Response of primary-secondary systems to short-duration, wide-band input

This paper examines systems consisting of a primary structure supporting a relatively light secondary structure. The primary structure may be a vehicle or a building, and the secondary structure may be equipment, instruments or a tuned mass damper. The paper shows that the response of such systems to short-duration, wide-band loads can have unusual and undesirable characteristics. To understand these characteristics, simple closed form expressions are derived for the response. These expressions show how the maximum secondary response, the response for small time, and the effectiveness of tuned mass dampers are related to the basic physical parameters of the primary-secondary system. It is found that the response characteristics for short-duration inputs are fundamentally different from those for long-duration inputs.