TRANSDUCERS FOR MEASUREMENT OF PILE FORCES

An aluminum load cell was designed and constructed for the purpose of measuring the peak force that is developed at the top of a pile during driving. The load cell can be used on square concrete piles up to 16-in. (410-mm) square. It contains 9 sensing elements distributed over the active area to accurately measure inclined or eccentric loadings. The load cell is relatively lightweight and portable, and was designed to interface with an electronic peak force readout unit that was designed and constructed on an earlier project. An alternate peak force transducing means was model tested in the laboratory and field tested on full-scale piles. The method utilizes encapsulated electric resistance strain gages rigidly bonded to the exterior pile surface with a rapid-setting epoxy. Test data consisting of driving records and maximum pile forces at the pile heads are presented for four 55-ft (17-m) long piles driven in soft silty clay. An example wave equation problem is presented to illustrate the application and use of the measured peak force. /Author/