A dynamic horizontal loading system based on the wave theory was developed as a new on-site pile testing method. In this test method, the horizontal resistance of piles is calculated by applying an impact load in the horizontal direction to the pile heads using a hammer and conducting wave motion analysis of the measured acceleration and strain. A series of dynamic horizontal loading tests of steel-pipe piles was conducted and results were compared with those of a static horizontal loading test conducted at the same site. It was shown that the relationship between the load and pile displacement and the coefficient of horizontal subgrade reaction obtained by the dynamic horizontal loading test has relatively favorable compatibility with the values from the static test.
