This paper discusses methods that were developed in the period 1955-1957 in the analysis of wave force mea¬surements;on a 30-inch diameter test pile in a water depth of 40 ft. in the Gulf of Mexico. Procedures for reducing the raw data to a form suitable for digital computer opera-tions are outlined. Measurements of wave elevation n (t) at the pile, obtained by motion picture camera, were suc¬cessfully checked with measurements of vertical reaction Rz(t) on the double-hinged pile, suitably adjusted by a numerical frequency response operator technique. Numeri¬cal filter techniques were used to erase unwanted vibrational frequencies from the records and frequency response oper¬ators used also to derive horizontal velocity and acceleration components (at the level of action of total force) from the records of rf(t) . It was found, however, that calculations of total force based on the measured horizontal reactions at the two supporting hinges clearly could not correlate with 77 (t) . This led to a search for identification of confusing wave systems which ultimately appeared to reveal themselves as independent wind sea and swell bearing at an angle of 57° 30' to each other. The use of an equivalent force, Fe(t) , for correlation with the velocity and accel¬eration components derived from 17 (t) , is finally justified by a pilot analysis of synthetic data, from which it was found possible to recover from the analysis technique the values of drag and inertial coefficients input into the syn¬thetic data. Presentation of over-all analysis results of the field data is reserved for a subsequent paper.
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