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3. Engineering Review of Tanks & Equipment Covered by CalARP Program C:\TRICH\Jobs\4515582 Leprino Tracy\Report\Leprino Tracy CalARP 040221.docx 3-14 Seismic capacities of the equipment anchorage were calculated. The approach is to estimate the earthquake level at which the demand shown on the left side of Equations 3-1 and 3-2 will exceed the capacity of the component under the particular failure mode. As existing equipment, we have used the design basis earthquake ground motion along with importance factor of I=1.0 to determine the seismic demand on the equipment. 3.4 Seismic Evaluation of the Building The QLC Engine Building has a plywood roof over 2x wood joists, which are in turn supported by wide flange steel girders to the concrete block walls. Blocking and straps centered below the blocking was observed along the north and south walls, perpendicular to the joists, to provide anchorage of the north and south masonry walls. The steel girders are also supported by these two walls and anchorage is expected at the girders. The joists appear to be attached to the east and west walls and have enough length to develop seismic forces into the roof. The Main Engine Building has a metal deck roof supported on steel girders and steel wide flange column with concrete block perimeter walls. Although most equipment in the Main Engine Building is newer than the 1988 UBC, the 1973 pumps indicate that if they weren’t moved from somewhere else, the building may be much older than the 1988 UBC. Drawings and years of construction were not available for either building. The age of the equipment is not a good indication of structure age as all of the equipment in a building may have been replaced or may have come from an older building. Equipment generally does not tend to last as long the buildings housing it. The key to these structures performing in earthquakes exceeding the design level earthquake is the attachment of the roof framing to the masonry perimeter walls. This would require review of the original drawings and any retrofit drawings. In the event of an earthquake ground motion that has a mean return period of 475 years strikes the ammonia machine buildings, some roof members and the roof membrane may be damaged slightly, but a release of ammonia is not expected.