The values of vertical stiffness of piles using for the monolithic analysis of a building and its foundation to estimate the earthquake-resistant performance are usually lead from load-displacement relationships of static axial compressive or pile-toe load tests. This procedure is not proper for such an extreme short-period load as earthquakes, and it is necessary to exclude creep from the test results. Applied the same method proposed by Tominaga (2004) for lateral load tests, it is found that the average ratio of the value of vertical stiffness excluded creep compared with the value involved creep is approximately 1.92.
