- 學位論文
低強度混凝土柱之耐震補強
Seismic Retrofit of Low Strength Concrete Columns
摘要
台灣一般老舊校舍及建築大多無法滿足現行耐震規範，且大多有耐震能力不足的現象，各方學者對此亦提出對應之補強方法。因此本研究採用一般常見的增設翼牆補強及擴柱補強，對於低強度混凝土柱進行補強研究；本研究規劃三座鋼筋混凝土柱，皆採用校舍中常見之柱斷面尺寸，並以其中一座原柱試體做為本研究之比較基礎，其餘兩座將分別進行翼牆補強及擴柱補強，藉此探討兩種補強工法的有效性及差異性。 由試驗結果顯示，翼牆補強對於結構物能有效提升抗剪能力，但因原柱柱體混凝土強度偏低，使其無法利用植筋讓新舊混凝土做有效之結合，導致翼牆及原柱柱身發生獨立的剪力破壞，其強度在側向位移較小時便達到最大值，隨後強度便快速衰減，故韌性強度無法有效的提升。擴柱補強可同時提升結構物抗彎及抗剪之能力，即便不考慮原柱柱體之貢獻，外圍之補強體仍能獨立抗彎抗剪，其韌性強度能有較大的提升，且不論新舊混凝土是否能有效連結，擴柱補強都能有效提升耐震能力。此外，本研究三座低強度混凝土柱試體除了進行反覆載重試驗之外，也分別利用側推分析，將分析所得之容量曲線與實驗所得之遲滯迴圈圖進行比較，探討分析結果之準確性與補強成效。
並列摘要
Most of old buildings in Taiwan are lack of seismic resistance and thus are vulnerable to a severe earthquake. Hence, the seismic retrofit of existing buildings with inadequate seismic resistance is of urgent need. In this study, an original RC column and its two strengthened specimens, where one is a RC jacketing column and the other is a column with installing wing walls, were tested in this study. The original column with low strength concrete was designed to comply with old design standards and thus the usual detailing deficiencies in existing buildings can be simulated. In this paper, the low strength RC columns were seismically retrofitted and cyclically tested. Test results reveal that either the column jacketing or wing walls can effectively increase the lateral shear strength. In addition, The RC jacketing can have a better improvement in capability of energy dissipation and in ductility when compared to installing wing walls. RC jacketing not only increases moment and shear capacity but also results in a flexural failure mode. Thus, the ductility increases. On the other hand, although RC wing walls can increase shear capacity, the original column and the wing walls cannot be integrated together and experience shear failure independently. After yielding the maximum lateral strength, the stiffness and strength are rapidly degraded and thus the specimen results in poor ductility. Apparently, the hysteretic loops can be classified as a typical failure mode, where stiffness degrading and strength degrading in addition to pinching are found.
參考文獻
延伸閱讀
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