How the O-Cell® Works

The award winning Osterberg Cell, or "O-Cell', gets its name from the inventor, Dr. Jorj O. Osterberg. The O-cell is a hydraulically driven, high capacity, sacrificial loading device installed within the foundation unit. As the load is applied to the O-cell, it begins working in two directions; upward against upper side shear and downward against base resistance and lower side shear (if applicable). By virtue of its' installation within the foundation member, the Osterberg Cell load test is not restricted by overhead structural beams and tie-down piles. Instead, the O-cell derives all reaction from the soil and/or rock system. End bearing provides reaction for the skin friction portion of the O-cell load test, and skin friction provides reaction for the end bearing portion of the test. Load testing with the O-cell continues until one of three things occurs: ultimate skin friction capacity is reached, ultimate end bearing capacity is reached, or the maximum O-cell capacity is reached. Each Osterberg Cell is specially instrumented to allow for direct measurement of expansion. Accordingly, along with compression and top of pile shaft measurements, the downward end bearing movement and the upward skin friction movement are known. O-cells range in capacities from 75 tons (150 kips) to 5,000 tons (10,000 kips). By using multiple O-cells on a single horizontal plane, the available test capacity can be increased to more than 30,000 tons (60,000 kips). By utilizing multiple O-cells on different planes, distinct elements within a shaft or pile can be isolated for testing. Using the O-cell, LOADTEST has elevated the application of deep foundation load testing, from expensive, time-consuming, small scale field tests to state-of-the-art, short-duration, full scale load testing of production shafts and piles. Patent US5,576,494