A METHOD FOR ESTIMATING STATIC ELASTIC PILE-HEAD SPRING USING THE IMPULSE RESPONSE EXCITED BY HUMAN POWER

Abstract

Recently, there are few construction works in vacant lot. Many construction works take place after demolishing the existing building. In such case, reuse of the existing piles is reasonable. We need a way to verify the performance of the existing piles for reuse. Therefore, in this paper, we proposed a simple method for estimating the static elastic pile-head spring using the impulse response excited by human power. We also proposed a simple method to simulate the impulse response of the pile-head. The steps for the proposed estimation method are as follows: 1. Attach the accelerometer to the target pile-head. 2. Hit the pile-head with an impulse hammer to obtain the time series data of the input and response of the pile-head. 3. Calculate the impulse response of the pile-head by using the data. 4. Pile-head spring we want is the reciprocal of the impulse response. Dynamic model proposed to simulate pile-head response is a beam-on-Winkler-foundation considering its own inertial force. Assuming homogeneous subgrade and applying some boundary conditions to the model, closed-form solutions of pile-head response can be obtained. By using these solutions, we can simulate the pile-head response easily. As a verification examination, we compared results of the proposed methods with results of static load tests. We conducted the examination on a total of five piles at three locations. As a result, we confirmed that the results of proposed methods agree with the results of static load test.