COLLAPSE STRENGTH PREDICTING METHOD

A collapse strength prediction method of a steel pipe includes deriving a prediction equation indicating a relationship among D/t obtained by dividing an outer diameter D (mm) by a thickness t (mm), material characteristics, a collapse strength dominant factor, and a collapse dominant proof stress (σ) of the steel pipe using a plurality of reference steel pipes collapse whose strengths have been obtained in advance, obtaining D/t, material characteristics, a collapse strength dominant factor, and a predicted collapse strength of a steel pipe that is an evaluation subject, obtaining a compressive stress-strain curve in a circumferential direction of the steel pipe that is the evaluation subject, obtaining a stress that causes a permanent strain to be generated in the steel pipe that is the evaluation subject as the collapse dominant proof stress on the basis of the compressive stress-strain curve, and computing the predicted collapse strength of the steel pipe that is the evaluation subject from the D/t, the material characteristics, the collapse strength dominant factor, and the collapse dominant proof stress, which have been obtained, on the basis of the prediction equation, and the permanent strain is set according to a value of the D/t of the steel pipe that is the evaluation subject.