五螺箍筋柱之雙曲率反覆載重試驗與離散計算剪力模型

Double-curvature cyclic test of columns with five-spiral reinforcement and discreet computational shear strength model

歐昱辰(Yu-Chen Ou) ； 李哲諺(Jhe-Yan Li)

《結構工程》 35卷3期 (2020/09) Pp. 85-97

https://doi.org/10.6849/SE.202009_35(3).0004

摘要

五螺箍筋運用在正方形斷面鋼筋混凝土柱已證實具有優於傳統方箍筋的圍束能力。本研究目的在於探討五螺箍筋之剪力強度，設計雙曲率反覆載重試驗，測試大型剪力破壞五螺箍柱與傳統方箍柱對照組。測試結果指出，箍筋體積比相同、鋼筋降伏強度與混凝土抗壓強度相似的情況下，五螺箍柱展現稍弱於傳統方箍柱的極限剪力強度，所有五螺箍柱過最大剪力強度後力量衰退速率皆小於傳統方箍柱。高軸力五螺箍柱之破壞模式為箍筋拉斷，而高軸力傳統方箍柱之破壞模式為彎鉤鬆脫導致過早破壞。本研究發展一套改進離散計算剪力模型用來計算五螺箍柱剪力強度。與試驗結果比較，改進離散計算剪力模型能保守估計五螺箍剪力強度，此外，本模型具有與規範剪力公式用於傳統方箍剪力強度之相似保守程度。

關鍵字

剪力強度 ； 五螺箍 ； 柱 ； 離散計算剪力模型 ； 反覆載重

並列摘要

Five-spiral reinforcement has been proved to have superior confinement capability to conventional rectilinear hoops. The objective of this research is to investigate the shear strength of five-spiral reinforcement. Large-scale columns with five-spiral reinforcement and control columns with conventional rectilinear reinforcement were tested in this research using double-curvature cyclic loading. Test results showed that with the same volume of reinforcement and similar reinforcement yield strength and concrete compressive strength, the shear strength of columns with five-spiral reinforcement was slightly less than that with conventional rectilinear reinforcement. However, the strength degradation after the peak strength for columns with five-spiral reinforcement was slower than that for columns with conventional rectilinear reinforcement. Under high axial load, the failure mode of columns with five-spiral reinforcement was fracture of spirals. In contrast, the failure mode of columns with conventional rectilinear reinforcement was the loosening of hook anchorage of the reinforcement. An improved discreet computational shear strength model is developed in this research and validated by the test results. The model can be conservatively used for estimating the shear strength of five-spiral reinforcement. Moreover, the model shows a conservatism for estimating the shear strength of five-spiral reinforcement similar tothat shown by the code shear strength equations for conventional rectilinear reinforcement.

並列關鍵字

shear strength ； five-spiral reinforcement ； columns ； discreet computational shear strength model ； cyclic test