Prof. Ing. Carlo Andrea Castiglioni Seismic Behaviour of Steel ...

Seismic behaviour of steel storage pallet racking systems . 131.1.4 Damage reported in the 1992 Landers earthquakeThe Landers earthquake, with a moment magnitude (Mw) of 7.3, occurred on June28, 1992, at 4:57 a.m. at a depth of 17.2 km. The epicenter was located near thetown of Landers in the high desert area of California about 190 km east ofdowntown Los Angeles. Because of the remote location, there was only one storewith storage racks accessible to the public located in the area of severe groundmotion. A relatively new Builders Emporium (opened two to three years earlier) waslocated very close to the epicenter, less than 100 meters from the fault rupture zone.The building was heavily damaged. Girders broke away from their anchorages in thewall columns and, in some places, battered their way through the walls. The ledgerswere almost completely destroyed. Unanchored gondola shelving units were notseriously damaged and were placed back into service, but a great deal of smallmerchandise fell from the shelves and, in some cases, the units “walked” over 30 cmfrom their initial positions. Many small items also fell off storage racks, but itemsmore than 60 cm in plan dimension (e.g., roof ventilators and HVAC pipes) stayedon the racks regardless of the height at which they were stored.1.1.5 Damage reported in the 1994 Northridge earthquakeThe Northridge earthquake, with a moment magnitude (Mw) of 6.7, occurred onJanuary 17, 1994, at 4:31 a.m. at a depth of 17.6 km. The epicenter was located inReseda in the San Fernando Valley. Because of the fault orientation and rupturedirection, ground motions were at or above design levels in the north end of thevalley and were just about code design levels in Santa Clarita, about 16 km north ofthe valley.Price Club, Northridge, California.No damage was observed except for the “soda wall” racks (storage racks fullyloaded with cases of soft drinks), which had failed longitudinally. It is believed thatthis failure resulted when floor-stacked merchandise toppled over and hit the racks,inflicting heavy damage, in fact identical racks standing nearby with the same orheavier loads were undamaged.Home Depot, Santa Clarita, California.This store was opened a few days before the earthquake occurred. Several bays ofracks failed completely in the cross-aisle direction, and there was also a considerableloss of contents (see from Figure 1.14 through Figure 1.20 courtesy of FEMA).