Displacement based seismic design procedure for rack structures

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Steel storage racks are self-standing structures designed to support many storage levels of heavy pallet loads. Konstant (Econo-Rack (2015) Inc.) is the largest Canadian manufacturer of racks that are extensively used in Canada for storage of goods in industrial and commercial applications such as production plants, warehouses or distribution centers. They are also used in retail areas open to public. Collapse of rack structures has been observed in past earthquakes, which can pose a major life safety hazard to the public and have considerable economic consequences. Rack structures must therefore be adequately designed to safely resist earthquake effects. Current Canadian seismic provisions for rack structures essentially consist in the traditional force-based design method used for building structures. The method does not reflect the actual seismic response of rack structures along their down-aisle direction. An alternative reliable seismic design method that can take advantage of the actual connection nonlinear properties is needed so that Konstant can offer a wider range of seismic-proof racking structures at more competitive costs. This project aims at developing a new displacement-based approach for the seismic design of rack structures that can fully exploit the large deformation capacity of the structure and control better of peak displacement demands. Guidance and limitations for the application of the method will also be developed. In particular, attention will be paid to the maximum height and/or minimum lateral stiffness and strength requirements that must be satisfied to achieve stable inelastic response when using the method. The study will be based on numerical simulations performed with detailed structural models developed and calibrated using connection and shake table test data available from the industry. Konstant will have direct access and integrate their day-to-day design practice the seismic methodologies, calculations, and technical information that will be generated in this research. This will give Konstant technical advantages that should lead to a broader coverage of the warehouse and distribution market's needs with more cost-effective, yet seismically safe rack designs.