# Shake Table Testing of Standard Cold-Formed Steel Storage Rack
## 1 Introduction  
Being part of the Pacific Ring of Fire, which is geologically active, New Zealand has experienced many large earthquakes in the past decades. One of the recent large earthquakes was the 2010 Canterbury earthquake (also known as the Christchurch earthquake or Darfield earthquake) that rocked the south island of New Zealand with a magnitude of 7.1 on the Richter scale. Figure 1 illustrates the various rack failure mechanisms observed and recorded after this earthquake. Some of the frames collapsed (Figure 1a) when a plastic hinge was formed in the uprights, which resulted in further drift and the amplification of second-order effects and thereby caused the failure of the system. It was also observed that, despite the basic assumptions for seismic design and stability analysis, \"linear deformation of the frame\" is not an accurate assumption and therefore not all the connections experience the same rotation along the frame height (Figure 1b). The use of an insufficient number of bolts in typical baseplate connections also led to excessive rotation and failure of the base plate, as shown in Figure 1c. The cyclic deterioration of such connections also triggered a progressive collapse of all frames in the warehouse [1; 2; 3; 4; 5] (Figure 1d), which indicates that the current racking codes and specifications are still weak about the cyclic features of the connections. Storage rack structures are mainly designed for seismic actions based on rack provisions, including the Rack Manufacturers Institute (RMI) specification [6], European code (EN 16681) [7], Australian standard (AS 4084) [8], Federal Emergency Management Agency (FEMA 460) [9], Canadian Standards Association (CSA A344) [10] and American National Standards Institute (ANSI MH16) [11]. Nevertheless, in many regions, the design of racking frames is still based on general seismic design codes due to the lack of enough guidelines for the dynamic design of rack frames. Additionally, some of the current seismic design standards allow the use of the equivalent static method to estimate the seismic forces and do not consider the sliding of the frame (or only consider the rocking of pallets on the rack beams) for the design procedure. It should be noted that a significant contribution to the seismic response of rack frames can be rocking [12; 13]. Therefore, to examine whether the principals provided in the codes are adequate and sufficiently accurate for rack systems, it is worth investigating their performance under severe seismic ground motions. Although static and cyclic tests and analyses can reveal the failure mode of rack components [14; 15; 16; 17; 18; 19; 20] and the associated base shear of a rack structure, a more realistic structural response (such as acceleration) can be attained through full-scaled shake table tests [21]. One of the first shake-table studies on storage racks was conducted by [PERSON] et al. [22; 23; 24] who tested four types of full-scale industrial steel storage racks under scaled ground motions of El-Centro (ELC) and Parkfield earthquakes. The shake table tests demonstrated that the P-delta effects meaningfully influence the response of the racks in the down-aisle direction. In another shake-table study, [PERSON] et al. [25] tested five different rack frames in both cross-aisle and down-aisle directions and reported that the ductility and energy dissipation capacity of the frame were significantly more in the down-aisle direction than in the cross-aisle direction. A comprehensive shake table program was carried out at the University of Buffalo on four steel storage rack configurations, and it was stated that the rotational stiffness of beam-to-upright connections was significantly affecting the down-aisle performance of pallet racks under seismic actions [26]. In another  
Figure 1: Different rack failure mechanisms during the Christchurch earthquake: (**a**) down-aisle mechanism, (**b**) down-aisle mechanism, (**c**) baseplate deterioration in cross-aisle direction, (**d**) progressive collapse of the entire system.