| Abstract | Aseismic design is handicapped by a lack of statistical knowledge of earthquakes and the difficulty of analyzing the response of a complex frame to these irregular forcing functions. Structures subject to earthquake motion present a complex picture of linear and non-linear vibration. An explicit solution in terms of the participation factors of the modes and spectrum of the earthquake is useful when considering linear vibrations of the structure but the introduction of non-linearities such as friction and plastic yielding make this approach untenable. The general complexity of both linear and non-linear cases has led to the simulation of structures by various mechanical and electrical models. These models are highlyidealized and, in general, simulate only the major motions of the structure such as shearing, bending, and rocking of the structure on its base. Mechanical modellhg produces satisfactory results but suffers from complexity and lack of versatility. Further, it is difficult to apply to a mechanical model, which is necessarily not small, a prescribed forcing function as complicated as that of an earthquake. On the other hand thismethod has the advantage that the structure may be more faithfully modelled than by other means. Electrical models of various types have been made and have the advantage that their parameters may be readilychanged over large ranges and measurements recorded by convenient instruments. |
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