膨脹錨栓力學行為之研究

Abstract

後置式膨脹錨栓係藉由錨栓底部在混凝土內部膨脹擴座產生錨定力以抵抗所承受之拉拔力，由於施工方便，已廣泛用於建築物外部構件或附加設施固定混凝土上。 本文內容主要針對國內廣泛使用之膨脹錨栓進行拉拔與力試驗，將所得結果與ACI-349附錄Ｂ及日本建築學會之分析設計規範比較。 試驗結果顯示膨脹錨栓受拉拔力而破壞時，為混凝土角錐狀破壞，破壞面與水平面之夾角約為30-45度之間。且套筒式膨脹錨栓受拉拔力作用時，較敲擊式膨脹錨栓有較大的韌性行為。ACI-349及日本建築學會之拉拔力分析設計值較本實驗所得結果小。 錨定間距和邊距不足會造成膨脹錨栓拉拔力之降低，隨著錨定邊距之減小，膨脹錨栓受拉拔力破壞模式由混凝土角錐破壞變為混凝土邊角崩離。 當膨脹錨栓受剪力作用時，其破壞模式為膨脹錨栓螺桿斷裂，與膨脹錨栓本身材質及試驗條件有關，和混凝土性質較無關連。

The expansion anchor has been used widely to affix the building envelope or annexed structure on concrete because they are easy to install. This study is to test the pullout and shear capacity of the expansion anchor which is generally used in our country. The results were compared with design codes of ACI-349 and Japan Architecture Society. The results show that when the expansion anchor fails due to pullout force, the failure model is concrete cone failure. The angle between the failure surface and horizontal surface is about 30-45 degree. The sleeve expansion anchor has better ductile behavior than the drilled-in expansion anchor when subjected to pullout force. Calculated value from design code is smaller than test data. Inadequate distance between anchors and distance to edge could decrease pullout strength of the expansion anchor. For the latter case, the failure model may become edge failure. When the expansion anchor subjected to shear force, the failure model is steel failure. Shear strength depends on the strength of steel material and test qualifications, it has little relation to concrete.