We talked with ITU Faculty Member Prof. Dr. Hasan Yıldırım about the issues coming to the agenda after the Kahramanmaraş earthquake. Yıldırım shared his comments with us, from basic material quality, building control to urbanization, from the possible Istanbul earthquake to the economic dimension of urban transformation.
Since it is kind of a bridge between the two continents, it is impossible to think of our country independent from earthquakes. Our history is written by earthquake stories from north to south, east to west. How and to what extent can building safety really protect us from earthquakes?
Building safety protects us from earthquakes. However, it protects only when we pay attention to the conditions and specifications in the structures we produce. The reasons for the demolition of old buildings are mainly making an unsuitable foundation where there is no good ground, not complying with the project of the building, not complying with the concrete quality and iron quality. We found out that the concrete is well poured, but the iron is bad. Or irons are good, and this time concrete is problematic, malpractice, or bad quality.
Similar buildings were built in an unconscious, thoughtless manner. It is said that 3% of the buildings destroyed in the Maraş earthquake are newly constructed buildings. This means that they solved the structure according to the new regulation, but they did not plan the structure according to the ground, the demolished buildings were built without sufficient basement floors, for example, on broken ground, or without piling if necessary, or without applying the required ground improvement. If you project a building based on that ground, these will not happen. Besides, if the choice of iron and the concrete is correct, that’s fine.
Let alone the new regulation, even if the building is built according to the 1975 regulation; if the area is not over the fault line and the ground is good, we have seen that the buildings in the area are not destroyed. So, it is understood from here that the specifications and regulations were not complied with in our country, and even if they were, the projects were not complied with. No attention was paid to quality.
We have to do whatever it takes to live in an earthquake zone.
In Japan, each building is projected according to the earthquake and planned to be “not-damaged” after the earthquake. In our country, only the hospitals are projected in this manner. However, the buildings should be like that, and the cost increases, of course. Our economy is problematic, and even with the current cost of less secure buildings, people cannot afford to buy a building or even afford the rent. In that case, of course, these requirements are discontinued because the cost is incurred in safer projected buildings. That is a problem. If we try to do it, we will, we never lack knowledge and experience. A policy should be developed to address these situations. This is very much related to the economy.
Tunnel formwork system, seismic insulator, radiation base… Which of these solutions included in our daily life is useful for what, where and what should be preferred?
Tunnel formwork means using completely reinforced concrete load- bearing shear walls instead of columns in the body of the building. Since the aim is to make the building faster here, the construction of the rough of the building is made with sliding molds on all sides. It’s a system invented to build fast buildings, but when you do it this way, every part of the building becomes a partition element. When it is a rigid, solid structure on all sides, even if the building topples over, it topples in the form of a box and the damage is reduced. However, the priority is the foundation, even if the tunnel is molded, the ground is very important, and it should never be ignored. We have to drive a raft foundation or pile, improve the ground and work according to what is necessary for that specific building.
As for the insulators; while the ground layer is shaking, the building on the insulator stands as if cut off from the ground and not affected by the impact, this also provides a suspension function and does not give the building the same intensity of the earthquake, naturally it becomes safe. We have seen this effect in hospitals during the earthquake and 99% of the insulators did their jobs. In 1% of them, maybe there were problems, for example, the system failed when side openings were not left for the release of the insulator building, and there were other such shortcomings. On the other hand, it is also important that the insulators used are of international quality, tested and approved. There is no use of these insulators, with newly established, uninitiated companies producing and claiming, “I produce it, it’s OK.”
The buildings built with a tunnel formwork system are claimed to be indestructible. On the other hand, buildings made with tunnel formwork create a uniform appearance. However, urbanity should also reflect the urban culture. How accurate would it be to equip historical cities like Hatay with buildings with tunnel formwork system? What kind of solution should buildings be built with to reflect the urban fabric?
Hatay is really a value for world history. It is true that tunnel formwork makes the appearance uniform. In the area of non-historical housing needs of the city, it is necessary to move forward with this solution and plan with original, architectural aesthetic concerns, suitable for low-rise and texture in historical areas. Not just the tunnel formwork, but any structure that does not reflect the historical fabric should not enter those areas. Architects and engineers must collaboratively solve the precious historical fabric in the region. Of course, there is a need to lead the way; when the texture and culture of the rebuilding process of the cities are taken into account, “construction in a very short time” should not come to an end, so that one can be happy to live, travel and see, as before.
Can you tell us about the building inspection process? What are the entire stages of the building process?
Jurists know more about this than I do, but there’s one thing I’d like to point out.
In the past, there was TUS, not building inspection, and it was doubtful whether even going to the building or not; therefore, the safety of such built structures was also controversial. After the 99 earthquake, this mechanism changed and developed with building control. There were mistakes, but solved, continuing to be solved.
For a period of time; there emerged contracting companies that supervised their own construction. This has also been avoided, with the pool system now randomly assigned a building inspection company. This way, the unlawful inspections performed by the front building inspection companies have been prevented. Thus, there is control with people who do not have a dialog between them.
Yet the experience, seriousness and work ethic of building inspection firms in our country is paramount. Building inspectors have a responsibility to ministries. They are also subject to control. At least they have a system to account for when they are complained.
“State cooperation with academic persons should be more systematic. We need to get on top of things together. We are already working together with both ministries and municipalities, but under one title, it is important to act more planned. These official collaborations will also make it easier to find loans.”
Do you think the earthquake regulation is sufficient? What are the aspects you find missing, what do you suggest will change?
I think this will happen, it changes year by year because there are deficiencies in the regulation and it is insufficient. For example, counting back a little bit, there were regulations 1968, 1975, 1997, 2007, and with the most recent change there was the regulation of 2018. In the latest regulation, to reflect the earthquake impact on buildings, the momentum is taken at 0.40 degrees. The last earthquake saw this acceleration increase to about 1.29. I think this low momentum should change in the new regulation.
One of the issues raised in the aftermath of the earthquake is control of the building stock and understanding whether it is earthquake resistant. What work needs to be done in this area in the current situation?
In Istanbul, municipalities are inspecting the buildings with a quick scan, taking the 99 earthquake as a milestone. I talked to Kartal, Şişli and Istanbul metropolitan municipalities, I personally went and saw them. For example, Kartal Municipality says, “We are thinking of renovating 17 thousand buildings”, they also consult academic teachers like us to examine them; there is an effort to do something, but this is not enough, 90 thousand building stocks are mentioned. This figure may rise to around 150 thousand- 200 thousand. The intention is big to do something, but we need money and credit. If the credit issue is not resolved, progress cannot be made.
Our country is in the earthquake zone in general but the Istanbul earthquake is more on the agenda due to its population and overall economic importance. What kind of consequences can we face when an earthquake strikes Istanbul? What are your general views?
Problematic building stock should be dealt with first. If it is not done, we will suffer many losses.
We have to leave it and do this job now! It is very important to be fast, strengthen the stockpiles where reinforcement is possible, as well as demolition and rebuilding. Like I said, credit issues need to be resolved.
State cooperation with academic persons should be more systematic. We need to get on top of things together. We are already working together with both ministries and municipalities, but under one title, it is important to act more planned. These official collaborations will also make it easier to find loans.
What concrete and cement products should be used to build earthquake-resistant structures? Some companies and engineers state that wrong application is made to save time in the field even though the right product is delivered. The truth is, how should it be done, both in production and in the field?
The materials used to make the structures are aesthetic-based. Well, I can’t say anything about those parts, but when it came to building security, people were mostly going for the expensive, beautiful stuff before the earthquake. That is, until you see how luxurious houses with flawless and well-stocked bathrooms weigh down with bad quality concrete and iron.
“People were mostly going for the one that was expensive and beautiful, with fine workmanship material in their building preferences, before the earthquake. That is, until I saw how luxury homes with impeccable and well-stocked bathrooms were ravaged by poor-quality concrete and iron.”
Carrier materials are important to us. Concrete quality, iron quality, cement quality and application in concrete… Cement quality in our country is very good, but conscious application is required. Iron and steel have enough quality, too, but we hear about the issue of iron from scrap too. This happened in the 99 earthquake, which left buildings using domestic production construction moors standing, but thousands of people were left under debris because of scrap iron imported from Bulgaria. Moreover, research after the Maraş earthquake has shown that most destruction occurred due to imported moors from Syria. However, the quality of iron and steel produced by our Iron-Steel factories established with the republic does not create such problems.
Supervision is important. Knowledge, experience is important. Production capacity is also important. Having a stock of sand, gravel and crushed stone is as important as saying that I produce concrete well. We will have a shortage of aggregates in the coming period, because most of the quarries have been closed. Licensing procedures for sand quarries have been extended. Of course, concreting is not a very popular thing, quarries should not be opened everywhere, but we have an urgent problem and these issues must be urgently addressed in order to solve this problem. If we do not have quarries and access to aggregate, we cannot produce good concrete and build good buildings.
There should be a breakthrough for aggregate quarries in bureaucratic matters. It is not a problem to be inspected under the right policies, we are one of the best countries in the world in terms of technical know- how in terms of construction. As long as we get people home safely.
Sir, recently, concerns have started to arise for damage assessment of buildings, such as core sampling by non- engineers and newly established companies.
Not only universities can do this, yes, because there is not enough capacity, because demand has increased after the earthquake. I also hear that plumbers are core sampling, this is a mistake, but if the engineer is in charge and the engineer is doing the test, the plumber can only do the coring operation under the supervision of the engineer.
The important thing here is that the company that will make the determination and experiment is reliable, experienced and referenced. When choosing, I think it is necessary to turn to reliable companies that have been doing this job for many years, and to entrust the work to sane people who are in cooperation with the consultancy of universities.