Earthquake Insulation in Buildings: Applications in Turkey
In buildings with seismic isolation applied, the column and beam dimensions on floors are reduced, and the need for reinforced concrete shear walls decreases significantly.
In addition to saving lives during major earthquakes, ensuring that economic investments in buildings and facilities remain undamaged, and that functions and operations continue uninterrupted after earthquakes, seismic isolation technology—a more advanced design and safer technology—should be considered alongside earthquake regulations.
Just as aftershocks continue in the Earth's crust following a major earthquake, aftershocks in the business world cause actual damage in the business and industrial sectors. They can cause a workplace or sector to remain closed for months, years, or even decades, resulting in financial losses and complete loss of market share for the sector.
Unfortunately, we cannot say that the business world is fully aware of this issue.
Seismic isolation is of vital importance for hospital buildings, emergency response centers, disaster coordination centers, strategic management buildings, data storage and information processing centers, historic buildings that must be preserved intact for future generations, museums, libraries and similar structures.
In addition to its application in these critical buildings, seismic isolation is also widely used in high-rise residential (condominium apartment) buildings, particularly in Japan.
However, the reason it is not used in many luxury apartment buildings being constructed in Turkey's major cities appears to be that investor companies are unaware of this technology, and perhaps unaware of the added value and increased profits that a seismically isolated apartment would bring.
Earthquake regulations are aimed solely at saving lives during major earthquakes. However, depending on the magnitude of the earthquake, they are not designed to prevent buildings from sustaining repairable damage for economic reasons.
For this reason, how could a person who purchases an apartment sold for millions of dollars accept such damage? Residential investment firms need to consider this matter deeply.
In buildings with seismic isolation applied, the dimensions of columns and beams at each floor are reduced, and the need for reinforced concrete shear walls is substantially decreased.
In buildings with seismic isolation applied, the structure moves with a gentle motion in major earthquakes as if it were a rigid box, users and their belongings remain safe, operations in the building continue uninterrupted, and the building can be used during and after the earthquake.
The application of seismic isolation to buildings and structures within the scope of civil engineering started quite late in Turkey when compared with the global process.
While seismically isolated structures, led by the USA and Japan, have found application in many countries to eliminate earthquake risk, seismic isolation, at its current technological level, was first used in Turkey with the 1991 Bolu viaducts with bending steel dampers, and in 1997 with lead-core rubber isolators on the Tarsus-Adana-Gaziantep (TAG) highway.
In Turkey, the use of seismic isolation applications in buildings and the beginning of awareness in this field, albeit slowly, occurred following the shock created by the 1999 Gölcük and Adapazarı earthquakes.
Despite this shock, the reality that structures with seismic isolation could withstand major earthquakes with minimal damage, and that important buildings such as health facilities could be immediately operational after earthquakes, became established in society and the engineering sector following the establishment of the Earthquake Isolation Society in 2006 and the Ministry of Health's recognition of the importance of this issue.
However, the strengthening and dissemination of this awareness and the application of seismic isolation in public and private sector buildings occurred following the establishment of the Earthquake Isolation Society.
Following these general explanations, some examples regarding seismically isolated buildings in Turkey and the development of seismic isolation can be mentioned.
Atatürk Airport terminal building is a building with three reinforced concrete floors and a space frame steel roof, constructed by a consortium under a build-operate-transfer system. It is approximately 240 m x 168 m in base dimensions.
During the 17 August 1999 Kocaeli earthquake (Mw=7.6), the Atatürk Airport terminal building, which was nearing completion at the time, sustained damage, primarily at the top and bottom levels of the columns supporting the steel roof on the third floor.
Inspection after the earthquake revealed that the existing lateral-load-resisting system consisted of weak columns and strong beams.
In response to this unexpected damage, the solution chosen was seismic isolation of the roof beams, the use of additional shock transmission devices on the roof, and strengthening of the reinforced concrete structure.
In 2000, 130 seismic isolators were placed below the beams at the top of the columns, and shock transmission devices (lock-up devices) were used on the roof that allow for thermal expansion in joints but lock during an earthquake.
Following the Atatürk Airport terminal building and as the second application of strengthening with seismic isolators, we see the Tarabya Hotel in Istanbul. The Tarabya Hotel was a reinforced concrete structure built in the 1950s, consisting of a 13-story high block and low blocks.
It would probably have suffered damage in a major earthquake, possibly collapsed. At that time, the building, which was under the ownership of the Employees' Pension Fund, underwent seismic isolation application including strengthening of the foundations, wrapping of ground floor columns, increased spacing between block joints, and installation of 101 seismic isolators at the top of the ground floor columns, below the floor slab.
However, after the building changed ownership, the installed isolators were removed and the building, without seismic isolators and undergoing renovation, took on a new identity as a hotel once again.
In Turkey, we see the Kocaeli University hospital building as the first new building with seismic isolation applied during construction. The hospital building consists of 6 eight-story blocks and 5 low blocks. Seismic isolation was applied to the high blocks of the hospital and the seismic isolators are located at the level below the first floor slab. 265 isolators were used in the building.
The terminal building was constructed in 1998 according to the 1975 Earthquake Regulation and is a 3-story reinforced concrete building. After its construction, the Antalya region was changed from the 4th degree earthquake zone to the 2nd degree.
Due to a 200% increase in seismic demand, a decision was made to strengthen it with seismic isolators. During the strengthening, columns were suspended and cut, and 500 seismic isolators were installed on the columns.
The first seismic isolation application in hospital buildings belonging to the Ministry of Health was at the 400-bed Erzurum Training and Research Hospital in 2006. The 400-bed Erzurum Training and Research Hospital has a plan dimension of 160 m x 140 m and a height of 29 m. Shear walls were extensively used in this reinforced concrete building.
In the building, which was desired to remain operational during the largest earthquake, 386 rubber and lead-core rubber isolators with dimensions of 800 mm, 900 mm, 1000 mm, and 1100 mm were used to apply seismic isolation.
The seismic isolation application in this building led, from 2009 onward, to the beginning of investigations regarding the applicability of this system in other hospital buildings of the Ministry of Health.
Following several years of research and studies, in 2013 a decision was made to apply seismic isolation with seismic isolators in hospital buildings exceeding 100 beds in the 1st and 2nd degree earthquake zones.
By 2006, with the increasing applications of seismic isolation and the emergence of this awareness, seismic isolator manufacturers and engineering firms came together and established the Earthquake Isolation Society.
The primary purpose of the Society has been to conduct various activities with the aim of promoting seismic isolation. In this context, in 2007, the Earthquake Isolation Society served as the local organizer for the 10th World Conference of ASSISI (Anti Seismic Systems International Society), based in Italy, held in Istanbul.
Nearly 200 presentations and papers presented at this conference and more than 200 participants greatly contributed to the development of awareness regarding seismic isolation in Turkey.
In this context, from 2008 onward, seismic isolation began to attract greater attention from civil engineers and design firms.
Another application during the same period was the Ankara Söğütözü Convention and Trade Center building, belonging to the Ankara Metropolitan Municipality, with seismic isolator installation completed in 2007. It has plan dimensions of 300 m x 100 m.
The structure below the seismic isolation plane was reinforced concrete, while the structure above was steel. This structure, with 210,000 m² of construction area and located 110 km from the North Anatolian Fault, was demolished together with the installed seismic isolators due to zoning issues, and the project was cancelled.
A seismic isolation application in 2008 was the Sabiha Gökçen Airport terminal building. For the seismic isolation of this structure with 160,000 m² of area, 252 seismic isolators were used.
The Ministry of Health's decision to apply seismic isolation with seismic isolators in hospital buildings exceeding 100 beds in the 1st and 2nd degree earthquake zones initiated a new phase.
At the beginning of this phase, in 2012, we see the 750-bed Erzurum Health Complex as a new seismically isolated hospital facility.
This complex, with 250,574 m² of construction area, is currently under construction and includes 1,248 seismic isolators.
At the 500-bed Van Central Health Campus, whose construction began in 2012, 542 seismic isolators were used.
While construction of some of the hospital buildings using seismic isolators by the Ministry of Health continues, others are in the tender, design, or planning phase, and the number of earthquake-protected hospital buildings with seismic isolation is increasing. Other hospital buildings in this group include those in Antalya, Çorum, Keşan, Biga, Gemlik, Taksim Emergency Aid, Elbistan, and others.
Other Integrated Health Campus and City Hospital projects managed by the Public-Private Partnership Department, a unit under the Ministry of Health's Directorate General of Health Investments, are being designed to be implemented with seismic isolators under the same rules. These campuses include very large health complexes that can reach up to 3,000 beds.
Additionally, some hospital buildings in Istanbul managed by the Istanbul Project Coordination Unit (İPKB) and financed with credit from international financing institutions are also being constructed with seismic isolators.
Currently, a lack of specifications and regulations is observed in the implementation of seismically isolated buildings in Turkey. For this reason, inconsistencies exist between institutions.
For example, while a hospital belonging to the Ministry of Health is being constructed with seismic isolators in a 1st degree earthquake zone, another hospital building in the same region can be constructed without seismic isolators by TOKI.
Similarly, while the İPKB prepares the specifications and design of a seismically isolated hospital building generically (open to all isolator manufacturers), it can prepare the design of three other hospital buildings based solely on one company's product.
Turgut Ersavaş / Ersavaş Seismic Devices - Senior Engineer Architect
It is hoped that these inconsistencies will be resolved when the Seismic Isolation Specifications, which AFAD is currently working on, are introduced in 2015 as a supplement to the existing Earthquake Regulations as expected.
Sources:
1. In the process that started in 2000 and continues to the present, because I was the person submitting seismic isolator proposals for the tenders of most of the seismically isolated structures mentioned in my article, I have information on the specifications and details of these projects regarding "Seismic Isolator Tenders for Seismically Isolated Structures."
2. Information acquired during my tenure as President of the Earthquake Isolation Society between 2006 and 2009, and presentations made at the 10th ASSISI World Conference on "Seismic Isolation, Energy Damping, and Active Vibration Control in Structures," which we organized as the Earthquake Isolation Society in Istanbul in 2007.
3. Presentations made at the "Seismic Isolation Methods and Applications Symposium" by Prota Engineering in cooperation with METU-Technokent in 2013.
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