- 期刊
化學植筋在低強度混凝土中剪力行為研究
Study on the Shear Behavior of Chemical Anchors in the Low Strength Concrete
摘要
植筋工程常被用於結構物補強工程中，如翼牆及剪力牆補強等工法，藉由對既有結構體進行植筋，將補強結構體與既有結構體相連接，以期發展出良好的耐震行為。國家地震工程研究中心於校舍補強案例中，發現老舊校舍結構常有混凝土強度偏低的問題，其平均混凝土強度約為17 MPa，甚至有低至5 MPa左右之案例，因此本研究探討低強度混凝土中植筋剪力行為，並探討現行ACI混凝土設計規範之適用性。本研究在混凝土強度分別為5MPa、10 MPa及15 MPa之混凝土試體中，進行一系列的植筋單向剪力測試，試體共計有192組，試驗控制參數包含植筋深度、邊距及混凝土強度。試驗結果與ACI規範計算值相比較後，發現ACI計算值在強度10MPa和15MPa之試體仍屬保守，但在5MPa試體之試驗值則與計算值相當接近，故ACI規範錨定計算公式應用於極低強度混凝土中可能會有不保守情況產生。此外，實驗發現有一種在低強度混凝土中的破壞模式屬鋼筋彎曲破壞，其強度介於邊距破壞與鋼筋剪斷之間，有別於ACI規範中所考慮之邊距、撬破和鋼筋剪斷三種破壞模式。最後，本文以國內實際RC剪力牆試驗與震害勘災結果，說明混凝土植筋界面剪力強度之重要性。
並列摘要
In order to increase seismic capability of structural system, retrofit techniques are usually applied. Traditional RC retrofit methods include adding RC shear wall, wing wall and RC jacketing. In addition to connect new structural members to old structural members,adhesive anchors (post-installed rebars) are used. From the investigation results by National Center for Research on Earthquake Engineering (NCREE), it wasfound that concrete strength of old school buildings is very low due to poor construction quality. Therefore, the behavior of post-installed rebarsin low strength concrete is very important. In this study, the concrete strengthof specimens are 5MPa, 10MPa and 15MPa.According to the minimum edge distance and depth of ACI code, this study proposed a series of anchorage and shear test, a total of 192 specimens. Control parameters are the embedded depth of the rebar, thedistance to edge, and concrete strength. The results of those experiments are compared with the calculated values of ACI code. It was found ACI calculated values remain conservative in strength 10MPa and 15MPa, but in the 5MPa calculated values is very close to experiment results.So, the formula of ACI codeused in low strength concrete may not be conservative. From the experiments of this study, it was also found a newfailure mode assteel bending failure. Finally, the importance of the shear strength of the interface between the post-installed rebar and concrete was addressed with an actual experiment of RC shear wall and the results of the reconnaissance of earthquake disaster in Taiwan.