The purpose of this study is to demonstrate the influence of human load on vertical dynamic characteristics of wooden floors. Free vibration tests for a wooden floor on which a person stood were conducted to measure the interaction force between the standing person and the floor. Shaking table tests changing frequencies and amplitudes reproduced vertical vibrations of wooden floors were conducted to measure the interaction force. The test results indicate, i). Human load mainly works as the damping force to wooden floors in the frequency range of 10Hz to 30Hz, as the phase difference of about 80 to 110 degrees between the displacement of floors and the interaction force occur; ii). The interaction force decreases in the frequency range of 10Hz to 30Hz, and the measured interaction forces are from 25 to 75% smaller than the product of the weight of the person and the acceleration of the shaking table; iii). Human loads hardly give the influence to the first natural frequency of wooden floors, as the phase difference of about 90 degrees and the deduction of the interaction force between the person and the floor simultaneously occur.
