Q&A with Professor Ihsan Bal

Professor Ihsan Bal of the research group Structural Safety & Earthquakes has been working at Hanze since 2017. Recently he has been assigned as Professor by Special Appointment in Digital Technologies in the Built Environment at the University of Groningen (RUG).

Text: Nathalie Meeuwsen

You’ve headed the Research Group on Earthquake Resistant Structures at Hanze since your arrival. What does your work involve?
One part of my work is being part of various evaluation committees and assessment panels involved in hazard and risk assessment (HRA) regarding Groningen’s earthquake issue. For example, I was part of a technical committee on accelerating strengthening of houses and a committee that was checking the NAM’s calculations on the earthquake risk for housing for the Ministry of Economic Affairs.

Can you give some examples of research projects?
When I arrived at Hanze, there was a lot of discussion on how to monitor structures. A TNO network paid for by NAM had equipped 300 houses with 300 sensors, but they were neither on the ground nor on the floor. So, we said this is not actually structural monitoring. To properly monitor a building, you need one sensor on the ground to measure how much the ground shakes and another on the wall to see how the wall reacts. The data from these two sensors together tell you how the building responds to shaking. In order to create a showcase, we instrumented Fraeylemaborg in Slochteren. For a long time, it was the only building in the whole of Groningen that is monitored based on classic structural health monitoring principles. We have been monitoring it since 2018, and our research is still ongoing. You need to monitor a building for a longer period to understand how a building is affected by earthquakes, what the damage is, what causes the damages and so on. This type of monitoring is expensive, so we only use it for important buildings. 

Another project was SafeGo, funded by RVO. It focused on monitoring, strengthening, and assessing structures against earthquakes. We tested walls on our shake table and increased the shaking levels gradually during testing. With visual inspection, we didn’t notice a lot of changes from the first test until the last. But by using sensitive equipment, we could measure changes that we couldn’t see with the naked eye. With enough sensors on a building, we can tell if the cracks are getting worse or not. The maintenance and operation of such sensors is expensive. So economically it is not a viable option, but it does show that visual inspection doesn’t tell you the whole story. It doesn’t reveal how damage spreads in a wall during earthquakes.  

You’ve mentioned a Comfort Level Earthquake (CLE). What does that mean?
It is a different type of compensation scheme for areas with induced earthquakes (earthquakes that are the result of human activities, ed.). It’s too late for Groningen, but it could work in other places with gas fields or mining activities. When these activities start, they always cause some disturbance. Even if nothing happens, the possibility that something might happen, disturbs people’s comfort level. In order to operate or a gas field or mining area, people must accept it, giving it their social license to operate (SLO).  
What I propose is a scientific basis for compensation instead of a legal one alone. Compensation should be based on engineering, not only on law. The current legal process takes too long. Everyone within the buffer zone should get compensation, with more given to those in the heart of the earthquake area and less towards the edges. A percentage of the gas revenue should be given to every family, because gas extraction creates a disturbance no matter what. If the disturbance exceeds a certain level and causes physical damage, then a physical damage compensation scheme should be activated. 

Now that the gas fields are closed, will Groningen still need earthquake resistant structures in future and for how long?  
The hazard, the potential of earthquakes occurring, will decrease because gas extraction has ceased. We don’t know when that hazard will reach zero, but it will decrease. Because of this, the risk of structures collapsing or incurring severe damage during an earthquake, will also decrease. But we don’t know when it will reach zero, so it wouldn’t be wise to shutdown institutions like NCG and others that have been built up around the Groningen’s earthquake issue. Because the real risk is that in a couple of years, we will be thinking ‘Okay, it was a bad nightmare, let’s forget about it’. So, we shut everything down and then, in ten years' time perhaps, there will be another earthquake of magnitude 3,5, for example. If this happens, we will be totally unprepared for it. Not only that, but people in Groningen will have a sinking feeling of ‘Oh no, not again!’. The impact would be much greater, and we would have to restart the whole operation.  

You’ve recently been assigned as Professor by Special Appointment in Digital Technologies in the Built Environment by RUG. How will this role help you in your research?  
Doing structural safety research is challenging, especially with our ageing infrastructure. Many structures, built in the 60s and 70s, are now old. For example, a bridge collapsed in Dresden, and the Morandi Bridge in Genoa also collapsed, causing fatalities. These incidents show that such problems can happen anywhere, even in Europe. 
The challenge is identifying weak bridges before they collapse, which requires a lot of resources, time, and money. Traditional methods, like human based inspections, no longer work because we don’t have enough people, money, and time. The same applies to earthquake damage. 
Digital tools are essential for this work. IMG, the Institute for Mining Damage Groningen, already uses digital technologies because their task is huge. They have a dedicated digital team, which is the only way to tackle this problem. These tools can also support our research at Hanze on structural safety and earthquakes, but digital tools themselves are another research area, and it is multidisciplinary. It involves computer science, applied mathematics, and applied physics, which is why we need RUG on our side. 

Do you think this type of collaboration between RUG and Hanze can be beneficial in other research areas as well?  
Yes, we cooperate a lot with people from Computer Vision. They develop technologies that can be used in health care as well as in developing nanomaterials, biosensors and solutions for the built environment. At the University of Groningen, they focus on the theoretical development of tools, and they need use cases, practical problems for them to work on. Built Environment is a very good use case. By cooperating with us, they can tackle real life problems, sharpen their technology and prove that it actually works. We can give them access to our facilities at Hanze and they give us access to their technology. So, it works both ways.