This seven-story university building is located in Northeast Arizona. The large structure was constructed utilizing large belled concrete piers drilled down 12’ below grade with intersecting grade beams between the columns.
A major leak in the water supply system allowed the building to fail at the columns and created an upheaval in the floor slab system.
Working with a local General Contractor, Power Lift installed 330 steel pilings on existing and newly built structural beams installed in the lower level. We needed to add load bearing capacity to the original concrete columns and add support for the 8” structural slab to be repoured. Several tons of rebar reinforcing was added to the structure incorporated in the new beams and floor slab.
Soil borings indicated that sufficient bearing was located at 45’. Final depths ranged from 45’-50’.
The excessive loads handled by the overhead crane system and the relatively weak load bearing soils, added to the already failing foundation system on this structure. There is an obvious deflection in the roof system just above the air compressor.
A massive excavation was completed to expose the load bearing columns and intersecting grade beams. The overhead crane was loaded to its maximum capacity and set above each pier location during the installation process.
The main structure was raised 1”-2” with select columns in the loading bay area being raised as much as 5.5”. Intersecting grade beams were subsequently piered and lifted to stabilize the entire system. Notice the alignment of the roof system after the lift.
The inspection and elevation study performed on the building revealed settlement of the east exterior wall and failure of the interior columns designed to support the roof loads. Elevation losses of up to 12” were found associated with the interior columns. The east exterior wall was piered, raised back into place, and stabilized.
Our focus then turned to the interior roof columns. Piers were driven on each side of the support pad on the affected columns. Five interior columns were raised simultaneously from 4” to 10.75”.
The roof had to be monitored during the lift process to re-establish the proper grade to the roof drains.
The columns were raised independently of the floor slab. The interior floor slab was pressure grouted to fill the voids and raise it more than 12”. More than 50 cubic yards of grout was pumped under the floor slab to accomplish this step in repairs.