中高樓層建築物耐震能力評估之研究

Abstract

台灣位處環太平洋火環帶上，大小地震頻繁，九二一大地震中慘重的災情，凸顯了台灣老舊建築物耐震能力不足的問題，因此國家地震工程研究中心針對校舍提出一套耐震評估法。然而在0206美濃地震中，維冠金龍大樓的倒塌造成115人死亡，顯示在地震中，中高樓層建築物的倒塌是十分致命的。找出耐震能力不足，需要補強的建築物乃當務之急，若全數進行耐震評估工程會極為浩大、不經濟且難以實施，而台灣尚未有針對中高樓層建築物的初步評估以快速篩選出耐震能力不足的建築物，故本研究參考校舍初步評估提出一套適用於中高樓層建築物的初步評估法，快速篩選出需要提升耐震能力的建築物，節省成本並提升效率。本研究使用的評估方法包括初步評估法、改良式極限彎矩平衡法之簡易詳細評估及詳細評估。初步評估法為只透過量測結構物垂直構件斷面積及樓層面積，即可得建築物的耐震能力。以初步評估結果篩選出耐震能力不足之建築物在進入詳細評估階段前，本研究提出簡易詳細評估，考量構件之強度、破壞形式等，以彎矩平衡法求得建築物之極限基底剪力，便可判斷其耐震能力，希望能提供工程師對詳評結果的參考，詳細評估是參考手冊三版之建議對建築物進行側推分析。為建立初步評估法，本研究透過簡易詳細評估，分析三棟實際中高樓層建築，將所得垂直構件之單位斷面積側向強度結果統計分析後分別得其平均值，再將其分別乘上斷面積後加總即可得初步評估之耐震容量，由耐震設計規範得耐震需求後，即可判斷其耐震能力。三棟案例中，初步評估法以基本耐震性能及性能地表加速度作為耐震能力判定依據，皆約為詳細評估之86%至95%間，顯示初步評估法實屬合理且不至於過份保守。探討上述耐震能力評估方法之可行性，以利日後該方法之推廣。 關鍵字：中高樓層建築物、耐震評估、初步評估法、改良式極限彎矩平衡法

Located on the Circum Pacific seismic zone, Taiwan has to face extreme earthquakes annually. The 921 earthquake brought Taiwan huge damage and warned people of the insufficient seismic capacity of old buildings. As a result, National Center for Research on Earthquake Engineering (NCREE) proposed a procedure of seismic evaluation and seismic retrofit for school buildings. In 2016, Weiquan Jinlong building collapsed in Meinong earthquake and 115 people were killed in the collapse. Thus, the collapse of mid- to high-rise buildings is very deadly. In order to make sure that the mid- to high-rise buildings will be safe during earthquake, we proposed a seismic evaluation method for mid- to high-rise buildings referring to a similar method for school buildings. The seismic evaluation for mid- to high-rise buildings includes preliminary evaluation, simplified detailed evaluation and detailed evaluation. The preliminary evaluation method measures the area of vertical structural members to estimate the seismic capacity and floor area to estimate seismic demand. At last, by calculating basic seismic performance and performance PGA (peak ground acceleration), we can find out the buildings requiring the detailed evaluation. Some of the buildings might need to be retroffited. We can lower the construction cost and raise the efficiency through the seismic evaluations above. In order to establish the preliminary evaluation method, we take the average of the vertical structural members’ lateral strength per unit cross sectional area. The values are defined by applying simplified detailed evaluation to 3 mid- to high-rise buildings and summed up from the calculation. We can also get the average of ductility capacity and the weight per unit floor area for mid- to high-rise buildings by simplified detailed evaluation. Using the preliminary evaluation method for the 3 buildings, we can find that the performance PGA are more conservative comparing to the detailed evaluation without excessive underestimation, which shows that the preliminary evaluation method for mid- to high-rise buildings is usable and applicable. This research studies about the feasibility of the seismic evaluations for mid- to high-rise building and we expect to promote them in the future.

Keywords: Mid- to high-rise buildings, Seismic evaluation, Preliminary evaluation, Simplified detailed evaluation