鋼筋混凝土梁剪力滑移之研究

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Title:	鋼筋混凝土梁剪力滑移之研究
Authors:	康家榮;Kang, Chia-Lung
Contributors:	土木工程學系
Keywords:	塑鉸外移;剪力滑移;斜向彎起鋼筋;剪力滑移容量
Date:	2018-08-24
Issue Date:	2018-08-31 11:29:25 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究繼先前計畫[6]，乃增加T頭鋼筋作塑性鉸外移設計，因提高臨界斷面彎矩強度同時，其剪力也會隨之增加而導致塑性鉸區產生明顯之斜向剪力裂縫破壞可能，且在塑性鉸區亦會有剪力滑移破壞產生。故本研究參考紐西蘭規範NZS 3101-2006塑性鉸區剪力滑移設計，以增加斜向彎起鋼筋方式防止梁剪力滑移破壞。其中，亦利用實驗製作兩支2.4m懸臂梁試體，主筋皆使用SD420W #8與#10號竹節鋼筋，梁箍筋使用SD420W #3鋼筋，混凝土強度為30MPa。第一支NB-K1為原型梁，而第二支NB-K2於上下側各增設一根於一倍梁深(hb)，斜度為45度之彎起鋼筋，用以抑制垂直剪力滑移之發生。試驗結果顯示，NB-K1於DR=2%時產生剪力滑移裂縫；而NB-K2之剪力滑移裂縫發生於DR=4%時，主因是斜向彎起筋於DR=3%時斷裂，否則應會更晚或不會發生剪力滑移現象。故從NB-K2梁試驗結果與分析，建議於斜向彎起筋之彎起處應多增設剪力箍筋，以防止在斜向彎起筋之彎起點產生不預期斷裂。文中亦研究先前計畫試體測試結果，發現紐西蘭NZS3101-2006規範，在規定檢核梁剪力滑移可能性之剪力滑移容量公式，會有不保守現象，建議應再作進一步探討。 ;The thesis follows the previous study[6], on which the hinge relocation design of Zew RC beams using additional T-head bars was discussed. This is because the shear strength increases as the moment strength was enhanced by the additional T-head bars, thus resulted in obvious diagonal shear crack and may cause sliding shear failure occur at the potential weak plane in the plastic hinge zone. Therefore, the purpose of the thesis is to study the design of RC beam sliding shear referring to the design code of NZS3101-2006. In the thesis, totally two 200 mm wide and 650 mm deep RC beams are tested and the length of beams is 2.4 meters. The longitudinal bars are arranged with two SD420 #8 in the top and two SD420 #10 in the bottom. The first tested beam NB-K1 is the prototype beam, and the second NB-K2 is the tested beam designed with a bent-up steel bar having 45 degree inclination in order to resist the occurrence of vertical sliding shear failure. The test results show that beam NB-K1 produces sliding shear cracks when DR=2% is reached, whereas NB-K2 sliding shear cracks occur when DR=4% is started. This is because the bent-up bar breaks at DR=3%. It is expected that sliding shear may not occur if bent-up bar is not breaking. Therefore, according to the analysis on the failure possibility, it is recommended that addional vertical shear stirrups at the bend-up point could prevent the failure. It is also found that the capacity of sliding shear stipulated in NZS3101 for checking the occurance of beam sliding shear failure may not be conservative. It is suggested to revise the sliding shear capacity for the future study.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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