Cost viability of a base isolation system for the seismic protection of a steel high-rack structure
- 329 Downloads
In this study the effects and costs of implementing a base isolation system for the mitigation of the seismic risk of an existing externally-braced steel frame rack structure are analysed by means of nonlinear static (pushover) analysis. Various plan asymmetric variants, with different realistic distributions of the payload mass and occupancy levels, have been investigated under two seismic intensities. The results obtained are presented as floor plan projection envelopes of the top displacements and as plastic hinge damage patterns of the superstructure. In the presented cost evaluation, the cost of the implementation of the proposed base isolation system is compared with the estimated costs of structural repairs to the damaged structural members of the superstructure, as well as with estimated expenses of the downtime period and content damage. The results have shown that base isolation is, in general, not economically feasible for lower ground motion intensities, whereas it could be of great benefit in the case of moderate and high intensities. A simple rough cost estimation study, based on the obtained plastic hinge patterns, showed that the inclusion of the downtime period costs and content damage costs might be important parameters, which — if taken into account — could make such an isolation system viable also for lower ground motion intensities. The other benefits brought by seismic isolation, such as savings on the building design costs, reductions in the threat to employees’ lives, and others, were, however, not included in the presented study. The comparison is done only for two deterministic scenarios of seismic attack, e.g. for design ground motion intensity (a g =0.175 g) and for increased intensity with a g =0.25 g indicating the Maximum Considered Earthquake level.
Keywordsrack structures base isolation cost efficiency mass eccentricity repair costs downtime costs content damage costs
Unable to display preview. Download preview PDF.
- Bruneau, M., Uang, C. M., and Whittaker, A. (1998). Ductile design of steel structures. McGraw-Hill, Boston.Google Scholar
- CEN (2005a). Eurocode 3: Design of steel structures — Part 1-1: General structural rules, EN 1993-1-1. European Committee for Standardization, Brussels.Google Scholar
- CEN (2005b). Eurocode 8: Design of structures for earthquake resistance — Part 1: General rules, seismic actions and rules for buildings, EN 1998-1. European Committee for Standardization, Brussels.Google Scholar
- CSI (2008). SAP2000 (v12.0.1) — Linear and nonlinear static and dynamic analysis and design of three-dimensional structures. Computer & Structures, Inc., Berkeley.Google Scholar
- Fajfar, P., Marušić, D., and Peruš, I. (2005). “Torsional effects in the pushover-based seismic analysis of buildings.” Journal of Earthquake Engineering, 9(6), pp. 831–854.Google Scholar
- FEM (2005). Recommendations for the design of static steel pallet racks under seismic conditions — prFEM 10.2.08. European Racking Federation, Birmingham.Google Scholar
- ICBO (1997). Uniform Building Code. International Conference of Building Officials, Whittier, California.Google Scholar
- Kilar, V. and Koren, D. (2010). “Simplified inelastic seismic analysis of base-isolated structures using the N2 method.” Earthquake Engineering and Structural Dynamics, 39(9), pp. 967–989.Google Scholar
- Krawinkler, H. (2011). “Challenges in improving earthquake resilience through performance based earthquake engineering.” Proc. Bled4 — International Workshop on Performance-Based Seismic Engineering Vision for an Earthquake Resilient Society, Institute for Structural and Earthquake Engineering of the Department of Civil Engineering, University of Ljubljana, Slovenia.Google Scholar
- Mezzi, M., Comodini, F., and Rossi, L. (2011). “A base isolation option for the full seismic protection of an existing masonry school building.” Proc. 13 th International Conf. on Civil, Structural Engineering Computing, Civil-Comp Press, Stirlingshire, Scotland.Google Scholar
- SEAONC (1986). Tentative seismic isolation design requirements. Structural Engineers Association of Northern California, San Francisco, California.Google Scholar