採最佳化摩擦係數設計公式之隔震實務設計流程

Structural Isolation Design Procedure with Optimal Design Formula of Friction Coefficient

王勝宣(Sheng-Hsuan Wang) ； 蔡易佑(Yi-Yo Tsai) ； 鍾立來(Lap-Loi Chung) ； 楊卓諺(Cho-Yen Yang) ； 高培修(Pei-Shiou Kao)

《結構工程》 31卷3期 (2016/09) Pp. 62-81

https://doi.org/10.6849/SE.201609_31(3).0003

摘要

由耐震設計中反應譜的觀念得知，當結構系統之週期較長時，有較低之設計地震力。隔震系統乃呼應此觀念，藉由延長結構系統之週期來降低上傳之水平地震力。摩擦係數在摩擦消能隔震系統扮演相當重要的角色。摩擦係數過低或過高，皆會提高上傳之地震力，隔震層設計位移則是隨著摩擦係數提高而降低，因此摩擦係數之決定相當重要。然而，目前業界通常是仰賴經驗以決定摩擦係數，而非一套有系統之方法。此外，由於地震震度與震波形式之不確定性，結構物於使用年限之間有可能碰到尖峰地表加速度(peak ground acceleration, PGA)更甚於設計地震之大地震，或是具低頻特性之近斷層震波。因此，本文嘗試將本文作者所發表之摩擦係數最佳化公式融入業界習用之隔震設計流程，是為摩擦係數最佳化隔震設計流程。為驗證最佳化流程之效果，本文考慮一假想隔震案例，並以設計地震、1.5倍設計地震、近斷層地震當作輸入，執行歷時分析，來驗證隔震效果及隔震層位移是否超過隔震位移限制。分析結果顯示，最佳化設計流程於三種外力下皆能有效降低加速度反應，但當外力為非設計地震力時，位移反應可能會超過隔震位移限制，代表最佳化流程可能無法滿足需求，因此本文嘗試改變設計流程之邏輯。首先固定位移，而後直接代入非設計地震之反應譜係數進行設計，此為修正最佳化隔震設計流程。本文亦以假想隔震案例進行設計，再以非設計地震力當作輸入執行歷時分析。由模擬結果可知此修正設計流程具有不錯的減震效果，隔震層最大位移反應亦小於隔震位移限制。摩擦係數最佳化設計流程相對於業界現行之設計流程僅多增加一步驟，並不會大幅影響工程師之設計習慣，但卻能作為工程師選用參數的依據。而修正最佳化隔震設計不僅步驟簡潔且又針對非設計地震需求設計，故本文認為此流程可以信賴。

關鍵字

鋼筋混凝土 ； 開孔牆 ； 側力位移曲線 ； 剪力強度 ； 剪力變形

並列摘要

According to the concept of earthquake response spectrum, the structure which equips with isolation system reduces seismicforce by extending the period.For isolation design, the friction coefficient is one of the main design parameters. Based on the experience, the isolation displacement get lower with larger friction coefficient, however, the structural acceleration get larger with lower or larger friction coefficient.In the conventional isolation design procedures, the energy dissipation parameters, like friction coefficient, is not determined by some certain criteria but engineers’ practical experience. Because structure may suffer nearfult earthquake orearthquake of which intensity is larger than design earthquake. This article incorporates the optimal friction coefficient into isolation design process which called optimalisolation design process of friction coefficient. In order to verify effect of the process, the article choosesdesign earthquake, 1.5 times design earthquake and nearfult earthquake as input to do time history analysis in an imaginary case. The simulation result indicates that structural acceleration reduce effectively but isolation displacement may be larger than displacement limit except under design earthquake. Therefore, the article change design logicthat fixes displacement first and designs with non-design earthquake response spectrumto develop modified optimal isolation design process and chooses non-design earthquake as input to do the timehistory analysis in an imaginary case.According to the analysis results, the isolation displacement will be lower than design displacement andstructuralacceleration reduce effectively. Because the difference between the optimal design procedures of friction coefficient and the conventional one is insignificant, engineers will feel comfortable to adopt the optimal design procedures to determine isolation parameter. The modified optimal isolation process’s steps are concise and base on non-design earthquakeresponse spectrum, so the article refer the process as credible.

並列關鍵字

isolation systems ； frictional coefficient ； optimal design procedure ； isolation systems simulation