LAUSR

State-of-the art medical & material science imaging technologies are pushing the limits of ground vibration tolerance. Modern technical instruments such as Transmission Electron Microscopes are calling for tighter functional vibration limits far below the threshold of human sensitivity and at lower and lower frequencies to facilitate analysis of details on the scale of individual atoms. In one particularly demanding case, an instrument proposed for a university research building called for vibration levels not to exceed 50 µ-in/s at frequencies as low as 1 Hz, and this instrument would be needed while heavy construction is ongoing at nearby surrounding properties. Meeting this strict criterion without limiting the use of the surrounding land required special low-noise instrumentation, an in depth geotechnical analysis of the site, and a comprehensive isolation scheme to achieve up to a 95% reduction in ground vibration. This paper will discuss the steps taken to evaluate the site vibration conditions and ...