Online information source for semiconductor professionals

Michael Willford, Arup, London, UK,
Caroline Field, Arup, San Francisco, USA

ABSTRACT

The development of sophisticated semiconductor technologies requires ultralow vibration research and production environments. Human footfall is a significant source of vibration and if its effects are not assessed accurately during the design of a facility the workspaces may be rendered unusable for sensitive equipment. In view of the importance of achieving an adequately low vibration environment in modern facilities it is perhaps surprising that the design methods employed by most structural and vibration engineers comprise very simple and semiempirical hand calculations based on research available in the 1970s. In order to provide clients with greater confidence in the performance of their structures Arup has developed new and more accurate ‘performance-based’ prediction procedures incorporating recent comprehensive experimental research into footfall forces, and taking advantage of the capabilities of modern design-office computer software. The new methods are not limited by the approximations and inaccuracies inherent in the old empirical approaches, and extensive calibration against field measurements has shown them to be far more reliable than other methods currently in use. Use of these methods can also bring substantial cost benefits in some cases.