Hayakawa residence is a rural mansion, which is a preeminent modern Japanese-style house in Gifu prefecture.
Most heads of rural mansions had interaction with entrepreneur and major merchants. They were highly sophisticated, intellectual and also tea ceremony masters. Furthermore, before architects gained its profession, the heads of the family, which had deep insight and intuition for architecture mainly planned and designed the residences, rather than the carpenters. There are many historical materials preserved at Hayakawa residence. In detail, they describe the role of the head, when constructing residences. Also, many buildings of Hayakawa residence were severely damaged by the Nobi Earthquake that took place in 1981 and was reconstructed immediately after the Earthquake.
The following details of the seismic countermeasure taken place whilst the reconstruction can be identified:
1) The ground water level is 2.4m below the current ground level. 40 holes were dug at ground water level. In each hole, 9 to 10 pine pillars were placed for the foundation. The pillars' diameter is 15cm and is about 3m long.
2) Concerned of the thin pillars at the formal Japanese room weakened by the penetrating tie beam, the master carpenter's suggested binding the pillars and the penetrating tie beam with round iron bolts.
3) A round timber called "Jishinbari" was put together in a cross above the ceiling as a brace.
4) Besides "Tokobashira" pillars' sizes are all over 15cm squared.
5) A specific joint is used at the foundation, where it cannot be seen from the outside, to prevent it from sliding.
6) The main Carpenter gave and advice on whether the number of braces is enough or not.
7) Penetrating tie beams are all plugged to the pillars.
8) The pivot used at pillars alternatively reaches to the base.
9) The beams were not patched, using one timber.
10) In addition to the seismic countermeasures that can be verified by the historical materials, which are listed above, it can be seen in the remaining buildings that an angle beam is inserted at the corner of the girder and the roof boards are attached diagonally.
Since Last of Edo and Meiji Era, along with the modernization of architecture in our country, traditional timber construction has also changed and innovated in modernization.
Especially from the repeated seismic disaster after the Nobi Earthquake in 1891, seismic countermeasures have evolved through architects with the degree. They pointed out the weakness of the traditional construction and devised a resolution plan. As one of the first examples, "A Document on seismic countermeasure of timber structure residences" was published by the Investigation Committee for earthquake disaster prevention, which was established in June 1892, after a year from Nobi Earthquake, to use it as a guideline at Yamagata Prefecture, Sakata area's reconstruction residence's structure. In addition, Tamekichi Ito insisted the necessity of braces and foundation, as well as devising fixed hardware and showed an example of how to use them in the thesis he publicized at “Journal of Architecture and Building Science”. He devised that there are four defects in the traditional wooden frame construction:
1.The weight of the roof is too heavy. 2. The pillars are isolated. 3. The structures are being cut for joints and elongating. 4. The binding done by penetrating tie beam and wedges are only temporary.
Under these circumstances after Nobi Earthquake, Shuzo Hayakawa analyzed the seismic damage by himself, and when at reconstruction, he introduced construction method of foundation and wooden frame structure as a countermeasure for the earthquake. His pioneering acts are admirable.