圓形New RC柱的核心混凝土在圍束作用下的應力應變模式

Abstract

摘要 建築結構中採用New RC有降低斷面尺寸，減少材料用量以及增加使用空間等優點。但由於New RC易發生脆性破壞這一特點，使得其在應用中有困難需要克服。在混凝土柱結構中，高強度混凝土柱在可以提供高軸力的同時，在應力下降段表現出明顯脆性破壞，對結構安全有嚴重影響。因此，原本適用於普通混凝土的規範公式無法完全適用在New RC上，需要針對研究。 柱結構中，通過增加鋼筋量的方法可以有效提升圍束從而增加柱的韌性，但鋼筋量的選取同時受到結構安全與施工難度的限制。本次研究針對高強度圓形鋼筋混凝土柱，通過調整箍筋間距，箍筋強度以及有無繫筋等條件分析圍束作用下高強度鋼筋混凝土柱的軸壓行為，包含韌性比分析，應力應變曲線對比，應力應變模型建立。 本次研究相關試驗結果顯示減少箍筋間距，增加繫筋，增加箍筋強度都可以明顯提高試體的韌性。對核心混凝土來說，箍筋強度的提高在上升段並沒有明顯體現，但在下降段箍筋強度高的表現出更好的韌性，說明在柱受力達到峰值時，高強度鋼筋強度未能利用完全。降低箍筋間距和添加繫筋都可以提高核心混凝土峰值應變，在保證箍筋配筋率不變的情況下，在上升段兩者效果近似，但在下降段添加繫筋的補強作用較好。

Abstract In the building structure, New RC is used to reduce the section size and the amount of material. Besides which, New RC can increase the use of space. But New RC is prone to brittle failure which makes it difficult to use in the application. In concrete column structure, while high-strength concrete columns provides high axial force ,.The descending branch shows brittle failure which results in serious implications for security. The original specifications applicable to ordinary concrete can not be fully applicable in the New RC. Column structure can effectively enhance the confinement conditions by increasing the amount of reinforcement , but the amount of reinforcement is limited by the structural safety and construction difficulties. The research for high strength circular reinforced concrete columns analyses axial compression behavior under confinement effects by adjusting the spacing of stirrups , stirrups strength and tie bar conditions including toughness ratio analysis , stress-strain curve and the stress-strain model . The results of the study showed that decreasing stirrup spacing , addition of tie bar , increasing the strength of stirrups can significantly improve the toughness of the specimen.For core concrete , the increasing of stirrups strength has no effect in rising branch , but the high- strength stirrups showed better resilience in descending branch , The results described that when the force reaches a peak , high-strength steel strength completely failed to take advantage . Reducing the spacing of stirrups and addition of tie bars will enhance the core concrete peak strain，In ensuring the stirrup reinforcement ratio unchanged, the effect of both phase approximation, but the addition of tie bars performs better in the descending branch.