Tangent Modulus of Piles Determined from Strain Data

When evaluating measurements of strain or telltale shortening of a pile subjected to loading test, precise knowledge of the 'elastic' modulus is necessary. By means of plotting and analyzing the increment of load (or stress) over the increment of strain versus the strain, i.e., the tangent or chord modulus of the stress-strain curve, the modulus can be determined. The paper provides the mathematical background to the analysis and presents examples of the method.