穿孔樓版之振動特性

Abstract

本論文以有限元素法分析軟體ANSYS來建立穿孔樓版模型，在固定支承與簡支承兩種不同邊界條件下，以模態分析探討穿孔樓版之動態特性，針對不同版厚、開孔直徑、開孔位置與邊界條件找出結構自然振動的頻率及振動模態在這些變因下的變異狀況。 研究結果顯示：不論邊界條件、開孔直徑及開孔位置改變，所有模型的第一模態振動行為皆相同。第二與第三模態為重覆模態，振動行為相同，只是相差90度相位角，所以頻率也相同。在固定支承下，當厚度持續增加時，振態會由Z軸方向的變位轉變為XY平面方向的變位，如果振態為Z軸方向的變位時，頻率隨厚度增加而增高，如果振態為XY平面方向的變位時，振動頻率幾乎維持定數不變。在簡支承下，當厚度持續增加時，振態甚至於會轉變成XY平面的扭轉現象，此時頻率則隨厚寬比增加而下降。開孔位置與大小的改變對於模態頻率影響不大。

The purpose of this thesis is to study the vibration characteristics of floor with hole at different design parameters. The effects of design parameters , such as boundary condition , thickness , diameter and position of hole. The finite element model of the floor with hole is created by the use of ANSYS computer program. The results show that whatever parameters changed, the first mode are the same. The second mode and the third mode have the same frequency and the behavior of the vibration . For fixed condition, the mode shape is changed from Z axis direction motion to the motion in XY plane with the increase of floor thickness. When the floor vibrate in Z axis direction, vibration frequency increases with the increase of floor thickness. The frequency keeps constant for the motion in the direction of X-Y plane with the increase of thickness. For hinge condition, torsional motion in XY plane occurs with the increase of thickness. In this case frequency is decreased with the increase of thickness. Other parameters has no significant effects to the dynamic characters of floor.