| Report # | 101 |
| Report Date | 15-10-2003 |
| Country | TURKEY |
| Housing Type | RC Structural Wall Building |
| Housing Sub-Type | RC Structural Wall Building : Moment frame with in-situ shear walls |
|
Author(s)
|
Ahmet Yakut, Polat Gulkan |
|
Reviewer(s)
|
Svetlana N. Brzev |
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
This type of rapidly constructed, multi-unit residential form has been used in Turkey since the late 1970s and early 1980s. It has demonstrated superior earthquake resistance and has also been increasingly utilized as permanent housing in post-earthquake reconstruction programs. Initially, the tunnel form building was targeted for multi-unit residential construction for public or privately sponsored housing projects. Typically, a single building may contain 15 or more stories and up to 40 or 50 residential units.
This contribution has been motivated by our intention to not only familiarize readers with the architectural or structural features of the building type, but to also underscore its noteworthy seismic performance that stands in stark contrast to Turkey's recent experience.
1. General Information
Buildings of this construction type can be found in Virtually everywhere in the country in densely populated urban areas with limited land available for development. During the last decade, tunnel form buildings have also been the choice for rebuilding earthquake-affected towns and urban areas because they fulfill the requirements of easy and rapid construction, and because their acknowledged excellent earthquake performance that makes them popular with occupants. This type of housing construction is commonly found in both sub-urban and urban areas.
The use of "suburban" in this text does not correspond to its commonly understood connotation in, e.g., the USA. We mean districts and areas in newly developed parts of urban areas that are located on the outskirts or peripheries of existing settlements.
This construction type has been in practice for less than 100 years.
Currently, this type of construction is being built. .
Figure 8: An Application of Half-Tunnel Forms
|
2. Architectural Aspects2.1 Siting
These buildings are typically found in flat terrain. They do no share common walls with adjacent buildings. The Turkish Building Development Law requires a minimum separation distance of 6 m for detached buildings. Tunnel form buildings are usually in the 12-16 story range, so the space between them is converted into common lawns by developers, and the buildings have substantial separation distances between them When separated from adjacent buildings, the typical distance from a neighboring building is 10 meters.
2.2 Building Configuration
The buildings enjoy a wide variety of plan and elevation shapes as illustrated in Figures 1-6. The construction sequence, described in detail in Section 4, creates walls and floor slabs typically without openings during the primary concrete placement. Windows looking outside and interior doors or partitions are usually crafted from precast panels or lightweight concrete blocks. When architectural form allows it, doors may also be formed by leaving openings in the formwork during the primary casting.
2.3 Functional Planning
The main function of this building typology is multi-family housing. In a typical building of this type, there are no elevators and 1-2 fire-protected exit staircases. Internal staircases are the primary means of escapes during fires and other types of emergencies. In a number of instances owners have installed external spiral steel staircases when the internally provided staircases did not meet the size and space requirements of the official specifications.
2.4 Modification to Building
The peculiar contruction technique does not allow any structural modifications to the building.
Figure 1: Selected Plan Configuration-1
| 
Figure 2: Selected Plan Configuration-2
|
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) | ☐ |
3.2 Gravity Load-Resisting System
The vertical load-resisting system is reinforced concrete structural walls (with frame). The walls and the slab carry all gravity loads. Gravity loads are transferred uniformly to the walls by slabs. A mat foundation is commonly used to transmit the gravity loads to the soil.
3.3 Lateral Load-Resisting System
The lateral load-resisting system is reinforced concrete structural walls (with frame). Structural walls provide the lateral-load resistance. The walls and the slab are cast in a single operation using specially designed half-tunnel-steel forms (upside down U shape) that maintains a certain size as shown in Figures 7 and 8. This cuts down the construction time significantly. The wall and the slab form a monolithic joint. The following construction sequence is implemented.
1) The tunnel forms are first cleaned and coated with form oil. Then they are placed in their positions by using the kicker as the guide (Figures 7 and 8). 2) The wall reinforcement is placed before the tunnel formwork is positioned. Reinforcement steel and electric conduits are set in their places on the tunnel form (Figure 9). 3) Walls, slab and kickers are cast. The next morning the formwork is ready to be stripped and carried to the next location by a crane. In accordance with the design, steel blockouts may be installed on the formwork panels to form the plumbing openings. Figures 10 and 11 show the elevation and plan of a typical building constructed by this technique. Figures 12 to 15 show samples of the reinforcement detailing and the structural drawings taken from the blueprints of a typical building.
.
3.4 Building Dimensions
The typical plan dimensions of these buildings are: lengths between 10 and 30 meters, and widths between 10 and 30 meters. The building has 10 to 15 storey(s). The typical span of the roofing/flooring system is 3-5 meters. Typical Plan Dimensions: The multi-story housing construction of this type typically has a rectangular plan. The ratio of long side to short side has a typical range of 1.0 to 2.0.
Typical Number of Stories: The reconstruction applications in the earthquake-affected areas have number of stories between 2-6. But the multi-story residential houses are taller typically 10-15 stories high.
Typical Story Height:The tunnel forms used allow story height to range from 2.30 m to 3.0 m.
Typical Span: Typical span lengths have a range of 2.1 to 5.70 m. The typical storey height in such buildings is 2.8 meters. The typical structural wall density is up to 10 %. 2% - 6%
The typical density of structural walls is about 4 percent of the area of one floor. This density may vary from 2 to 6 percent depending on the thickness of the wall, the span and the plan dimensions of the building. Both principal directions usually have the same 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 | ☐ |
It consists of reinforced concrete end-bearing piles and reinforced concrete skin-friction piles.
Figure 3: Selected Plan Structural Configuration-1 | 
Figure 4: Selected Elevation Configuration-1
| 
Figure 5: Selected Elevation Configuration-2
|
Figure 6: Selected Elevation Configuration-3
| 
Figure 7: Half-Tunnel Forms Handled by Cranes
| 
Figure 9: Reinforcement Details for Walls with and without Openings |
Figure 10: A Typical Tunnel Form Building Nearing Completion (Note Masonry Facade Elements) | 
Figure 11: Structural Plan of the Building in Figure 10 (Building Footprint Measures 25x27 m, and Its Height is 25 m) | 
Figure 12: The Structural Plan of a Typical Floor
|
Figure 13: The Structural Plan of a Typical Floor
Reinforcement Detailing for a Wall Section Extracted from the Plan Given in Figure 12 | 
Figure 14: Drawing for the Reinforcement Detailing of a Typical Floor | 
Figure 15: Strip Reinforcement for Section a-a of Figure 14 |
|
4. Socio-Economic Aspects4.1 Number of Housing Units and Inhabitants
Each building typically has 21-50 housing unit(s). 40-50 units in each building.
Since the number of stories vary, a unique number for the units in a building is hard to assign. Typically there are four apartment units per floor and average number of floors is 10-12. 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. The average size of a family residing in a unit of this type of construction is about
4. During the day, one or two habitants reside in their units.
4.2 Patterns of Occupancy
Nearly all occupants are single family or co-family.
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) | ☑ |
Economical level of inhabitants depends strongly on the address of the building which also influences the price of the house unit. In Turkey, there is probably a poor correlation between the income and the price of the house unit people own.
Economic Level: The ratio of price of each housing unit to the annual income can be 6:1 for middle class and 3:1 for rich class families.
| 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 number of successful developers have constructed multi-family housing of this type during the last quarter century. The way it works is as follows: Families wishing to invest in a dwelling
unit enter a private contract with the developing company that sets the conditions for the payments and delivery dates. Well managed enterprises have enabled tens of thousands of families to have their own house. Another scheme is for prospective homeowners to form a cooperative whose state of objective is to built multi-unit family housing. In this, families must typically finance about half of the cost of the finished building with the remainder coming from the government housing administration, a government housing financing scheme that was created in 1984 to address the housing shortage in the country. Many of the 1.1 million housing units constructed during 1984-2001 were financed by the housing administration. In each housing unit, there are 1 bathroom(s) without toilet(s), 2 toilet(s) only and no bathroom(s) including toilet(s).
4.4 Ownership
The type of ownership or occupancy is renting, outright ownership and individual ownership.
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) | ☐ |
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 | | The walls being the primary load-carrying members are proven to be the most effective members against eartquakes. Wall density helps in reducing the unit shear, and enables almost elastic response during even strong ground shaking. | Facade elements are usually pre-cast reinforced concrete panels that are placed after the walls have been formed, and attached along their periphery by welding. These have been observed to exhibit minor separation or cracking along their boundary, but this is not considered to be a structural deficiency.
|
| Frame (Columns, beams) | Spandrel beams formed above door openings have been observed to experience cracks when the building is subjected to strong seismic action. This is of little structural significance.
| | The spandrel beams above the door openings have been observed to suffer shear cracks. This does not lead to a reduced seismic capacity of the system therefore is considered as minor damage. |
| Roof and floors | | The honey-comb pattern of walls and slabs enables slabs to respond in their elastic range. | |
| Other | | | |
In Turkey, the observations from past earthquakes proved that the structures with adequate amount of shear walls performed quite well.
5.3 Overall Seismic Vulnerability Rating
The overall rating of the seismic vulnerability of the housing type is F: VERY LOW VULNERABILITY (i.e., excellent seismic performance), the lower bound (i.e., the worst possible) is F: VERY LOW VULNERABILITY (i.e., excellent seismic performance), and the upper bound (i.e., the best possible) is F: VERY LOW VULNERABILITY (i.e., excellent 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 |
| 1999 | Izmit, Turkey | 7.4 | X (MSK) |
| 2003 | Bingol, Turkey | 6.4 | VII+ (MSK) |
This construction type has experienced the two major earthquakes of 1999 and the earthquake of 2003. Neither demolished nor damaged buildings of this type have been reported after these earthquakes. Figures 16-20 demonstrate the conditions of several buildings after these earthquakes. Several buildings surviving the earthquakes of 1999 are shown in Figures 16-18. The building in Figure 16, that is virtually untouched, is located 3-4 km from the fault that was ruptured during the earthquake. In the city of Bingol, although extensive damage was observed in reinforced concrete frame structures, a group of five story tunnel from buildings (Figure 19) performed superbly without any sign of structural damage. Only minor nonstructural damage in the form of separation of the precast panels from the floors was observed.
Figure 16: The Building Is Part of a Multi-unit Housing Complex That Survived the Earthquakes of 1999 in İzmit without Damage | 
Figure 17: The Post-Earthquake Condition of Another Tunnel Form Building of a Different Housing Complex in
İzmit | 
Figure 18: This Tunnel Form Building Located in Bekirpasa/Izmit Also Suffered No Damage during the Earthquakes
in 1999 |
Figure 19: Tunnel Form Buildings after the Bingol Earthquake of May 1, 2003 |
6. Construction6.1 Building Materials
| Structural element | Building material | Characteristic strength | Mix proportions/dimensions | Comments |
| Walls | Concrete Reinforcing Steel | 25 MPa/ 500 MPa | | |
| Foundation | Concrete Reinforcing Steel | 25 MPa/ 500 MPa | | |
| Frames (beams & columns) | | | | |
| Roof and floor(s) | Concrete Reinforcing Steel | 25 MPa/ 500 MPa | | |
6.2 Builder
The construction of this type requires certain capacities the large construction companies have, thus it is typically build by experienced developers.
6.3 Construction Process, Problems and Phasing
See Structural Features. The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size. The tunnel form buildings are built in one construction cycle, and no increments or
modifications are possible at a later stage.
6.4 Design and Construction Expertise
Turkish contractors have gained much experience with tunnel form building construction, and have successfully applied this experience in many cases for foreign contracts, e.g. in Russia, North Africa, Caucasia and the Middle East. Although formal engineering registration does not exist in Turkey, these buildings go through a strict design, check, and supervision process. There is currently no specific set of requirements for this construction type in the current seismic design code. The walls are designed and detailed according to the specifications for reinforced concrete walls. Therefore, the choice of strength reduction factor, R, depends on the preference of the design engineer and the contractor for the building at hand. In general, a value between 4 to 6 is used by considering the economy. The higher value requires more restrictive detailing requirements and wall thicknesses that lead to a trade-off rating between speed of construction and cost.
6.5 Building Codes and Standards
This construction type is addressed by the codes/standards of the country. Title of the code or standard: 1. Regulations for Buildings to Be Built in Disaster Areas (1998) 2. TS 500: Requirements for Design and Construction of Reinforced Concrete Structures (2000)
Year the first code/standard addressing this type of construction issued: The seismic requirements have been first issued in 1945. The first edition of TS 500 was in 1969. We refer to Contribution No. 64 for a detailed account of the development of building codes and standards in Turkey.
National building code, material codes and seismic codes/standards: Most material codes have been issued by the Turkish Standards Institute at different dates.
When was the most recent code/standard addressing this construction type issued? 1. The seismic requirements have been last issued in 1998. 2. The last issue of TS 500 is dated 2000.
Developer submits designs and other required documents to the relevant local government to receive the construction permit.
6.6 Building Permits and Development Control Rules
This type of construction is a non-engineered, and 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, Owner(s) and Tenant(s).
6.8 Construction Economics
The average estimated unit construction cost for post-earthquake housing including utilities but excluding land is $154/m2. This usually corresponds to $ 15 000 per housing unit. The approximate cost for the utilities is $30/m2. The total cost of a housing unit including land strongly depends on the location and its architectural finish. One of the main advantages of this construction type is the speedy construction process. The formworks are handled by cranes and the ready mix concrete use minimizes the labor dependency. The cost efficiency is gained by optimizing labor, using less concrete, and minimizing the finishing work. This construction technique greatly reduces construction time by as much as 50% and the costs by 20 percent relative to the convential methods. It may take up to one year for the construction of a typical building to be completed.
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 unavailable. DASK, a recently established entity similar to California Earthquake Authority, provides mandatory country-wide insurance for all property up to a ceiling of $40,000. For amounts in excess of this owners must purchase voluntary insurance. Although this construction type has an excellent earthquake performance, the current earthquake insurance coverage treats all concrete structures under the same category when determining the premiums. DASK employs three classifications for the construction type, namely concrete structures, steel structures and masonry buildings. A second factor that is taken into account when determining premiums is the seismic region (based on current seismic zone map) in which the building resides. Work is underway to establish a more refined tariff structure. Insurance provided by DASK covers structure only. In high-hazard areas a dwelling of the type described under this section will have an annual premium of some $40-50.
8. Strengthening
8.1 Description of Seismic Strengthening Provisions
Strengthening of Existing Construction :
| Seismic Deficiency | Description of Seismic Strengthening provisions used |
| Shear cracks in spandrel beams. | Epoxy injection. |
Since no reported cases of significant damage have been encountered for this construction type, there are no widely experimented techniques of retrofitting developed and used for this construction type.
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?
The minor damage observed in the spandrel beams is generally accounted for in the design phase thus is repaired by epoxy injection.
Was the work done as a mitigation effort on an undamaged building, or as repair following an earthquake?
Not applicable.
8.3 Construction and Performance of Seismic Strengthening
Was the construction inspected in the same manner as the new construction?
Not applicable.
Who performed the construction seismic retrofit measures: a contractor, or owner/user? Was an architect or engineer involved?
Not applicable.
What was the performance of retrofitted buildings of this type in subsequent earthquakes?
Not applicable.
Figure 20: A Practically Unscathed Building Subjected to the Bingol Earthquake |
Reference(s)- MESA Construction Co. website, www.mesaimalat.com.tr
- Turkish Government Housing Administration website, www.toki.gov.tr
- MESA Imalat, personal communication
Akt
- Turkish Prime Ministry, Project Implementation Unit, personal communication
Kahraman,M.
Author(s)- Ahmet Yakut
Assistant Professor, Department of Civil Engineering, Middle East Technical University
ODTU, Ankara 6531, TURKEY
Email:ayakut@ce.metu.edu.tr FAX: + (90) 312-210 1193
- Polat Gulkan
Professor, Department of Civil Engineering, Middle East Technical University, Ankara 6531, TURKEY
Email:pgulkan@metu.edu.tr FAX: +90 312 210 1193
Reviewer(s)- Svetlana N. Brzev
Instructor
Civil and Structural Engineering Technology, British Columbia Institute of Technology
Burnaby BC V5G 3H2, CANADA
Email:sbrzev@bcit.ca FAX: (604) 432-8973
