Seismic engineering design for public safety

38 min read

Nicholas Kyriakides
Assistant Professor at the Civil Engineering and Geomatics Department of the Cyprus University of Technology and member of the Eratosthenes Centre of Excellence for earth observation. He holds a PhD in the field of “Earthquake Risk Assessment of RC buildings”. His research interests include the vulnerability assessment of structures under seismic loading and the quantification of the earthquake hazard and risk in Cyprus.

Professor Marc Bonello
Professor Marc Bonello is currently Head of the Department of Civil & Structural Engineering within the Faculty for the Built Environment at the University of Malta. He has been lecturing and carrying out research within the structural engineering field for the past 30 years. In the last decade, Professor Bonello directed his focus upon the seismic vulnerability of unreinforced masonry (URM) structures within the Maltese Islands, particularly those buildings with underlying soft storey basement car parks. Professor Bonello was also involved in the recent EU-funded ERDF Project SIMIT, carried out jointly between Maltese and Italian academic institutions and civil protection departments. This research project led to the formulation of rapid seismic vulnerability assessment forms, which may be used within pre- and post-earthquake assessments of the seismic vulnerability of local URM buildings.

Joining us on this episode today is Professor Mark Bonello and Professor Nicholas Kyriakides. Professor Mark Bonello, currently Head of Department of Civil and Structural engineering within the Faculty for the Built Environment at the University of Malta. He has been lecturing and carrying out research within the structural engineering field for the past 30 years. In the last decade, Professor Bonello directed his focus upon seismic vulnerability of unreinforced masonry structures within the Maltese islands, particularly those with an underlying soft-story basement carpark. Professor Bonello was also involved in the recent EU funded ERDF project, SIMIT, carried out jointly between Maltese and Italian academic institutions and civil protection departments.

Professor Kyriakides is an assistant professor at the civil Engineering and Geomatics Department of the Cyprus University of Technology and member of the Eratosthenes Centre of Excellence for Earth Observation. He holds a PhD in the field of earthquake risk assessment of reinforced concrete buildings. His research interests include the vulnerability assessment of structures under seismic loading and the quantification of the earthquake hazard and risk in Cyprus. The purpose of this call today is to bring awareness about the importance of designing buildings to withstand earthquakes, so that the public, tenants, building owners, authorities, as well as insurers, appreciate the severe socio-economic impact of earthquakes on properties in terms of loss of life, cost, damage, down-time, and sustainability.

This is quite a mouthful, right? And not all of us know much about seismic engineering or earthquake engineering. Perhaps if I may, Professor Bonello, would you be able to give us an introduction of what earthquake engineering is and why it is so important?

It is a means of quantifying the effects of ground motion and also dealing with it in design. I think, you know, the media has on several occasions shown images of the buildings which have collapsed during earthquakes, especially in zones which are very prone to strong earthquakes like Iran and Turkey and Japan and these places. And, of course, these images are very striking. But like anything else in life, if they don't, let's say, affect you directly, you tend to kind of look the other way and move on with life. Now as structure engineers and earthquakes engineers, we have the response of ensuring that the buildings that are constructed do not pose a danger to the occupants of the building, or to passers-by in the street, or even to the emergency rescue services because following an earthquake, of course, you know, we hear about people being trapped in the building, people who are killed by falling debris and also firemen and let's say civil protection personnel who either cannot get into the building or are actually trapped themselves into the building as well. So, I think as responsible engineers, we need to be able to somehow model, quantify and design against these earthquakes. Now this is not something which is very easy, and you know in our work there are lot of uncertainties involved in the estimation of loads. Some loads are less uncertain than others, but I would classify earthquake loading, seismic loading, as one of the most uncertain loading that we can have.

Reason being, first of all, we cannot really with any precision quantify the date and time of the next earthquake. We can't even quantify its magnitude or its nature. In other words, you know what percentage of the earthquake intensity will be translated into a horizontal component or a vertical component, or both. And therefore, I think there have been now over the years, and it's also with, I happen to be also the Maltese delegate on the Eurocode TC-250 SC 8, Eurocode 8, and as you may be some of the viewers and listeners are aware there will be a new, let's say, regime, of new codes coming out in the next few years; and a lot of the research that has gone into earthquake engineering will, let's say, be incorporated within this new issue of the codes that will replace the current codes that were issued in 2004.

I think the main problem and again just to give my colleagues here some more time to perhaps express their opinions, but certainly in Malta, I have to say that you know the local seismologists with whom we work, you know very closely, have estimated that the peak ground acceleration for the Maltese islands for a return period of around 475 years, percentage exceedance in 50 years of 10 percent is around 0.1g - 10% of g [acceleration of gravity g = 9.8 m/s2]. That's about 1 meter per second squared, which in comparison to, let's say other areas and locations in Europe is not that high. For example, Cyprus has a far higher peak ground acceleration, if I'm correct, of course it depends on the seismic zonation map, in other words, different parts of Cyprus might be subjected to different intensities, but certainly we're talking about three to four times the intensity of the Maltese islands.

And yet, because of this, let's say low to moderate intensity of earthquakes in Malta, there is a certain complacency that has crept in. This complacency is also due to the fact that the strong earthquakes in the Maltese islands are very few and far between. The last strong earthquake that damaged buildings in the Maltese islands occurred in 1693. Now that's almost 320 years ago. There were others that followed. Not as strong, but generally speaking, the tremors that happened regularly around the Maltese islands, have an intensity of around 2 to 3 on the Richter scale, which is, you know, really nothing. Sometimes we feel a tremor, other times not, and so there is this complacency which has crept in the local population. There is a kind of loss of memory, even though we have recorded in history, the potential, let's say damaging effects, and also, let's say serious effects strong earthquakes can have, but yet it’s as if we are immune.

And this also permeates into the authorities and the architects themselves. So very often you find you know architects taking a very lax attitude towards seismic loading. I have to say, however, that the design of structural steelwork and reinforced concrete buildings, composite buildings in the Maltese islands are generally designed, at least lately, to be earthquake resistant. The main problem lies with unreinforced masonry buildings, which are primarily load bearing buildings, very often with soft storey basements. In other words, basements where the roof is of the basement is a transfer slab that allows for a larger circulation for car parking in the basement, and where these load-bearing buildings are essentially designed for vertical loading. In other words, with very little lateral resistance. I have been carrying out research in this aspect now for many years, at least for the last decade, perhaps I'll have the occasion to say something about this later on in this discussion, but I have to say that the vulnerability, the seismic vulnerability of these buildings is very high and therefore you know to answer your question, Dr. Abela, the earthquake engineering is a means of, therefore mitigating the risks, that our buildings face during earthquakes, minimizing the seismic vulnerability by technique appropriate actions both in design, or perhaps even after design of existing buildings by means of retrofitting techniques.

We have mentioned many points in that, you know, in the answer to the first question and I wonder whether Professor Kyriakides maybe you can let us know from your point of view, from a Cypriot aspect, you know, we know we have mentioned that in the Mediterranean basin, there are various parts or various parts of even the same country which have a different susceptibility to undergo earthquakes. From your experience, how do we go about or how did you go about so, in Cyprus, regarding the understanding of the vulnerability of some of these buildings? And by that, I mean both heritage and new buildings, because in Cyprus, similar to Malta, we have traditional buildings that have been built several 100 years ago, which obviously would be in danger, but maybe you can give us some background, to offer from your experience on that please.

Thank you Doctor Abela and thanks Professor Bonello for your introduction. Indeed, Professor Bonello managed to feed and discuss and outline most of the issues involved in earthquake engineering. Now just to add to his words, earthquake engineering is, has found, it has increased its visibility, let's say among civil engineers as one of the most significant design related sections of civil engineering in the 20th century, and obviously this was this was as a result of various events that created several problems, damages and fatalities and injuries around the world. Now in the last part of the 20th century, we have witnessed several of such distracting events happening in our region of the world as well, like Greece, Cyprus, Turkey, Italy, and the eastern Mediterranean in general, and that is more or less when we have all started worrying more and trying to find ways of mitigating, let's say, the effects and the impacts of this event.

Now, as, Prof. Bonello said, as far as the design of new buildings in our part of the world in Europe, this has been, this is now being undertaken by new uniform codes that are being used in the whole in all European countries depending on how strong the earthquake hazard is at each country, so that is defined as a country-based parameter. Now this solves one of the problems that we had, which is how do we go on securing the new buildings. And this is something that at the moment we feel that we are doing quite well, but the problem is that the vast majority of the building stock in these countries, as was mentioned by Dr Abela were built before the enforcement of those codes, so we have a problem with what's happening with the existing buildings and how do we face that issue. Plus, we have another, well, we have another thing, we have another problem that we need to find ways to solve, as to how we deal with building categories that are not well documented in the codes. And this is something that Professor Bonello referred to when he mentioned about the URM [unreinforced masonry] buildings in Malta. So, the codes cover the design of new buildings for standard and categories of building classes and categories that are, let's say, are the most popular in Europe and very well documented, but cannot at the moment cover, at the same level, the design of all building classes.

So, this is something that we need to find ways to increase our, let's say the knowledge we have around the around this topic. The way we have acted in Cyprus, to answer your question, Cyprus is located close to Malta, we are in a moderately seismic hazard zone because we have, we have the effect from the Cyprian Arc, which is the boundary between, at least that's one of the theories, let's say that's the boundary between the African and Eurasian plates. It's moving, the African plate is moving north-eastern, north-western sorry, and it's creating some stresses in the tectonic plates in the vicinity of Cyprus, and those stresses at some, when they reach their maximum capacities, a thrusting occurs. And then we have earthquakes, more or less around 30 to 50 years, we have an earthquake that is felt and that creates damages, especially as I said to older buildings or buildings that were not built with the seismic codes. Now, similarly to Malta we haven't had any code provisions or guidelines related to the design of new buildings until mid 80s, and this happened because we had an earthquake that was felt around the island, created damages, in Pathos, so discussions started arising about how were securing buildings, and some guidelines, very short guidelines were prepared and used by the engineers, by the civil engineers for the design of new buildings, including a small proportion of horizontal load for the design.

So, we moved from using only vertical loads for our design, to estimate our design forces, we moved to accommodating horizontal forces as well, and that was the first move, that was the first step. This happened in ’86, 1986. Since then in between 1986 and 1992 we had, we were, we were working on preparing the first seismic code and that was finalized and enforced in 1994. So, from 1994 onwards we have used the code, we have a code that was used, which can, we can say that it was more or less at the same level of the codes used at other European countries, such as Italy & Greece. So, the checks, the concept of the code, the design, the methodology was more or less the same, following the same steps as what was happening in that moment in Italy and Greece, and also other countries outside Europe. Now obviously the seismic hazard was lower in Cyprus and that is something that was in our favour, but we had all the, all the construction that, all the building stock that were designed before the enforcement of this code, because obviously about approximately 70% of our building stock was designed and constructed before the enforcement of this code, so we had to deal with that.

The last development, let's say as far as the design of the building is concerned, is the enforcement of the European codes, the Eurocodes, which took place in 2011, and since then we are feeling confident, and with the code, a new seismic hazard map was included in the National Annex and with increased design reference peak ground accelerations, and at the moment we can say that from then onwards we have something solid that we can use that is uniform and follows the European countries with similar or higher seismic data than we have.

Now as far as the existing buildings is concerned, which is the major problem that we are facing, the concept was to start protecting public buildings. And the initial idea was that we should start from schools and in other public buildings that were designed prior to the enforcement of these codes. And I must say that a very large programme initiated in the beginning of 2000, for assessing the risk from earthquakes and proposing and enforcing retrofitting measures of schools, and at the moment we have approximately 97% of our schools retrofitted based on the knowledge of course that we had during that period - because this is the thing about earthquakes, you can never, you're always using the knowledge, then there are uncertainties, and you're trying to accommodate the uncertainties, given the data and the information that you have. And obviously these changes are based on many factors. So, at the moment we can say that we have secured our schools and we need to find ways of updating the retrofitting measures in a few years.

The way we tackled existing buildings is different than the way we tackle new buildings. Obviously, with new buildings you have refined methodologies, you have approaches depending on how they can sway, whether they can deform, and by how much you want them to deform. If you want them to deform and you follow that concept and you assure that you design something that will perform based on a predefined performance level. So, you accept, you select a performance level, and you follow a design procedure, and you meet the specific performance point. Now with the older buildings the approach was different. The approach was more related to a life-cycle assessment methodology. So, you assess the building and define the retrofit methodology based on an assessment of how obviously, you want to eliminate fatalities and injuries, how you want to eliminate large damages on the building, but you are aware that you cannot make an [existing] building that is at the same level as the new ones. So, you accept that you will have some sort of damage after the earthquake, but that damage will not be enough, will not reach the level leading to collapses, that lead to fatalities and injuries and so on and so forth.

So we have used a life-cycle cost analysis methodology to define retrofitting measures for existing buildings and this methodology is based on a different approach, rather than accepting a performance level, you accept a return period of the retrofitting, so you accept that you will retrofit the building and in 10 years I will come back and see what else I have to do or what else can I do to increase its capacity. It can be 10 years. It can be 20 years. It can be 30 years, so different return periods were well accepted. And this is more or less the concept behind the flow to assess and retrofit existing buildings. So you have to accept that we cannot have the same level of risk as we have in the new buildings, we can, but we don't, we may not need to reach the same level of risk as the new buildings, so we may have higher risk with existing buildings that we have to secure that we will eliminate collapses that lead to fatalities and injuries, and that the investment in retrofitting them will be sufficient, so as to ensure that the damage after the earthquake will be replaceable and it can, can be restored after the earthquake and be used quickly after the earthquake.

Now just to add very quickly to the new buildings. I mentioned that Eurocodes cover various building categories, but obviously they don't cover all building categories. There are building categories in Malta that we do not find in the Eurocodes, there are building categories in other Middle Eastern countries let's say, that we don't find in Eurocodes. So, for these specific building classes, we need to combine research, with legislation, with testing, with the new design guidelines so as to ensure that we have followed design guidelines. So, the Eurocode can provide us with what is needed for the specific categories that have been researched, but further revision is to be conducted for categories that have not been investigated yet and this can only be done through a combination of testing. So, testing of such buildings needs to take place either at full scale or at scale specimens in large laboratories, to see how they react during earthquakes, and this is what happened with the design guidelines that are now in the Eurocodes. So, we have to test them first to see how they react, get results from their test, from a number of these tests, and then try to simulate those results using mathematics, and then try to see how we can adjust our design methodologies. This is the route towards introducing new building classes and making sure that we have the same level of risk as we have in the building classes that are included in the Eurocode.

Thank you, Professor Kyriakides. My concern was, while you were discussing this, is that this depends a lot on the perception of how safe things are, not just by engineers, but also by the general public. Because this is a two-sides-of-the-coin [issue], right? The engineers are designing for people; now, whereas we understand the mathematics and we can understand how things work, it's going to be very difficult for people maybe to understand - the general public to understand - safety and how this is achieved. Because let's say I am a person who just bought a house or an apartment, how am I going to be sure that my property is safe? So, I think that maybe we can, we can discuss, maybe Professor Bonello from your experience in the local industry, how can we ensure that people are made aware of this without necessarily unnecessary worry? Because engineers do their job properly. But maybe we can understand even Professor Kyriakides can tell us from a Cypriot point of view, how the public perception was of all of this, because as you said, we are complacent. We are not acting on it actively at the moment - at least the general public is not acting on it, but how would we start to understand that this is a requirement in the near future to start looking at retrofitting to make our structure strong again - strong for earthquakes.

You actually get a very important point. How do people ensure that their investment in purchasing a property, for example, is sensible and is safe? Now let me take the case of unreinforced masonry buildings in Malta. As I said before, this constitutes the largest, let's say chunk of Urban Development in the country. I would say about 75% of buildings are unreinforced masonry buildings. The older buildings do not usually have-soft story basements. Because the plan generally repeats down to the basement level. It is the buildings which have been constructed, let’s say from the 1960s onwards, which pose a problem. Now that's a long time, we're talking about almost 60 years of construction. Imagine how many buildings were built in the last sixty years. The reason being is that when the precast prestressed concrete floor planks, floor units were introduced in the Maltese islands, at the time they were hailed as the, you know, the structural engineers dream where, you know we could actually have open basements and then build load-bearing masonry apartments from the transfer slab, in other words, the roof over the basement upwards.

And at the time, of course, it seemed sensible, and I have to say that there was nothing that prohibited unreinforced masonry construction from being constructed the way it was. However, I have to say that when Malta eventually became an EU Member State in 2004, and therefore took upon itself, let's say, the obligation to respect the norms of European principles and values, with it came along, the lets say, I won't say obligation because if one had to look at the legal requirements of using Eurocodes – Eurocodes are in Malta required only in public projects, so in other words, structure engineers in the Maltese islands can use any code of their choice, provided that they can demonstrate that their design, according to whatever code they choose, satisfies the requirements, the safety and serviceability requirements.

So going back to the issue, of is this a safe building or not; well, I think structural engineers and architects in Malta have known for at least the past 20-25 years that ignoring horizontal loading in unreinforced masonry construction is foolish. It's irresponsible. And yet, this persists, and I have to say it also persists because of pressures that are put upon them by developers. You see, developers have traditionally been constructing buildings in this way for many many years, and so when architects come up and say listen, “We require sway resisting systems within the unreinforced masonry buildings. We require shear walls, shear cores, tie beams,…”. Of course, the developers look at the bottom line and say, well, you know, “I mean, we never had these requirements before. All this is going to remove, is going to lower my bottom, my bottom-line profit, and so if you're not going to do it, I'll go to some other architect who will avoid me, you know, getting into this expense of additional anti-seismic, let's say design”.

And unfortunately, I have to say the profession actually is to blame because there are architects who comply. Now let me say that when it comes to the Eurocodes, as Professor Kyriakides said just a while ago, the Eurocodes are actually very specific with respect to modern building design, employing reinforced concrete, precast concrete structures, steelwork composite buildings, etc. However, when it comes to masonry buildings, there is a bit of a problem and the reason is because, as one will appreciate when we talk about masonry, the material itself varies from country to country. It varies in density, in porosity, in consistency, and so, different countries have developed different, let's say unreinforced masonry construction methodologies that suit their particular, let's say, material. And so you will find certain unreinforced masonry construction systems in some countries which you don't find in others. And so, what the, what the Eurocode has tried to provide is, let's say, a general framework that can be applied to all the Member States irrespective of the construction systems. But there will be, and I have to say, there will be country specific measures that will need to be taken up by the corresponding authorities responsible for building regulations in that particular country.

I also touch upon the point that Professor Kyriakides, actually mentioned just a while ago, and this has to do with retrofitting. Given that we have a lot of buildings that have been built in the past 60 years that do not satisfy modern seismic engineering codes, what do we do about them? And, of course, quite rightly there are the public buildings and there are the private buildings.

Public buildings, like schools, hospitals, theatres, townhalls, cinemas, etc. These can be intervened upon, and very often it's not a problem to intervene upon them because usually the owner is either a public authority or it is, let's say, a corporation in whose interest it makes sense to retrofit these buildings. So far so good.

The problem starts when we go into the private sector regime. So unreinforced masonry construction owned by the private sector. So, imagine you have bought an apartment on the second floor or the third floor of an apartment block; an assessment is carried out by the Town Council engineer or by the let's say, a structural engineer engaged by the administrators of the block, and it is found that this building needs to be retrofitted. First of all, who is going to allow structural members, additional structural members, such as steel cross-bracing elements, vertical posts, etc, to be introduced within their apartment? Secondly, what about the cost? Who is going to bear the cost? If I bought an apartment which should have been structurally sound, I didn't buy an apartment that was only adequate for vertical loading. I mean, who am I to know, I'm just an ordinary citizen. I bought an apartment. I paid good money for the apartment and now I'm told that the apartment is unsafe in the case of earthquake loading. So, there are these practical problems. And also, legal problems which I think are a major stumbling block and, and I don't know, perhaps Professor Kyriakides can shed some light on this. If in Cyprus they've started to tackle the issue with private sector ownership, but I can see huge problems in Malta. I mean think about it this way, if I buy an apartment, and I see a crack in the ceiling because of shrinkage, very often, you know there's a whole dispute with the contractor and the architect for a shrinkage crack in the slab. Imagine if an owner is told that his apartment is unsafe for earthquake loading and I have to say this, that whilst we discuss all this, okay and I'm sure that, this podcast will be broadcast and there will be viewers from Malta who will see this and they will be shocked to hear that there are many, many buildings in the Maltese islands that will not be able to withstand the 1693 type earthquake.

As professor Kyriakides said earlier, you know, we base our designs upon reference peak ground accelerations that have been determined from past data. But who is to say that the next earthquake won't be even stronger than the 1693 earthquake? So you know, I mean, in fact research has shown us that at least in as far as the unreinforced masonry buildings are concerned, okay, whilst it might be possible with retrofitting, to prevent collapse you know, we talk about existing buildings so very often the limit states we refer to, are the significant damage and the near collapse limit states, so it might be possible if retrofitting takes place to prevent collapse from occurring, but it might not be sufficient to prevent damage, that of course is repairable. So here we're talking about the damage limitation limit state. So this means, might mean, that after a strong earthquake, the building finishes will need to be replaced or repaired. The facades, for example, the windows, the doors, the floor tiling, etc. But at least the risk life is averted. So there are these huge problems which I think, I mean, certainly I think what's important, this is just like a patient that's entered the emergency and accident department in hospital: the first thing you do is you stop the loss of blood, you try and stabilize the patient. And this is what we should do.

So, I have been now for quite some time, been insisting with the local authorities, the Building Industry Consultative Council and the Building Construction Agency to enforce building regulations with respect to the type of designs that should or should not be permitted with, with respect to unreinforced masonry construction. That at least will take place, we will take care of the problems from now onwards.

We still have to deal with past problems, and as I said, the main issue here is private unreinforced masonry construction property. I have to say as well that we have been carrying out research at the University of Malta to look at the seismic vulnerability, to evaluate the seismic vulnerability of unreinforced masonry buildings in isolation, so if they're just buildings on their own or within a building aggregate that is bounded by streets, and there has been some interesting results, we’ve had so far. Of course, this is ongoing research. The building aggregate effect is usually beneficial, but up to a certain extent. So just to give an example, if a building, an unreinforced masonry building with a soft-story on rock for example, can be built, and can withstand a seismic event, a strong design seismic event in the Maltese islands, if it doesn't exceed, say, three floors, in a building aggregate, the limit is about five floors. But what do we see? We actually see in Malta, I have a few, I have actually 2 photographs, I'm not sure if it's possible to share these in this podcast, maybe not, but there are cases where we have unreinforced masonry buildings going up well, 15 floors height-width ratios of about 10 or 11. It's madness, of course, from a vertical point of view they are sufficient, because of course, the materials that have been used for you know, to prevent crushing of the concrete crushing of the block work, and the masonry is sufficient, but from a lateral resistance point of view clearly these buildings are very deficient and very susceptible to seismic events.

So, to conclude, in a nutshell, therefore, coming back to your question, Dr Abela, with respect to you know, what people expect. People expect their buildings to be safe and people expect structural engineers to do their work properly, and this includes therefore taking account of all the risks involved from the loading, so not only gravity loads, but I’m also talking about the vertical dead load and imposed load coming from: the dead load of course, is the self-weight of the building, the imposed load is of course the vertical loading imposed by the use of the building. It could be a residential building. It could be a store. It could be a a place of congregation, but the horizontal loading, and when we talk about horizontal loading, generally we're looking at wind. But very often wind is certainly not as strong as earthquake, and therefore earthquake loading, which so far has, at least in unreinforced masonry construction, been ignored, and the reason why this has happened in my view is because, as I said before, complacency, loss of past memory of how serious, stronger threats could be but also the fact that since traditionally unreinforced masonry buildings are heavy and therefore the wind check - the horizontal wind loading check, is usually not required, this has been also somehow translated into seismic loading, so if we don't need to check for wind, we don't need to check for seismic loading. Wrong. Seismic loading can be and is very often much stronger than horizontal wind loading.

So there's a lot to be done, and I you know, I mean the purpose of this podcast is not to create a sense of alarm within the viewers, especially those from the Maltese Islands, but certainly I think that as consumers, you know property owners, or the future property owners should demand that their properties are safe and this means that they should also be certified as being designed seismically according to the Eurocodes. Now you know, as we discussed earlier, if we're talking about earlier buildings, this might not be possible, or certainly we would have to expect a certain amount of risk. But certainly with respect to new buildings, you know, we have the means today to mitigate these risks. I shan’t say eliminate. There's no guarantee that if you use your codes, a building will not suffer damage, hopefully it won't suffer collapse, but certainly new designs equip architects with the possibility of resisting earthquakes in a far more efficient manner than there has been, so far.

Yes. Some food for thought there, Prof. Bonello, I don't know whether Professor Kyriakides could give us the Cypriot version of this. I appreciate that when you mentioned earlier you have a methodology that you have adopted in Cyprus and that there are levels of assessment of safety. So, linking this to the investment that one should do when you retrofit a structure, what is your opinion about you know, the level of retrofitting that needs to be achieved? Is there an optimum level? Is there a minimum? How did you go about this in Cyprus?

Now before I answer your question, I would like to add to your previous question about the awareness of the public, and indeed that is a big issue. And it's a big issue because earthquakes have low frequency and in most cases they’re not destructive, and this was the case in Cyprus as well for many years. So, before the 90s, let's say, and the earthquakes that happened in Cyprus, but also in the vicinity, in Greece and Turkey - the public awareness was minimal. And given the other hazards that we have to face as an island, which is, let's say, fires and floods, the earthquakes were not the, let's say, a priority for the state as well. Now, we have witnessed a few earthquakes in the 90s and in the early 2000s, that increased the awareness and that means what? It means that the state moved towards ensuring that specific measures are being taken to protect the existing building stock, and that means, first of all, as the assessing and retrofitting the public buildings, secondly, forcing the Eurocodes for all new construction, and this is something that it's imperative, I mean, it has to happen, at the moment given the complexity and the sophistication that is included in the Eurocodes. And obviously finding ways of accommodating any new construction that is being included by Eurocodes, as the ones that have been mentioned by Professor Bonello.

Now in that case, the local authorities, both governmental and municipal authorities at the moment, they require proof of the strength of the materials that will be used, and they require thorough methodology that has been accepted internationally for the design of those specific categories, that are not included in the Eurocode. So, it's more it's more well structured, let's say, the way we deal with these categories in Cyprus, then, well, the one what happens in Malta given what Professor Bonello mentioned before. So, it's, indeed the public needs to be aware, but the state needs to enforce the measures, legislation, and guidelines that should be taken under consideration. So, we shouldn't just accept the fact that the public is not aware and that they cannot find ways or instruments to check what they are buying and that is enough. I mean that is just, that is just an additional parameter. The state needs to be aware. The state needs to take the measures, needs to enforce the legislation. The professional bodies that are part of this, like the civil engineering professional bodies or college and professional bodies, I don't know what professional bodies are in Malta, but they need to push the parliament and the government towards accepting and introducing guidelines for construction, that is not included in Eurocodes, but also for methodologies, for the assessment.

Now, in our case, what we've done, because as was mentioned in the case of private buildings, it’s always a problem, it's a big problem. I mean, public buildings is much easier to assess and retrofit because, maybe because you have one owner that you need to deal with. Now in the case of private buildings, we started gradually, so we started enforcing legislation about… so when, when you are increasing, when you upgrade, your building for energy efficiency, you are obliged to assess it for seismic design. Now this is a measure that has been proven to work, because a lot of financial support has been provided for energy upgrading of existing buildings, and in most cases this energy upgrading, is complemented by an assessment of the seismic capacity, and in some cases by the retrofitting of this building, given, if they have low seismic capacity. So this is one thing that we've tried to enforce through legislation.

The second is in case that you're adding additional floors, let's say to an existing building, so you are obliged to assess the building and retrofit it, in case it is needed. So, we are moving gradually towards, because these two cases, the energy upgrading and the adding of floors, they are very common cases in Cyprus at the moment, with existing buildings. So, we are using these, these factors let's say, to increase the information in the assessment of the existing buildings.

Third measure, let's say that we're trying to enforce, and we're at the final stages, is the certificate for each building. So, introducing a certificate for each building, which will provide information about this seismic capacity. It may not require an upgrading of the building, but at least it will provide information on the current state of the building as far as its seismic capacity is concerned. So in this case, if this starts to get enforced, if this gets enforced and we have information about the, the current state of the building stock, we will be able to find ways and concentrate on the most problematic cases and promote financial incentive for those cases, because at the moment there are a lot of private buildings, obviously, but maybe not most of them, do not really require significant upgrading, because they are low rise, because they are one floor, because they are two floors, because, for many reasons, so we are trying to enforce this certification. And through this certification we will get the opportunity to isolate and focus on specific building categories or even, on other areas in the island that need more attention. And they promote financial instruments, national financial instruments from the state to provide them with the opportunity to upgrade them.

Now all three of the measures that I have mentioned require that you have established methodologies for the assessment. So, if you are, what I've mentioned in my first, the, the first time we discussed this life-cycle cost analysis approach is favourable for such assessment, because you cannot ask an owner to upgrade its building to the full capacity of a new building. That could be one option, but it cannot be the only option, because you know, in all cases the question here is to minimize the risk and minimize the collapses. That is the question here, minimize the collapses and minimize the significant damages.

So, if we can bring our existing building stock to a level where we accept some sort of some damage levels after the earthquake, but we will not have collapse and significant damage, that is acceptable by the society. At least that is our understanding in Cyprus. I'm referring to how we deal with this here. So, we've, we have established methodologies, with various levels, so a first level methodology, a second level and third level. So the first level could be just, just to get an idea, an optical assessment, let's say, a visual assessment of the building stock and then identify which are the most vulnerable ones and move to the second stage of the assessment and then to the third stage of the assessment, that so, that is one of the instruments that we have provided, which is important, because in order to assess you need to have the appropriate instruments.

And the second instrument we have provided is the different levels of earthquakes that these buildings can be assessed. So, the owner, with the engineer can decide, given information about the earthquakes that may happen in the area and given information about the reduced hazard that can be accepted so as to prevent collapses and severe damage, they can decide which level of earthquake they want to assess their buildings for. So, they have learned ways of assessing it. They have various levels of earthquakes to decide, so an owner may decide that I will assess my building to have, let's say, the severity or the magnitude let say of a modern building and I will do that for 20 years and then I will come back and either find ways to retrofit again or I will throw it down and build a new one. I don't know, it's, it's a decision, that...

So we are providing this opportunity, and this is important because if you don't give them the opportunity to choose the level of seismic hazard that they should accommodate, and if you don't provide the engineers with various levels of assessment, instruments of assessment tools, the assessment of private buildings is very hard to take place, and I think that is, it will find many obstacles in the society. So, in, just to, just to conclude, yes, the professional bodies have a very crucial part to play in this process. They have very crucial parts to, in obtaining these methodologies and also in providing them with the acceptable hazard levels. And given that these are provided, I think that the state, the Parliament, and the other authorities will find it easier to adopt them and enforce them to the general public.

I actually just wanted to add a point on what, Professor Kyriakides was saying with respect to certification. I think it is actually an excellent opportunity to encourage and stimulate property owners to retrofit or to demolish and rebuild. Why am I saying this? Take our experience, for example, with respect to energy certification in buildings in Malta. As you know there is a European directive where at the sale of a property, on the contract the owner has to submit what is known as an energy performance certificate, an EPC. Now this EPC is usually prepared by an engineer who has been trained in the estimation of the thermal, the insulation properties of the materials used in the building and the walls, the roofs, the window and door apertures, etc. And eventually this certificate comes up with a certain value which is then recorded in a certificate. Now so far in the Maltese islands, there is no minimum requirement for energy performance. In the sense that when a property is sold, there is a performance certificate that is attached to the contract and that's it.

If you have a discerning owner, in other words, an owner who says I want value for money. So not only do I like the building as it is, but I also want to be sure that the certificate the energy performance certificate, is adequate so that I will obviously, avoid having considerable or significant heating costs or cooling costs during the use of the building, and therefore there could be owners and hopefully there will be owners who will give importance to this certificate. There could also be the case where, for example, at some point in time the Maltese authorities, say for buildings that have been, that are being built from 2021, for example, onwards, the minimum energy performance requirement shall be such, and therefore buildings not conforming to this standard will be, for example, certified as unusable, not habitable, which would be a huge, let's say, impact upon the developer.

For previous buildings, of course, one has to take the view of what the market forces will dictate. In other words, if a property is on the market, let's say two properties are on the market, same gross floor area, same, let's say, locality, but one which has a better energy performance certificate than the other, then one would expect that this is also reflected in the market price. Because the discerning owner will pay more for a well-designed building than for one which is not weld designed.

Where am I getting to this? What I'm trying to say, is, if this, reasoning is applied to seismic, certification, so if, let's say, the authorities say from now on, we shall require seismic certification, we should not put a minimum as yet for the older buildings, from this point onwards the minimum shall be satisfying the Eurocodes, for example. With respect to past buildings, there should be a certificate which will say whether or not the building is resistant to the design earthquake of the Maltese islands. So, a simple yes or no. So, imagine now the properties on the market, 2 buildings were the same or say, two properties with the same gross floor area, one which has a seismic resistant certificate and the one which does not, I would believe that the market forces will dictate that an owner should pay more for a well-designed building, OK? So, what does this mean?

If you have property owners who are lumped with a property that cannot sell because they do not have the required seismic certification, especially if the local society, the population becomes more aware of the need to have seismic resistant buildings, what is the developer going to do? One of two things. The developer is either going to retrofit the building, to upgrade the certification for seismic resistance or the developer is going to demolish the building and rebuild. When I say developer, this could also be an association of owners. Imagine that you have an association of owners of apartments in a block, that realize that their investment is hampered, is handicapped by the fact that their building is not seismic resistant? What do you think they will do? Well, if they are sensible, they will come together, agree amongst themselves. They will try and retrofit the building. In the extreme they will demolish the building, redevelop it and re-occupy the building.

Now of course who pays for those costs is another matter. They might decide to sue the previous architect and the previous owners or the previous developer for not constructing a building, which was seismic resistant. But my point is, the government has to be very careful, not to legislate and make seismic resistance, at least for the older buildings prescriptive. Because by doing so it will take upon itself also, the obligation to let's say assist or carry out those works itself, and that becomes tricky. So, I think the market forces can be a solution. So, I think I agree very much with Professor Kyriakides that certification can play a major role in encouraging property owners, at least of existing buildings, to retrofit, or to demolish and rebuild so that at least takes care of the big headache we have with private buildings of the past that need to be retrofitted and as far as new buildings are concerned, they have to and they must, and again, this is something that I'm working with the Building Construction Agency Authority in Malta, to issue guidelines in this respect, new buildings must satisfy the Eurocodes, end of story. We cannot have any derogations, OK? Because that that will spell disaster. So that's really what I, what I had to say about the, the way forward, at least on the Maltese islands.

And just to add very quickly to what Professor Bonello said, it's very, that's exactly, as I started thinking a bit behind our decision with for the certification, the classification in effect, it also provides the opportunity to the state, to the government, to identify the higher vulnerabilities, let's say. And that is crucial because you may have the financial instruments to promote a program for upgrading, but you need to spend them where it's needed, you need to spend them strategically. It doesn't… so you need to spend them given, based on risk-based analysis, on risk-based assessment, which is what we are discussing here. So, first of all, through this certification, these assessments will be conducted so, it will be identified. Plus, it would also provide the government, the authorities with an opportunity to modify their development plans for certain areas. Even there, their, our contingency plans. So it's crucial, as information both to the public obviously, and the construction industry, but also to the authorities and the government.

That’s right. I think this conversation has brought to light many takeaways. Many bits of information for many stakeholders within the built environment because we've talked about, you know the effect of the public buying property. We've talked about the role of designers and how they should be approaching the design. We've also talked about risk, and therefore, you know, insurance and that other world, or another part of the built environment, and not least, the authorities. How the authorities can have a positive effect on this and how we can bring forward these certifications, these other ways of ensuring safety to our building stock, our existing and future building stock.

I would like to thank both of you for this podcast. It was very interesting, understanding the similarities yet differences between two very relatively close Mediterranean countries. So, thank you so much for joining us today. Thank you very much.

Our guests today were Professor Mark Bonello and Professor Nicholas Kyriakides, and you were listening to the human agenda. Thank you so much for joining us in this episode.

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