過去國內對於螺紋節鋼筋於鋼筋混凝土中之握裹行為研究顯示，鋼筋之握裹性能與鋼筋表面節高與節距比值Rr值、混凝土強度、保護層厚度及橫向圍束鋼筋配置等有關，而鋼筋表面Rr值更是直接影響鋼筋所能發揮之握裹強度，美國ACI 408委員會亦建議竹節鋼筋之Rr值應介於0.1至0.14間。
本研究為探討竹節鋼筋於鋼筋混凝土中之直線握裹行為，共進行20組梁構件鋼筋握裹試驗，試體採用之鋼筋與混凝土強度均分別為420 MPa與42 MPa，本研究主要變動之參數為鋼筋表面節高與節距比值Rr值與試體配置之橫向鋼筋間距，固定鋼筋中心至試體頂面及側面距離(cb)，藉由改變橫向圍束鋼筋量(Ktr)調整劈裂指數，以了解劈裂指數變化對於竹節鋼筋握裹行為之影響。期透過本研究之試驗結果，能夠建議一符合現行規範之竹節鋼筋Rr合理下限值，並提出符合竹節鋼筋之建議直線伸展長度公式。另外針對預鑄工法中所使用之旋楞鋼管進行握裹試驗，共進行36組直接拉拔試驗，主要探討配置旋楞鋼管試體所發揮之握裹強度是否能與未配置旋楞鋼管試體相同甚至更高，以確保旋楞鋼管使用於預鑄工法中之握裹性能。主要變動之參數為鋼筋直徑與旋楞鋼管直徑，試體所配置之混凝土強度、砂漿強度及鋼筋強度分別為80 MPa、120 MPa及490 MPa。
本研究之試驗結果顯示，當劈裂指數大於現行規範所限制之2.5上限值時，破壞模式仍為劈裂破壞，且試驗結果計算之握裹應力亦隨劈裂指數增加而提升，因此認為劈裂指數之上限值應能適當放寬，較能符合竹節鋼筋之握裹行為。而鋼筋表面Rr值部分為影響鋼筋握裹強度之重要因素，且隨橫向鋼筋量增加其影響效果將越趨明顯，透過回歸分析顯示，竹節鋼筋表面Rr值應至少大於0.087較能符合ACI 318-14規範之握裹應力需求。本研究以ACI 318-14為基準，提出建議之修正公式，其中劈裂指數上限值部分放寬至本研究所配置之3.70進行計算。旋楞鋼管與鋼筋之直接拉拔試驗結果顯示，配置旋楞鋼管試體所能發揮之握裹強度普遍能夠與未配置旋楞鋼管試體相同，認為在這樣的試驗配置下搭配本研究所使用之旋楞鋼管類型，能夠有效將鋼筋之握裹應力傳遞至旋楞鋼管上。

According to the researches, done in Taiwan, on the bond behavior of threaded bars in reinforced concrete, there is a correlation between the bond performance, the rib height and rib spacing ratio, the compressive strength of concrete, the thickness of the protective coatings, and the placement of stirrups. The rib height and rib spacing ratio, however, has an even more direct impact on the bond performance. ACI Committee 408 also advises that the rib height and rib spacing ratio of deformed bars should lie between 0.1 and 0.14.
This study aims to discuss the bond performance of deformed bars in reinforced concrete through twenty sets of beam end tests adopting rebars and concrete, and the strengths of which are 420 MPa and 42 MPa respectively. The variable factors of this study are the rib height and rib spacing ratio and the spacing in the placement of the stirrups. To understand the impact of the altered splitting index on the bond performance of deformed bars, the examination is done with a fixed cb to alter the splitting index by changing Ktr. It is hoped to come up with a Rr of the deformed bars which is within the regulation while providing an advised formula for straight development length of deformed bars. Additionally, the steel corrugated duct used in Precast is put through a bond examination, which involved 36 sets of pull-out tests to mainly discuss whether the bond strength is the same as, if not higher than, the specimens without steel corrugated duct, to ensure of the bond performance of the steel corrugated duct used in Precast. The main variable parameters are the diameters of the rebars and steel corrugated duct while the strength of the concrete paired with the specimens, the strength of the cement mortar the strength of rebars are respectively 80 MPa, 120 MPa, and 490 MPa.
The results of this research indicate that when the splitting index is over the regulated rate of 2.5, the failure mode remains a splitting failure, and the bond performance inclines as the splitting index. Therefore, the limits of the splitting index should be expanded accordingly to situate the bond performance of the deformed bars. The rib height and rib spacing ratio, however, is a crucial element whose impact increases as the transverse reinforcement increases. According to the regression analysis, the rib height and rib spacing ratio of deformed bars should be no less than 0.087 in order to better fit the requirement of the ACI 318-14 regulation. This study is based on ACI 318-14 to provide a revised formula.

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