Abstract
The loss of foundation characteristics is very important to predict the structure born sound in rooms. The level of the structure born sound is often evaluated in the plan stage of the building project and tends it to be demanded evaluation in a short time. A method of Yamahara that foundation is assumed to be no mass and to be rigid surface foundation is generally used in the evaluation of input loss of foundation. However, it is difficult to use the method of Yamahara as for the cases that long and thin foundations which in itself cannot consider to be rigid in comparison with the hardness of the neighboring ground. From the above a simplified evaluation method of soft foundations using an advantage of Yamahara's method is suggested. In addition, measurements of the input loss of foundation of three buildings excited by the railroad vibration were carried out and this method is applied to these measurement results and is confirmed the validity.
