Study on Stabilization Technology of Base Isolation Layer Using Air Floating Technology by Shaking Table Test

Abstract Japan is one of the world’s most earthquake-prone countries, and in facilities dealing with ultra-fine processing equipment, there is a focus on maintaining system functionality during earthquakes below a certain magnitude to prevent facility damage during major earthquakes. This emphasis aims to reduce downtime and production losses by minimizing equipment stoppages and facilitating restarts after earthquakes below a certain magnitude. To meet these performance requirements, the development of new seismic isolation technologies is being sought. While air floating units exhibit high vibration isolation performance against horizontal input, concerns have been raised about the stability of load support performance in the vertical direction [1,6]. To address this, additional spring elements have been introduced to maintain the load support performance of the air floating unit. However, there are concerns that the introduction of spring action may worsen the vibration conditions of the seismic isolation target due to rocking vibrations. This paper introduces additional spring elements to suppress rocking vibrations on the upper part of the air levitation unit and presents the performance evaluation results from vibration table experiments. As a result of adjusting the additional spring, it was confirmed that rocking vibrations could be suppressed even during simultaneous vertical and horizontal input, maintaining horizontal seismic performance. Additionally, the analytical model was validated against the experimental results, confirming the validity of the analytical model.