Abstract:

Damping ratio testing method of a foundation was studied theoretically and experimentally based on the corresponding Chinese measurement and design codes. It is shown that there is a relatively large difference between numerical results of codes and approximate formulae based on elastic half-space analytical solution. Therefore, six-degree-freedom time histories of the center of mass center of a foundation are calculated from three-component vibration curves of some points on the foundation surface to be selected as the analytical time-history of some dynamic parameters such as compressive stiffness, rotational stiffness, shearing stiffness, torsional stiffness, damping ratio and mass of vibration of subsoil. It is recommended that the vibration sensors should be pre-embedded in some proper positions of the foundation bottom surface to improve the precision of subsoil dynamic parameters measurement.

Key words: subsoil damping ratio, measurement method, motion of mass center, time-history