The Berkeley Art Museum and Pacific Film Archive: Saving a Local Landmark with an Innovative Underpinning Solution

摘要

The new home for the Berkeley Art Museum/Pacific Film Archive (BAM/PFA) combines a challenging adaptive re-use with an extensive downward and outward expansion of a 1930s-era printing press facility in the middle of downtown Berkeley, California. Degenkolb Engineers served as the Construction Means and Methods engineer on the project, working with general contractor Plant Construction, L.P. and shoring sub-contractor Condon Johnson and Associates, Inc. to help the construction team get from Point A (existing conditions) to Point B (new facility). The most challenging aspect of the project was the underpinning of the Admin Block, a three story, 20,000 square foot existing concrete structure that would be used as offices for the new museum. Programming for the new facility required up to 30 foot excavations adjacent to and beneath the existing structure, resulting in the need to underpin most of the structure and suspend it high above the construction site. Degenkolb devised a system of (18) 50-foot long W36×300 "Needle Girders" running through the building's first floor windows with threaded rods and spreader beams dropping through the first floor to cradle the building from below. The Needle Girders spanned to drilled piers flanking both sides of the building. The piers served the dual purpose of providing both gravity and lateral support to the Admin Block during construction, ensuring that the building would neither settle under its own weight nor translate laterally from differential soil pressures, nor from a wind or seismic event. Degenkolb's innovative underpinning design and associated jacking sequences allowed Plant to gently lift the Admin Block off of its existing supports, perform excavation and construction activities beneath the building, and safely set it back down on new foundations with minimal complications.