|摘要: ||台灣近年來經濟急速起飛，導致社會高度都市化，人口多集中都市地區，再加上都市用地面積有限，在經濟效益之考量下，建築物有愈蓋愈高的趨勢。由於結構物的高度增加，使得其勁度較一般建築為小，當受到風力擾動時，往往會造成過大的結構反應，尤其高層建築反應更容易與風場形成互制時，對安全將造成嚴重威脅。台灣屬於海島型氣候，颱風及季風一年四季交替發生，風害對高層建築具有潛在的威脅，如何減低高層建築受風力作用時所產生的振動問題實為目前工程界亟須解決的要務。 隨著風工程的發展，對於高層建築而言，橫風向反應因渦散現象引起之非線性氣彈力影響，尤其是理論與實驗資料之關連性建立仍在發展中。眾所皆知，設計高層建築時應盡量避免產生橫風向共振鎖定，因此大部分的文獻皆在討論風速未達產生共振鎖定之前的行為。為更進一步釐清在臨界風速下之共振鎖定現象，本研究之主要目標為探討其產生之物理機制，並在假設合理之理論模型下配合必要之風洞試驗資料，建構不同斷面外型之高層建築結構在共振鎖定時之氣動力參數資料庫，並提供必要之反應預測法，以作為爾後業界設計時之參考 本計劃共分三年進行，第一年(2010/8-2011/7，前年度)之主要工作為在前導期研究之基礎上，利用所導得之解析解(Scanlan理論模式)及氣動力參數識別流程，進行一系列不同二維斷面模型在達共振鎖定時之氣動力參數識別，同時探討廣義Van der Pol理論模式(Generalized Van der Pol Oscillator，GVPO)與Scanlan理論模式之異同(目前已完成，見第一年研究報告)。根據此二維理論模型與解析解為基礎，第二年(2011/8-2012/7，去年度)之主要工作為推導三維高層建築模型(單一自由度之剛性模型)在達共振鎖定時之理論模型與解析解，以及其對應之氣動力參數識別流程，並進行一系列不同斷面之三維高層建築模型在達共振鎖定時之氣動力參數識別(目前已完成50%)。第三年(2012/8-2013/7，今年度)之主要工作為以模態分析法建立一套預測方法，稱為間接預測法，藉由第一年研究內容所得到之二維斷面模型氣動力參數來預測三維高層建築模型之反應。 本研究近程且最直接之研究目標是建立二維斷面模型與三維高層建築模型在達共振鎖定時之氣動力參數資料庫，遠程目標則是第三年之主要研究內容，亦即建立藉由二維斷面模型氣動力參數來預測三維高層建築模型反應之準確間接預測法。預計成果無論對學界或業界結構設計將有所助益。|
Due to the economical development of Taiwan in the past decades, the modernization renders to the rapid population growth in cities, and further facilitated more and more construction of higher buildings in many urban areas where the space is highly limited. Because of their stiffness lessened, these buildings become more susceptible to wind excitation. Especially for high-rise buildings in which the excessive responses are even interacted with the wind flow, the so-called aero-elasticity forms. Therefore, searching a possible solution to relieve the threat of wind hazard to high-rise buildings in Taiwan, where is even located in the typhoon-prone region, is inevitable and compulsory. According to the recent development in wind engineering, the researches on the across-wind effect, in particular the theoretical link with experimental data, are still remain challenging. It is well recognized that the resonance and lock-in effect in the across-wind motion of high-rise buildings should be mostly avoided, which initiate many building designs that mainly focus on the response before the lock-in stage. However, to better understand the behavior of across-wind resonance and lock-in, this study aimed at investigating its mechanism by adopting conceivable theoretical models to identify the aerodynamic parameters through wind tunnel tests (such as aerodynamic damping and stiffness), and developing an accurate method to predict the response of the high-rise building near lock-in as well. The data base of the aerodynamic parameters and the prediction model obtained can be used as useful guidance for the industrial applications. This project is scheduled to be completed in three years. The tasks in the 1st year (2010/8-2011/7) is to identify the aerodynamic parameters of a series of 2-dimensional section models near lock-in based on our preliminary study on the theoretical model, analytical solution (called Scanlan model) and the corresponding identification scheme. Meanwhile, another theoretical model called generalized Van der Pol oscillator (GVPO) and its corresponding identification scheme will be also investigated. This part has been completed and published in the 1st year report. According to these results and experience, the tasks in the 2nd year (2011/8-2012/7, last year) is to derive the theoretical model, analytical solution and the corresponding identification scheme for the high-rise building gimbals models near lock-in, and perform the wind tunnel tests to identify the aerodynamic parameters for a series of 3-dimensional building models. This part so far has been completed in 50%. Based on the results in the 1st and 2nd year, the mission in the 3rd year (2012/8-2013/7, this year) is devoted to develop an accurate method to predict the response of the high-rise buildings (called indirect prediction method) by using the modal analysis that will employ the aerodynamic parameters obtained from the 2-dimensional section models. The short term outcome of this study is to obtain the database of aerodynamic parameters near lock-in for the 2-dimensional section models and 3-dimensional high-rise building models. The long-term goal is to obtain an accurate method to predict the response of the high-rise building near lock-in by employing the aerodynamic parameters obtained from the 2-dimensional section models. It is expected that this successful outcome will be promisingly contributed to the wind engineering society.