Proceedings of the IASS Annual Symposium 2016
“Spatial Structures in the 21st Century”
26–30 September, 2016, Tokyo, JapanK. Kawaguchi, M. Ohsaki, T. Takeuchi (eds.)

Design theory of Haraichi Kindergarten based on Japanesetraditional structural detailing
Kuniaki ITO*, Junichiro MATSUMOTOa, Toshimi KUSHIDAb*

Prof. Emeritus of TOHOKU Univ. & Kuniaki ITO Arch. & associates
1-1-7, Kurosuna, Inageku, Chiba-city, Japan 263-0042
Email : kunaiki1114ito@gmail.com
aDirector of Junichiro MATSUMOTO Arch. & associatesbStructural Engineer, TOJU Industry Co,LtdAbstractThis laminated wood structure for a kindergarten is based on the same housing-design method of“Shinkabe; wooden column-exposed wall construction” which has been used for the Japanese traditional
wooden houses for a long time. This kindergarten, in spite of containing relatively wide span rooms likeschool gymnasium, class rooms and meeting room has no big size members. Not only from the view
point of artistic detailing but also in economical and modular co-ordination factors, laminated woodcolumns and beams are one-side same thickness members (width size 12cm). To obtain the necessary
performance as the kindergarten , they are used frequently as the members of part of Three Dimensional
Truss or those of Rigid Rahmen frame using reliable glued-in rod connection.
As a result, we could achieve a long-span school gymnasium having high-side light, deep eaves andwalls with smooth suface. They were necessary to assure for children to be active,

Keywords: Japanese traditional detailing, reference line, bare wooden frame, integration of rooms with different
sizes, same thickness wooden members, mitigating light & wind, deep eaves, three dimensional truss, glued-in rod.

Figure 1: Looking up at the three dimensional frame of all-purpose room as a gymnasium and an assembly hall

Copyright © 2016 by Kuniaki ITO, Junichiro MATSUMOTO and Toshimi KUSHIDA
Published by the International Association for Shell and Spatial Structures (IASS) with permission.

Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

1.Introduction
This kindergarten has the history more than 45 years in the same place which is a part of the precinctof Ryougonji Temple. The owner of this kindergarten is the priest of this temple,too. Through theseyears, next to next several buildings were attached according to the increasing children. But upon
experiencing the earthquake of 2011.3.11, the owner decided to rebuild the main school building worthyof healthy, strong and aesthetic ones. We responded to his hope by planning one-story school buildingin which a variety of rooms with different sizes are integrated in a simple plan, using laminated woodconstruction in which a variety of structural method are adopted to achieve the architecturalrequirements and detailing various parts carefully to ensure for children to move around in safety.

Figure2: Deep and long eaves sheltered children from the midday sun, yet free from structural obstacles.

2. Integration of a variety of rooms with different sizes
Genarally speaking, a kindergarten facility consists of a variety of rooms with different sizes. Therefore,structural system is apt to be exaggerated by adopting large-size colum and beam system. In thiskindergarten, we thought to make use of each partition-wall as bearing wall according to Japanesetraditional housing system -Shinkabe- in which walls are set on the reference line and parts of walls are
not bulged out of the width of columns. Furthermore the high precision of laminated wood members
and embedded metal joints enabled to make the flat surface detailing between walls and columns without
discrepancy. In case of the rooms especially requiring long-span such as class rooms and gymnasium,
Structural truss were incorporated achieving effective control of ventilation and sun light in the summer
seasons..

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Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

Figure3:Simply integrated plan

Figure5: Elevations and .exterior finishing

Japan is a humid country, then since the old age our ancestors have used structural wooden members inbare condition letting them breathe in the natural air for preventing damage from the decay.
Fundamentally columns and beams were not wrapped except for fireproof buildings like storehouses or
castles with thick mortal. In the house buildings each partition was simply modular coordinated using
the dimension of nearly 910mm length or multiple length. Therefor in the market like commercial homecenters in Japan a lot of flat building materials are sold on 910 mm size or its multiple dimension. Foreliminating waste of materials, for shortening the thinking time for planning and for achieving rational
construction including extension and structural alteration, this 910 mm modular coordination systemstill remains as a deep-rooted social system. Even in the roof, this system is an extension of this idea3

Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

despite roof tiles or metal sheets. In this case, roof is covered by standing seam construction of color
stainless steel and galvanized steel in which the interval of standing seam is 455mm of a half of 910mm. .
And for setting the snow slide stopping bars or the outside-air-conditioner-machine stands, effective
fasteners are used. In this kindergarten these methods are totally combined. This kindergarten has a plan
to set solar power panels on the roof using these fasteners for further functional addition in the future.,

Figure4:Structure for high side lights

Figure6: Outside machine

Figure8: Fastener

3. Structural details making multi-purpose room

Figure9: Structural isometric of multi-purpose room.

Figure10: Detail of long spanThis multi-purpose space are used for a gymnasium, a meeting room and an assembly hall with morethan 300 people when the entrance ceremony or the school play are held. So the sufficient ventilationand light are needed to keep comfort for people. To achieve them, the high side lights being set between
symbolic large beams like bird wings are designed and those spatial beams mitigate the rapid flow ofwinds in the typhoon season and the strong sunshine in the summer season. The longitudinal long-spangirders are extended into the upper parts of the stage which has 9 meter-wide house-curtain of folding
up system. For opening it, the winch machine and wiring devices are set by making use of vacancy oftruss holes on the stage. 5 units of stair boxes are put away in beneath the stage floor usually. According
to the kind of event, they are drawn out from this storage space. Especially when the commemorative
picture is needed, this device demonstrates its ability as tiered stand.
4Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

Figure8: Hight side light

Figure9: Stair boxes under the stage Figure:10 Winch above the stage

4. Structural details making class rooms and deep eaves
To increase the continuity between class rooms and ground was the most important item offered by theclient. We answered this demand by making 3.6 m cantilever canopy without any posts at edge using
spatial truss as knee joints and string beam. In the backward of of this spatial truss, horizontal beem are
set compounding T mode beam to take responding stress from spatial truss This fundamental method
was inherited since more than one thousant years ago in Japanese carpenters. In the country like Japan
having relatively long rainy season, various devices for making cantilever have been developped
through the histry. One of the most impressive example is the tower of five story pagoda you can see
every place in Japan through the north to the south. And also we intended that this large roof could be
looked afloat by separating roof from walls visually inserting transoms with sashless glass fixed bystructural sealing. To emphasize the sharp edge-line of the eaves, horizontal gutters were setbacked
inwards about 1.2m.

Figure11: The place where activity occurs

Figure13:: Sharp-edged eaves

Figure12: Structure plane Y2-35

Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

Figure13: Looking outside through the window

Figure14: Spatial Knee Joint

5. Structural Calculation
The characteristic of this structure is based on traditional wooden post and beam structure meaning
exposed frame which is adequate to Japanese climate. Main members have the same width, 120mm.
Depending on the position, another depth dimension is changed according to occurred stress like 90,
120,150,180,210,240,300 and 450mm. Structural glued laminated lumber made by larch tree E105-F300
was used for stablility of strength and flexibility of length. We confirmed the horizontal rigidity bypartially located 24mm structural plywood ceiling zone.being put up on the toilets and other smallchambers.
Vertical structural walls of X direction are composed of wooden braces flanked with double plasterboards of 12mm thickness. In the calculation they are evaluated from the view point of allowable shear
strength and deformation. Vertical structural elements of Y direction are mainly composed of wooden
rigid rahmen frame which resists the horizontal loads from the earthquake. At the joint of column andbeam, glued-in rod construction was adopted with epoxy resin injected deformed bar. In this case,regarding strength and rotational stiffnes we used the confirmed experimental data for structural
calculation.
For the stress analyzation, replacing both rigidity of posts and beams and rigidity of joint deformationof braces into rigidity of steel brace, adding rotational stiffness of glued-in rod joint, the main structural
calculation was done by using the three -dimensional stress analization software, STAN/30 of KOZOKEIKAKU ENGINEERING Inc.
Under the rule of Japanese Architectural Regulations, Rout 1 (Allowable Stress Calculation 1) was used.
At the general joint points, the ready-made metal joint- Tec.One- was selected. for the reason of little
sectional loss. At the glued-in rod joint points, we evaluated the occurred stress considering ultimate
bending strength Mu together with ductility factor μ ( SMa=0.2×Mu×(2μ−1)1/2 , μ = 1.30 )Figure15: T mode beam Joint Figure16: R-H construction Figure17: T mode beam backing truss
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Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century
Table 1: Sum total of surface area, volume, weight of all members

6. Conclusion
The features of Japanese traditional wooden structure consists of clear plan, backed up by modular
coordination systems which has been rooted in the social system, and large roof which wraps up therooms and human activities under itself.
One of the weakest point of this structure was in the large sectional lack of wooden members around at
the joint of beams and columns. But recent progressive metal joints and glued-in rod construction are
now overcoming its condition and new designs for this construction appear with new esthetics added.
Not only housings but communal buildings, carefully detailed structure can offer human size spaces
with marketable parts and members.
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Proceedings of the IASS Annual Symposium 2016
Spatial Structures in the 21st Century

Acknowledgements
First of all, we must thank for the leadership of Mr. Sekiya INADA, the founder and the principal ofHaraichi Bunka Kindergarten. He has accumulated a lot of know-how through the actual work for morethan 45 years on the same place-1032, Kawarabuki, Ageo-City, Saitama Pref.-. This project is based on
his experiences and philosophy. Mr. Hiroshi ISHIKAWA, Mr. Hideaki INADA and Ms. Fumie
SHIMAMURA fulfilled their mission as the front man of the client side.
Next, we have to say gratitude to a lot of persons concerned in the site, above all, the site foreman ofChiyomoto Construction Co.,Ltd, Takashi HOSODA.
Mr. Katsutoshi KOBAYASHI, mechanical engineer and Mr. Makiyo OTAKI, electric engineer
contributed to integrate the agreeable inner space by their abundant experiences.
Finally, the authors would like to express an appreciation for the checking aids in presentation from Mr.
Douglas KAWANO, who has watched our works for many years.
All photo credits reserved by Kuniaki ITO.

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