The foundation slab of the four-cell box girder provides a basement area for locating the blow-down and other accumulators for the servo-hydraulic actuators, access to the underside of the tie-down floor for the anchoring of test fixtures, and general storage. Headroom in the basement is about 8 ft, and the space is used to run electric power and hydraulic lines to and from experimental equipment on the floor above. The basement also houses an experimental preparation area.
Hydraulic hardlines feed the laboratory from an external pump house just outside the southeast corner of the building. Also, seven ports along the centerline of the laboratory floor provide access to feed, return and drain lines to reduce the need for long runs of hydraulic hose.