Seismic Ratchetting of Single-Degree-of-Freedom Steel Bridge Columns

Abstract:

Nonlinear time history analyses of SDOF bridge columns with elasto-plastic flexural behaviour which are subject to eccentric gravity loading are conducted to quantify the effect of ratchetting. Peak and residual displacements were used as indicators of the degree of ratchetting. The effects of member axial loads and design force reduction factors were also investigated. It was shown that displacement demands increased with increasing eccentric moment. For eccentric moment of 30% of the yield moment, the average maximum and residual displacements increase by 4.2 and 3.8 times the maximum displacement, respectively, which the engineers calculate using static methods without considering ratchetting effect. Design curves for estimating the displacement demands for different eccentric moments are also developed. The current NZ1170.5 (2016) provisions were found to be inadequate in estimating the maximum displacement for steel structures, and hence, new provisions for steel structures should be presented.

• Periodical: Key Engineering Materials (Volume 763)
• Pages: 295-300
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.763.295
• Online since: February 2018
• Authors: Khaled Saif, Chin Long Lee*, Trevor Yeow, Gregory A. MacRae
• Keywords: C-Bent Column, Residual Displacement, Seismic Ratchetting, Seismic Structural Analysis, Steel Bridge, Steel Columns

References

[1] K. Saif, C. -L. Lee, G. MacRae and T. Yeow. Effect of Eccentric Moments on Seismic Ratchetting of Single-Degree-Of-Freedom Structures. New Zealand Society for Earthquake Engineering conference. New Zealand, Wellington (2017).

DOI: 10.4028/www.scientific.net/kem.763.295

[2] Standards New Zealand. NZS1170. 5: 2004 Structural Design Actions Part 5 Earthquake actions New Zealand. Incorporating Amendment 1 (2016).

[3] F. McKenna, G. Fenves, M. Scott, & B. Jeremic. Open System for Earthquake Engineering Simulation (OpenSees) University of California, Berkeley (2016).

[4] J. Bauschinger, Ueber die Veranderung der Elasticitatagrenze und dea Elasticitatamoduls verschiadener Metalle, Zivilingenieur, vol. 27, 1881, p.289–348.

[5] M. Menegotto, PE. Pinto. Method of analysis of cyclically loaded RC plane frames including changes in geometry and nonelastic behaviour of elements under normal force and bending. Preliminary report IABSE, vol. 13, Zurich, 1973, p.15–22.

[6] Federal Emergency Management Agency (FEMA). Quantification of building seismic performance factors: FEMA, 2009, P-695.

[7] G. MacRae, and K. Kawashima, The seismic response of bilinear oscillators using Japanese earthquake records. Journal of Research of the Public Works Research Institute, 30 (1993).