XL Construction Nearly Moves Mountains for Lockheed: XL Relocates Massive Structural Test Stands and Constructs a Towering High Bay to House the Test Stands
XL Construction vividly demonstrated its creative problem-solving skills when faced with a monumental project from long-time client Lockheed Martin. The goal: Construct a 125-foot tall single-story high bay, then relocate and reinstall two structural test stands – one weighing 250,000 pounds, the other 280,000 pounds – inside the newly constructed high bay. The problems: To support the massive test stands, the facility had to be supported and anchored into the muddy soil of the San Francisco Bay, and the test stands, located across the Lockheed Martin campus two miles from their new home, were too heavy to be moved by any conventional means.
First, the Building
XL Construction
built a new 32,000 s.f. building including a 13,000 s.f. 125 tall high
bay to serve as Lockheed's Structural Test Area (STA) facility. The
high bay is designed to house the reaction floor and two test stands
used to conduct structural and dynamic testing of spacecraft,
components, and ground support equipment. A 30-ton overhead bridge
crane with a 110-foot hook height and a span of nearly 69 feet covers
the entire high bay. Four additional 3-ton jib cranes in the high bay
also support the test stands.
Reaction Floor
The high bay's 40 x 65-foot
reaction floor has seven 60-foot-long beams located 5 feet apart. The
beams – designed to support a rated load of 12,000 pounds per foot –
were embedded in a base slab of 5-foot-thick reinforced concrete
supported by 40 piers 2 feet in diameter and 40 feet deep.
Test Stand Base Assemblies
The foundations for the Test Stands consist of an 11 foot deep base
assembly on top of drilled piers, or caissons. In addition, crawlways
were required under the base assemblies to enable Lockheed engineers to
make adjustments to the testing equipment.
The base assemblies were created by forming underground chambers with nearly 1,500 tons of steel plate girders that were ultimately filled with 308 cubic yards of concrete. The concrete – equivalent to 31 truckloads – was poured through 2-inch holes in the top steel plate from 8:00 p.m. one evening until 6:00 a.m. the next morning. (The holes were later plugged with steel bolts.)
Because the base assemblies and crawlways were below the water table in the muddy bay ground, XL Construction crews had to shore the excavation and dewater the site at a rate of 750,000 gallons of water per day each day, for nearly two months to accomplish the construction.
Test Stand Base Plate
The test stand floors were finished with a 4-inch thick, 24-foot-square
steel plate finished to a near-zero level of flatness – and installing
this plate became a project in itself. The plate arrived in five
sections: two for one test stand, three for the other. A robot welded
the sections together using a submerged welding method. Each joint took
121 passes, and the robot could complete 17 passes in one day. A total
of 2,100 pounds of welding wire was used to complete the job. Grinding
the plate enabled XL Construction to achieve the flatness standard
required for the rigorous tests that Lockheed conducts.
Once the high bay was completed, the final challenge was to move the two structural test stands, 70 feet and 60 feet tall and weighing 250,000 to 280,000 pounds, from across the Lockheed Martin campus and into the new high bay. The test stands were hydraulically lifted onto rails and moved out of the existing building. Two cranes tied together then lifted the test stands and slowly moved them into place in the new building.
With the new test stands installed in their brand-new high bay, Lockheed Martin has been able to conduct important testing for a variety of critical programs.
