5 critical details about the collapsed building: 'Illegal floors have a great impact' | The expert explained the main place to look

In previous years, the collapse of buildings in Istanbul without an earthquake raised questions about the safety of the structures and the impact of subsequent interventions on the load-bearing system. Such events reveal how important the changes that old buildings undergo and possible interventions on the load-bearing system are.

This time, a partial collapse occurred in a 7-storey building in Maltepe. While the team's work continued after the incident that took place in the morning hours on Doğu Street in Cevizli District, remarkable details about the history of the building emerged.

THE BUILDING HAS 5 FLOORS IN THE PROJECT, BUT 7 FLOORS IN REALITY!

Maltepe Mayor Esin Köymen announced that during the examination of the municipal archives, there were 5 floors in the project of the building, but two illegal floors were later added to the building. Köymen used the following statements:

"In the morning, we received a report about sitting on the ground and lying on its side. When we arrived at the scene, we saw that the building was sitting on the basement floor and first floor and was leaning backwards. We opened all our archives at the municipality, we checked whether there was an application regarding whether the building was risky or not, and whether any action had been taken regarding this. We did not receive any complaints. The issue is how many floors the building has in the settlement. It is a building built in the 80s, and when we removed its project from the archive, we saw that the building had two illegal floors on it. "The occupancy appears to be 5 floors, but two floors are illegal. We checked all the records in our municipality archives and the building has such a situation."

It is a matter of curiosity how much additional load these floors added to the building, which was built in 1987 after the incident, brought to the load-bearing system and to what extent they affected the safety of the building.

The presence of a textile workshop on the ground floor of the building has also raised allegations of possible interference with the carrier system. It is also wondered whether changes have been made to the columns or beams in the past, whether the load-bearing elements have been interfered with, and whether such an intervention has an effect on the collapse.

1- TO HOW MUCH COULD THE BUILDING OF TWO FLOORS LATER AND INNEGALLY WEAKNESSE THE BUILDING?

Master Architect Neda Yağlı said, "After all, this is a building that was originally designed as a 5-storey building and its license was obtained in this way. The illegal addition of two floors later brings an unforeseen extra load to the load-bearing system of the building. While the columns and beams were initially designed to carry the load of 5 floors, when two more floors are added, the load to which the carrier system is exposed increases."

"Moreover, we are talking about a building that is approximately 38 years old and a building that has experienced earthquakes in the past," added Yağlı, adding, "The load-bearing system has already been damaged. Therefore, unfortunately, the impact of illegal floors in this collapse without any earthquake or other significant external factor is great."

Buildings are designed to bear a certain weight and earthquake load according to the regulations and projects of the period in which they are built. Illegal floors added later, built outside the architectural project and license, put extra load on the load-bearing columns and foundation system of the building. Although it is not a single cause, buildings built with illegal floors cause serious damage and increase the risk of collapse.

Urban Transformation and Real Estate Appraisal expert İbrahim Cihan Kurtulan

2- WHAT DOES THE COLLAPSE OF THE LOWER STORIES WHILE THE UPPER STORIES REMAIN STANDING TELLS US?

"This situation requires a detailed examination of the load-bearing system, especially on the lower floor," said Neda Yağlı, adding, "The load of the building is transferred from the top to the foundation. In other words, from the roof to the foundation. Meanwhile, the columns on the floors are very important. The ground floor of the building is a shop, we have both heard stories of cutting columns and seen examples in terms of design. Awareness and supervision should be increased on this issue. Sanctions should be very heavy."

3- HOW CAN YOU KNOW WHETHER THE CARRIER SYSTEM HAS BEEN INTERVENED IN THE PAST IN THE WORKPLACE ON THE GROUND FLOOR?

"Actually, this is not very difficult to determine. The current situation can be compared with the carrier system in the building's license and static project by a civil engineer. Even if the project cannot be accessed because it was built in 1987, some things can be understood from the current state of the carrier system," said Neda Yağlı, adding, "In reinforced concrete structures, the openings between columns and how to pass these openings are clear. For example, if there is a very wide opening, it must be solved with a suitable beam or a different carrier system. Therefore, if an unexplained gap is seen in the carrier system, there are columns or other structures in the past. "It must be investigated whether the beam has been interfered with. In some cases, such changes can be noticed even visually. It is also possible for municipalities to initiate an inspection by comparing the current situation with approved projects."

These investigations are carried out by experts during the engineering investigations to be carried out in the area where the building is built. If there is a real estate appraisal report prepared before for the building, it can reveal more clearly whether such a possibility exists.

İbrahim Cihan Kurtulan

4- SITTING ON THE FLOOR AND LYING ON THE SIDE IN THE BUILDING WAS DETECTED. SHOULD THE GROUND OR THE CARRIER SYSTEM BE EVALUATED FIRST?

"When both tilting and collapse are seen in a building, it would not be right to attribute the problem only to the ground or only to the carrier system. Here, more than one factor needs to be evaluated together," said Neda Yağlı and continued as follows:

-- The quality of the material used is very important. Many factors such as the strength of the concrete, the amount and quality of the reinforcement used, and whether the iron corrodes over time directly affect the load-bearing performance of the building. Especially in old buildings, material quality and construction standards applied in the past should be investigated. We know that in the past, practices such as the use of sea sand and the use of inadequate reinforcement could cause problems in buildings.

-- Here we are talking about a building that is approximately 38 years old and two illegal floors that were added later. When the age of the building, the earthquakes it has been exposed to in the past, subsequent additions, material quality and ground conditions are evaluated together, a holistic examination is required to understand why the building has reached this point.

-- The point I attach particular importance to is that we should not focus only on the collapsed building. I think the surrounding buildings should also be checked and a regional ground survey should be carried out. Because there are many buildings sharing the same ground. After determining the bearing capacity of the ground and the possible risks in the area, performing a priority risk scan in the surrounding structures may be very important to prevent a similar incident from occurring.

5- WHAT ARE THE MOST CRITICAL RISKS TODAY IN A BUILDING CONSTRUCTED IN 1987? WHAT SHOULD CITIZENS PAY ATTENTION TO?

"When we look at buildings abroad, we see that 100-year-old, 500-year-old, even 1000-year-old buildings are still standing and even protected by the state. Therefore, I do not think that the mere fact that a building is old is the sole reason for its collapse," said Neda Yağlı, and underlined very important information:

-- When we look at Turkey's construction history, we know that construction inspections, especially in the past years, were not as strong as they are today. Therefore, rather than the age of the building, how it was built, what materials were used, how much it was inspected and whether any subsequent interventions were made are important.

-- For this reason, I think much more emphasis should be given to urban transformation. In particular, buildings that have been affected by earthquakes or are at risk of collapse and collapse in the future need to be quickly identified and transformed. As architects, our expectation is that people live in safe and healthy buildings. For this, I believe that risky buildings should be identified and urban transformation processes should be carried out faster, more planned and more effectively.

Buildings are not constructed according to a single legislation, but based on more than one basic law and regulation according to the purpose, security, technical equipment and environmental conditions of the building.

Within the scope of Türkiye's building earthquake regulations, the Report Format along with the Soil and Foundation Survey Application Principles and the planned areas zoning regulations are the most basic regulations.

As a result, the basic issue is that both the construction process and the ground type of the building are suitable, and if one of these two factors is not calculated correctly, the building is likely to be demolished.

İbrahim Cihan Kurtulan