Abstract
Conservation of historical timber structures is a socially relevant issue. However, techniques to estimate the mechanical properties of timber using non/minor destructive test (NDT/MDT) methods are still not well established. Their establishment is an urgent issue for the conservation of such structures.In this study, NDT/MDT test methods such as drilling resistance and ultrasonic propagation velocity were applied to evaluate the soundness of the old timber members of cultural property. Prior to application, research into the relationship between NDT/MDT indicators and compressive strength of timber of a building was performed, and an evaluation equation was proposed.It was found that estimated determined by the drilling resistance measurement equipment was closely approximated the actual strength oft he timber pillars.Based on the research, the authors estimated the residual compressive strength of an important cultural monument built 100 years ago (i.e., the Gifu Park Pagoda). The strength of the central column and the four surrounding columns varied from 20 MPa to 25 MPa. It was found that these values met the regulated strength for present buildings. The members exposed to a high humidity environment tended to decay. Although through visual inspection, the north outside facing pillar was confirmed to have deteriorated, the internal sections were found to be sound. The south outside facing pillar was found to have decayed significantly. Although through visual inspection, the west outside facing pillar was not confirmed to have deteriorated, the internal sections were decayed. Thus, NDT/MDT methods provided valuable information to assist in conserving this historical timber structure.
https://ror.org/05sj3n476 
