傳統 木構造 추녀 이음 接合部의 構造的 補强에 관한 實驗的 硏究

Abstract

In this study, we performed joint reinforcement with steel plate tests for deformation due to structural behaviors of hip rafter members of traditional wooden buildings and damages by wood rot and had come to these conclusions.

1) In the hip rafter member reinforcement test, yield load of reinforced specimen TypeⅠ increased 21.6% to 71.5%, that of reinforced specimen Type Ⅱ 6.0% to 39%, compared to the standard specimen, while maximum load of TypeⅠ fell 34%, and that of TypeⅡ 33.1～51%. These results show that although damaged portion of old members was vertically cut, with new members being vertically joined and steel plates being inserted, and all of them were reinforced by buckling with bolts and nails, the members and reinforcing members failed to be connected with each other, lowering load from the beginning. However, this growing load began to divide the vertical joint of members, making the steel plate and members contact with each other and behave together to increase displacement. In comparison of reinforced specimens, we found that regarding yield load of double T-type steel plate reinforcement, Type Ⅱ with a higher out of length ratio showed a higher reinforcement effect than Type I.

2) As far as ductility factor was concerned, that of T-type steel plate reinforced specimen Type I decreased 69.5%, that of double T-type steel plate reinforced specimen 55.5%, and that of reinforced specimen Type Ⅱ 61.6%, respectively, compared to standard specimens,, which means that compared to standard specimens, ductility of reinforced specimens decreased.

3) Compared to standard specimens, initial strength decreased 78% and 77.8% in T-type and double T-type steel plate reinforced specimen Type Ⅰ and Type Ⅱ, respectively. Plastic zone strength also was 82～84% lower in Type Ⅰ and Type Ⅱ than standard specimens. These results indicate that strength of reinforced specimens was lower than standard specimens despite reinforcement by means of vertical joint with new members replacing old ones, seemingly because of the failed buckling.

As follows, above results of the tests for hip rafter members of traditional wooden buildings showed that despite vertical cutting of damaged portion of old members and replacing them with new members, followed by inserting steel plate and buckling with bolts and nails, the steel plate and members failed to behave together, resulting in the 20 to 30 mm crack in the vertical joint and increased displacement as the steel plate and members contacted with each other and behaved together. Standard specimens showed rigidity destruction as load increased, but vertical joint reinforced members showed sharp increase in displacement as a result of increasing load, applying physical strength to the steel plate. Due to limits in making samples, we couldn’t insert steel plates into wood deep enough to buckle tightly, and it seems necessary to conduct studies on how to insert steel plates as deep as half the height of the wood or higher to buckle wood of vertical joint member and reinforcement members.