TxDOT Research Library - Publication Details

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Title:

The Osterberg CELL for Load Testing Drilled Shafts and Driven Piles

Authors:

by Jorj O. Osterberg

Published:

1995

Washington, DC

United States. Federal Highway Administration

Type:

Hard copy + Online document

1 volume (88 pages)

Online Access:

https://ntrl.ntis.gov/NTRL/dashboard/searchResults...

Access Note:

2.9 MB

Summary

The Osterberg Cell (CELL) technology is a new concept of load testing conceived to revolutionize conventional deep foundation load testing, facilitate future refinement of design methods, and realize significant cost savings. Instead of applying a downward load at the top of a drilled shaft or pile, the load is applied at the bottom, using the shear resistance on the shaft's side as a reaction to the downward end bearing load. A specially designed CELL placed at the bottom expands as hydraulic pressure is applied. No surface reaction system in needed because, at any pressure, upward force is always equal to downward force. The pressure is increased until the shaft or pile reaches its ultimate capacity in side shear resistance, end bearing, or both. From an applied pressure-total load calibration, the upward and downward force is obtained for any applied pressure. A tell-tale extends from the CELL bottom to the ground surface and measures the downward movement of the bottom of the CELL, from which the end bearing load-deflection curve can be plotted. A dial at the top of the shaft and/or a tell-tale at the top of the load CELL measures the upward movement of the shaft, from which the side shear load-deformation curve can be plotted. CELLs as large as 1.2 m (4 ft) in diameter have been used, and load tests to an equivalent top load of greater than 53,400 kN (6,000 tons) have been performed. Installation, testing, results and the types of applications are discussed in the text. Descriptions of many job applications are given in the appendices. Calibration and accuracy of the CELL and test methods are reviewed. Advantages and limitations of the CELL are compared to conventional load testing methods.

Publ. Place

Washington, DC

Notes

"February 1995"