縱向鋼筋比及高寬比對鋼筋混凝土橋柱遲滯衰減行為之影響

Effects of Longitudinal Reinforcement and Aspect Ratios on Deteriorated Hysteresis Behaviors of Reinforced Concrete Bridge Columns

王柄雄(Ping-Hsiung Wang) ； 鄭維中(Wei-Chung Cheng) ； 張國鎮(Kuo-Chun Chang)

《結構工程》 36卷3期 (2021/09) Pp. 93-110

https://doi.org/10.6849/SE.202109_36(3).0005

摘要

為了解縱向鋼筋比及高寬比對鋼筋混凝土橋柱遲滯衰減行為之影響，本研究規劃五座矩形橫箍筋橋柱之反覆載重試驗，考慮之縱向鋼筋比為0.75%、1.5%及3.0%，橋柱之高寬比為3、6及10。再加上文獻相關圓形螺箍筋橋柱之試驗結果，以綜合探討不同斷面圍束型式及設計參數對多項結構性質之衰減特性，如強度衰減、勁度折減及束縮行為之影響。試驗結果顯示，橋柱之勁度折減程度及加載路徑之束縮嚴重程度，皆會隨著縱向鋼筋比的降低而趨於嚴重；而高寬比對勁度折減之影響不甚明顯，但加載路徑之束縮效應則是會隨著高寬比的降低而趨於嚴重。此外，在相同的縱向鋼筋比及滿足耐震設計規範最低橫向鋼筋用量的前提下，圓形螺箍柱因有較好的圍束作用，其衰減幅度會比矩形橫箍柱來的輕微。在試體破壞模式的比較方面，矩形橫箍柱主要因其箍繫筋之彎鉤外撐鬆脫以致圍束失效，而產生漸進式的強度衰減破壞；圓形螺箍柱則為螺箍筋發揮至極限應變斷裂以致圍束機制崩解，而發生急遽的強度損失破壞。

關鍵字

鋼筋混凝土 ； 橋柱 ； 縱向鋼筋 ； 高寬比 ； 遲滯行為 ； 衰減

並列摘要

To study the effects of longitudinal reinforcement and aspect ratios on the deteriorated hysteresis behaviors of reinforced concrete (RC) bridge columns, five rectangular RC column specimens with hoop and tie reinforcements are tested under cyclic loading considering longitudinal reinforcement ratios of 0.75%, 1.5%, and 3.0% and aspect ratios of 3, 6, and 10. Furthermore, another five circular RC columns with spiral reinforcement and similar test scheme obtained in the literature are included to further compare the differences of deterioration characteristics resulting from various confining mechanisms. Test results show that the stiffness degradation and pinching severity of column would increase as its longitudinal reinforcement decreases. The pinching severity of column would also increase with decreasing aspect ratio, but the stiffness degradation is barely affected by the aspect ratio. Moreover, due to the well confinement effects, the severity of deteriorations of circular columns are less than those of rectangular columns with the same longitudinal reinforcement ratio and the minimum transverse reinforcements required by seismic design codes. Besides, the failure of rectangular columns is mainly caused by the loosening of transverse reinforcements at seismic hooks, leading to gradually deteriorated confinement and strength. In contrast, the failure of circular columns is primarily induced by the fracture of spirals, resulting in destruction of confinement mechanism and sudden strength loss.

並列關鍵字

reinforced concrete ； bridge column ； longitudinal reinforcement ； aspect ratio ； hysteresis behavior ； deteriorations