鉛直接合部がすべりを生じる傾斜型あと施工アンカーを適用した袖壁補強RC柱の終局強度 [in Japanese] ULTIMATE STRENGTH OF RC COLUMNS WITH EXTENDED WING WALL STRENGTHENED BY DIAGONAL POST-INSTALLED ANCHOR WITH VERTICAL JOINT SLIP FAILING [in Japanese]
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To strengthen reinforced concrete constructions and the like against seismic events, design methods are being established to fit the interiors of existing structures with steel braces or shear walls, as well as to retrofit existing structures with steel braces on exteriors of existing frame for seismic protection. For example, when steel-braced frames are used for seismic retrofit, indirect connections using post-installed anchors are frequently employed, such that many post-installed anchors are required for each existing structures. The connection with existing structures and reinforcement elements in seismic retrofitting of concrete construction must be effective for stress, if the strength of the connection is not adequate and if the details are not properly designed, the structure as a whole is not likely to display effective seismic performance.<br> Usually, anchor bars of the connection are vertically installed in a concrete surface. There are regulations diagonal angle for post-installed anchor in Japan Building Disaster Prevention Association (JBDPA), design standard for the reinforced concrete structures. However, when shear resistance is expected in post-installed anchors, I think that post-installed anchor using diagonal anchor bars improves shear strength. Because installing diagonally the anchor bars changes the resistance mechanism such that the anchor bar is subject to forces along the axial direction, which is predicted to produce great resistance. I think that construction method of diagonally post-installed anchor is applicable in the reinforced concrete and steel reinforced concrete columns with extended wing wall strengthened.<br> In this research, I confirmed the mechanical behavior of reinforced concrete columns with extended wing wall strengthened by diagonal post-installed anchor subjected to axial and horizontal loads through the structural tests. The considered parameters in the structural tests are as follows, presence of inclination of anchor bars and failure mode of existing reinforced concrete column (failing in a flexural and shear mode). Diagonal post-installed anchors was applied to the vertical joint in the column and the wing wall. Test specimens were designed so that anchor bars yielding mode happened earlier than the concrete failure mode in the vertical joint. Main discussion is concentrated on the maximum strength, the behavior before and after the attainment of the maximum strength and hysteretic characteristics.<br> All test specimens experienced shear slip failure at the vertical joint between the both sides of the reinforced concrete column and the extended wing wall. From the structural tests, it was shown that the reinforced concrete columns with extended wing wall strengthened which used diagonal post-installed anchors clearly improves ultimate strength regardless of the failure mode of existing column, and ductility does not change so much regardless of the presence of inclination of anchor bars. Moreover, it is found that the ultimate shear strength can be evaluated using the present equation recommended in JBDPA. However, this evaluation method cannot consider shear strength at the vertical joint and failure mode of the existing column. Therefore, I proposed the new evaluation method for ultimate strength based on stress transfer mechanism. The calculated value by that has good accordance with the test results well.
- Journal of Structural and Construction Engineering (Transactions of AIJ)
Journal of Structural and Construction Engineering (Transactions of AIJ) 81(728), 1713-1722, 2016
Architectural Institute of Japan