings Subject to Earthquake Attack". Building Research Association of New Zealand. Study Report 78. Judgeford.
Cooney. R.C. and Collins. M.J. (1979). (revised 1982, 1987, 1988). "A wall bracing test and evaluation procedure”. Building Research Associario11 of New Zealand, Technical Paper P2l. Judgeford.
King, A.B. and Lim. K.Y. (1991). "An Evaluation Method of P21 Test Results For Use With NZS 3604: 1990", Building Research Association of New Zealand. Technical Recommendation No 10. Judgeford.
Deam, B.L. and King, A.B. (1996). "Pseudo-dynamic seismic testing of structural timber elements". Proceedings, International Wood Engineering Conference, New Orleans, Lousiana, 1: 53-59.
King A.B. & Deam B.L. (1998). "A Rational Engineering Basis for Assessing Timber framed Bracing Panels under Earthquake Attack". Proc. Australasian Structural Engineering Conference, Auckland, New Zealand. 2: 949-955.
Dean. J.A., Stewart. W.G. and Carr. A.J. (1987). "The Seismic Design of Plywood Sheathed Timber Frame Shearwalls". Pacific Conference on Earthquake Engineering, Wairakei, New Zealand. 2: 165-175.
Park, R. (1989). “Evaluation of Ductility of Structures and Structural Assemblages from Laboratory Testing". Bulletin New Zealand National Society for Earthquake Engineering 22(3 ): 155-166.
Dean, J.A., Stewart, W.G. and Carr, A.J. (1986). "The Seismic Behaviour of Plywood Sheathed Shearwalls". Bulletin New Zealand National Society for Earthquake Engineering 19(1): 48-63. DOI: https://doi.org/10.5459/bnzsee.19.1.48-63
Stewart, W.G. (1987). 'The Seismic Design of Plywood Sheathed Shearwalls". Thesis submitted in partial fulfillment of PhD Degree, University of Canterbury, Christchurch, New Zealand.
Foliente, G.C. (1997). "Modelling and Analysis of Timber Structures Under Seismic Loads: State-of-the-Art". In Foliente, G.C. (ed) Earthquake Performance and Safety of Timber Structures, Forest Products Society, Madison, Wisconsin.
Dean, J.A. (1994). Personal communication.
Deam, B.L. (1997). "Seismic Ratings for Residential Timber Buildings". BRANZ Study Report 73, Judgeford.
Filippou, F.C., Bertero, V.V. ancl Popov, E.P. (1983). "Effects of bond deterioration on hysteretic behaviour of reinforced concrete joints". EERC Report No. 83-19, University of California, Berkeley.
Standards New Zealand (SNZ) (1992) “Code of Practice for General Structural Design and Design Loadings for Buildings", Standards New Zealand, NZS 4203, Wellington.
Clow, K., Davidson, B. and Matthews, J. (1995). “A methodology for calculating the optimal bilinear seismic isolation system". New Zealand National Society for Earthquake Engineering Annual Conference, Rotorua. p 15.
Clough, R.W. and Penzien, J. (1975). Dynamics of Structures. McGraw-Hill. New York.
Thurston, S.J. (1994). "Field Testing of House Pile Foundations Under Lateral Loading". Building Research Association of New Zealand. Study Report SR58. Judgeford.
Paulay, T. (2000). "Understanding Torsional Phenomena in Ductile Systems". Bulletin New Zealand Society for Earthquake Engineering 33(4): 403-420. DOI: https://doi.org/10.5459/bnzsee.33.4.403-420
Folz, B. and Filiatrault, A. (2001). "Cyclic Analysis of Wood Shear Walls". Journal of Structural Engineering. 127(4): 349-472 DOI: https://doi.org/10.1061/(ASCE)0733-9445(2001)127:4(433)
Kamiya, F. (1988). “Nonlinear earthquake response analysis of sheathed wood walls by a computer-actuator on-line system". In: Proceedings. 1988 International Conference on Timber Engineering; September 19-22; Seattle, Washington. 838-847
Takanashi, K. et al. (1974). "Seismic failure analysis of structures by computer pulsator on-line system". In: Journal of the Institute of Industrial Science, University of Tokyo. 26( 11 ): 13-25 (in Japanese).
Seible, F.; Hegemier, G.A.: Priestley, M.J.N. (1991). "Full-scale testing of structural masonry systems under simulated seismic loads". In: Proceedings, Pacific Conference on Earthquake Engineering. 20-23 November, Auckland, New Zealand. 2: 197-208
Mahin, S.A.; Shing, P.B. (1985). "Pseudodynamic method for seismic testing". Journal of Structural Engineering 111(7): 1482-1503. DOI: https://doi.org/10.1061/(ASCE)0733-9445(1985)111:7(1482)
Thewalt, C.R. and Mahin, S. A. (1995). "An Unconditionally Stable Hybrid Pseudodynamic Algorithm". Earthquake Engineering and Structural Dynamics. 24(5): 723-731. DOI: https://doi.org/10.1002/eqe.4290240508
Nakashima, M.; Kato, H. (1987). "Experimental error growth behaviour and error control in on-line computer test control method". Research Paper No.123. Building Research Institute, Ministry of Construction, Japan.
Hilber, H.M.; Hughes, TJ.R.; Taylor, R.L (1977). "Improved numerical dissipation for time integration schemes in structural dynamics". Earthquake Engineering and Structural Dynamics. 5(3): 283-292. DOI: https://doi.org/10.1002/eqe.4290050306
Girhammar, U.A and Andersson, H. (1988). "Effect of Loading Rate on Nailed Timber Joint Capacity". Journal of Structural Engineering. 114(11): 2439-2456. DOI: https://doi.org/10.1061/(ASCE)0733-9445(1988)114:11(2439)
Thurston, SJ. (1993). "Report on Racking Resistance of Long Sheathed Timber Framed Walls With Openings", Building Research Association of New Zealand, Study Report 54, Judgeford.
