DESIGNWORKS Vol.14

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Topic清泉女子大学本館耐震改修‐プレストレス導入によるレンガ補強‐Earthquake - resistant structures for the main building of Seisen University - Prestressing for brick reinforcement -既存の仕上げを傷めることなくそのままの状態でレンガ壁にプレストレスを導入して耐震補強工事を行う技術を日本で初めて開発し、ルネッサンス様式のレンガ造建物である清泉女子大学本館に適用した。プレストレスを導入することにより、各レンガ及び目地部を締め付けることができるため、地震時のレンガ壁の損壊を最小限に食い止めることが可能となる。本技術を用いた実験検証結果は、通常のレンガ壁と比べ耐力が4.6倍以上、レンガが元の形に戻ろうとする変形性能は16倍以上という結果も出ており、実験終了後も若干のひび割れは残るものの試験前の形状を保持することを確認している。本技術では水を使わないコア抜き工法を用いてレンガ壁内部にPC鋼棒を設置しているため、外観に変化は生じない。よって、従来の耐震補強に活用されている、RC壁補強Takenaka was the first company in Japan to develop a technology for the seismic retrofitting of brick walls through the introduction of prestressing, making it possible to retrofit structures as is without damaging the existing finish. This technology was applied to the main building of Seisen University, a Renaissance style brick structure. Prestressing enabled each brick and joint to be tightened, minimizing the damage to the brick wall in the event of an earthquake. Experimental verification using this technology revealed that a brick wall reinforced in this manner has a load-bearing capacity at least 4.6 times greater than that of an unreinforced brick wall, and that the deformation performance of the bricks attempting to return to their original state was 16 or more times greater. Although minor cracking remained after the conclusion of the experiments, the results confirmed that the bricks retained the shape that they had prior to the experiment. As this technology adds reinforcement inside the brick wall by means of a core removal method that does not involve the use of water, there is no や鉄骨フレーム補強などの外付けの耐震工法、また既往の削孔方式によるプレストレス補強工法のように、内装を全て取り除く必要も無い。そのため、漆喰など創建時の貴重な内装仕上げについても保存が可能となり、伝統建築分野におけるレンガ組積造の歴史的価値を守るために適した工法となっている。(北嶋 裕)所在地:東京都品川区延床面積:1,794㎡構造:レンガ造階数:地下1階 地上2階当初建設:1915年設計:ジョサイア・コンドルchange in the outer appearance and no need to remove all of the interior furnishings as in the case of external retrofitting methods (such as reinforced concrete wall retrofitting and steel frame retrofitting) and other conventional methods used to retrofit brick walls or prestressing retrofitting using the existing hole drilling method. For this reason, it is also possible to preserve the plaster and other interior furnishings that may break if they are removed. Accordingly, a method has been achieved that is appropriate for protecting the historical value of traditional buildings of brick masonry construction. (Hiroshi Kitajima)Location: Shinagawa-ku, TokyoTotal floor area: 1,794㎡Construction: Brick constructionNumber of stories: 2 floors above ground plus 1 basement floorArchitects: Josiah ConderRepair design: Mitsubishi Jisyo Design Office, Takenaka Corporation (Antiseismic reinforcement)Repair construction work: Takenaka CorporationRepair construction term: July 2009 to September 2009 (Antiseismic reinforcement), to March 2010 (Finishing turning)改修設計:三菱地所設計竹中工務店(耐震補強)改修施工:竹中工務店改修工期:2009.7~2009.9(耐震)2010.3(仕上)30Topic