087 - Structural FSE inspired by earthquake engineering with Negar Elhami Khorasani

[00:00:00] Wojciech Węgrzyński: Hello everybody welcome to the Fire Science Show. In the fire science and engineering community is not that we always have to come up with solutions from scratch. It's always great idea to inspire by success of other groups of engineers. Because they may have solved some of the things we are desperately looking for. And one of such an inspiration comes from earthquake engineering, community or civil engineering related to earthquakes. Who are using performance base engineering and in fact, probabilistic performance based engineering, a lot in their practice. And that inspired some fire engineers to try. And use that approach for fire safety. And as you may guess, that's exactly the subject of today's episode.

[00:00:44] Wojciech Węgrzyński: I have invited Dr. Negar Elhami Khorasani University of Buffalo to talk about the use of probabilistic approaches in structural fire engineering. I know structural fire engineering is already advanced thing on its own. And here [00:01:00] we are going one step above in the complexity, but trust me, it's worth it. You will learn a lot of interesting stuff related to building performance in fire, which in essence is some sort of.

[00:01:14] Wojciech Węgrzyński: Distribution of possible scenarios and damage and failure rates. It's very natural to position that as a, as a probabilistic problem. And that's what we're going to talk today. We're not going to talk about probabilities. We are going to discuss a framework. A really useful tool that can be directly applied to engineering. So even if you're not very interested in instructional fire engineering, I hope that this topic will be interesting to you because this framework can be adapted for any other body of. Fire safety engineering, I guess now, before I let you into the podcast episode, I have to share some stuff about the podcast. I have to look into statistics. The January is ending and I am absolutely astonished with the. Growth of [00:02:00] the show who there has been over 5,000 listens to the podcast in January. That's the best month ever by far in the show. And it makes me very, very happy that the podcast is reaching.

[00:02:11] Wojciech Węgrzyński: So many engineers. I also see a lot of traffic on older episodes. That means a lot of people are listening through the whole of the show, which also is a good indication that. You like it. And, uh, I see a lot of new people in the podcast. Uh, And that that makes me truly, truly happy. So I have not had the chance to, to welcome all of you new listeners to the Fire Science show. So please feel welcomed to this family. I hope the podcast is useful to you. I hope you find a lots of great resources in a year.

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[00:03:09] Wojciech Węgrzyński: Off today. Well, that's been the intro and jump into it

[00:03:13] Wojciech Węgrzyński: as always, I would like to express my gratitude to the, OFR Consultants who are a sponsor and the partner of this podcast. OFR Consultants are a multi award-winning independent consultancy dedicated to addressing fire safety challenges. OFR is the UKs leading fire risk consultancy is globally established team has developed a reputation for preeminent fire engineering expertise.

[00:03:59] Wojciech Węgrzyński: With [00:04:00] colleagues working across the world to help protect people, property and planets in the UK. That includes the redevelopment of the print with building in Canada water. One of the tallest residential buildings in Birmingham, as well as historic structures. Like the National Gallery National History Museum and the National Portrait Gallery in London.

[00:04:18] Wojciech Węgrzyński: Internationally. It's word ranges from Antarctic data. Comma desert in Chile. And the number of projects across Africa In 20, 23, OFR will grow its team, And it's keen to hear from industry professionals who want to collaborate on fire safety futures this year.

[00:04:33] Wojciech Węgrzyński: Getting touch@oilforconsultants.com.

[00:04:36] Wojciech Węgrzyński: And now back to your episode on probabilistic, structural fire engineering.

[00:04:41] Wojciech Węgrzyński: Hello everybody. Welcome to Fire Science Show. Today I'm here with Dr Negar Elhami-Khorasni from University of Buffalo. Hello Nagar.

[00:04:49] Negar Elhami Khorasani: Hi Wojciech,. Thank you so much for having me. Uh, it's a pleasure for me to, participate in this fire science show.

[00:04:56] Wojciech Węgrzyński: that's so Uh, very happy to meet you to do this interview.[00:05:00] the topic I've proposed for the today's talk is on, probabilistic structural fire engineering, which I guess is, uh, step up from just structural fire engineering, I guess is, is gonna be, Interesting.

[00:05:12] Wojciech Węgrzyński: I've had an episode with Thomas structural fire engineering on the podcast, but maybe we could give a short introduction to anyone who missed that one to, uh, what a structural fire engineering, uh, is and how it differentiates from, this typical code-based, fire engineering we used to.

[00:05:31] Wojciech Węgrzyński: So, so let's start with structural fire engineering, and then we're gonna up the game to the probabilistic one.

[00:05:37] Negar Elhami Khorasani: Sure, definitely. I listened to your podcast with, Thomas, uh, great, uh, friend and colleague, and I w wouldn't be able to beat him on that definition, but I'll try. So, to put on perspective for, For your audience. Uh, the prescriptive approach, we all know it's basically you follow the code, uh, or the rules and it's presumed that it provides [00:06:00] acceptable performance. Uh, but we don't actually check what performance we're gonna get at overall the structural system, whereas with, Structural Fire Engineering, or I'm gonna link it to performance based design is basically a procedure that, it enables the design of the structure, whether it's a building, whether it's a tunnel, whether it's a bridge, that you look at the performance of the structure and you make sure to get this predefined or desirable performance, whatever that is, that's set acceptable for project.

[00:06:32] Wojciech Węgrzyński: Yeah, and I, I know in the US, a lot of people are doing a lot of effort to make performance based, uh, structural fire engineering, um, a thing in, in the design. So, so maybe let's, let's take it, uh, A little step further. What, what, what does it enable? Like what's, what's the benefit of, of me if I'm a, I'm a billion dollar investor in my building and I want, I would like to go that path.

[00:06:54] Wojciech Węgrzyński: How, how would you sell it to me? Is it even

[00:06:57] Negar Elhami Khorasani: Right, right. as part of, again, the [00:07:00] academia, when we talk about it, we definitely focus a lot on the safety side. And we say, okay, with, um, advances in new materials, in new, different techniques and structural systems, it's definitely. Safer if you design using structural fire engineering so that you know, uh, how the structure would perform.

[00:07:21] Negar Elhami Khorasani: Uh, once we start talking with the industry. However, we definitely also bring in the aspect of economy and how it makes sense for the industry to, invest, uh, in the approach because they could, uh, save money. One of the examples that. Demonstrated, not necessarily in terms of, we haven't, quantified the cost yet, but in terms of, uh, quantity of material, for example, it's this composite floor system that, even with, one of your, uh, podcasts on BRE and CARDINGTON test and the work that they've done, here in the US V also adopted [00:08:00] that. Sort of knowledge to the US system and said, said, okay, let's say you've got composite floor system. You've got this beam steel beams and steel girders, and then concrete slab on top. If you remove the insulation on, uh, the beams, interior beams, you do not necessarily, have issues with. the fire safety side. And then if you have a multi-story structure, then imagine how much installation you're saving. Not just in terms of material, but also the labor cost of applying that, um, installation. So these are some of the cases that we actually, through this. Um, there was a project, in the US again, foreign industry, uh, companies got involved and one of the primary. systems that they looked at was this type of system and then they applied structural fire engineering compared it with prescriptive approach and showed that okay, they're actually buildings. Fulfill the requirement even if the installation was not applied everywhere. So it, that's the economy [00:09:00] side of things. but uh, we also have challenges in the US , so it's

[00:09:04] Negar Elhami Khorasani: not just all good stories. Uh, we, in the US we are, um, pushing towards structural fire engineering at this stage. Uh, it is officially in the code. Uh, we have this A S C E seven. it describes all the loads. Uh, so in the appendix, this performance based design for fire. So, but now it means that it's official and, industry can use it. however, uh, what we are trying to do as part of the community here in the US is to, spread the knowledge.

[00:09:36] Negar Elhami Khorasani: and train a workforce because until we have enough people who are comfortable using structural fire engineering, it probably won't, um, get used too much. So that's another, aspect that we are trying to contribute to, to make sure that this concept gets established in the.

[00:09:56] Wojciech Węgrzyński: I wonder within the current paradigm of, fire testing [00:10:00] of, structural performance of the building being the defined, uh, in terms of, you know, classes, ratings as it is now Given the pace of, of the development of new technologies, new solutions, new materials.

[00:10:14] Wojciech Węgrzyński: at some, at some point, it must a factor that either slows down or a factor in which, uh, risky solutions get passed through because someone gamed the index and, and they found a way I, I guess, , if you look at it from this point of view, I, I guess fire engineering is inevitable.

[00:10:33] Wojciech Węgrzyński: I wonder how long the paradigm can sustain. What, what's your thoughts on this challenge? Challenging,

[00:10:39] Negar Elhami Khorasani: there there are two two potential outcomes here. One is that, We manage

[00:10:46] Negar Elhami Khorasani: to push this forward quick enough that, uh, it gets, used and, people keep up with it. the other way, which is not perhaps, a positive outcome is, when maybe we get [00:11:00] structures that are, we don't know exactly how they perform and then something goes wrong, and then there will be the. societal impact and people will not be happy, right? As, as soon as, you know, something finds its way in the news and then, everybody would know about it. That okay, there was a mistake or there was a lack of knowledge. it's definitely not something we want to happen, but often when something like. again occurs then, the, the Ians and industry and everybody tries to move quickly and find the solution and say, okay, now sorry, we should have done this. Okay, maybe now it's time to adopt structural fire engineering. So, uh, hopefully we end up with Path one,

[00:11:41] Negar Elhami Khorasani: where, we realize how important it is, as a community and. try to again, develop the competency to use it,

[00:11:51] Negar Elhami Khorasani: uh, across, nation The, One, um, challenge we are facing here in the [00:12:00] US is that, um, so a lot of people realize that how important it is. And, when I talk about structural foreign engineering, it's not about, okay, every single building needs to be designed using structural farming.

[00:12:11] Negar Elhami Khorasani: It's just not. May be worth it if you have a two, three story structure. If it's a regular structure, that's not the argument we are trying to make here. That okay, you, you have to apply for it and prescriptive design is gone. No, no, no, no, no. That's not the idea. It's about all these special cases or cases that it's, the prescriptive approach will not provide a, perhaps a safe design. then may maybe people start listening.

[00:12:34] Wojciech Węgrzyński: Yeah. But, but with the variety of materials, the variety of solutions, the, uh, creativity of architects, uh, and just having, uh, Puzzle as an enabler for creativity. You know, because there is a way you can, uh, maybe make a very interesting building, which was prohibited because of the rigid, requirements of the code before.

[00:12:53] Wojciech Węgrzyński: Maybe that's something that would push for, for more creativity in this space. And the more of this variety comes in, the, the more, the [00:13:00] bigger role structural fire engineering. uh, that, that's already a big jump from something where you, um, assume the safety or acceptable performance to the point where you measure acceptable performance.

[00:13:13] Wojciech Węgrzyński: And now let's make another leap into the probabilistic aspect. So wh where does the probabilistic aspect comes from? What does it replace in the. Paradigm of structural foreign engineering and in, in general may. Maybe let's start with how did you start working on this? As what, what made you think that this worth spending many years of your career investigating?

[00:13:34] Wojciech Węgrzyński: Yeah.

[00:13:35] Negar Elhami Khorasani: Sure. Uh, it actually for me started, as part of my PhD.

[00:13:39] Negar Elhami Khorasani: I started 2010 and a lot of my thinking has been influenced, by the work in earthquake

[00:13:46] Negar Elhami Khorasani: engineering. So, well performance based design in earthquake engineering. it's mature relatively to, you know, structural fire engineering and, it breaks down the problem. Into these four boxes.[00:14:00]

[00:14:00] Negar Elhami Khorasani: They call it hazard analysis. Structural analysis, fragility analysis, which is equivalent to damage, quantification of damage, and then loss analysis. So these four boxes, they're linked together. So they, you start from hazard, you go to analysis, structural analysis, then fragility, then loss, and uh, each box is a model or set. Uh, and these models depend on uncertain inputs. They're, they, they're not necessarily deterministic, they can be right. But, uh, within the probabilistic approach, each box has its own uncertain inputs and parameters that produces a probabilistic outcome. and then the probabilistic outcome of One Box feeds into, uh, the next box, which itself could also have other, specific probabilistic inputs. if, if I wanna explain each box within the structural fire engineering, uh, world, the first one I. Trivial, it's [00:15:00] the hazard box. So it's about modeling the fire scenarios and the likelihood of those events. So we won't stop us saying that. Okay. we're gonna have, let's say, a compartment inside a building. And it has a one fuel low density. It has one ventilation factor, and let's use, you know, parametric model and we get a temperature time care. We, it won't stop at that. there are inputs to that box. I mentioned two of them, ventilation and fuel, low density. Now we make them, we assign a, uh, distribution to those. and therefore instead of getting one temperature time curve we get a series of temperature, time curves

[00:15:41] Wojciech Węgrzyński: So here, In, uh, the previous paradigm? Or, or just, just the basic way of thinking. You would have a scenario that is described either by the code, which could be like, um, standard fire. Curve, which, which also is a, is, is kind of a scenario.

[00:15:57] Wojciech Węgrzyński: Or you could use some sort of model, like a zone model [00:16:00] or CFD model to come up with your temperature. But then again, you are limited here to what you've put into the model, which was most likely a certain. Data point, like a fuel load, like you said, a ventilation factor, where in reality it's like, uh, hundreds of outcomes that that can come up.

[00:16:17] Wojciech Węgrzyński: So how, how do you define them in this probabilistic framework you provide ranges of, of these values and where do you take these ranges from?

[00:16:26] Negar Elhami Khorasani: exactly. So, there are a couple of, points here. One is, uh, correct. First you, As a user of this procedure, you have to decide which model you want to use. and as you uh mentioned, it can range from, okay, the, well, I'm gonna set aside the standard fire curve

[00:16:44] Negar Elhami Khorasani: because that's just set. But from, let's

[00:16:46] Negar Elhami Khorasani: that's, that's,

[00:16:47] Wojciech Węgrzyński: where you should go, .

[00:16:49] Negar Elhami Khorasani: Sorry.

[00:16:49] Negar Elhami Khorasani: Right. So that aside, we have the perme, maybe temperature time curve all the way to, we could have CFD model, we could have Z Zone models in between. [00:17:00] So the level of complexity, uh, differs and therefore the l different, each model records different inputs with, let's say, the perme, fire, we list all the inputs. We could do. So I'm kind of gonna deviate now for each of, uh, these models. You can do a sensitivity

[00:17:20] Negar Elhami Khorasani: analysis. That's the first. So you, you say, okay, these are all my inputs. Now I need to, it's not one, one value per input. There's a range now for each of them. let's say few load. that was a study by itself.

[00:17:34] Negar Elhami Khorasani: We've spent, um, a year or two just looking at survey. Surveys that are out there, fuel load density surveys, and try to quantify the uncertainty in fuel load density. And it's not an easy task because it varies. It's based on occupancy and, um, it could change based on country even because the type of loads you may have, the type furniture you may have.

[00:17:59] Negar Elhami Khorasani: It [00:18:00] kind of, it may vary from place to place.

[00:18:02] Wojciech Węgrzyński: Even stuff like company culture, like one company would have a clean desk policy and keep everything in, in, in closets. Others would like, well, like my, my desk is not very clean

[00:18:14] Negar Elhami Khorasani: No, I, we actually encountered that. We did office. just, uh, parenthesis as part of this discussion. um, there was a study, uh, supported by National Fire Protection Association and fba, and um, actually this study was, collaborative, project with Thomas Gnet, professor Gnet.

[00:18:30] Negar Elhami Khorasani: And we, wanted to apply a new method to survey, uh, field Density, but I'm gonna jump into the conclusion. because that's relevant to this

[00:18:40] Negar Elhami Khorasani: discussion. We, uh, surveyed offices at universities because we were just, the point of that project was to develop the meta methodology, not necessarily getting, you know, a few low density and, apparently, uh, admissions, we have a lot of books and papers and

[00:18:56] Negar Elhami Khorasani: exam notes and all of that.

[00:18:58] Negar Elhami Khorasani: So the [00:19:00] amount of fuel, uh, density that we calculated was much, much higher. Than perhaps what's in the code. And, uh, what we had expected because a lot of paper and those papers all burn. Uh, so it, again, if it was under category of office, but it was just an office inside a university building,

[00:19:18] Wojciech Węgrzyński: Okay. A different type of

[00:19:20] Negar Elhami Khorasani: different type of office.

[00:19:21] Negar Elhami Khorasani: So it makes a difference

[00:19:23] Negar Elhami Khorasani: Indeed.

[00:19:24] Wojciech Węgrzyński: So, so you have this different inputs. Let, let's continue on.

[00:19:28] Negar Elhami Khorasani: So you have, um, different inputs. So fuel, again, you do surveys, ventilation, you still have to assign a distribution, uh, with ventilation. There are different approaches. If you really don't know, I'll give an example then. If you really don't know and, you could still make engineering judgment in the sense that there's a minimum, there's a maximum, right?

[00:19:48] Negar Elhami Khorasani: Because you've got windows, you've got doors, and you can assume that, okay, it will vary within that range. It's not gonna be outside of that range.

[00:19:56] Negar Elhami Khorasani: So knowing those inputs, you put it into the model. [00:20:00] There's also, if you wanna make it, you know, really complete. There's also the model uncertainty

[00:20:05] Negar Elhami Khorasani: in a sense that, um, if you are working, with a certain zone model or certain C f D, the idealization that goes into the model also makes a difference in terms of the output you're getting. So you should be considering some uncertainty on the model side as.

[00:20:24] Wojciech Węgrzyński: and, and what's the benefit of going through all this hassle? Why not just picking the worst case scenario? How does this change your, uh, like what, what's the benefit you get from, from going through this?

[00:20:34] Negar Elhami Khorasani: Because at the end of the day, when you go through all the four boxes, you get basically the probability of, uh, having the loss and the distribution of that loss. Uh, so rather than getting one value, you're gonna get a distribution and then your performance. Objective should technically be defined also, probabilistically in in a sense that, So it's not defined that, okay, for this given worst case [00:21:00] scenario, you should have, let's say life safety. Life safety is always there, but, um, further performance objectives such as. Building should be operational and so on. you have it, in a probabilistic way as in, for a hazard with a given, rate of return. the expected outcome or loss should be, you know, X. So, and you do this because it's just so much uncertainty involve the whole process.

[00:21:27] Negar Elhami Khorasani: So that's why you try to, um, actually capture that.

[00:21:31] Wojciech Węgrzyński: I also observe that, that we often, when we don't have, very good data, we keep adding. Margins of safety. They, they multiply by each other. You know, if you add in, in, in some steps of your analysis. I add, um, a margin of safety to my, uh, Fuel load. I add a margin on my evacuation.

[00:21:50] Wojciech Węgrzyński: I add a margin, you know, on the structural performance. And all of this add together. And at the end you don't even know what's the total margin of safety of your building, whi which, which can [00:22:00] be actually enormous. And when we're talking about, uh, economic gains or, benefit in the end for the client or for for the building is, is by.

[00:22:08] Wojciech Węgrzyński: Smart reduction of these safety margins that, could potentially be unnecessary in a way. So, so I understand, uh, that, good data is, is, is somehow required to, to, to start forward. So you have your. Input. So you have for, for your hazard analysis, you said there are four boxes. I'm gonna reiterate them.

[00:22:28] Wojciech Węgrzyński: Hazards, structures, then fragility, which is also damage. And then the fourth one, last one. Loss. The economic loss in that. So, uh, moving from just hazards to, to structures. What's happening, uh, there.

[00:22:41] Negar Elhami Khorasani: so let me just because to connect the four boxes

[00:22:44] Negar Elhami Khorasani: and then I'll go into the second box. This is more like a conditional probability type of thing. So that's why you kind of break them down. So you say, uh, now connecting the first two boxes, you say, well, how is the structure going to performance?

[00:22:56] Negar Elhami Khorasani: So what's the probability of having the structure reaching, [00:23:00] for example, such and such deflections just making it up given. a hazard. So now let's say you have thousand different scenarios coming out of the, uh, hazard box. But per each scenario, given that scenario, you can start looking at the structural analysis part of it, the the problem. And that itself is not going to have one answer per scenario. You may have different. Given the uncertainties that go into the structural analysis box. Now here we are dealing with material properties. We are dealing with the applied load on this structure, you know, dead load, live load, and so on. And Typically, I'm gonna draw again a parallel line to earthquake engineering or other hazards, the material properties at ambient temperature. the uncertainty there compared to the uncertainty in the hazard, which for earthquake engineering is ground motion is much smaller. So the uncertainty you get in ground motions much harder. So it makes sense. [00:24:00] If you wanna drop something, you would drop the material property on certainties for fire. Um, it's not. easy as that because we actually have variation temperature with temperature comes, changing. If you have steel yield strength, if you have concrete, you have if privacy, all that, which again, when we collected the data, is a large variability. There's a large scatter in the data, so it's hard to drop that. Uncertainty. Another level of uncertainty going into the structural analysis. within, again, fire. The first step is always heat transfer. Then you do the structural analysis, right? So

[00:24:38] Negar Elhami Khorasani: all the properties that go into the heat transfer analysis, such as terminal conductivity of uh, your fire protection, um, and as well as your, again, steel, if you have steel or concrete, they all make a. We have done sensitivity analysis and for example, one of the parameters that, came out to make quite a difference. So it's hard to make that parameter de [00:25:00] deterministic is again, terminal conductivity of the fire protection, which is a variable at least, uh, at this stage is hard to know exactly what it is, which also changes with temperatures.

[00:25:12] Negar Elhami Khorasani: So one thing is to get the variable at ambient temperature from, the producer. manufacturer of that material. Another thing is to actually know the variability with temperature, which there's not much data there. That's one thing. Another thing is, um, it, it varies from material, but you know, for different materials.

[00:25:31] Negar Elhami Khorasani: So, um, something that's hard to drop in this process and make it determin.

[00:25:37] Wojciech Węgrzyński: We had similar experiences. Our colleagueuh Piotr Turkowski, who was on on the show as well, he produced an internal book of, basic, Properties and there are change in temperatures that, uh, we are secretly using. And the same goes with a specific heat. Uh,

[00:25:53] Negar Elhami Khorasani: Right,

[00:25:54] Wojciech Węgrzyński: it's, it's very temperature dependence.

[00:25:56] Wojciech Węgrzyński: So there are these funny things you have to start [00:26:00] worrying about when you are doing a fire. Uh, one, one thing I was wondering, uh, and I've read some of your papers before this interview, you've also done work. on, on load modeling and, and, how to define loads. And I found that very interesting, that loads are also something that, not, uh, same over many buildings, right?

[00:26:18] Wojciech Węgrzyński: And.

[00:26:19] Negar Elhami Khorasani: Right, exactly. And, uh, actually that paper, we, Ruben, uh, van Coile was, leading that work. And the issue we were facing before that paper was that in the literature there were. Different models with

[00:26:32] Negar Elhami Khorasani: different assumptions. And what happened was that, uh, again, in the literature, you know, we kept either referring to one or the other.

[00:26:40] Negar Elhami Khorasani: So, there were a number of papers referring to case a number of papers referring to case B. So we, we weren't sure, uh, okay. What's the right, probabilistic model we should be using. Uh, so we just, went into the background of, those assumptions made, and, Ruben and [00:27:00] his student with the larger group, um, Thomas, Danny Hopkin, uh, eventually, arrived at. A model that seemed to be most logical, given all the assumptions, again, behind these models. And, uh, it does definitely make a difference because I wanna tie it back to one of our more recent studies, so in the US we have prescriptive approach, right? And.

[00:27:24] Negar Elhami Khorasani: A lot not being applied and we said, okay, let's say you've got a multi-story structure and you have all these columns in across the building, and they're all designed based on a FI rating requirement.

[00:27:37] Negar Elhami Khorasani: Now that we have all these models over years, we know developed, let's, quantify probability of reaching a limit state for all those columns across the building. And see, we get similar probability because technically if you want to have, what I'm calling it, harmonized safety, you shouldn't have a different, probability of failure on the [00:28:00] seventh floor versus the second floor.

[00:28:01] Negar Elhami Khorasani: Right.

[00:28:02] Negar Elhami Khorasani: It, it's the same building.

[00:28:03] Wojciech Węgrzyński: a, or in a, core versus the edge of

[00:28:06] Negar Elhami Khorasani: right?

[00:28:07] Negar Elhami Khorasani: exactly. So we didn't vary much the assumptions on the hazard size because we were saying again, that given, you know, whatever hazard inside a building, what's the probability? And, as somewhat expected, the probability of failure

[00:28:21] Negar Elhami Khorasani: actually varies.

[00:28:22] Negar Elhami Khorasani: across the building over the um, so two, two things change from, upper floors. Let's say two lower floors. One is the, uh, section factor or the size of the column because as you go down,

[00:28:33] Negar Elhami Khorasani: gets heavier. and then the amount of applied load, because the bottom floor is collecting load.

[00:28:39] Negar Elhami Khorasani: So you have, uh, you may have different utilization ratios for the column. So going back to the load effect, it makes a difference. And in the prescriptive approach, at least here in the us, it's not fully incorporated. Uh, that effect of the, uh, load is not fully incorporated. Therefore, you get various policies [00:29:00] of failure across which may not be something we want to have, but it

[00:29:05] Negar Elhami Khorasani: is what It,

[00:29:05] Negar Elhami Khorasani: is

[00:29:05] Wojciech Węgrzyński: I mean, going just, the descriptive way. You just have one , one safety, one assumed safety. And it doesn't say that you, you're safer on the seventh floor versus, uh, on the second floor. Well, it doesn't even explicitly say you are safe. It's just we assume you are. Once you follow that.

[00:29:22] Negar Elhami Khorasani: Yes, indeed. Indeed. So that's why, I mean, we are, we made an towards the end, I mean, that paper basically concluded that, we are not saying exactly as you, we are not saying that this is safe or not, we are not, Criticizing, let's say that the prescription or creating an alarm, that, uh, okay, people, this is not safe.

[00:29:40] Negar Elhami Khorasani: What, what we are advocating for is more harmonized safety, in a sense that if you set the safety level, let's make sure that we have that level of safety all across, even just

[00:29:51] Negar Elhami Khorasani: one structure.

[00:29:52] Wojciech Węgrzyński: a, I'm a huge advocate of that, that type of thinking because I also believe we are spending a lot on safety. I'm not saying we're spending [00:30:00] too much on safety, but we, we are spending a lot. And, uh, a huge chunk of a building coast goes into safety, especially pacifier safety, you know, uh, , even the, the concrete you add, uh, over your rebar.

[00:30:11] Wojciech Węgrzyński: So you protect them from, from being heated up. Th these are the costs that add up. And if there's a chance that this money could be spent in a better way to provide more safety, why not doing that? Why spending it on stuff that does not matter when you could, uh, spend it money on stuff that matters.

[00:30:29] Wojciech Węgrzyński: But to know that you need to know that you need to calculate that. And today we do not.

[00:30:33] Negar Elhami Khorasani: Exactly. Exactly.

[00:30:35] Negar Elhami Khorasani: Okay. So with the, the structural analysis box, after you quantify all your, you do your structural analysis using, again, choices up, up to the user. You

[00:30:47] Negar Elhami Khorasani: either use, um, finite element, uh, software level of complexity.

[00:30:51] Negar Elhami Khorasani: You go through that. But what another important aspect is to decide how you want to characterize the response [00:31:00] in a sense that what's coming out of that box Are the forces in your elements? Is it the deflection, the formations in your elements? Is it, for structural function, you can actually work with temperatures, you know, temperature in the rebar.

[00:31:13] Negar Elhami Khorasani: I don't know. It's

[00:31:14] Negar Elhami Khorasani: just the heat transfer part, so you have to. Decide what, parameter or parameters you will be using to characterize, um, your structural response. We call these within, I'm borrowing the terminology from earthquake engineering, but I've been using it the same for structural fire engine.

[00:31:31] Negar Elhami Khorasani: We call them engineering demand parameters. So basically these are your demand parameters that move into the next box, which you will be using to quantify damage

[00:31:44] Negar Elhami Khorasani: or fragility of the

[00:31:46] Negar Elhami Khorasani: structure.

[00:31:47] Wojciech Węgrzyński: Let's let, let, let's go

[00:31:48] Negar Elhami Khorasani: Let's go there. Okay. So with the damage, the in simple, you know, terms, when I say fragility again, thinking about damage is, okay, you have a deformation.[00:32:00]

[00:32:00] Negar Elhami Khorasani: that the formation, um, means what is the level of damage typically, we, Borrowing again from other fields. We want to, uh, simplify the process in a way that, uh, you can communicate it easily. So, uh, you could have categories, categories as in, um, slight damage, moderate damage, severe damage, and maybe. almost near collapse. So something like slight damage. Uh, it later on maps to, you know, in next box it, it basically means it, it comes with definition. So slight damage means, uh, you could potentially safe for your occupants to go back and inside the structure, and you don't have to spend much to repair.

[00:32:48] Negar Elhami Khorasani: Okay.

[00:32:49] Negar Elhami Khorasani: And it could be also even just cosmetic repair and something like that. And then you move on to, you know, moderate damage. Well, it means that maybe it's not safe, right? For [00:33:00] occupants to immediately go back, but it's repairable. You don't have to necessarily demolish. And then once you go into the severe or near collapse, then at that point, you are probably better off. demolishing and rebuilding rather than repairing because it's too much, um, to repair.

[00:33:17] Wojciech Węgrzyński: Sorry, and, and again, this, this levels of damage is something you define for your particular building is not just, saying that the crack of this size or, or something, however you could define, is, is, is, is module damage is related to your structure in use is operations. Right.

[00:33:35] Negar Elhami Khorasani: Right? Yes. true. But it can be categorized

[00:33:38] Negar Elhami Khorasani: for different structural systems. So in a sense that ju you could basically lump things

[00:33:45] Negar Elhami Khorasani: together for certain categories so that it gives guidance, for, again, the user. So if somebody's using it, they don't have to start from basically

[00:33:52] Negar Elhami Khorasani: scratch. If you have a, steel frame with, um, a certain [00:34:00] characteristic, maybe it's a. Brace system and composite floor system and so on. Then you define these categories for specifically for that and high rise, like higher than certain number of stories. Uh, I am going to completely, put a twist here and just give an example. Let's say, let's say now you've got a tunnel, because I've worked in

[00:34:21] Negar Elhami Khorasani: that, you know, let's say now you've got a reinforced concrete, uh, tunnel, uh, liner. you still, you can come up with these categories, uh, based on, the level of, I don't know, the crown, displacement. That

[00:34:34] Negar Elhami Khorasani: means okay, that probably at certain level of def formation, probably. Certain crack widths, and that probably maps to a certain amount of repair

[00:34:44] Negar Elhami Khorasani: requirements and so on. Uh, so that goes in the category of tunnels and certain lining type. So what we have actually in, in the seismic world, they have, invent inventories or databases [00:35:00] of what they call fragility functions.

[00:35:02] Wojciech Węgrzyński: Okay.

[00:35:03] Negar Elhami Khorasani: and these fragility function. are basically, developed for a suit of different structural types, structural elements, and they're all a function of, so it's important.

[00:35:15] Negar Elhami Khorasani: So on the X axis you have some sort of an intensity measure or the engineering demand parameter, right?

[00:35:24] Negar Elhami Khorasani: So that's where the engineering demand parameter comes into the picture. You say, given this amount of deflection, what's the probability? This is all probabilistic. What's the probability of exceeding a certain damage state? And those damage states are slight, moderate, severe, and you know, so on complete,

[00:35:43] Wojciech Węgrzyński: So instead of our, let's say L 30 criterion, uh, which is sometimes used or it's often used, you, you would now have a probability function that says, okay, with this level of deflection, the severities is this as it rises, it changes. Okay.

[00:35:58] Negar Elhami Khorasani: Right, exactly. [00:36:00] And, you, it's again, what's important is that you pick an engineering demand parameter that reflects.

[00:36:06] Negar Elhami Khorasani: That level of damage. So you can't just pick any, you, you,

[00:36:09] Negar Elhami Khorasani: you want to make sure that it, it actually maps to that level of damage. And then, the seismic ward, they use it the way that it happens.

[00:36:17] Negar Elhami Khorasani: That let's say you have this fragility functions for your, connections. For your columns, for even, I'm gonna go even a step further. They're trying, they're, they're not there yet, but they're trying to level all of these for non-structural components,

[00:36:34] Negar Elhami Khorasani: Mm-hmm.

[00:36:35] Negar Elhami Khorasani: right? Um, walls and so on. So once you have your hazard, then they go to student structural analysis, then they end up with this third box.

[00:36:45] Negar Elhami Khorasani: the, the user doesn't have to do the,

[00:36:47] Wojciech Węgrzyński: Hmm.

[00:36:48] Negar Elhami Khorasani: that specific case, they go to these reference fragility functions and they start saying that, okay, now I know my deflection for, column or horizontal, you know, deflection. I know the, [00:37:00] some sort of parameter for temperature maybe in the connection and so on.

[00:37:03] Negar Elhami Khorasani: And then they look at, what would be the level of damage and then, Make a conclusion that this building, maybe you've got a component that's in damage state, slight, but you've got a key component that

[00:37:17] Negar Elhami Khorasani: has reached, a severe damage state. Then your pro, most likely, your structure overall is gonna be in the severe damage state.

[00:37:25] Wojciech Węgrzyński: So the user would go through the probabilistic analysis of the hazards, going through the iterating, through the scenarios, then going into the structural modeling, whatever model they choose, uh, to demine a certain, uh, parameter of their, of, of their structure, which they, they can compare with.

[00:37:43] Wojciech Węgrzyński: now a standardized or, or preproduced set of, Outcomes based on this value, they know the outcome would be like this. It's severe, not severe, and, and based on the severity they can figure out what to do. Well, I guess that's a step four when they go

[00:37:58] Negar Elhami Khorasani: Exactly. [00:38:00] That's exact. So it's, it's, that's the part that, so as soon as you know, your dumb state, it maps to a repair cost

[00:38:07] Negar Elhami Khorasani: and it maps to losses. Now, those losses, it definitely can go beyond, uh, economic losses.

[00:38:14] Negar Elhami Khorasani: Um, you Potential for casualties, societal causes, social causes, you name it. but, it makes a direct, connection there. So what, uh, I would say within structural fire engineering, uh, the turret box, so I, I, I, I think fourth box is, um, more or less outside of my.

[00:38:34] Wojciech Węgrzyński: Mm-hmm.

[00:38:34] Negar Elhami Khorasani: Area because that again, brings in social aspects, economic aspects.

[00:38:38] Negar Elhami Khorasani: Uh, so the third box is where, perhaps I'm focusing on more now than

[00:38:45] Negar Elhami Khorasani: the other boxes, because I've been working on the first box.

[00:38:47] Negar Elhami Khorasani: Then the second one. So kind of moving.

[00:38:49] Negar Elhami Khorasani: Now I'm in the third box trying to quantify damage. for certain structures. And, one thing that in the past, two, three years, for example, we, we [00:39:00] don't have the answers yet. We are still working on it and I think it probably takes another few years, is again, that example of a tunnel, uh, lining reinforced concrete that I mentioned where okay, we, know that most likely won't collapse based on the analysis, but it's all about the down. Of the tunnel because, especially again, in the US you may not have a redundant, route within the transportation network. So if you shut down the tunnel because there was a fire, how long is it gonna take for the repair and quantifying the damage? It's not as easy well, let's, let me put it this way. we do not find a lot of literature and experimental, data on what happens after cooling. if you are applying this, it's a structural fire engineering, you're not assuming, a standard fire, right? You want to do this realistically. So you have this cooling phase and you want to not only test during heating, but as well cooling [00:40:00] and let it cool down until it's finds this new equilibrium and now measure, okay, what's the deflection? What is the, locked in stresses and.

[00:40:11] Wojciech Węgrzyński: I love how you position it with tunnels. Uh, what, what you're describing here is, is what, what we call here, resilience of the tunnel. And I actually had an episode with an engineer from Switzerland Ingo Reiss about the resilience of tunnels. He was focused more on the use of, of, uh, active fire protection in that you are focusing more on structural, performance of tunnels.

[00:40:32] Wojciech Węgrzyński: But, uh, in the end it's the, the same thing viewed from, uh, from the inside and from the mountain side of the, of the tunnel. Very, very interesting how, how both, uh, worlds, uh, go, go through each other. And I, I think that this is very, Interesting point of view. It is kind of generic to say, oh, we need to, to understand our structures better, or we need better way to measure the damage, to take better informed decisions.

[00:40:58] Wojciech Węgrzyński: Of course we [00:41:00] are that, that's kind of obvious, but I, I love how here you are, not just talking about it, we need that it is that you have a framework that can be adopted for that, a framework That allows you to work with it. It's, it's, it's not a, a beautiful thought. It's a tool, uh, that, that you present here.

[00:41:18] Wojciech Węgrzyński: So in, in the world of earthquake engineering, I guess there's, probably more than a hundred years of experience doing that. Uh, so, so, Was this type of thinking, this type of framework in the world of earthquake engineering, did, did it go into the, the codes, into the low, into the standard? How widely disused is it even possible to employ such a framework in, in, in the codified world we will live in?

[00:41:41] Negar Elhami Khorasani: yes. So the, the earthquake engineering will definitely, um, it's more advanced.

[00:41:45] Negar Elhami Khorasani: So, and one of the perhaps, um, Would say wake up calls or what, what,

[00:41:51] Negar Elhami Khorasani: what things, when things changed for them? Uh, it was after, the, uh, 1994 Northridge Earth, earthquake, [00:42:00] uh, in the US and California. And, there were a number of, buildings did not perform

[00:42:06] Negar Elhami Khorasani: as they had taught or wished, you know, for, so they started making really significant changes and right now at this stage, they performance based design.

[00:42:17] Negar Elhami Khorasani: You can definitely, Come up with many, many, many buildings, um, let's say in the, on the west coast of the US that they're built, uh, high-rise structures built using performance based design. So one thing that I wanna mention is, Perhaps given that, again, it's uncertain and all the variability that you get and going through this procedure, it's not that you, if you follow performance-based design, you say that, okay? Uh, with hundred percent certainty. This is going to happen because still they don't know also and they acknowledge that. and they also argue that maybe what they build necessarily, it's not, um, [00:43:00] because they also have their own simplified or prescriptive approach that they can follow. Nothing, you know, stops them. the argument is they hope, and I believe this is true, I that using this approach, they are going to get buildings that perform, better or to the level that they have calculated. So they get some sort we've used the term safety, that they're comfortable.

[00:43:25] Negar Elhami Khorasani: now, what they are moving, again, far from where we are and perhaps may not necessarily directly apply to structural fire engineering, but they have reached the level that they, uh, believe they've solved the collapse prevention problem in the sense that what they build is not going to collapse and they are really pushing for. Immediate occupancy. in a sense that nowadays say, okay. a lot, a lot of that economic losses after an earthquake across a region is going to be [00:44:00] because people cannot go back because of the downtime and everything. And the downtime, I'm relating it to, again, to the tunnel project because that's the, the motivation there as a single structure versus many buildings across the region after an earthquake. but, they think that, okay, now that we've solved collapse prevention, let's move on to, work on non-structured components and make sure that we can have occupants or minimize, the functional recovery, what they call. So they want to be able to optimize that functional recovery. Now, within fire engineering world, if you have a fire inside the building, no matter what, you still need to clean it up. So in terms of the furniture, in terms of, again, non-structural components and things like that, so that directly doesn't map to what we do. But if you really have a structure, that's critical, that has a certain, Uh, essential service that you want to be able to recover quickly, then you can at least [00:45:00] work on the structural components from my perspective, structural engineering aspect of it, to make sure that you stay within that down state, one or two where you can repair it rather than you have to, basically demolish and.

[00:45:15] Wojciech Węgrzyński: I, I think in fire we are What's different from the earthquake is that the fire is localized even within your building, it doesn't necessarily affect the whole building. And you, you may be quite okay with like, uh, let's say losing or, or having one fire compartment destroyed if your building is compartmentalized, but having the, the, the functionality of the rest of the building, and, uh, undisturbed.

[00:45:39] Wojciech Węgrzyński: And so, so, so like what you don't want to have is like, some sort of progressive collapse or, or some, some sort of, Damage to the hole that, that's in a way unnecessary. In, in earthquake. I guess it's an event that, that touches the whole building. So if you have lightweight walls, it's gonna destroy them in every floor.

[00:45:59] Wojciech Węgrzyński: So, so [00:46:00] you worried, worried more maybe on, on this aspect and in fire, we have ways to mitigate that. But again, going back to, the thing that triggered this discussion, we don't know how much we have. We have absolutely no idea to what fire will cause, what sort of damage and what you propose.

[00:46:18] Wojciech Węgrzyński: Here is another way to, to look into that, that that could finally give us this answer that I believe we desperately need. I also liked how, how you've placed it, you can build a catalog of of the losses.

[00:46:33] Negar Elhami Khorasani: Right, correct.

[00:46:34] Wojciech Węgrzyński: I, I think also like going, applying this methodology to some set of standardized or typical buildings can reveal their, um, functionality.

[00:46:44] Wojciech Węgrzyński: Even, you know, applying this method to, to, to structures, uh, That are codified, like following the, the, prescriptive codes could, could, uh, unravel their ultimate level of safety. That would be funny thing to, to, to have. So, so [00:47:00] I really see a lot of implementation of frameworks, like, like the one that you've proposed and, for the end, to, to highlight the probabilistic aspect.

[00:47:08] Wojciech Węgrzyński: And in earthquake engineering, I assume they work with targets that are also tied to probabilities, right.

[00:47:13] Negar Elhami Khorasani: Yes, yes. It's, you know, col, 2% probability of collapse for a, um, earthquake with a return period. X, you know, such and such. So, both of the terms, so the hazard return period, as well as, the chance of collapse, they're specified in a probabilistic term.

[00:47:31] Wojciech Węgrzyński: So the methodology starts probabilistic set of, uh, scenarios, likelihoods, uh, Which are ties to probabilistic, uh, ventilation factors, fuel load densities, all the aspects that drive the, the growth of the fire. The loads on, on the building itself could be probabilistic. Then you go through, Structural modeling with, uh, with, with some sort of, let's say conditional probabilities.

[00:47:54] Wojciech Węgrzyński: That, that scenarios that have certain probabilities that lead to certain engineering, [00:48:00] uh, demand parameters that can translate into fragility damage and then losses. I got it right. I hope

[00:48:06] Negar Elhami Khorasani: Yeah, you definitely got it right. Perfect. The one thing I wanna mention quickly uh, another thing, that sort of, it's an assumption that

[00:48:16] Negar Elhami Khorasani: goes into the, this procedure, but it works, is that you assume that the variables in this, analysis going from one box to another, uh, they're, from Pablo point of view, they're conditionally independent,

[00:48:29] Negar Elhami Khorasani: right? So when you're in one. You're just in that box and you're not dependent. You, you are dependent. But in terms of, um, you can assume that, okay, given a hazard, now what? I

[00:48:41] Wojciech Węgrzyński: you have a set of different branches

[00:48:43] Negar Elhami Khorasani: yes. So you don't have a fee, like you

[00:48:45] Negar Elhami Khorasani: don't have to go back and forth, but, which makes it easier for application in a sense that, you don't have to have to be an expert in all four boxes.

[00:48:56] Negar Elhami Khorasani: Right. If you, you can rely on someone. [00:49:00] focus is on hazard analysis, right?

[00:49:03] Negar Elhami Khorasani: You say, here's your problem statement, here's the building or whatever the, the tunnel, whatever the structure is. Uh, can you do me, a hazard analysis and give me a suit of, uh, potential scenarios? Then maybe on the structural analysis, I really don't know.

[00:49:20] Negar Elhami Khorasani: I, I know how fire works because I'm a structural fine engineer and all of that,

[00:49:24] Negar Elhami Khorasani: but, At the end of the day, I'm maybe not comfortable using a CFD or whatever, so I ask somebody else to do it, give me the output. Then I use that as an input. So breaking it up, even within that probabilistic approach, it, it gives you the opportunity to bring in experts where you need them in whatever box

[00:49:43] Wojciech Węgrzyński: and essentially what you need from them is, uh, an output plus, uh, probability of that output. And, and then, then you're good. Right? I, I really enjoyed, I'm, I'm doing a lot of projects on wind and fire engineering at, at the moment. I, I think in wind and fire it's a little more [00:50:00] complicated because if you want to do it right, you have to, um, get the feedback, you know, like.

[00:50:06] Wojciech Węgrzyński: I cannot have a set of fires and then, uh, apply a set of winds to them because the wind will completely change the fire. So, so wind and fire are now in my one box is a set of, of branches. So every scenario is dictated by two probabilities. One is the wind and the second is the fire. But, the, the structure could, could be the same.

[00:50:24] Wojciech Węgrzyński: You are giving me a lot of ideas how to, how to structurize my, my thinking in this regard because if it's not structurized, it's not gonna.

[00:50:33] Negar Elhami Khorasani: Not to deviate, but just

[00:50:34] Negar Elhami Khorasani: again, a parentheses because, uh, something that I've got involved recently is application of exactly these boxes and this framework to, communities and wildfire.

[00:50:44] Wojciech Węgrzyński: Okay.

[00:50:45] Negar Elhami Khorasani: Very different sort of problem because it's not, not just a single structure, now it's a community because it doesn't make sense for wildfires to have one structure that's wildfire

[00:50:54] Negar Elhami Khorasani: proof because everything else will still get burned down. but I'm thinking about wildfires. [00:51:00] uh, I just don't have the knowledge. Maybe if I study, yes, but I do not have the knowledge to, uh, simulate wildfires in the white.

[00:51:08] Negar Elhami Khorasani: And you brought up the wind, which is pretty much, you know, wind modeling inside the community, outside the community is part of the problem. But if somebody else gives me the wildfire scenario as its approaches the community,

[00:51:23] Negar Elhami Khorasani: I can take that. And then if somebody else gives me the windfield, in velocity over time. I can also take that and then I can run my simulation, which is basically fire spread within the community and then move that into again, the damage box and so on. So, again, same sort of thinking, uh, and framework Now, a completely different.

[00:51:45] Wojciech Węgrzyński: Uh, that's what I love about fire science. There is no, unrelated, you know, topics to discuss. what has been, uh, 40 something minutes of discussion on structural fire engineering. Now with this one tiny twist, someone who's doing [00:52:00] wildfire research can say, oh, okay, that's, uh, that's directly applicable to them and it's directly applicable to my wind engineering studies.

[00:52:06] Wojciech Węgrzyński: So, , thank you very much. That has been a very useful, I, I really enjoyed this. I, I, I love the structure. I love the, how it is a framework. It's not, uh, nice thought. It's not. philosophical discussion. It is a tool. Uh, I didn't know it is a tool before this discussion. So I'm very happy you've helped me discover it is a tool.

[00:52:27] Wojciech Węgrzyński: so I, I guess that's it. Uh, now for the, before We Pathways, uh, maybe. If someone would like to learn more about that, any resources you could recommend to, to learn more? I'm gonna link the, the fuel load paper in, in the, in the show notes and the review of, practice to the lift load modeling.

[00:52:47] Wojciech Węgrzyński: Maybe they're small.

[00:52:48] Negar Elhami Khorasani: yes. Uh, we do papers on as well on material models.

[00:52:52] Negar Elhami Khorasani: I can definitely, uh, send them to you. I do want to, uh, actually, because the very [00:53:00] first paper on the topic. Which again adopts the idea from, um, earthquake Engineering is actually by, uh, professor David Lange and Professor Asif Usmani and, Dr.

[00:53:15] Negar Elhami Khorasani: Sean, Deney, and the, if I'm not mistaken, the, the title of the paper was an application of the Peer Performance Based Engineering Framework, two Structures in Fire that goes back in 2014. So, it, it basically lays out, you know, these steps, right? The way that I, I describe 'em as boxes, but they have like a figure and they say, okay, you go from here to here, and so on. So I, I'll definitely send you that paper as well because that, uh, within, I think our community does set the tone, for this procedure. And, um, I'll take a look at my publications. If there's anything relevant, I'll send it.

[00:53:53] Wojciech Węgrzyński: Fantastic. And I also had an, actually, as you mentioned, David, I had an episode with David, David and, and, [00:54:00] EZ, who was, uh, doing maximal damage, method. Uh, so I guess they, they covered the fourth box with the losses. Uh, yeah. Fantastic. So all, all of it ties together. Super thankful for, for this interview.

[00:54:13] Wojciech Węgrzyński: I hope people found it interesting. It's advanced structural fire engineering. I know in many places we're not there yet, even with, uh, with just structural fire engineering. I think that's, that's a very promising future and it's, it's fantastic to learn what you can achieve and what you can do with, uh, with these advanced methods.

[00:54:32] Wojciech Węgrzyński: So, Someone chooses to, to go for them. They have a better understanding of what they get, what the benefits are, and uh, what it can bring to a project. So Nagar, thank you very much for this. It was a fantastic, uh, talking

[00:54:44] Negar Elhami Khorasani: Thank you.

[00:54:45] Negar Elhami Khorasani: so much for having me. Uh, it was, great, being here on this podcast. And just a final note.

[00:54:51] Negar Elhami Khorasani: I'm teaching course on Structures and

[00:54:54] Negar Elhami Khorasani: Fire here. Um, at. Buffalo. And, uh, as part of the course, you know, the [00:55:00] students have a project.

[00:55:01] Negar Elhami Khorasani: They have to do case studies and read about it and come back and, you know, and, I'll be assigning, uh, not my own podcast, other podcast, the, the other ones I'm going to assign them to, uh, listen to your podcast and come back and provide summaries and things they've learned from the podcast.

[00:55:18] Negar Elhami Khorasani: So, thank you for doing this. You, you are contributing to even, you know, our, uh, my students here at ub.

[00:55:24] Wojciech Węgrzyński: Fantastic. I hope they enjoy it and, and get something out of it. If they don't let me know, that means I have to get a new episode coming.

[00:55:33] Negar Elhami Khorasani: Noah, thank you so

[00:55:34] Wojciech Węgrzyński: Thanks. Cheers.

[00:55:35] Wojciech Węgrzyński: And is it as promised a little bit complicated. Maybe a little bit difficult. Definitely a step up from just structural fire engineering, but very natural concept in the end. If you think about the nature of fires. And the nature of safety to view this true probabilities scenarios. Uh, damage and in the end of the possible loss, that can [00:56:00] be the result of the damage.

[00:56:02] Wojciech Węgrzyński: So I believe this a probabilistic framework Negar can be applied to many places in far engineering. Like in the end of the podcast episode, we discussed how she's applying that to wildfire communities and wildfire preparedness. I believe that's brilliant. I already see how I can apply this.

[00:56:20] Wojciech Węgrzyński: To my wind and fire coupled modeling. So. I really enjoyed listening about this too. I must say I've never heard about this approach or this structure of an approach to probabilistic, fire engineering. And I'm very happy. I did learn it. And I hope some of you have learned something new along me today.

[00:56:44] Wojciech Węgrzyński: Thank you very much for listening to the today's episode. As I've mentioned in the intro to this episode, they see lots of new people in the podcast. AC a lot of of listeners around. So, uh, let me take this opportunity to ask you for leaving me some five star [00:57:00] reviews on Apple Podcast, Spotify, or you can leave a review directly on my webpage. These reviews are tremendously helpful to the growth of the podcast because they heavily influenced the search algorithms.

[00:57:13] Wojciech Węgrzyński: In the internet and as, you know, search rules, everything. So. By leaving me a review. You're highly improving somebody's chance to stumble upon this, uh, this show that may be useful to them. I hope that. And, uh, also. As I've noticed through my serve you well of mouth is number one tool to grow the podcast. So if you can pass the knowledge about this podcast to your friends and colleagues, I will certainly appreciate that.

[00:57:43] Wojciech Węgrzyński: Because that helps me affect more engineers worldwide. And that's some sort of my goal. So thank you very much for sharing the podcast. If you find it useful, please do so. And that's it for today's episode. Thank you for the great month of [00:58:00] January. I'm still looking for questions for Q and a of January. I don't have too many. So if you wish to ask me questions, please do so.

[00:58:09] Wojciech Węgrzyński: Uh, you can do that through the SpeakPipe on the website, or you can send me an email and I'll try to answer that or find someone who can answer that on my behalf. The Q and a episode will be published more or less after 8th of February. That's not a coincidence. 8th of February is the deadline for IFSS paper submission. So if you're a fire scientist, I guess you have a very similar deadline as I do.

[00:58:36] Wojciech Węgrzyński: In this regard anyways. Thank you very much for being here. See you here next Wednesday. Cheers.