Resistance Pier Applications
Resistance Piers are used primarily for underpinning and the repair of residential and commercial buildings, retaining structures and slabs. They can be installed in either interior or exterior locations. They have been used to repair equipment and machinery foundations, warehouse buildings, tower foundations, etc. Special remedial repair brackets can be connected to either the bottom or side of an existing foundation. They can also be connected to the sides of circular or flat building columns.
Resistance Piers not only stop settlement, but can also be used to raise the structure, thus closing cracks and correcting other structural flaws resulting from settlement and/or ground movement.
The design process should involve professional engineering input. Specific information involving the structure, soil characteristics and foundation conditions must be evaluated and incorporated into the final design.
Resistance Piers from MDTI
For Resistance Pier applications, MDTI supplies the Atlas Resistance Pier which is a manufactured, two-stage product designed specifically to produce structural support strength. First, the pier pipe is driven to a firm bearing stratum; then the lift equipment is typically combined with a manifold system to lift the structure (if required). This procedure provides measured support strength.
Piers are spaced at adequate centers where each pier is driven to a suitable stratum and then tested to a force greater than required to lift the structure. This procedure effectively load tests each pier prior to lift and provides a measured Factor of Safety (FS) on each pier at lift.
Workspace is not normally a problem when using Atlas Resistance Piers. They can be installed using portable equipment in an area that measures approximately three feet square. The pier may be installed from the interior or on the exterior of the footing.
Pushed Pier Systems History
The history of piling systems extends back to the ancient Greek, Roman and Chinese societies. Although numerous methods and materials have been utilized throughout the centuries, modern construction methods and practices have mandated the repair and remediation techniques of today’s structures. The use of excavated foundations, footings, walls and beams, although providing adequate support in some soil conditions, have proven to be less desirable in a multitude of soil and site profiles. Fill areas, compressible soils, organics and expansive soils offer a greater challenge in the long term stability of foundations and are an underlying cause of billions of dollars of structural remedial repairs worldwide. The need for deep foundation underpinning systems increased dramatically in the 20th century with the building booms and growth in metropolitan areas.
In 1896, Jules Breuchaud, a contractor and civil engineer residing in New York, patented an “improved method of underpinning the walls of existing buildings” by a system of driving hollow, tubular column sections to bedrock or other firm strata using hydraulic jacks and a transverse beam system. Two sets of columns driven at opposite sides of the wall and beneath a transverse beam or beams utilized “the superincumbent weight of the building to resist the pressure of the hydraulic jacks, whereby the latter exerts a very powerful force in driving the column sections to bearing strata”. This method allowed for permanent or temporary support and raising or lowering of structures by patent definition.
In 1897, Richard S. Gillespie, another New York entrepreneur, patented a similar method of underpinning existing buildings by means of a reaction, or “pressureresisting” column that provided the reaction force to drive “cylindrical columns” using a system of cantilevered beams, tie-rods and hydraulic rams restrained to the reaction column to allow for sinking pipe sections to bearing strata for support. This cantilevered approach allowed for placement of pipe supports beneath the
middle of the building wall in lieu of the twin-column method developed by Breuchaud and also provided a method for driving deep foundation piles for new construction.
Another substantial advancement was developed and patented by Lazarus White, again of New York, in 1917. White addressed long-term stability issues encountered in previous similar methods by introducing the practice of pre-loading or as he termed it “the first or temporary load” encountered from the reaction during pushing the pipe against the structure load to a pre-determined capacity equal to 150% of the required load which is consistent with the installation methodology ATLAS RESISTANCE® Piers use today.
Additionally, White also documented theories of the soil “pressure bulb” created at the pile tip which assumes compression of the soil beyond the periphery of the pile for contributing to “a load in excess of that attributable to the resistance of the
area of the end of the pile”.
One early documented adaptation incorporating the use of a steel, eccentrically loaded bracket with pushed piles as a load transfer method was revealed in a 1959 patent application by Guy Henry Revesz and Jack C. Steinsberger of Illinois. This patent, which was recognized in 1961, cited references to the early work of Breuchaud and Gillespie. The method of 150% pre-loading which was prevalent in the White Patent of 1917 is also a standard criterion in this 1961 patent methodology. Numerous similar patents for pushed or jacked piers surfaced in the 60’s and 70’s, further extending the work of these early pioneers.