拡張Rayleigh減衰モデルの3次元骨組解析への適用

<p>Recently, large scale time history response analyses are increasing mainly due to the large improvement of computer performance. Since it is well known that the internal damping of many materials is comparatively frequency independent, the Rayleigh damping model is often used for such kind of analyses. However, the accuracy and the availability of the model are not high when the users want to fit the damping ratio from low to high frequency modes.</p><p>On the other hand, modal damping shows frequency independence in a wide frequency range, but since the damping matrix is dense, it is difficult to use due to the problem of storage area in large-scale analysis. </p><p>Hysteretic damping is known as damping that does not depend on frequency, but it is difficult to use it for time history analysis because of causal failure. However, recent studies have devised a causal hysteresis model that approximately satisfies the causality within a limited frequency range. Furthermore, as a more practical damping model with a reduced computer load, a damping model combining Rayleigh damping and causal damping was devised. </p><p>In this paper show its practicality and verify, Considering the application of frequency-independent damping to large-scale time history analysis that has not been feasible until now, comparing the required memory area, calculation time, and modal viscous damping with the classical damping model. </p><p>In order to confirm the validity and effectiveness of extended Rayleigh damping, this damping model is applied to a realistic building as an example, and the damping constant for each mode is evaluated from the free vibration analysis and seismic response analysis results. Based on the results, we first examine the fitness of the damping amount in the assumed adaptive frequency range using a simple multi-mass system model, then perform free vibration analysis, compare the response with the conventional damping model, and Benchmark test required memory area / calculation time.</p><p>As a result, followings were obtained.</p><p>1) For only horizontal or only vertical seismic motion, the accuracy and the availability of ordinal Rayleigh damping is not bad. However, for simultaneously horizontal and vertical or 3-dimensional seismic motions, the accuracy of ordinal Rayleigh damping is not enough.</p><p>2) On the contrary, the accuracy and availability of extend Rayleigh damping are confirmed for these seismic motions since its responses correspond well to those of modal damping.</p><p>3) For large scale models, computational load of extend Rayleigh damping are almost the same as that of ordinary Rayleigh damping and much less than that of modal damping.</p><p>4) From above, the availability of extended Rayleigh damping for large scale models are confirmed.</p>