鋼纖維混凝土五螺箍柱與外部梁柱接頭之反復側推行為研究

Abstract

添加鋼纖維於混凝土可以提高混凝土的抗拉強度和抗剪能力，此外鋼纖維能減緩混凝土在強度點後力量衰退行為，大幅提高了混凝土材料的韌性，因此適合用於解決許多關鍵傳力構件因鋼筋過密，而導致的施工不易問題。甚至能替代並減少橫向鋼筋用量，提高構件性能表現和損傷容限。 本研究探討應用鋼纖維混凝土於五螺箍柱之行為表現，並評估以鋼纖維取代五螺箍筋、降低橫向鋼筋使用量的可行性，總共設計並實驗2座同樣斷面之鋼纖維五螺箍柱試體，分別驗證其受單向軸壓以及雙曲率反復載重下的反應。此外，本研究另就應用鋼纖維混凝土於梁柱接頭進行探討，共設計2座梁柱接頭試體，嘗試於試體梁柱接頭區域使用鋼纖維混凝土替代所有橫向鋼筋，並且縮短梁主筋錨定長度，驗證應用鋼纖維混凝土取代橫向箍筋並縮短梁主筋伸展長度可行性。 實驗結果顯示出，使用鋼纖維混凝土於五螺箍柱達到預期中的耐震能力，初步確認了本研究使用的設計概念具有可行性，設計過程中要求試體在添加鋼纖維後具有相近的軸向試驗韌性，以期兩者可表現出相近的耐震效能。本研究所實驗的單向軸壓試驗結果顯示出，五螺箍柱的實驗韌性值，基本符合設計時所預估的韌性值，且實驗值比預估值略大，有一定保守度；另外，鋼纖維五螺箍在軸壓試驗上也得到符合且超出預期的最大軸向強度。綜上所述，可觀察出鋼纖維在取代五螺箍柱橫向鋼筋後不論是承受軸向或側向載重都能保有取代前的性能。而由梁柱接頭的實驗結果可以驗證使用鋼纖維混凝土替代接頭橫向鋼筋並縮短錨定長度具有可行性，並且通過規範對於特殊抗彎矩構架的耐震標準。

Adding steel fibers to concrete can enhance the tensile strength and shear capacity of the concrete. Furthermore, steel fibers can mitigate the post-peak strength degradation behavior of concrete, significantly improving the toughness of the concrete material. This makes it suitable for addressing many critical load-bearing components where dense reinforcement steel results in construction difficulties. It can even replace and reduce the amount of transverse reinforcement, thereby improving the performance of the components. This study investigates the behavior of steel fiber-reinforced concrete applied to five-spiral columns and assesses the feasibility of replacing five-spiral reinforcement with steel fibers, thereby reducing the usage of transverse reinforcement. A total of two steel fiber-reinforced five-spiral column specimens with the same cross-sectional layout were designed and tested to verify their behavior under uniaxial compression and cyclic loading. Additionally, this study investigates the application of steel fiber reinforced concrete (SFRC) in beam-column joints by designing two beam-column joint specimens. SFRC was used in the joint regions of the specimens, with all transverse reinforcements removed. Furthermore, the study attempts to shorten the anchorage length of the beam's main reinforcement, aiming to verify the feasibility of using SFRC to replace transverse stirrups and reduce the extension length of the beam's main bars. The experimental results indicate that the use of steel fiber-reinforced concrete in five-spiral columns achieved the expected seismic capacity, preliminarily confirming the feasibility of the design concept used in this study. During the design process, it was required that the specimens, after adding steel fibers, exhibit similar axial test toughness to demonstrate comparable seismic performance. The results of the uniaxial compression tests in this study show that the toughness values of the five-spiral columns generally matched the estimated toughness values during design, and the experimental values were slightly higher than the estimated values, indicating a certain level of conservatism. Additionally, the steel fiber-reinforced five-spiral columns achieved the expected and exceeded the anticipated maximum axial strength in the compression tests. This observation suggests that replacing the transverse reinforcement in five-spiral columns with steel fibers retains the performance in both axial and lateral loading conditions. The experimental results of the beam-column joints validate the feasibility of substituting transverse reinforcements with steel fiber reinforced concrete and reducing the anchorage length. Moreover, the joints comply with the seismic standards for special moment-resisting frames.