不同箍筋型式之混合無預力鋼絞線橋柱反復載重試驗研究

Cyclic Behavior of Concrete Bridge Columns with Longitudinal Reinforcement Mixed with Unstressed Steel Strands and with Different Types of Transverse Reinforcement

張峻嘉(Chun-Chia Chang)

指導教授 ： 歐昱辰

國立臺灣大學/工學院/土木工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003712

摘要

本研究主要探討新型RC橋柱的結構行為，在先進自復位橋柱的設計中，縱向鋼筋包含傳統鋼筋與無預力部分無握裹高強度鋼絞線，在地震力作用下，無預力部分無握裹高強度鋼絞線維持彈性，以提供橋柱於傳統縱向鋼筋降伏後之勁度，以及震後自復位之能力。此先進自復位橋柱與傳統旗幟型自復位橋柱相比，具有較高強度與遲滯消能，且因無須使用預力，因此成本較使用預力鋼絞線低，並免除混凝土因預力而潛變的問題。本研究將探討不同箍筋型式對先進自復位橋柱性能之影響，以研擬最佳化的箍筋型式設計。
為此，本研究設計三座大尺寸先進自復位橋柱試體，依箍筋型式的不同，可分為傳統箍筋(編號CSC4)，傳統箍筋且增量塑鉸區的箍筋(編號CSC5)、以及特別使用五螺箍作為箍筋之試體(編號CSCF)；其中使用無預力部分無握裹高強度鋼絞線以及傳統箍筋之試體(編號CSC3)已由Ade與吳振維於2018年執行試驗，為探討鋼絞線有無握裹對試驗結果之影響，設計試體CSC4之無預力高強度鋼絞線為完全握裹，其餘試體之無預力高強度鋼絞線為部分完全握裹。
試驗方式為於柱端執行反復加載，柱上下兩端以預力鋼棒施加軸力，以模擬先進自復位橋柱抵抗側向力之真實結構行為，加載歷時按照ACI 374.1之規定，以利將來若與其他先進自復位橋柱試體進行比較與資料庫之建立。除此之外，本研究亦對不同形式的箍筋使用於部分握裹無預力鋼絞線梁與塑鉸區混凝土圍束之關係進行探討。
在後降伏勁度方面，根據本研究之先進自復位橋柱試驗結果與Ade和吳振維於2018和2019年的試驗結果相互比較指出，不同箍筋型式與先進自復位橋柱試體之後降伏勁度有顯著之關係，良好的混凝土圍束有助於提升柱之後降伏勁度，最後於文末將基於所得實驗結果，探討先進橋柱之受力行為與設計方法。

關鍵字

鋼絞線 ； 新型橋柱 ； 近斷層地震 ； 裂縫控制 ； 殘餘變位 ； 後降伏勁度

並列摘要

The research mainly discusses the structural behavior of new RC bridge columns. In the design of advanced self-centering bridge columns, the longitudinal steel bars include traditional steel bars and non-prestressed steel strands. Under the action of seismic forces, the unstressed steel strands maintain elasticity to provide the stiffness of the bridge column after the traditional longitudinal steel bars yielded, and the ability to self-centering after an earthquake. Compared with the traditional flag-type self- centering bridge column, this advanced self-centering bridge column has higher strength and energy dissipation, and because the steel strands are non-prestressed, the cost is lower than that of prestressed steel strands, preventing from the problem of creeping. This study will discuss the influence of different transverse rebar types on the performance of advanced self- centering bridge columns to develop an optimized types of transverse rebar.
The research designed three large-size advanced self-centering bridge column specimens. According to the different types of stirrups, they can be divided into traditional stirrups (CSC4), traditional stirrups and the incremental stirrups in plastic hinge area (CSC5) and the five-spiral (CSCF). Besides, the column with non-prestressed steel strands and traditional stirrups (CSC3) has been tested by Ade and Jhen-wei Wu in 2018.Thus, the non-prestressed steel strands of CSC4 are completed bonded, and the non-prestressed stee of other specimens are partially bonded.
The test adds cycling lateral force at the top of the column and use pre-stressed steel bars to apply axial force to simulate the real structural behavior of the advanced self-centering bridge column against lateral force. The loading procedure is in accordance with the provisions of ACI 374.1. In addition, this research also discusses the relationship between the use of different forms of stirrups in partially bonded non-prestressed steel strand columns and the concrete confinement in the plastic hinge area.
In terms of the post-yield stiffness, according to the comparison between the test results of the advanced self-resetting bridge column in this study and the test results of Ade and Jhen-wei Wu in 2018 and 2019, it is pointed out that the post-yield stiffness is highly-relative with different stirrup types and a good concrete confinement helps to increase the post-yield stiffness of the column significantly. Finally, based on the results of the experiment, the behavior of the column and design methods of advanced bridge columns will be discussed at the end.

並列關鍵字

Steel strands ； New bridge columns ； Near-fault earthquakes ； Crack control ； Residual displacement ； Post-yield stiffness

參考文獻

[1] Pratiwi, A.Y. (2018)."Flag-Shape and Post-Yield Hardening Systems for Residual Displacement Reduction of Bridge Columns" Ph.D.Dissertation, National Taiwan University of Science and Technology, R.O.C.

[2] ACI 374.1, "Acceptance Criteria for Moment Franes Based on Structural Testing and Commentary.": American Concrete Institute, 2005.

[3] Iemura, H., Takahashi, Y., and Sogabe, N. (2001). “Hybrid earthquake loading tests of UBRC bridge piers.” The 14th KKNN Seminar on Civil Engineering. 5-7 November, Kyoto, Japan.

[4] Iemura, H., Takahashi, Y., and Sogabe, N. (2004). “Development of Unbonded Bar Reinforced Concrete Structure.” The 13th World Conference on Earthquake Engineering, 1-6 August, Vancouver, B. C., Canada.

[5] Iemura, H., Takahashi, Y., and Sogabe, N. (2006). “Two-level seismic design method using post-yield stiffness and its application to unbonded bar reinforced concrete piers.” Struct. Eng./Earthquake Eng., 23(1), 109s–116s.