引きボルト式集成材フレーム接合部のせん断長さと破壊特性に関する実験的考察

Abstract

Tensile bolt joint is one of the joint methods of timber frame structure. In the failure mode of this joint method, shear fracture from the tensile bolt fixed portion to the beam or column “butt end” (= the surface of the end of beam or column) is very brittle. Therefore, it is important to predict precisely the fracture load of this failure mode. This study aims to propose the fracture load formula of tensile bolt fixed portion of glued laminated timber frame with tensile bolt joint from the relationship between “shear-length”, maximum load and failure mode. First of all, the destruction tests of the tensile bolt fixed portion of the same grade glued laminated timber were carried out. Moreover, the relationship between shear-length and fracture load or the area of tensile bolt fixed plate and fracture load are analyzed. The knowledges from this study are as shown below: 1) About the load-deformation relationship of the specimen that the shear length is over 240mm, after the maximum load experience, deformation proceeds without lowering load. On the other hand, the specimens that the shear length is less than 180mm are destroyed in less load than the specimens that the shear length is over 240mm. 2) When the shear length is up to 300mm, shear failure is the major failure mode, and the fracture load is increased in proportion to the shear length. When the shear length is over 300mm, compression failure is the major failure mode, and the fracture load is about the same regardless of the length. 3) The fracture load formula of tensile bolt fixed portion of glued laminated timber frame with tensile bolt joint was proposed. About the range of shear length from 120mm to 420mm, it is confirmed that the proposed formula can predict the fracture load to a safety side.