傾斜滑動支承之理論分析與實務應用

Abstract

近年來，越來越多建築物加裝隔震系統以提高耐震能力，並降低結構物於地震下的加速度反應。目前常見的隔震支承墊主要分為三大類：類彈簧支承墊、滾動式支承墊以及滑動式支承墊。大部分的支承墊都是線性系統，因此上傳加速度會隨著位移增加而增加。為了控制支承墊上傳的加速度大小，一種新式隔震支承墊—傾斜滑動支承隨之誕生。傾斜滑動支承由上支承版、下支承版以及兩支承版之間的滑動子所組成，它最大的特色就是具有固定的最大上傳水平加速度以及摩擦消能機制。 本研究提出了簡化與精確的運動方程式，並分別利用兩公式建立了模擬方法，經由數值分析去探討簡化公式所忽略的項次所造成的影響。另外，本文也利用實驗資料驗證簡化與精確公式的模擬效果。結果顯示，精確公式能夠更精準的預測傾斜滑動支承的實際運動。除此之外，本研究尚探討了其他影響傾斜滑動支承行為的影響因子，包括垂直向輸入震動以及碰撞效應。其中，垂直向輸入震動對傾斜滑動支承的水平加速度反應有很大的影響，而碰撞多為高頻反應，對上部結構物的損害或許不大。 基於實務應用方面的考量，本文提出了一套設計傾斜滑動支承的設計流程，以及使用商用軟體模擬傾斜滑動支承的方法。利用這套設計流程與方法，設計了一傾斜滑動支承，並使用SAP2000模擬其在地震下的反應，與摩擦單擺支承的隔震行為比較。由模擬結果可看出在所選的地震下，傾斜滑動支承能夠有效控制位移反應，且其最大加速度反應與輸入震波無關。

Seismic isolation system is a great solution to reducing the acceleration responses of buildings under earthquakes, and it has been widely-used over the past decade. There are three types of isolation bearings that are most common nowadays: elastomeric bearings, rolling-type bearings and sliding-type bearings. However, most of them are linear systems which cause acceleration increases with displacement. In an attempt to control the transmitted acceleration, an innovative isolation bearing system called sloped sliding-type isolation bearing (SSB) is introduced. The isolation bearing is comprised of an upper bearing plate, a lower bearing plate and a slider sandwiched between two plates. It features a constant transmitted horizontal acceleration and friction-based energy dissipation mechanism. In this study, simplified and general equations of motion are derived and analysis program is developed. The influences of the simplification assumptions are numerically investigated. Moreover, the accuracy of both equations are also experimentally verified. The results indicate that the general equations predicts more successfully than the simplified equations. In addition, the key factors, which include input vertical excitation and pounding, in the SSB dynamic behaviour are examined. It is concluded that the input vertical excitation affects the response horizontal acceleration greatly, and that the pounding-induced responses are high-frequency, which may have little impact on the superstructure. A design procedure of the SSB system is proposed to enable practical application of the isolation bearings. Furthermore, a model that can be easily applied to most commercial software is proposed as well. The seismic isolation performance of the SSB is then compared to that of the FPB using SAP2000. The simulation results suggest that the displacement responses of SSB is well-controlled under selected excitations and that the response acceleration of SSB is independent of the input excitations.