The "Special File" section of the March-April 2024 issue of the Construction World Magazine delved into the topic of "Earthquake Performance, High-rise Structures, and Retrofitting Techniques." Answering our questions within the framework of this file, Founding Architect Gökhan Avcıoğlu from GAD Architecture stated, "GAD Architecture aims to be involved in the meticulous construction process of new settlements and all new buildings according to structural/earthquake engineering rules, while adhering to urban planning and urban design principles."
Throughout millions of years of evolutionary process, living organisms have constructed enclosed spaces to meet their sheltering needs and sustain their vital activities. Over time, these spaces have acquired an adaptive character based on parameters such as climate, geography, intended use, and necessity. Creating sustainable and safe spaces for users forms the foundation of sheltering needs. Meeting this need cautiously, planned, and accurately is essential.
LESSONS FROM HISTORY
Anatolia has been a significant region hosting many civilizations for over 12,000 years. This rich historical heritage is based on various factors such as the region's fertile lands and favorable climate. However, Anatolia's geological structure has also played a vital role in shaping this historical richness. Located on an active fault line, Anatolia is a region frequently exposed to earthquakes. These natural disasters have destroyed many civilizations over time, hindering continuity between civilizations. The region's propensity for disasters can be clearly seen from historical records.
Unfortunately, this information has not been adequately considered in the region's settlement and urbanization policies. This has led to many destructive earthquakes throughout history. However, every disaster has been followed by a new beginning. New cities have been built, and new civilizations have been established after earthquakes. This process demonstrates that Anatolia is in a constant state of change and transformation.
Anatolia's seismic history has deeply influenced the region's historical, cultural, and social structure. Earthquakes can be devastating, but they also present new opportunities. Therefore, the development of civilization in Anatolia cannot be thought of independently of earthquakes. By learning from the past, it is crucial to build earthquake-resistant cities and create a settlement plan compatible with the region's history. With this approach, the effects of future disasters can be minimized, and the region can enter a sustainable development process.
THE IMPORTANCE OF THE HOUSING AND CONSTRUCTION SECTOR
At this point, the housing and construction sector stands out as one of the locomotive sectors in Turkey, as in all countries. Increasing population, changing demographic structure, urban and rural migrations, and flexibility in building regulations and zoning laws have adversely affected building construction processes, leading to the deterioration of indoor spaces.
EARTHQUAKE RISK AND THE IMPORTANCE OF QUALIFIED SPACES
According to the 2004 Building Inspection Commission report, considering that 93% of Turkey's geographical structure and 98% of its population live in earthquake-prone areas, the presence of inadequate spaces in terms of quality and quantity poses significant risks. Anatolia, with its tectonic position, has been shaken by earthquakes, especially in the past centuries with earthquakes occurring on the North Anatolian and East Anatolian Fault Lines, which can produce large-magnitude earthquakes causing serious casualties. The Marmara and Aegean Regions also have fault lines capable of generating high-magnitude earthquakes. Therefore, constructing earthquake-resistant buildings and spatial design in almost every part of this vast geography is one of the most important architectural and construction qualifications.
THE IMPORTANCE OF EARTHQUAKE-RESISTANT STRUCTURES
By ignoring the existing building stock, it is possible to create a new living space and construct residential areas with high living quality and environmentally friendly. Considering Turkey's extensive area of 800,000 km² and imagining 30 million families of 3 or 4 people each, totaling a population of 90 million. If we build 1 acre of land and a 125 m² house for each family, there will be 875 m² of cultivable land left for each family. This means that a total of 120,000 km² will be used for structures such as houses, ancillary buildings (schools, factories, etc.), roads, and railways, each of which is 30,000 km². Thus, the remaining 680,000 km² or 700,000 km² can be preserved for natural habitats such as mountains, rivers, lakes, natural sites, and forests.
Without the need to reorganize existing cities, it is recommended to use new places with more favorable and modern infrastructure. Existing buildings, streets, and neighborhoods with distinguished, historical, and memory-filled places can be preserved by narrowing them down. New settlements should be planned within a circle of 2 or 3 km in diameter, where all needs can be reached within a 15-minute walking distance. Areas within this circle should be arranged to include squares, schools, small bazaars, marketplaces, cafes, and local government units.
Assessing the current situation, the presence of an active fault capable of causing fractures and earthquakes from a tectonic and seismological perspective indicates that earthquake risk is always present in that region. This emphasizes that the most important parameter in building construction practice is the strength of the building. Considering that the total building stock in Turkey has reached 24 million, the resistance to earthquakes, sustainability, quantitative, and qualitative values of these structures are of great importance.
Buildings to be constructed on parcels should be designed considering earthquake risk. Buildings should be constructed by pulling back half the height of the building according to the building height regime in the region. Although there is no obligation for seismic isolators for buildings up to five floors, open or closed projections should not be made. If there will be any projections, isolators or other earthquake-resistant building technologies must be used. Depending on the load-bearing system of the buildings, the beam thickness can carry up to 50 cm outside, and this part can be evaluated as a sunshade or balcony.
Regardless of the height regime, if a height of more than 4 meters is designed for any function on the ground floors, the ground floor bearing system must be reinforced with tie beams. Building a technical area is encouraged to meet technical area requirements. If the ground values in the region foresee possible liquefaction during an earthquake, at least one basement floor must be built.
RESPONSIBLE PARTIES AND SOLUTION PROPOSALS
At this point, local governments, building inspection companies, civil engineers, architects, urban planners, non-governmental organizations, academia, administrative managements, and state institutions have a significant role to play. The solution to this problem is only possible through a systematic approach and cooperation. I also have thoughts on different forms of management, heritage, and electoral systems, but they are not the subject of our article.
INSUFFICIENCY OF EXISTING LEGISLATIONS
Although dozens of Regulations have come into force and revised regarding buildings to be built in Disaster and Earthquake Zones in Turkey in 1940, 1944, 1949, 1953, 1961, 1968, 1975, 1998, 2007, 2018, and finally on March 1, 2019, unfortunately, none of these regulations have been able to increase the earthquake performance and resilience of buildings.
Approximately twenty years of "urban transformation" practice has not transformed the earthquake-resistant building stock nor ensured the earthquake resistance of the new structures it has produced. Moreover, the increase in building heights has been increased with decisions that are disastrous at the planning scale.
GAD'S WORKS AND SOLUTION PROPOSALS
As GAD, we have made serious project designs especially in recent years with innovative solutions brought by the developing technology to construct earthquake-resistant structures and urban living spaces at the architectural and engineering scale. In the future, GAD would like to be involved in the meticulous construction process of new settlements and all new buildings according to structural/earthquake engineering rules while adhering to urban planning and urban design principles.
Some projects of GAD include significant and important representatives in terms of structural expression in terms of earthquake resistance. Yalova Elyaf, Aksoy-Technical, Esma Sultan, Borusan Müzik & Sanat Evi, Divan Kuruçeşme, Balık Pazarı, Susona Lobby – Restaurant, Tuz Ambarı are some of the examples with strong earthquake resistance in the steel structural expression type. In the use of bare concrete, Kadıköy Park Toilet, Kuum Lobby – Restaurant, GAD Park office can be considered as advanced examples in terms of earthquake resistance.