| Report # | 86 |
| Report Date | 21-11-2002 |
| Country | JAPAN |
| Housing Type | Timber Building |
| Housing Sub-Type | Adobe / Earthen House : Mud walls |
|
Author(s)
|
Norio Maki, Satoshi Tanaka |
|
Reviewer(s)
|
Sajal K. Deb |
Important
This encyclopedia contains information contributed by various earthquake engineering professionals around the world. All opinions, findings, conclusions & recommendations expressed herein are those of the various participants, and do not necessarily reflect the views of the Earthquake Engineering Research Institute, the International Association for Earthquake Engineering, the Engineering Information Foundation, John A. Martin & Associates, Inc. or the participants' organizations.
Summary
Japan has a long tradition related to wood construction. The main building of the Horyuji-temple, which was constructed in the late 7th century, is the oldest existing wooden structure in the world. Most Japanese housing is of wood construction. In 1993, 68.1% of the 45.8 million units of housing stock consisted of wooden structures. However, in newly constructed housing, the percentage of wooden structures is decreasing. In 1995, the percentage of wooden structures in newly constructed housing was 45.5%. The Hanshin Awaji earthquake disaster in 1995 damaged
many wooden structures, especially housing that was constructed according to the pre-1980 building code. Despite the severe damage at the time of the Hanshin earthquake and governmental encouragement of seismic upgrading, retrofitting of these houses is not common.
1. General Information
Buildings of this construction type can be found in Wood structures comprise a major structural type throughout Japan. Only in the Okinawa prefecture in the southern part of Japan does the non-wood structure housing stock exceed the wood structure housing stock. This type of housing construction is commonly found in both rural and urban areas.
In 1993 the percentage of non-wooden structure housing in urban areas (40.8%)
was larger than that in rural areas.
This construction type has been in practice for less than 100 years.
Currently, this type of construction is being built. .
Figure 1: Ordinary housing in 1970s-80s (wall: mortar finish) | 
Figure 2: Ordinary housing after 1990s- (wall: metal, ceramic finish)
source:http://inpaku.dpri.kyoto-u.ac.jp/en/join/live/index.html | 
Figure 3: Traditional housing in old downtown (Japanese Shophouse, Machiya) source: http://www.machiya.or.jp/ |
|
2. Architectural Aspects2.1 Siting
These buildings are typically found in flat terrain. They do no share common walls with adjacent buildings. There is no specific data on a typical separation distance between buildings. Minimum separation distance is decided mainly by building code regulation for the insulation duration within a room. The Civil Code also regulates a minimum distance of at least 50 cm. Traditional shop houses in Japan, Machiya, do not have a separation distance between buildings When separated from adjacent buildings, the typical distance from a neighboring building is 0.5 meters.
2.2 Building Configuration
It is different throughout the country, depending on the location of the housing. Single-family housing in urban and suburban areas is typically just one building, and farmers' houses in rural areas consist of 2-3 buildings, including the main house, storage, etc. There are also apartment houses of wood in urban areas. In 1998 single-family housing was still the major architectural type in Japan (57.5%), and 93% of single-family houses were wooden structures.
2.3 Functional Planning
The main function of this building typology is single-family house. Many types of wooden structures are used for housing, including the traditional
shop house, "Machiya," which exists in old downtown areas (a mixed-use building), and wooden apartment buildings, "Mokuchin," which are cheap rental housing. In a typical building of this type, there are no elevators and 1-2 fire-protected exit staircases. There is no special requirement for exits in 2-3 story single-family houses. However, there are strict requirements on the materials used for the window frames, walls, and roofing in urbanized areas to prevent fire spread.
2.4 Modification to Building
Modification of utilities in the kitchen and bathroom, or extension of the living space is common. However, seismic retrofitting is not very common.
Figure 4: Traditional housing for wealthy merchant 1 (Yoshijima family house in Takayama) |
3. Structural Details3.1 Structural System
| Material | Type of Load-Bearing Structure | # | Subtypes | Most appropriate type |
| Masonry | Stone Masonry
Walls | 1 | Rubble stone (field stone) in mud/lime
mortar or without mortar (usually with
timber roof) | ☐ |
| 2 | Dressed stone masonry (in
lime/cement mortar) | ☐ |
| Adobe/ Earthen Walls | 3 | Mud walls | ☑ |
| 4 | Mud walls with horizontal wood elements | ☐ |
| 5 | Adobe block walls | ☐ |
| 6 | Rammed earth/Pise construction | ☐ |
Unreinforced masonry
walls | 7 | Brick masonry in mud/lime
mortar | ☐ |
| 8 | Brick masonry in mud/lime
mortar with vertical posts | ☐ |
| 9 | Brick masonry in lime/cement
mortar | ☐ |
| 10 | Concrete block masonry in
cement mortar | ☐ |
| Confined masonry | 11 | Clay brick/tile masonry, with
wooden posts and beams | ☐ |
| 12 | Clay brick masonry, with
concrete posts/tie columns
and beams | ☐ |
| 13 | Concrete blocks, tie columns
and beams | ☐ |
| Reinforced masonry | 14 | Stone masonry in cement
mortar | ☐ |
| 15 | Clay brick masonry in cement
mortar | ☐ |
| 16 | Concrete block masonry in
cement mortar | ☐ |
| Structural concrete | Moment resisting
frame | 17 | Flat slab structure | ☐ |
| 18 | Designed for gravity loads
only, with URM infill walls | ☐ |
| 19 | Designed for seismic effects,
with URM infill walls | ☐ |
| 20 | Designed for seismic effects,
with structural infill walls | ☐ |
| 21 | Dual system – Frame with
shear wall | ☐ |
| Structural wall | 22 | Moment frame with in-situ
shear walls | ☐ |
| 23 | Moment frame with precast
shear walls | ☐ |
| Precast concrete | 24 | Moment frame | ☐ |
| 25 | Prestressed moment frame
with shear walls | ☐ |
| 26 | Large panel precast walls | ☐ |
| 27 | Shear wall structure with
walls cast-in-situ | ☐ |
| 28 | Shear wall structure with
precast wall panel structure | ☐ |
| Steel | Moment-resisting
frame | 29 | With brick masonry partitions | ☐ |
| 30 | With cast in-situ concrete
walls | ☐ |
| 31 | With lightweight partitions | ☐ |
| Braced frame | 32 | Concentric connections in all
panels | ☐ |
| 33 | Eccentric connections in a
few panels | ☐ |
| Structural wall | 34 | Bolted plate | ☐ |
| 35 | Welded plate | ☐ |
| Timber | Load-bearing timber
frame | 36 | Thatch | ☐ |
| 37 | Walls with bamboo/reed mesh
and post (Wattle and Daub) | ☐ |
| 38 | Masonry with horizontal
beams/planks at intermediate
levels | ☐ |
| 39 | Post and beam frame (no
special connections) | ☐ |
| 40 | Wood frame (with special
connections) | ☐ |
| 41 | Stud-wall frame with
plywood/gypsum board
sheathing | ☐ |
| 42 | Wooden panel walls | ☐ |
| Other | Seismic protection systems | 43 | Building protected with base-isolation systems | ☐ |
| 44 | Building protected with
seismic dampers | ☐ |
| Hybrid systems | 45 | other (described below) | ☐ |
There are several structural systems that are used in Japanese wood housing.
While post and beam construction is most common, some buildings of this type are of balloon frame construction.
3.2 Gravity Load-Resisting System
The vertical load-resisting system is timber frame. Gravity load-bearing structure consists of a system of posts and beams. Wooden posts, with cross-sectional dimensions ranging from 105 to 150 mm, carry gravity loads. The roof structure is made out of wood and it is covered by roof tile or slate. The roof load is transferred to the wood frame. The roof-supporting system in Japan is different from that of western countries and it is based only on vertical and horizontal members. There are no diagonal members, common for similar construction in western countries.
3.3 Lateral Load-Resisting System
The lateral load-resisting system is timber frame. Japanese wooden housing is built using "post-and-beam" construction. Lateral load resistance is provided by wooden shear walls with interior diagonal brace members or alternatively, with plywood or manufactured wood panels ("particle board") nailed to the vertical wooden members. The building code regulates the number and dimensions of shear walls. Metal joints and plates are used to stiffen the wood frame in recent wooden housing.
However, the traditional Japanese house did not have a diagonal brace. A thin lumber running through posts, called Nageshi, and a thick wood post, provide lateral resistance. The traditional Japanese carpenter was reluctant to use a diagonal brace because it could cause a diagonal crack in a mud-plastered wall.
3.4 Building Dimensions
The typical plan dimensions of these buildings are: lengths between 0 and 0 meters, and widths between 0 and 0 meters. The building has 1 to 3 storey(s). The typical span of the roofing/flooring system is 1.8-2 meters. Typical Plan Dimensios: There is a wide variation in dimensions.
Typical Numbe of Stories: Building code regulations limit the height of wooden structures to a maximum of three stories. A special permit is necessary for wooden buildings with four or more stories.
Typcial Story Height: This story height measurement does not include the height of the basement. Therefore, the story height of first floor includes the typical story height, plus the height of basement and is usually 3.4 meters.
Typical Span: Modular coordination is conducted according to Tatami mat size in Japanese housing. The typical module dimension in Japanese housing ranges between 0.9-1 meter. The typical
span (distance between the posts) is equal to two modules (i.e. 1.8-2 m). The typical storey height in such buildings is 2.8 meters. The typical structural wall density is none. There is a wide variation in wall density.
3.5 Floor and Roof System
| Material | Description of floor/roof system | Most appropriate floor | Most appropriate roof |
| Masonry | Vaulted | ☐ | ☐ |
Composite system of concrete joists and
masonry panels | ☐ | ☐ |
| Structural concrete | Solid slabs (cast-in-place) | ☐ | ☐ |
| Waffle slabs (cast-in-place) | ☐ | ☐ |
| Flat slabs (cast-in-place) | ☐ | ☐ |
| Precast joist system | ☐ | ☐ |
| Hollow core slab (precast) | ☐ | ☐ |
| Solid slabs (precast) | ☐ | ☐ |
Beams and planks (precast) with concrete
topping (cast-in-situ) | ☐ | ☐ |
| Slabs (post-tensioned) | ☐ | ☐ |
| Steel | Composite steel deck with concrete slab
(cast-in-situ) | ☐ | ☐ |
| Timber | Rammed earth with ballast and concrete or
plaster finishing | ☐ | ☐ |
| Wood planks or beams with ballast and concrete or plaster finishing | ☐ | ☐ |
| Thatched roof supported on wood purlins | ☑ | ☐ |
| Wood shingle roof | ☐ | ☐ |
| Wood planks or beams that support clay tiles | ☑ | |
Wood planks or beams supporting natural
stones slates | ☐ | ☐ |
Wood planks or beams that support slate,
metal, asbestos-cement or plastic corrugated
sheets or tiles | ☐ | ☐ |
Wood plank, plywood or manufactured wood
panels on joists supported by beams or walls | ☐ | ☐ |
| Other | Described below | ☑ | ☑ |
3.6 Foundation
| Type | Description | Most appropriate type |
| Shallow foundation | Wall or column embedded in
soil, without footing | ☐ |
Rubble stone, fieldstone
isolated footing | ☑ |
Rubble stone, fieldstone strip
footing | ☐ |
Reinforced-concrete isolated
footing | ☐ |
Reinforced-concrete strip
footing | ☑ |
| Mat foundation | ☐ |
| No foundation | ☐ |
| Deep foundation | Reinforced-concrete bearing
piles | ☐ |
Reinforced-concrete skin
friction piles | ☐ |
| Steel bearing piles | ☐ |
| Steel skin friction piles | ☐ |
| Wood piles | ☐ |
| Cast-in-place concrete piers | ☐ |
| Caissons | ☐ |
| Other | Described below | ☐ |
Infrequently, deep foundations are also used.
Figure 5: Traditional housing for wealthy merchant 2 (Yoshijima family house in Takayama) | 
Figure 6: Structural system (source: Uchida, 2001) | 
Figure 7: Roof (Source: Uchida, 2001)
|
Figure 8: Traditional walls (source: Uchida, 2001) | 
Figure 9: Wall (source: Uchida, 2001)
| 
Figure 10: Basement (source: Uchida, 2001)
|
Figure 11: Modular coordination (source: Uchida, 2001) |
4. Socio-Economic Aspects4.1 Number of Housing Units and Inhabitants
Each building typically has 1 housing unit(s). 1 units in each building.
As noted above, most wood housing is still single-family, 1 unit per building.
However, for multi-family housing, the average number of units is 8.78. The number of inhabitants in a building during the day or business hours is less than 5. The number of inhabitants during the evening and night is less than 5. In 2000, the average number of members in a Japanese family was 2.69 persons.
4.2 Patterns of Occupancy
In 1998 single-family housing still constituted the dominant housing stock (57.5%). However, the percentage of multi-family housing continued to increase from the 1965 level of 12.5% and comprised 37.8% of the housing stock in 1998. (The percentage of semi-detached housing had decreased to 4.2% by 1998). This data is based on the entire housing stock in Japan, and not just on wooden structure housing and unit base.
4.3 Economic Level of Inhabitants
| Income class | Most appropriate type |
| a) very low-income class (very poor) | ☐ |
| b) low-income class (poor) | ☐ |
| c) middle-income class | ☐ |
| d) high-income class (rich) | ☐ |
There is no specific data about each economic class and each housing type. In
2002, the average condominium price in Tokyo was JPY 39 million compared to the average annual salary of JPY 7.4 million.
| Ratio of housing unit price to annual income | Most appropriate type |
| 5:1 or worse | ☐ |
| 4:1 | ☐ |
| 3:1 | ☐ |
| 1:1 or better | ☑ |
What is a typical source of
financing for buildings of this
type? | Most appropriate type |
| Owner financed | ☑ |
| Personal savings | ☑ |
Informal network: friends and
relatives | ☑ |
Small lending institutions / micro-
finance institutions | ☐ |
| Commercial banks/mortgages | ☑ |
| Employers | ☐ |
| Investment pools | ☐ |
| Government-owned housing | ☐ |
| Combination (explain below) | ☑ |
| other (explain below) | ☐ |
A quasi-governmental housing loan company distributes low interest housing loans for the middle class and 32% of the housing stock constructed after World War II has been purchased through this financing. In each housing unit, there are 1 bathroom(s) without toilet(s), 1 toilet(s) only and no bathroom(s) including toilet(s).
Housing units without a private bathroom number 1,278,700 and housing units
without a private latrine number 290,400. .
4.4 Ownership
The type of ownership or occupancy is renting, outright ownership , ownership with debt (mortgage or other) , individual ownership and long-term lease.
Type of ownership or
occupancy? | Most appropriate type |
| Renting | ☑ |
| outright ownership | ☑ |
Ownership with debt (mortgage
or other) | ☑ |
| Individual ownership | ☑ |
Ownership by a group or pool of
persons | ☐ |
| Long-term lease | ☑ |
| other (explain below) | ☐ |
59.8% of the housing was owner-occupied in 1993.
5. Seismic Vulnerability5.1 Structural and Architectural Features
Structural/
Architectural
Feature | Statement | Most appropriate type |
| True | False | N/A |
| Lateral load path | The structure contains a complete load path for seismic
force effects from any horizontal direction that serves
to transfer inertial forces from the building to the
foundation. | ☑ | ☐ | ☐ |
Building
Configuration | The building is regular with regards to both the plan
and the elevation. | ☑ | ☐ | ☐ |
| Roof construction | The roof diaphragm is considered to be rigid and it is
expected that the roof structure will maintain its
integrity, i.e. shape and form, during an earthquake of
intensity expected in this area. | ☑ | ☐ | ☐ |
| Floor construction | The floor diaphragm(s) are considered to be rigid and it
is expected that the floor structure(s) will maintain its
integrity during an earthquake of intensity expected in
this area. | ☑ | ☐ | ☐ |
Foundation
performance | There is no evidence of excessive foundation movement
(e.g. settlement) that would affect the integrity or
performance of the structure in an earthquake. | ☑ | ☐ | ☐ |
Wall and frame
structures-
redundancy | The number of lines of walls or frames in each principal
direction is greater than or equal to 2. | ☑ | ☐ | ☐ |
| Wall proportions | Height-to-thickness ratio of the shear walls at each floor level is:
Less than 25 (concrete walls);
Less than 30 (reinforced masonry walls);
Less than 13 (unreinforced masonry walls); | ☑ | ☐ | ☐ |
Foundation-wall
connection | Vertical load-bearing elements (columns, walls)
are attached to the foundations; concrete
columns and walls are doweled into the
foundation. | ☑ | ☐ | ☐ |
Wall-roof
connections | Exterior walls are anchored for out-of-plane seismic
effects at each diaphragm level with metal anchors or
straps | ☑ | ☐ | ☐ |
| Wall openings | The total width of door and window openings in a wall
is:
For brick masonry construction in cement mortar : less
than ½ of the distance between the adjacent cross
walls;
For adobe masonry, stone masonry and brick masonry
in mud mortar: less than 1/3 of the distance between
the adjacent cross
walls;
For precast concrete wall structures: less than 3/4 of
the length of a perimeter wall. | ☑ | ☐ | ☐ |
| Quality of building materials | Quality of building materials is considered to be
adequate per the requirements of national codes and
standards (an estimate). | ☑ | ☐ | ☐ |
| Quality of workmanship | Quality of workmanship (based on visual inspection of
few typical buildings) is considered to be good (per
local construction standards). | ☑ | ☐ | ☐ |
| Maintenance | Buildings of this type are generally well maintained and there
are no visible signs of deterioration of building
elements (concrete, steel, timber) | ☐ | ☑ | ☐ |
| Other | | ☑ | ☐ | ☐ |
5.2 Seismic Features
| Structural Element | Seismic Deficiency | Earthquake Resilient Features | Earthquake Damage Patterns |
| Wall | See Structural Features | See Structural Features | See Structural Features |
| Frame (columns, beams) | See Structural Features | See Structural Features | See Structural Features |
| Roof and floors | See Structural Features | See Structural Features | See Structural Features |
| Other | See Structural Features | See Structural Features | See Structural Features |
5.3 Overall Seismic Vulnerability Rating
The overall rating of the seismic vulnerability of the housing type is A: HIGH VULNERABILITY (i.e., very poor seismic performance), the lower bound (i.e., the worst possible) is A: HIGH VULNERABILITY (i.e., very poor seismic performance), and the upper bound (i.e., the best possible) is A: HIGH VULNERABILITY (i.e., very poor seismic performance).
| Vulnerability | high | medium-high | medium | medium-low | low | very low |
| | very poor | poor | moderate | good | very good | excellent |
Vulnerability
Class | A | B | C | D | E | F |
| ☑ | ☐ | ☐ | ☐ | ☐ | ☐ |
5.4 History of Past Earthquakes
| Date | Epicenter, region | Magnitude | Max. Intensity |
| 1923 | Kanto | 7.9 | 7 (JMA) estimated results |
| 1964 | Niigata | 7.5 | 6 (JMA) |
| 1995 | Hyougo-ken-Nannbu | 7.3 | 7 (JMA) |
| 2000 | Tottori-ken-Seibu | 7.3 | 6+(JMA) |
The magnitude of each earthquake is JMA magnitude. The 1923 Kanto earthquake killed more than 140,000 people, heavily damaged 120,000 buildings and burned 440,000 buildings. Fire following the earthquake was the most prevalent cause of damage. There were many earthquakes during the 1930s and 40s, such as the Tottori in 1943, which killed 1,083 people, the East Nankai in 1944, the Nankai in 1996, and the Fukui in 1949, which killed 3,769 people. There was a reduction in the number of earthquake disasters during 1950s-80s. However, the Niigata earthquake in 1964 spotlighted damage by liquefaction and the Miyagiken-oki earthquake in 1978 spotlighted damage by a landslide occurring at a
hillside housing complex. The 1995 Hyogo-ken Nanbu earthquake killed 6,435 people. They died mainly from the collapse of wooden housing. In 2001 during the Tottori-ken Seibu earthquake, many wooden housing units were damaged by ground motion and liquefaction.
Figure 12: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) | 
Figure 13: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) | 
Figure 14: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) |
Figure 15: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) | 
Figure 16: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) | 
Figure 17: Wooden structure housing damage at the 1995 Kobe earthquake (photo by Michio Miyano) |
Figure 19: Tools used in construction process (source: http://www1.sphere.ne.jp/tknk-mse/dougu/B3.htm) |
6. Construction6.1 Building Materials
| Structural element | Building material | Characteristic strength | Mix proportions/dimensions | Comments |
| Walls | Sliding (synthetic resin, metal, ceramic) plywood mortar+wood mud + bamboo | | | The most traditional wall of Japanese wooden housing was made from mud on bamboo frame. Though mortal finish on
wood frame was popular in modern wooden structure, now siding on plywood becomes most popular in ordinary wooden structure housing.
|
| Foundation | RC No foundation (just foundation stone) | | | Traditional Japanese wooden structure does not have foundation. It is just put on foundation stone. |
| Frames (beams & columns) | Wood RC Steel | | | Usage of metal joint is encouraged by a present building code. However, metal joint was not used in traditional
Japanese housing.
|
| Roof and floor(s) | Roof tile on mud Slate Wood RC | | | Heavy roof made of mud and roof tile caused collapse of housing at the time of 1995 Kobe earthquake. |
6.2 Builder
The builder lives in this construction type.
6.3 Construction Process, Problems and Phasing
Please refer to figure 7a-7h. The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size.
6.4 Design and Construction Expertise
The building standard mandates that buildings of this type must be designed by a licensed architect. The licensing system for architects in Japan is unique in that the license is issued to engineers. There are three licensing levels: Wooden Structure, Second Class, and First Class. To take the examination for a license for Wooden Structure, one must have graduated from a school of architecture or civil engineering; for a 2nd class license, two years experience in the field is required. The 1st class license requires two additional years experience after the 2nd class license is issued. Any licensed architect can design wooden structure housing. For this type of building, the role of the engineer and architect is not large. The building is designed and constructed mainly by a licensed design builder, who is a contractor responsible for both the design and construction of the structure.
6.5 Building Codes and Standards
This construction type is addressed by the codes/standards of the country. Title of the code or standard: Japanese Building Standard
Year the first code/standard addressing this type of construction issued: The first building standard was established in 1919 and dealt mainly with buildings in urban areas, primarily large-scale wooden structure housing. In 1950, the Japanese Building Standard was issued, which addressed almost all wooden structure housing.
When was the most recent code/standard addressing this construction type issued? The last amendment was issued in 2000. The main objectives of this amendment were 1) performance-based regulation, 2) enforcement of a building inspection system, 3) involvement of the private sector in building inspections.
Drawing check - interim inspection - final inspection. The requirement for an interim inspection depends on the scale of the housing. Interim inspections were introduced by an amendment of the building standard in 2000.
6.6 Building Permits and Development Control Rules
This type of construction is a non-engineered, and not authorized as per development control rules. Building permits are required to build this housing type.
6.7 Building Maintenance
Typically, the building of this housing type is maintained by Builder and Owner(s).
6.8 Construction Economics
JPY 0.4-1 million/3.3 m2. Average cost of carpenter/day: JPY 10, 000 - 20,000 without cost.
Figure 18: Stages of housing construction (source: http://member.nifty.ne.jp/koso/hokushin/jiban.html) |
7. Insurance
Earthquake insurance for this construction type is typically available. For seismically strengthened existing buildings or new buildings incorporating seismically resilient features, an insurance premium discount or more complete coverage is available. Premium discounts were issued according to the seismicity of the area, age of the building, structure type and quality of the building. The government subsidizes earthquake insurance. Maximum coverage is 50 million yen for structures and 10 million yen for personal property.
8. Strengthening
8.1 Description of Seismic Strengthening Provisions
Strengthening of Existing Construction :
| Seismic Deficiency | Description of Seismic Strengthening provisions used |
| Poor frame joint connection | Fix frame joint using metal connector or plates |
| Poor connection between foundation and framing | Fix using metal connector |
| Absence of diagonal brace | Add a diagonal brace or structural plywood into frame |
| Heavy roof | Use light roof tile or slate |
8.2 Seismic Strengthening Adopted
Has seismic strengthening described in the above table been performed in design and construction practice, and if so, to what extent?
Yes. The new building code requires usage of metal joints and of a diagonal brace.
Was the work done as a mitigation effort on an undamaged building, or as repair following an earthquake?
In spite of encouragement by the government through low interest loans, retrofitting work for housing is not very popular. In earthquake recovery activities, people prefer to reconstruct their housing rather than to repair it with seismic upgrades with a view toward its resale value.
8.3 Construction and Performance of Seismic Strengthening
Was the construction inspected in the same manner as the new construction?
No. Few people get building permission for repair or renovations, though the building code requires getting permission for large-scale repairs or renovations.
Who performed the construction seismic retrofit measures: a contractor, or owner/user? Was an architect or engineer involved?
The contractor is the main retrofitter. Building repair by a homeowner is not so popular. Recently, some private companies that are not specialized for building construction have begun to promote housing retrofit service.
What was the performance of retrofitted buildings of this type in subsequent earthquakes?
No data.
Reference(s)- 1998 Housing and Land Survey
Statistics Bureau & Statistics Center, Government of Japan, http://www.stat.go.jp/english/data/jyutaku/index.htm
- System of Earthquake Insurance (In Japanese)
Non-Life Insurance Rating Organization of Japan, http://www.nliro.or.jp/contents/rate/index.html
- Gap between price of mid-raised condominium and average annual salary (In Japanese)
Urban Developers' Association of Japan, http://www.udaj.or.jp/kairi2002kami.htm
- Building structure system
Uchida,S.,
Ichigaya syuppansya 2001
- Japanese Housing, Rev.2, Gyousei
Housing Bureau, Ministry of Construction, Japanese Government 1998
Author(s)- Norio Maki
Chief Research Scientist, 4F Human Renovation Museum, EDM NIED
1-5-2 Kaigan-dori Wakihama Chuo-ku, Kobe 651-0073, JAPAN
Email:maki@edm.bosai.go.jp FAX: -5786
- Satoshi Tanaka
Assistant Professor, College of Environment, Fuji Tokoha University & Disaster Research
325 Obuchi, Fuji Shizuoka 611-0011, JAPAN
Email:tanak_s@fuji-tokoha-u-ac.jp FAX: -372511
Reviewer(s)- Sajal K. Deb
Associate Professor
Dept. of Civil Engineering, Indian Institute of Technology Guwahati
Guwahati 781 039, INDIA
Email:skdeb@iitg.ernet.in; skd_iitg@yahoo.com FAX: 91 361 2690762
