螺紋節鋼筋直線伸展握裹研究

鋼筋與混凝土間之握裹性質是最基本且重要的力學關係，為推動New RC之發展，兩者高強度材料間之握裹性能必須符合預期。本研究為了解高強度螺紋節鋼筋與高強度混凝土之握裹行為，共計進行66組鋼筋直線握裹試驗，除探討螺紋節鋼筋表面幾何特性、材料強度及影響鋼筋直線握裹性能等因素外，亦提出適當的螺紋節鋼筋直線拉力發展長度設計模型，並建議合理且符合握裹應力需求的節高與節距比值（R_r值，鋼筋表面之相對節面積）限制。試驗之分析結果顯示，本研究之螺紋節主筋均能達到符合ACI 318-14規範預期之握裹性能；然而，當混凝土強度不受ACI 318-14之70 MPa上限約束時，唯有R_r值大於0.17之螺紋節鋼筋方可滿足計算需求，且混凝土有效計算強度可適當提升至100 MPa。鋼筋表面幾何尺寸方面，螺紋節鋼筋表面節高與節距之比值是影響鋼筋握裹性能之重要因素，且鋼筋握裹性能伴隨表面節高與節距比值之增加而提升。最終，本文亦分別提出適用於螺紋節鋼筋直線拉力伸展長度計算之詳細式與精簡式，其鋼筋與混凝土之有效計算強度上限可放寬至690 MPa與100 MPa。

關鍵字

螺紋節鋼筋；直線握裹；節高與節距比值；握裹性能

並列摘要

The Integrated Project of ＂Taiwan New RC Project＂ was launched to develop the high-strength reinforcements and concrete, 690 ~ 790 MPa and 70 ~ 100 MPa, respectively by the NCREE (National Center for Research on Earthquake Engineering). This work focuses the bond behavior between high-strength threaded bars and concrete by 66 groups of straight bonding tests to investigate the surface geometry characteristic of threaded bars, material strengths and bonding factors. The test results show that when the concrete strength is limited to 70 MPa by ACI 318-14 recommendations, all sets of threaded bars can provide the expected bond strengths. However, when the concrete strength is not limited to 70 MPa, only the threaded bars with relative rib area R_r exceeding 0.17 can provide the expected bond strengths. In addition, the correlation between relative rib area and the effectiveness of the bonding performance is approximately perfect. Finally, this study also provides both detailed and simplified equations for calculating the straight development lengths in tension for threaded bars, and the upper limitations of reinforcements and concrete strengths can be adjusted to 690 MPa and 100 MPa, respectively.

並列關鍵字

threaded bars ； straight bonding ； surface geometry properties ； bond performance

國際替代計量

螺紋節鋼筋直線伸展握裹研究

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