Concurrent optimal design with application to structural dynamics

This paper presents a new methodology for multi-attribute design of structural dynamic systems. Utility analysis helps construct a design evaluation function that represents the designer's preferences and willingness to make trade-offs between conflicting design criteria. We demonstrate a technique for integrating qualitative design criteria into quantitative utility analysis. The methodology is illustrated through the design of an office building that is dynamically excited by rotating machinery contained within the structure. The competing design attributes are structural cost and the effect of vibration on the building's occupants. We describe a new technique for integrating into the design the qualitative criterion of ‘discomfort level'. Using information from the system transfer function and resulting displacement spec- trum, this technique uses a two-dimensional optimization problem with an equality constraint to minimize the maximum discomfort level. This analysis results in a quantitatively assessed measure of the qualitative description of comfort. The maximum of the multi-attribute utility function results in the optimum combination of occupant discomfort level and structural cost. The methodology presented here is general and can be applied to other design problems in structural dynamics; the technique described for integrating occupant discomfort into the design evaluation may be generalized to other qualitative design criteria.