An interview with Kārlis Pugovičs, guest lecturer at the Department of Wood Processing, LLU Faculty of Forest and Wood Technologies
In Latvia, scientific work is happening, but there is an impression that “there is a lot of talk about how little people talk about science”… Is that the case?
I don't want to agree that there is little talk! There is talk, but… are we good at promoting ourselves and making our work or ourselves interesting enough to be talked about? One thing is publications in relevant industry or scientific journals; another is a story for the general public. When it comes to the general public – not everyone knows how to talk to them, and (that is certainly true) it isn't always necessary! One of the modern requirements is the need to present oneself publicly to people beyond one's colleagues and one's own industry. That is an important matter! Due to personal peculiarities and a lack of experience, we sometimes don't know how, in what way, and what to talk about – what exactly might be interesting to someone who is not involved in science and who reads magazines or newspapers for entertainment. The facts you relay are only half the job. Who we “present” them to, how we do it, and when it happens is the other half. This “second half” has less to do with science and more to do with public relations.
In a recent interview with a Latvian builder and architect, I heard about the break in timber construction traditions during the 50 Soviet years… Is something like that felt in the Wood Processing Department as well?
In the department's building and in our collective, definitely not! One could argue about the extent to which there was a break in traditions and to what extent it was an attempt to create new, artificial ones. Thank God I didn't happen to live in the Soviet years; I can only judge that from stories! The great experiment known as communism, those 50 years in Latvia, failed irredeemably. There is a generation, or rather a part of it, still active and in its prime, which does not really know how to operate in the modern regulatory system and needs a different approach. A certain way of thinking prevailed during the Soviet years. Consequently, a clash of thinking styles can be observed from time to time. If we look at how engineered wood products and technologies have developed, allowing for the construction of timber high-rises… We had the materials we had, we had the regulations we had, we had the technologies we had, and the production capabilities we had. That has left consequences. The big problem is in the regulations! We can build a six-storey building, but we see that more work goes into the regulations, into the skill of convincing people that one can build with wood! It is necessary to dispel unscientific and irrational prejudices about wood and other materials. Proving that one can build with wood, and that it is safe, is by no means a simple task!
Are the people working on these regulations professionals who work with wood, or is it done by those who just know that wood exists somewhere?
Both! As far as I know, people associated with the industry are also working on the regulations. A new revision of Eurocode V is expected soon, which includes many “fresh” things about timber construction. Without knowing the behind-the-scenes details, it is not easy to judge in more detail.
I have asked the President, former politicians, and people in the industry about the use of the word “expert”… What makes a scientist an expert?
If I have to talk about a person I would be ready to turn to, the answer is elusive… There are many important factors: how much a person knows, how they use that knowledge, how they present and share it, how much they listen to others, how ready they are for discussion, how they view materials, how they evaluate global principles, etc. I would go to someone who knows the regulations, the academic issues, and the practical matters as well. It must be a person with whom it is possible to discuss, and this discussion will be fruitful regardless of the result. The reputation of an expert precedes them! I personally like a paraphrase of Margaret Thatcher's saying: “If you have to tell someone that you are an expert, you most likely aren't!”
What is the topic of your doctoral studies?
Connections with inserted rods. A large majority of authorities in construction acknowledge that the most complex stage in design is the choice of the correct fasteners: which one to put where, how they will work, etc. Connections with inserted rods could currently be considered a bit of a “fashionable topic” in research. A couple of years ago, we could encounter and get acquainted with mountains of publications in scientific literature, and publications are still being written. The topic of my doctoral thesis arose from my master's thesis, where I studied how glued-in rods “behave” in birch plywood. The concept of the connection is very simple: we have a wooden element into which we drill and glue a rod – steel, carbon fibre, polymer material, etc. We get a very rigid, hidden connection, and if we glue in a metric thread, it is relatively simple to attach a steel part to the wooden element.
Conceptually it is relatively simple, but there are a great many factors that affect the performance of these connections. As I mentioned, there is a lot of research. The first studies began as early as the 80s, but there is still no unified standard for how to “calculate” these connections, there is a lack of knowledge about how they “behave” in the long term, there is no consensus on whether we can use them in outdoor conditions (Service Class III), and there is no clarity on how they will react under direct fire impact. In summary – theoretically, we could assume that the performance should be very good, but data to directly prove this is lacking.
The set of all factors I mentioned affects the performance of these connections and affects them in an interconnected way. Not all relationships can be expressed mathematically in the form of linear functions, and not all relationships are relevant if one of the elements changes. That actually makes research “tricky,” because the number of variables cannot be unlimited. Most studies to date have been oriented towards tensile loading, “pull-out” – namely, we have one or more rods glued into a specific material which, by applying force parallel to the axis of the rod, we pull out (similar to pulling out a nail). Such a force can also affect real structures. Here, it is equally important not only to understand how much such a connection can withstand when assessed in numbers, but also in what way the connection fails. This is important for safety reasons. Research is currently taking place under laboratory conditions.
If we use steel rods, it sounds unusual, but steel should be the weakest element, because steel is characterized by ductile failure. It stretches slightly, we can determine that collapse will happen, and evacuate the building. (Wood bends slightly and then collapses; this is called brittle failure!) When people talk about buildings, they often ask – whether and why it is worth looking at “how” this building will collapse… Knowing how it will happen is very important because it can decide whether people will have time to be evacuated or not. A few years ago, there was an incident in the Czech Republic: in a newly built sports hall that was scheduled to be commissioned the next day, a floorball game was taking place in the hall on the evening before the building was handed over, and in the video, you can see the game going on, and suddenly people start running out of the hall. As we saw in the video – it was winter, snow was falling, and the roof started to collapse. It didn't happen in one short, dramatic moment, but gradually sliding; no one was hurt, everyone managed to run out. In this case, something was not calculated and technically solved correctly, but precisely because of the steel structures, the collapse happened slowly enough for people to leave the building.
So – these connections are already used in construction, they are known, but research is underway regarding their more precise, safer use?
Yes! So that we can understand in more detail and more accurately how it works! The connections are used in many places. The best example that one can see is the Metropol Parasol building in Seville, Spain, which was the largest wooden structure in the world for a long time. All its connections use glued-in rods. Then one can mention the bridge in the Netherlands near the city of Sneek, where acetylated pine materials were used.
The connections are used, but for both these projects, calculations were performed based on experimental research. We do not have regulations on how to design and use them precisely.
In Latvia, I cannot name an example, but this type of connection can also be considered somewhat exotic in Europe. The mentioned examples exist and can be viewed, but – it must be said – the examples are always accompanied by research carried out for the specific building. In so-called “popular construction,” they are not used because we don't really know how to calculate it all! That would be research with a view to the future!
The research sounds broad – wood (which tree it came from), glue (composition), rod material – the possibilities and variations are different.
Research can be infinite! Therefore, we reduce it and think about things and materials that are used in everyday life! If we are talking about wood, we are interested in glued laminated timber (so-called “glulam”); talking about rods – steel. If we look at glue, the situation gets complicated because the glue must be intended for gluing wood and metal. We look at epoxy-based glues or polyurethane-based glues, or phenol-resorcinol-based glues. The latter show the lowest strength indicators, the results of polyurethane glues lag slightly behind epoxy-based glues, but – polyurethane is significantly cheaper and more flexible! Epoxy, on the other hand, is quite brittle. A large part of the research uses polyurethane-based glue, and we look at what is available on the market for this type of glue; the list shortens. In research, the most interesting things begin when we think about how deep we glue the rods, how far apart we place them, how thick the glue line will be, how we fill the glue, how we prevent manufacturing process defects, because it is necessary to ensure that the hole is full of glue even when a rod is inserted into it. How to ensure that there are no air bubbles in the glue? In laboratory conditions, we can, but ensuring quality control in production conditions is another story! How to solve potential problems if the connections are used in outdoor conditions? How will the connection work in the long term? These are the things and questions on which one should and is worth focusing. Especially the last two – outdoor conditions and long-term performance! The potential is there, this type of connection is competitive, but – one must learn to work with it properly! It is rightly said that there is enough research on the material, it is inexhaustible, but – a large part of the questions has already been looked at previously. I mean situations where we reduce the scope of the research – in one study, we look at what happens in the case of different gluing depths. We have already learned that the strength of the connection increases up to a certain gluing depth, after which (as the depth increases) there are no significant statistical differences in strength. For example, according to research, if we glue a rod with a diameter of 10 mm to a depth of 10 and 15 cm, there shouldn't be a big difference in strength, provided there are no other factors. The next question – how far the rod is placed from the edge, how far apart the rods are from each other. When we start to expand the questions to which we want answers – the rod diameter “appears,” the steel grade… it is easy to get lost in numbers, experiments, and meaning…
Careful planning is necessary – what and how we research and look at!
How does a high school student step by step end up in a doctoral program?
The idea of studying for a master's and a doctorate was there, but I didn't think about it too much. I said – if there's an opportunity, I'll use it! I ended up in the field of wood processing by chance; I was studying at a gymnasium where mathematics and physics were important. A flyer came into my hands that such a university existed; they gave it to me with the text: “This might interest you!” Doctoral studies were stimulated by several factors – I started working at the Forest and Wood Products Research and Development Institute (MeKA) during my bachelor's studies, I prepared my bachelor's thesis, stayed for my master's, started working in the department, and then it was clear that the academic path had to be followed to the end. Partly I wanted to myself, partly – there was an opportunity!
Is there any cooperation in the research with those who use and apply these connections? How does that go?
Thinking about what research is needed, we consult with manufacturers! For MeKA, most of the research comes from the industry! That is the charm of the institute, that we are a bridge between the industry and academics. I think we have a great story about how this scheme works. Latvia is not large and our industry is also not huge; cooperation also happens while chatting at the lunch table! There is very good soil for research! If advice is needed – it doesn't have to be looked for far!