低強度鋼筋混凝土柱之耐震補強實驗研究

Experimental Study of Seismic Retrofitting of Low Strength Reinforced Concrete Columns

張順益(Shuenn-Yih Chang) ； 陳亭偉(Ting-Wei Chen) ； 林忠毅(Chung-Yi Lin) ； 羅閎譯(Hung-Yi Lo) ； 陳玉強(Ngoc-Cuong Tran)

《結構工程》 29卷2期 (2014/06) Pp. 41-62

https://doi.org/10.6849/SE.201406_29(2).0003

摘要

本文針對低強度鋼筋混凝土柱進行耐震補強實驗研究，試驗結果顯示不管是擴柱或是增設翼牆補強都能有效提高側向抗剪強度，其中擴柱補強的韌性比及遲滯消能能力都遠優於增設翼牆補強。這是因為經擴柱補強後，其抗彎及抗剪的能力都能有效的提升，且試體係由撓曲破壞所控制，因而能提高韌性強度。另一方面，增設翼牆補強後，雖然抗剪能力得到有效的提升，但原柱柱體與翼牆卻分別發生彼此獨立的剪力破壞，且側向強度在位移相對較小時即達最大值。在側向強度達最大值之後，試體之強度及勁度隨即出現快速衰減，因而使韌性強度不佳，是以遲滯迴圈出現典型的剪力破壞模式以及嚴重的遲滯迴圈收縮現象。擴柱補強係將原柱柱體完全封閉式的包圍在中央核心，因此即使不考慮原柱的貢獻，外圍的補強體將如同一中空柱能獨立的抗彎抗剪，如此一來，不管原柱柱體與補強體是否能完全有效連結，擴柱補強都能穩定的提高耐震能力。雖然翼牆補強是希望透過植筋使新舊混凝土完全結合在一起共同抵抗外力，但因混凝土強度偏低植筋並無法達此目標，以致於原柱柱體與翼牆分別發生彼此獨立的剪力破壞，即使如此，翼牆補強由於優異的力學機制仍能達到有效提高抗剪能力的目的。

關鍵字

低強度鋼筋混凝土柱 ； 耐震補強 ； 擴柱 ； 翼牆 ； 反覆載重試驗

並列摘要

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. The jacket around the original column can be considered as a hollow column and thus it can resist both flexural moment and shear force. Consequently, RC jacketing can effectively increase the resistance to moment and shear whether the connections between the original column and new jacket are good or not. It is anticipated that the post-installed anchors can integrate the new and existing concrete together to resist seismic force for RC wing walls. However, this goal cannot be achieved due to the low strength concrete. As a result, an independent shear failure is found for the original column and the two wing walls. Even so, it is evident that RC wing walls can still enhance the shear capacity due to the very good mechanism.

並列關鍵字

low strength ； reinforced concrete column ； seismic retrofit ； column jacketing ； wing wall ； cyclic loading test