Daisuke Tsukishima

A Study of Test Methods on Alkaline Resistance and Creep Characteristic for Post-installed Bonded Anchors

When using post-installed bonded anchors in concrete structures, we need to check long-term durability concerned with the safety of concrete structures. In Japan, there was an incident caused by such anchors in recent years, so there is a pressing need to establish an evaluation method for durability. However, the details of the test results have been standardized only partly by certain mechanical standards such as ETAG as an evaluation system for individual products. We therefore verified test methods on alkaline resistance and creep characteristic which post-installed bonded anchors possess, referring to test methods of ETAG. In alkaline resistance test, we chose six products and tried to evaluate alkaline resistance by setting several parameters such as bonding materials, diameter of steel plate in pushing-out test and dry state of sliced specimen. As a result, in order to improve the accuracy of the test results, we found we had to consider the following points: eliminating filling defect specimens and arranging sampling position in sliced specimen, confining power for sliced specimen and dry state of sliced specimen. In creep characteristic test, we chose three products and tried to evaluate creep characteristic by setting several parameters such as bonding materials and creep load. As a result, we couldn’t find a relationship between the ratio of peak load after creep loading test to peak load in pulling-out test and diameter of steel plate. Moreover, we found it was hard to pull out anchor rod influenced by creep load even though pull-out value while creep loading test was bigger than that of peak load in pulling-out test. Therefore, we have to consider inconsistency of the test results when evaluating creep characteristic.

THE APPLICATION OF THE CONCRETE PILES REINFORCED BY STRANDS, FOR EFFICIENT CONSTRUCTION IN THE SITE WITH LIMITED SPACE IN HEIGHT, TO A PROJECT WHICH INPROVE AKIHABARA STATION

作業空頭が制限された空間での施工に適した場所打ち杭構造として, 軸方向鋼材に高強度でフレキシブルな曲げ性状を有するストランドを用いて, 軸方向鋼材の継ぎ足しを省略したストランド場所打ち杭を開発した. 空頭制限下で場所打ち杭を施工するJR秋葉原駅改良工事にストランド場所打ち杭を使用し, 設計・施工を検討して工期およびコストを従来工法と比較した. 設計においては, ストランド場所打ち杭の部材岡性とコンクリートとの付着を考慮した以外は, 鉄筋コンクリート杭を用いた場合とほぼ同様に設計した. また, 施工においては, 同程度の空頭制限下で施工された従来工法に比べ, 鋼材建て込み作業時間が大幅に短縮され, コストにおいても, 従来工法より割安となった.