結構補強為現今國內外土木工程界重要的課題之一。在設計時設計者多會要求剪力強度到達極限時先讓彎矩達到破壞以有試體延性的預警時間,但若剪力強度無法比彎矩強度高則會造成無預警的剪力破壞,故在補強設計時,剪力補強的效果評估和預測為梁補強之研究方向之ㄧ。 本研究探討高分子複合材料(CFRP)補強剪力強度不足矩形RC梁之功效進行探討,試驗方式採用四點載重試驗法,本研究共製作8組採用不同形式碳纖維貼覆補強之矩形RC樑試體,並設計試體補強前後皆為剪力破壞,未達彎矩破壞,以探討不同碳纖維貼覆型式之剪力補強功效,並觀察試驗過程中試體之破壞發展行為。 試驗結果顯示試體貼覆之碳纖維破壞模式皆為碳纖維自試體表面剝離,U型貼覆試體由上緣剝離而反U型由下層剝離,而試驗中各種補強型式皆能增加試體剪力強度,顯示碳纖維貼覆於梁側面可有效的控制裂縫發展並增加試體強度,而試體僅貼覆四點載重試驗受剪區之試體強度和試體全貼覆補強效果差異甚小顯示剪力補強時可只補強剪力區,而補強效果最佳之試體為U型貼覆並於試體上緣以寬5公分碳纖維貼覆之試體,此因補強試體於試驗中皆因碳纖維由試體上緣產生脫層而喪失強度,此補強試體上緣碳纖維貼覆給予錨碇之功效。
Structural retrofit is one of the important subjects of domestic and international civil engineering circle now. The designers always ask for the flexural failure early then shear failure in order to have the early warning time ,but if the shear strength is higher then moment strength, the structural will be unable to prewarn the shear failure. While retrofit design, shear strength retrofit assessing and prediction are the main directions of beam retrofit study. This research is focus on shear strength retrofit by CFRP on insufficient shear strength RC beams,the test method is four-point bending test, there were eight kind of CFRP wrapping’s effects of shear strength retrofit in this test design,and discussion the test result. Test results show that the CFRP failure is CFRP debonding, the CFRP sheet of U wrapping type debonded on the top of specimen, and the against U wrapping type is debonded on the bottom of specimen. The difference between test strength of U wrapping type and the U wrapping type only on shear region is similar. The most effective retrofit specimen is U wrapping type with stick 5cm CFRP strip on the top of the CFRP wrapping because of the anchored mechanism.