242 - Learning from Earthquake Engineering with Negar Elhami-Khorasani and Justin Moresco

Being a part of broader civil engineering and built environment sciences, we have the unique opportunity to learn from other "sister" disciplines, rather than coming up with everything on our own. Especially, when those disciplines have 100+ years of experience in investigating stuff that has recently emerged as one of the leading challenges in our field.

The other discipline is Earthquake Engineering.

The interesting stuff - community resilience and managing safety across tens of thousands of buildings exposed to the same hazard.

Our field of application - Fire Safety of WUI communitites.

And most importantly, my diligent guests: Negar Elhami-Khorasani from University at Buffalo, and Justin Moresco from Applied Technology Council.

In this episode we discuss how earthquake engineering deals with hazards through four steps: 

1. Hazard assessment, 
2. System response (exposure)
3. Damage assessment (vulnerability)
4. Level of loss (consequences)

You will learn what are fragility functions and how they are applied. We will also discuss building archetypes and how we can use them to increase or decrease the level of detail in our analysis.

If you want more:

• Conceptualizing a probabilistic risk and loss assessment framework for wildfires
• Toward Probabilistic Risk Assessment of Wildland–Urban Interface Communities for Wildfires

Recommended follow-up podcast episodes:

• 156 - Trigger Boundaries with Harry Mitchell and Nick Kalogeropoulos
• 215 - Lessons from the 2018 Camp Fire with Eric D. Link
• 222 - Integrating WUI risk management and fire safety engineering with Pascale Vacca

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

Transcript

Justin Moresco 0:00

Hello everybody. Welcome to the Fire Science Show. I always find it an amazing opportunity when we can learn something useful from experiences of other fields of engineering. It's not that we have to discover or come up with, uh, everything on our own, actually given the limited resources we have, that would be actually quite stupid if we tried to do that. And uh, there have been others who have been dealing with natural disasters and other things that threaten people in somewhat similar ways as fires in the past. We can take their knowledge, we can apply their knowledge to our problems. We can build on it and we can grow. And one of such fields is earthquake engineering. We have not talked about earthquake engineering, yet in the podcast, uh, fires are a big part of earthquake engineering because, uh, post earthquake fires are quite a thing and they're quite scary. Uh, regardless. Earthquake engineering deals with how structures respond to earthquakes and what happens to the whole cities and communities after earthquakes. And you can, you already see a ling in here because today we are talking about communities and societies and their resilience all the time In the fire, safety, engineering, and specifically in the wildfire, we engineering and I have found two guests that can confidently talk about transferring knowledge from the world of earthquake engineering into world of fire safety engineering, and those guests are. Professor Negar Elhami-Khorasani from university at Buffalo Negar is a structural engineer and she's been in the podcast a few episodes ago. She just won the Magnussen in the world at IFSS. And the second guest is Justin Moresco from Applied Technology Council, who's also uh, an earthquake engineer and who. who works a lot in transferring this knowledge from the space of earthquake engineering into the space of fire safety engineering. So in this particular episode, we will discuss about how. Earthquake engineering works with the disaster. What are the approaches that these guys are using? Uh, which of them are transferable to define safety engineering? What are the similarities? What are the differences? And basically what are the best things we can learn from earthquake engineers? And trust me, there is a lot of them. And they're not only applicable to wildfires, they're also applicable to normal building fires because some of this is, is. Pretty universal. They have a different views on stuff that we do. They definitely use a lot of probabilistic methods and risk in their assessments. I like it very much. So, yeah. Let's spin the intro and jump into the episode.

Wojciech 2:58

The Fire Science Show podcast is brought to you in partnership with OFR Consultants. OFR is the UK's leading independent multi-award winning fire engineering consultancy with a reputation for delivering innovative safety driven solutions. we've been on this journey together for three years so far, and here it begins the fourth year of collaboration between the Fire Science Show and the OFR. So far, we've brought you more than 150 episodes, Which translate into nearly 150 hours of educational content available, free, accessible, all over the planet without any paywalls advertisement or hidden agendas. This makes me very proud and I am super thankful to OFR for this long lasting partnership. I'm extremely happy that we've just started the year four, and I hope there will be many years after that to come So big thanks, OFR for your support to the Fire Science show and the support to the fire safety community at large that we can deliver together. And for you, the listener, if you would like to learn more or perhaps even become a part of OR, they always have opportunities awaiting. Check their website@orconsultants.com And now let's head back to the episode. Hello everybody. joined once again by Negar Army, from University at Buffalo. Hey Nagar, welcome back.

Negar Elhami-Khorasani 4:21

Hello. It's great to be back and I'm really happy to be here this time, uh, with a wonderful colleague.

Wojciech 4:27

yeah, we've promised a quick return and, and we have delivered. And, uh, the interesting colleague is Justin MoCo from Applied Technology Council. Hey Justin, welcome to the Fire, sun Show.

Justin Moresco 4:37

It is great to be here, so great to be on this panel with Nagar.

Wojciech 4:41

Fantastic. And, uh, Nagar, you're already well known to the Fire Science Show audience. If you don't know Negar, there's an episode about structural fire engineering that you have to catch up just in, you're here for the first time. Maybe, uh, can you introduce yourself, what you're doing and what's Supply Technology Council doing

Justin Moresco 4:57

Yeah. So I'm, I'm a structural engineer and an earthquake engineer. I'm, I'm with the Applied Technology Council. We're a nonprofit based in the San Francisco Bay area, and we develop tools, technologies, and resources to help communities be more resilient to natural hazards.

Wojciech 5:12

Okay, and those natural hazards, I assume now evolve also wildfires.

Justin Moresco 5:17

They do? Yes.

Wojciech 5:18

Unfortunately. Yeah. we, we joined together, uh, Negar proposed to do this episode. and she got my attention by mentioning that you guys are trying to implement a lot of earthquake, uh, or earthquake engineering knowledge into improving resiliency of wildfire communities. And I found it very interesting, especially value those links between disciplines and, you know, learning from, from each other's. Maybe let's start with, uh, do you think, or why do you believe that, uh, engineering brings valuable lessons to, to wildfire, uh, resiliency?

Negar Elhami-Khorasani 5:54

So, um, earthquake engineering, um, research has been going on for many, many years, similar to wildfires, but earthquakes focusing inside the built environment and looking at, structures as well as communities, response and recover. And, um, it started with life safety, basically saving lives, building the way that we can, resist the, earthquake. And then it has expanded in years and now days in the US to focus on, it's what's called functional recovery. Basically the idea is that after, uh. an earthquake, not, not for every, uh, extreme earthquake, but given an earthquake intensity, want to have a functional, community after the event, to a reasonable extent. So

Wojciech 6:38

Hmm.

Negar Elhami-Khorasani 6:39

even the, uh, way they've been thinking about it and given the tools that they have developed, we think that we don't have to reinvent the wool for other hazards. So, you know, other hazards such as floods, for example, have been following and now wildfire. So we can't, we don't need to start from scratch.

Wojciech 6:56

Hmm.

Negar Elhami-Khorasani 6:56

Wildfire is specific to itself, the, in terms of the dynamics of the fire and the details of, um, how it's present inside communities. But, uh, we can learn how, uh, the tools and decision making happen in the earthquake and bring some of that into wildfire. And I'll let Justin, add to that. Um.

Justin Moresco 7:15

Yeah, no, I think what you said is spot on Nagar, that we've been fortunate, in the earthquake world in that we've had really, really well funded programs in the United States stretching back more than 50 years, where researchers and practitioners have been coming together to try to develop solutions to the problems of the hazard. And, and so then when we look over on, wooey Fires, uh, we see that a lot of these decision making tools don't seem to be there. And so we can then bring some of the learnings, um. Try to avoid the mistakes that were made over on the earthquake side and try to help move, um, Huey Fire, um, forward more quickly.

Wojciech 7:59

so, so, okay. What's the similarities? What's the differences? I, I, I would assume that similarity is in, in the outcomes, in the damage, the differences that come immediately. My hand is kind of, not sure if you can predict earthquake, um, not an earthquake scientist, but my feeling is it's difficult, uh, whereas, uh, with wildfire, you perhaps have a warning shortly after a few hours a day, two days before. How, how do you feel about differences and, and, and, and similarities between the, the two fields

Justin Moresco 8:29

in, in terms, well, I mean in terms of similarities, there's fundamentally, you have some sort of, you have a hazard, right? You have some, an intensity that can do damage, to the, the built environment. and so how you go about considering the interaction between that hazard and the built environment and then develop, estimates for what the outcomes of that damage may be. oftentimes it's, you know, expressed in terms of damage and fatalities and downtime, um, so that, you know, at, at the highest conceptual level, regardless of the hazard. I think that applies and we now have, like I said. Decades of experience demonstrating that we can do that and it can lead to informed decisions, right? So that communities can be more prepared and can hopefully reduce the expected losses, from, from future events. um, I think the, you know, at the highest level, that's where the, the similarities are. the, some of the, the differences are with wildfires. you do have a firefighting capacity,

Wojciech 9:38

Hmm.

Justin Moresco 9:39

that is, that is unique, um, at least to relative to the earthquake world. Um, you also have this, interaction between hazard and vulnerability. That is different, than the earthquake world. You, you could argue that you do have a similar pattern with other hazards like flood, for example, where you have debris that can be picked up and become part of the hazard. But on the wildfire side, you know, buildings that are highly vulnerable and therefore can become a source of the fire, um, create this sort of feedback loop that you don't get, over on the earthquake world. And then I think the other major difference that comes to mind for me is that you really have to be thinking at both the individual building level and the community level because. There is this, um, sort of herd. I, I like to use the term herd immunity concept, at least in my, in my, the way I conceptualize it. Where if you have a lot of buildings, if you take a typical, you know, say suburban neighborhood where you have a fairly dense, um, development, if some of those buildings catch fire and they're close to other assets, even if those other assets do have fairly fire resistant features, they're gonna be at a much higher probability of igniting themselves. And over in the earthquake world, you don't really have that phenomenon. You can, you can kind of largely sort of ignore the surrounding buildings. You can look at it more building by building, and, and still generate, you know, fairly accurate, expectations of loss.

Wojciech 11:15

This is very interesting concept. And in terms of the, the background experience, do you consider this like a, a global perspective or is it more like a West coast US perspective from what, what you've been doing so far with the earthquake engineering

Justin Moresco 11:30

Uh, from the earthquake side? No, I, I think at this point it's, it's global. There's, yeah, there's, there's research groups in, in Europe, Italy, um, Pavia comes to mind. Uh, London, uh, Japan has a lot of, um, advanced earthquake engineering, New Zealand Advanced Earthquake Engineering. there's probably, uh, south America, Chile is quite sophisticated and I think at this point, probably most people have more or less adopted, um, a, a pretty common methodology to how you think about risk from, from earthquakes. Yeah.

Wojciech 12:03

concepts that we're discussing today in the world of earthquake engineering. Please, uh, forgive me my ignorance, but I, I literally don't know this space at all. Uh, are they like, well matured? Is it something being developed or, or like, how far ahead is earthquake engineering with those concepts, uh, ahead from us.

Justin Moresco 12:21

It, it, it's, it's very well developed. Yeah.

Wojciech 12:25

Okay.

Justin Moresco 12:25

Yeah. Very well developed. Yeah.

Negar Elhami-Khorasani 12:26

I will just add something perhaps quick. Uh, so I agree with what Justin mentioned, the similarities and, uh, differences. Uh, what else I can think of perhaps on the, The life safety part again for me. So earthquake, um, you, as you mentioned, you don't get much warning right. So, uh, you really need to design your structures to stand up, uh, once the earthquake happens. So life safety is pretty important. Consideration.

Wojciech 12:56

Hmm.

Negar Elhami-Khorasani 12:56

Um, it's the same thing for ui. Life safety is super important, but I think it's easier hopefully, to be achieved because of the warning that you have. If you think about the evacu evacuation routes, if you, they're, they're properly designed, or alternatives. I know that, um. We have not the, the, the, at least in the US the idea is to have the community evacuated, not staying back and fighting the fire. But some of the recent fires extremely, intense and I would say that led to fatalities. For example, the Lahaina fire, it happened so close to the community. It basically was at the border of the community

Wojciech 13:34

Hmm.

Negar Elhami-Khorasani 13:35

the warning was not, you know, It wasn't a lot of time, and then there was a gridlock and people couldn't get out. So, um, it actually led to fatalities. So in those cases, maybe the option of having a shelter, inside the community, some, you know, other options to be considered, uh, so that people can, uh, not necess, they don't necessarily need to evacuate outside the community, but if there's a nearby shelter that they can get in for safety. But potentially, for me, I think the life safety problem in the should not be as hard as the earthquake side. However, the damage side, you know, after an earthquake, yes, you may have collapsed structures, hopefully not, but you, you still have buildings that might be standing and you just need to have to go back and repair. Whereas after Hui, technically what, where we stand right now, we look at communities where tens of thousands of houses are gone. There's nothing left. So the level of destruction is pretty, intense after these recent w events we've had in, especially in the us. So that site then is pretty much rebuilding from scratch again,

Wojciech 14:50

Hmm.

Negar Elhami-Khorasani 14:51

um, makes it, um, harder on the WWE side than the earthquake side.

Wojciech 14:55

Interesting about that aspect of, of, uh, wildfires, communities in a short notice and being able to escape. I had a really interesting, uh, interview with Eric Link and, and we've discussed, uh, NIST Escape Project, that, uh, I think that was campfire. It was campfire, yeah. So, so I would refer to, to that podcast episode. You'll find it in the shows. Of course, of course. You'll, uh, okay. Let's move, uh, so we know, uh, why should we learn from Meco engineering? And now you've convinced me that, uh, those people know some stuff that I'm potentially interested in hearing. So let's hear it out. What's, what's the paradigm of, building this resilience through the lens of, earthquake engineering? Where, where would we start in applying the knowledge from that space?

Negar Elhami-Khorasani 15:41

So, in earthquake engineering, the risk, um, probabilistic risk assessment methodology that's pretty well established, um, basically relates to this performance based design. So they have a very systematic way of, defining the problem. in. Specific pieces and then connecting those pieces together. And then the beauty of the, I would say, methodology is that, each piece, um, has its own uncertainty. So because it's extreme event, we don't, we can't, it's, it doesn't make sense to do deterministic analysis. So each, I would say, piece of the process will have its own uncertainties and we then can quantify them. I'll mention the four pieces, and then I'll let Justin to continue

Wojciech 16:27

I was, I was about to interrupt you and ask what the pieces are.

Negar Elhami-Khorasani 16:31

the pieces? Okay, I'm gonna mention the four pieces and then let, uh, Justin expand on it. So the first piece is the hazard. So it's, if we think of these as boxes, the first box is a hazard box. Then, um, there is what we call system response. Basically, let's say right now, let's think of it as a building. You're looking at earthquake response of the building. So hazard is the earthquake, and then you have the building response to that, uh, earthquake. Then what we call damage assessment. So now you had a response. What was the level of damage? And then finally from that damage was the level of loss.

Wojciech 17:05

and each of them would be considered from a probabilistic perspective.

Negar Elhami-Khorasani 17:09

Each, yeah, each box. So the hazard you have, you don't have one earthquake, you have a suit of ground motions. Um, the system responds. Basically you are looking at how your building is shaking and then quantifying that. And then, the third one, damage. You typically, quantify the probability of exceeding a certain, um, damaged state. Um, you lump these things because, otherwise it's gonna be very hard to, Do this process for every, I mean, there are different level of, we can get into this. This is perhaps after we, there are different level of details of, uh, quantification that you can do if you do a inventory of buildings at the community level versus if you look at one, a single building, that's, there's a different level of detail. You can look into this and then, but there is a probability of exceeding a damage state. So that's again, a probabilistic uh, approach. And finally, from there you get the probability of loss, which is risk.

Wojciech 18:06

I, I really love we're talking about frameworks and, you know, worked out stuff that that's potentially applicable, but yeah, please just expand on those.

Justin Moresco 18:16

so gi given and, and there are different terms that are used in different, you know, sort of applications or we might call them industries. Uh, I mean the terms that I, I sort of came up with using our, our hazard exposure, vulnerability and then consequences. and one of the powers that this enables is that, like Nagar was saying, that there's, there's different, um, sort of levels and complexity. You can apply, right? And you can, depending on the need and also sort of the, the sort of capacity that somebody has in terms of time and budget, you can make things ratchet up the complexity or the simplicity. but you know, just to give one, one really powerful tool is to go back and, and look at what would happen if a well-known historical event were to occur again. you know, at least in California where I'm from, one of the most famous earthquakes was in 1906 that devastated San Francisco. And so there's been a lot of work that's done to say, okay, given the current inventory that we have information about the buildings and the people in the region, if that same earthquake were to occur today, what would the expected losses be? and that because there's so much sort of public awareness of that event, when you then do that sort of study, it automatically becomes, um, of high interest to the media and the public and, um, and that, you know, bring some awareness to the current risk. And it can help emergency managers and their planning. It can help policy makers justify investing more in earthquake safety and, and resilience. Um, so that, that's like one single scenario event. Um, but then you can make that ratchet up the complexity and you can say, well, we're not just gonna consider rerunning, one historical event. We're gonna consider all potential future events that we, that we think are likely, uh, and the most sophisticated models out there would then have tens of thousands of potential. Individual events. And these, these models would have that same information about the, the existing inventory that's out there, but then they run each one of those, um, they carry through the uncertainties in terms of the level of shaking caused by each one of those events, the amount of damage that would occur, and then the losses that result. Um, you do that for tens of thousands of events and, and then you can generate, um, statistics, probabilities on, okay, well what do we think the what, what are the what, what are the average annualized losses, from all those events Or, um, what, what is the probability of, of exceeding a certain level of damage in the future? communicating that kind of information becomes more complicated because it's probabilistic. Um, so the places where that kind of information gets used is, within the insurance industry, right? So they would, um, insurance companies would want to be able to demonstrate that, they have enough claims, paying capacity, considering all possible future events. it also enables true or benefit cost analysis, right? Because to do a real sort of, you know, rigorous benefit cost analysis, you don't wanna just consider one possible event. You want to consider all possible future events. and so you can imagine, you could say, okay, well, Here's this new building code or these new important changes that we'd like to make to the way, um, cities are developed or buildings are constructed, say, with with enhanced resistive capacities to, in this case earthquakes, but it could also be to, to other hazards. Um, if we were to make those changes, what would the benefits be? And, and the way you would look at those benefits is you would say, okay, well let's, let's imagine that all these events occur under the status quo and now and get our. Expected annualized losses. and now let's, let's imagine that that a certain percentage of the buildings or all of the buildings and all of the communities are built to this higher standard. And then we, and now we, now we run the models again and, the losses should come down. And so you can compare the losses under the current status quo versus the expected losses under the, that enhanced sort of building practices. and there should be a, a big delta, we hope. Um, and then you can, and you can use that over, you know, you, you've gotta take into consideration the, the time value of money. but you can then arrive at a present day, cost benefit analysis, and, and.

Wojciech 23:09

Yeah, I, I see the direct applicability of that approach. However, I also see like an imminent problem with it because, uh, the scenario definition, I believe for earthquake it would be just the earthquake, while the severity of the fire will largely depend on level. So you have an nasty feedback loop within there, right?

Justin Moresco 23:28

Exactly.

Negar Elhami-Khorasani 23:29

Right, right. So, so I'll, let me, um, dive in a little bit on the earthquake side and then bring it back to your question and the community side. So when we do this type of analysis, again, the level of, um, complexity, um, may vary. You may look at one structure or you may look at a whole inventory of structures.

Wojciech 23:48

Hmm.

Negar Elhami-Khorasani 23:48

you're looking at one structure. there's this concept of fragility function in earthquake engineering that quantifies damage. And that is a function of, um, XA is basically your hazard. Like your, either depends again, but it, it's a, it's a function of your hazard intensity or the impact of the hazard on your structure. So in earthquake, for example, drift, how much your structure is deforming, right? That's a function of your earthquake intensity. And then the Y axis is the probability of exceeding a damage state. And that again is lumped as is a slight damage, moderate damage, extreme damage or collapse. And when we say slight or moderate, then these. Have their own specific definitions. So slight damage is just, you know, crack some cracks, minor cracks, something that, doesn't really compromise safety all the way again to collapse, right? So, you look at these and you say, okay, this can be derived for individual structures as a function of your structural system. A steel moment frame will have a different and a high, and also number of stories. So a high-rise steel moment frame will have different set of fragility functions compared to a low rise, concrete structure with shoe roll

Wojciech 25:04

Hmm.

Negar Elhami-Khorasani 25:04

up something. Okay? So this is how we categorize an earthquake engineering, try to, Basically quantify again, the uncertainties, but then scale it up where you can look at the inventory of structures.

Wojciech 25:17

Mm-hmm.

Negar Elhami-Khorasani 25:18

Now, if I wanna tie back to your, uh, question on the, the one approach, again, it's, it's, it's conceptual. We haven't done it yet, but, it is not sufficient to look at these fragilities or develop these fragilities basically at the structural level, even if it's just a residential. You know, we categorize as this house has certain number of features with this level of vulnerability. So this is going to be the, the probability of exceeding certain damage state. But I think we may need to look again broader and think about, Community archetypes or neighborhood uh, representation of the conditions because of the dependence of your hazard intensity on the vulnerability because the houses become the fuel themselves. They start burning, they create the intensity for houses downstream, and therefore there's that feedback loop loop again. So if you have more vulnerable neighborhood, it means that there may potentially all catch on fire the amount of heat, energy and potentially fire spotting that other houses will receive, it's gonna go higher. So it won't be enough just to perhaps look at, and we can derive, we can develop these fragilities and it could potentially be maybe binary. I don't know how much in between damage we get for these timber. Yeah, pretty much, right? So either Yeah. But, um, at the neighborhood level, then we have to, um, and, and you don't have to come up with a fragility function. You can always come up with a fragility surface, for example. So you have multiple X axis in terms of ca, um, characterization of the community, like structure, separation distances. You know, you need to combine some of these, parameters that influence the hazard and the outcome.

Wojciech 27:15

who's the user of that is so, so this tool in that sense is not perhaps guided towards a single house investor. Like, I'm building my house. I would like to understand how to build my house best, because then you just apply, you know, the best guidance that that exists. Uh, there are guidelines how to, um, your structure. I think that's the correct word, hardening, uh, structures. Yeah. But, uh, this is more guided towards community and, and, and like urban management. Right.

Negar Elhami-Khorasani 27:47

Yes. So emergency management, the fire department, the, these commun communities, typically in the US they have their, wildfire protection plans, community, wildfire protection plans. And, um, the PE people around the table again include, um, the Fire Chief, the Office of Emergency Management, um, and they are trying to understand the risk to their community basically prepare for it, prepare if the risk is too high, they, they think they have to do something right.

Wojciech 28:20

I'm asking this because, uh, you know, I, I assume that in earthquake engineering, this process is a part of designing a building and figuring out how I should do the PPD for this particular building, it's also done at community level.

Negar Elhami-Khorasani 28:33

is also that community. Just,

Justin Moresco 28:34

so on on, on the earthquake side, so for, the, the classic way is you're develop, you're designing right? An an individual building and, there are, within structural engineering, considering earthquakes, um, there, there, what's most commonly is to follow prescriptive methods. So it, it's important to emphasize that it's not that every building is being designed with performance-based design, but it, it's still a small percentage. However, what's been done over the years as those prescriptive designs have been tested, um, using this sort of risk framework that we were described to build confidence that those buildings following the prescriptive methods, achieve a certain reliability. That, that is, that they have a very small, probability of collapse, in a very extreme event. and so what, what comes to mind for me is that we now are seeing, and for, and I apologize, I'm most familiar with what's happening on the west coast of the us and, and I know your audience is much broader than that, but, um, but at least, in the west coast of the United States, there's now this growing interest in more hardened structures. And there, there is a, ICE International Code Committee, code, right, that can, that is being increasingly adopted. But I don't think any nagar you can say, but I, I don't think anyone can, could tell us, well, what is the expected performance of a community that designs its, its buildings, its communities to these prescriptive rules. And so one thing you could do then, if you have a. kind of tool, the beginnings of tools that Nagar was just talking about is we could start to test analytically, well, what kind of performance do, do we actually expect to get?

Wojciech 30:24

what would happen

Justin Moresco 30:24

Uh,

Wojciech 30:24

had more

Justin Moresco 30:25

yeah.

Wojciech 30:26

buildings in our community? Not

Justin Moresco 30:27

right. And then, yeah, and then that comes back to, you can say, okay, well, what's the performance that we'd expect under the status quo?

Wojciech 30:34

Hmm.

Justin Moresco 30:35

Um, under d And you'd have to be, you'd have to consider many different, um, ey fire scenarios. Right. Um, you can't just pick one individual scenario, but, but then you could also start to look at, well, yeah, if we start changing the way that we're designing our buildings and, designing our communities, how do the outcomes improve? And, and then you could also start to incorporate costs. I mean, I know all this is. There's a lot of hand waving that I'm doing right now. It it, it's not simple but you could imagine in the long run through some hard work, we could maybe get to the point where you actually could start doing that kind of analytical testing and then that could help to justify changes in the way that we develop our communities.

Wojciech 31:19

That's an interesting concept. Yeah.

Negar Elhami-Khorasani 31:21

Right. And I will just add, so, um, it, it's my experience for example, working in, uh, one community. they have limited resources. So for them, the questions that where do they want to spend their resources to have the maximum impact? typically, again, like a fire chief of a community, they have a good feeling based on their experience of where could potentially be their vulnerabilities. But once you start showing them the quantitative assessment and, potentially say, okay, we rerun the simulations, now we implement, and working with communities means that they actually, uh, bring to the table that these are our options. We can, for example, in terms of we doesn't have to be, uh, it, it, well structure hardening is, um, definitely something they want to consider, but, cutting vegetation inside the community, for example, that's something that might be easier for them to implement from the policy perspective. And it's, it's in their control. Uh, so they want to see the change in, let's say, The level of damage that they eventually get if they implement something like that, cutting vegetation in a specific neighborhood because they don't really have the resources to do it all across, for example, the community. So then you look at historically where could be the ignitions, right? So the hazard, the variability in the hazard. Whereas potentially the higher risk of having higher likelihood of having a fire an an ignition that will go outta hand. And during a season with a wind condition that will impact your community. and those are the things that I think, again, drawing parallels that will fall under the hazard box, where we start looking at ignitions and directional wind, blah, blah, blah, and then damage how much damage you're gonna have. And then the community stakeholders will decide that, okay, potentially we might, if we have X amount of dollars right now, this is where we're gonna go in and actually do something in this neighborhood.

Wojciech 33:34

do you also involve calculations of ability to evacuate people, for example, like, firefighting operations in that, or you're just looking at from the damage layer perspective? That's it.

Negar Elhami-Khorasani 33:46

um, ideally yes, we should include all of that again from the earthquake side. We look at things holistically with infrastructure, transportation, power, water, all of that on the we, so let me just expand a little bit on the earthquake side, the concept of fragility that I mentioned. We now have fragility functions for water pipelines for bridges. Right for transportation bridges. So, so you know your bridge type, you know, your bridge structural system, it's, it's a steel girders single span. So you have this fragility, you know, the potential earthquake scenario, and then you apply and say, okay, the, the likelihood of exceeding, you know, extreme damage for this specific bridge is such and such, which then means that, uh, because after an earthquake, again, the emergency response, they need to, it's chaotic. They need to, get to the community. If, if, uh, and I, for earthquakes, I've also had experience working with a community and they were worried about creating islands where they, if they have too many bridges and if those bridges get damaged, means that they could potentially have an island, like a neighborhood that may not be reachable. So these are the things that they look on the earthquake side, uh, on the side, I would say that, um, there's a lot of research, very excellent research going on, on the evacuation side. definitely, um, well, there's some research going on on the impact of fire on Water, but integrating them all together within a, I would say, community resilience assessment. We're not there yet

Wojciech 35:23

That's another.

Negar Elhami-Khorasani 35:23

have been doing research in pieces, but with the same community. Uh, we were looking at the level of damage and what resources you have. They actually had a separate study going on with a separate group, at their evacuation plan.

Wojciech 35:40

Good, good, good. It's, I, I mean, I'm, I'm scouting, where are we and what's to be done? I know that evacuation part is growing and we had, uh, example, in podcast, um, mentioned multiple times. We had a Ty episode as well, which has, again in the show notes. Um, let's, uh, change the focus a little bit. You mentioned earlier the archetypes of buildings. Perhaps this is something interesting to discuss, and again, something that's not very familiar to me from my fire safety engineering experience, but perhaps something very obvious for earthquake engineers. So what do you mean by archetypes of buildings and how this concept can be used?

Justin Moresco 36:17

The idea is that in order to try to do this sort of community scale risk assessments, that we're, it's not gonna be a realistic to define every single building, in great detail, right? And so we want to try to identify what are the features of these buildings that are most. Determinant of the building's response, um, and therefore damage, um, given ground shaking. And so over the years, there's been a lot of work done on this where the, the sort of key features that get distinguished are the, the structural system. is, is it steel and what are some of the, and then within steel there's, there's different types of, um, structural systems, braced frame or moment frame and, and, and others, is it reinforced concrete? Um, and then there's subcategories of that. Is it wood framed? And there's sub-categories of that. So that's the structural system. Then the height. Of the building is, is quite significant. and the, the vintage, um, and, and the, the reason the vintage is so important is because, um, that tells you what building standards it was designed and constructed under. And, and so, um, you can combine all that information with, you know, other studies that have been done, both experimental and um, um, numerical. to then, describe their potential for damage, um, their, their fragilities. and once you've built up enough of a catalog of these fragilities, um, you can, when you go into, um, analyzing a community or if it's an individual portfolio, um, going again, that, that could be say for an insurance company or if you just wanna look at schools within a community or hospitals within a community, having that catalog then allows you to more readily assign the fragilities, within that portfolio that you're looking at.

Wojciech 38:19

Are you defining them primarily through the lens of how they are built? Do you take into account where they are located? Like for example, in wildfires, the terrain would have a significant, uh, impact on your potential damage. So here it's not just what's the building, but where is it? What's around, like how, how

Justin Moresco 38:41

Yeah.

Wojciech 38:42

translate this concept to, to wildfire?

Justin Moresco 38:44

earthquake side, the, um, where, where it's built would be directly related to how it was built. um, and, and so that, that's gonna give you information about the, the codes that were in place. And, and then that, that in turn tell can help you understand, you know, how effective those codes are and therefore how effective the building is in, in resisting forces. the effect of the, the local site conditions. I'm not sure if that's what you were talking about, but at least within the earthquake world, and maybe there's an analogy here for, for Woo, we fire to pass it over to the guard. But in the earthquake world, if you have really soft soils, those then amplify the shaking,

Negar Elhami-Khorasani 39:28

Yes.

Justin Moresco 39:29

right? And so that, that local site condition affects the hazard, but it doesn't affect the capacity of that individual building to resist those forces. Uh, and so we're able to distinguish the two pretty cleanly. and so now I'll pass it over to Nagar.

Negar Elhami-Khorasani 39:46

that, what I was thinking that you, so on, on the earthquake side, because the soil type makes a difference on the hazard side in terms of what is actually the building is feeling.

Wojciech 39:58

Mm-hmm.

Negar Elhami-Khorasani 39:59

then, that, that part is definitely incorporated in the hazard box. Uh, for the, um, w I would say topography, uh, still probably fits best in the hazard part, although we have, again, that feedback loop. So the hardest part with the oui fires, that feedback between the vulnerable and hazard, the, the two boxes will have a cycle back and forth. uh, and it's not a clean one way direction. Um, I will also mention this, uh, that, uh, when, when we are talking about these archetypes So one, I would say 2, 2, 2 points. Point number one, we do see that age built, like the year built of a, um, structure actually makes a difference in

Wojciech 40:47

Right.

Negar Elhami-Khorasani 40:48

fires. There, there are studies, if you look at campfire, um, so I'll mention Laina for example. There was a neighborhood, neighborhood, built just couple years before the fire event. And only five out of hundreds of houses in that neighborhood burned down. Everything else survived primarily because of the, it wasn't, they were built to the code. Uh, the most recent code. And the idea was it wasn't necessarily following detailing for fire, but they had upgraded the code for wind. And there were details there such as, you know, the, um, eaves and, you know, things that benefited the fire side. So embers, for example, didn't, accumulate or didn't cause ignition. So the idea of, and this is something that I think we are borrowing when we look at year built, the idea is coming from, again, different hazards. When we, in the we, we look at California fires and we look at the inventory of buildings and we categorize the structures. We are doing something exactly in parallel what happened in earthquake engineering. And then say, okay, if it was built to the code from this state to this state, from this state to this state, are we seeing improved performance of the building inventories? And at well, that that will depend based on what I've seen on the level of intensity of the fire. In cases that the fires are really extreme and we have had a few, um, we are not building bunkers, we're still building houses. So at some point these houses will break regardless of how well you design them. but for more moderate fires, you actually see a difference. You see structures that are built more recently to better code actually survive, which then themselves reduce the hazard. Again, that feedback loop.

Wojciech 42:48

Mm-hmm. wonder how much of that is also evolution in materials and just, uh, general trends perhaps, you know, and a new material for exterior of your building is more trendy in, in the recent years. And it, by the way, it is also better for fire. I wonder if we're capable of, of capturing those trends along the codes changes because code changes. I mean, it sounds easy. Just follow when the code has changed. But it's probably a madness to follow that on a great scale. But I, I, I wonder how much materials also change and how big differences there are.

Negar Elhami-Khorasani 43:23

of it, I think it's definitely, I mean, as years past, we definitely have improved materials. Some of it on the, especially the West coast, US, California, I can mention this, is that, they have their own, chapter related to, um, Hui so when we look at, The building inventory. We look at the year that this chapter went into effect, and that is specific to detailing, not just material, but also the way you build. And, um, yes, roofing, siding, all of those features, uh, specifically focusing on fire hazard and some of that, I think, um, well, all of it is helping, uh, in terms of lowering the risk because, a parcel that follows that chapter, um, has to fulfill certain criteria.

Wojciech 44:12

also, I also wonder how much you can expand it into the future, because we have massive changes. One in terms of, of just the climate and, you know, the, the hazards, but also you have extreme changes in the building culture, you know, photovoltaics, energy storage, electric cars. You didn't have that five, 10 years ago. So that, that's, that's really tricky, right.

Negar Elhami-Khorasani 44:34

that's really tricky and I look at it, uh, I would maybe make two comments, comment number one. Um. As part of this uncertainty, I'm not an expert on climate models, but I work with atmospheric scientists. There are a lot of uncertainties in those models. I get it. But it's probably better than, not doing anything. So we can incorporate some of those future predictions. Uh, well, yeah. Future predictions in terms of potential change in. temperature, humidity, uh, wind, all of that for projections. so rather than only using historical data, I think that may not be the proper approach for this risk assessment for future. So if you just look at historical approach, you may actually find a community is not even vulnerable to a fire. Whereas given the fact that, better systems are changing, climate is changing, that community's now in a, fire danger zone. So, uh, bringing some of those models for future protect projections, that might be helpful. then the other thing I'll mention, I know we have been thinking about, uh, oui fires and now you mentioned how we are building and, cars, everything. we are looking at an external fire, like let's say you actually have, uh, so coming out of the, house, like basically timber frame type structures, even our steel and concrete structures, let's say your critical facilities, that's another thing in earthquake engineering, when they do inventories and they look at response. One thing is your residential inventory. The other thing is the critical infrastructure and structures inside your community. Those could be hospitals, your schools. so on the fire side, you, you have, if you go back to campfire, we see, um, schools and hospitals burned down. These are not timber frame structures. But the fire came from outside. It's not a typical also, structure fire problem where the fire starts inside, it's a compartment fire, and then it grows. It's coming from outside. So I think that's another place where we need to look at. and tie back this maybe performance based design or the, the type of archetypes we're looking at. Um, you've got these type of structures that could be, uh, exposed to external fires and those external fires, depending on the community, the EV cars, like what's happening around there, if the fire happens, what kind of exposure you are going to get for these, critical infrastructure that you have to save, because your community is relying on it.

Justin Moresco 47:24

And, and just building off of that. So o over in the earthquake world, um, we disti, as Nagar said, we distinguish between more common types of buildings and in these essential facilities. And, um, those essential facilities have to be built to a much higher, standard, a lower probability of failure. Um, and, and maybe there's already parallels, uh, for, forgive me, um, in, in fire signs if, if there is. Um, but you could imagine one, once we. Hopefully start getting a better understanding of expected future performance. we could start ratcheting up the requirements around these essential facilities for resisting wy fires. I think, I think that's where you're going to guard. I just wanted to put it in, in my, my own terms. Yeah.

Negar Elhami-Khorasani 48:14

We don't necessarily have any specific methodologies to design these essential facilities for. It is probably case by case right now,

Wojciech 48:23

What's the practicality of this clustering or those archetypes? It allows you to, to reduce the complexity of your analysis. Like you're basically now looking on broader behavior within the clusters rather than individual structures. So where does this lead?

Negar Elhami-Khorasani 48:39

uh, let's say you are eaten fire Altadena, um, damaged something along, along the lines of, um, 10,000, structures in Altadena area. So let's say we wanna look at, performance of that, that community to fire. Uh, right now we need to run explicitly the fire spread. And let's say we wanna do a probabilistic assessment. So it means that we, even if we just sell for thousands of simulations, not tens of thousands, just thousands of simulations, we are looking at a lot of computational cost, right? From the re I know this is more from the research perspective. I think Justin, you can tie it into the industry side of things. But from the research perspective, yes, we can do that. But, um, that's perhaps something that only researchers can do. Uh, we need something more streamlined, or not streamlined, but more efficient, uh, in terms of computational costs to be able to get the response without running individual, single simulations thousands of times. And those clusterings and archetypes, uh, and tying them into fragilities will very quickly give you. Um, but I then I say very quickly compared to the individual simulations, relative, um, the outcome.

Justin Moresco 50:02

Yeah, I would just, I think it, I mean, that's a great question because it, I think with these things, because this, these risk-based frameworks and the kind of numerical simulations we're talking about, because they can get so complex it, you want to keep in mind what, what is the intended use, right? And then that, that in turn influences the complexity. So, it, when you're doing these, like Nagar was saying, when you're doing these community scale types of analyses, you have to do these simplifications. And the, i, the hope is that you've built up enough experience, doing post-event reconnaissance, but also doing experimental tests and numerical tests to, to feel as though, okay, we've identified what those key parameters are to describe the expected response. And there's uncertainty around. You're placing on the response, recognizing that, yes, saying that this fragility is representing a three story wood frame building, and you're capturing the median with the distribution around that median, um, then, then that, that is giving you enough accuracy to be able to move forward on that community level analysis, right? it would be different if you're using this kind of analysis to do an individual building design, right? If you're doing an individual building design, then you want to bring in all the features that you can, uh, and make it, you know, capture everything that you think might have an impact and do the analysis, right? So, so it comes back to the, the use case.

Wojciech 51:32

Hmm. Fantastic. Uh, we're running out of time, but there's one more thing I want to go back, which you mentioned off the record, Negar, which is going beyond the structures to utilities, to water services, because I, I found it very interesting. Uh, how does earthquake engineering, uh, grow beyond the structure and what we can learn from that?

Negar Elhami-Khorasani 51:52

So on the earthquake side, they actually can, let's say, model A, um. Community, whole community, whole city and say, here's the building inventory, this is the transportation network, this is the power network, this is the water network, um, communication network. Yes. All those layers of, infrastructure. they actually can also, uh, capture the dependencies. these, um, infrastructure. So after an earthquake, if your water network rely on pumps and you don't have backup power at a pumping station and the power is damaged, maybe your water network is not damaged. But if you rely on the power and the power goes out, actually your water network gets impacted because the pressure goes down, um, because of the pump. So there are all these, they call it interdependencies because there's sometimes so dependencies just between two layers, but interdependencies, um, there could be, um, feedback from the same, uh, infrastructure layer back to, another one. So model all of these, um, they do similar, very similar They have the fragility functions, they apply the damage, and then at the end of the day, the idea is that as a structural engineer, we can. Build structures remain, standing and safe to be occupied after an earthquake. But if inside the community you don't have power and you don't have water and you don't have gas, people can't really go back inside their buildings and live there because you don't have the lifelines working. for the community to remain functional, you need all these layers to be functional.

Wojciech 53:42

sorry, which is actually very interesting in the context of what we just spoken about 10 minutes ago with the know changes in, in, in how the buildings look like, because if you have your own battery pack, you are perhaps less, uh, vulnerable to the power outage. If you have, uh, a Starling network connection, you are most likely gonna have communications. Right? So it go, it's, it's not the world, the world is not just worsening. There are positive things happening around.

Negar Elhami-Khorasani 54:11

Look at the positives. Exactly.

Wojciech 54:13

It took me, it took us 55 minutes to find a positive yes

Negar Elhami-Khorasani 54:17

like reducing dependencies

Wojciech 54:19

no, but this.

Negar Elhami-Khorasani 54:21

Yeah, exactly.

Wojciech 54:22

Well, you know, I, I love when you're speaking about those, those dependencies to me they are like absolutely obvious. And you know why? Because 30 years ago I played hours and hours in Sim City, 2000. And it, it is in that game, if you had an earthquake and it broke your electricity line, your pump went down and now your community's in sewage and you had to fix it all one by one. Like, I, I said it before when there are mayor elections for a city, like, show me your best sim city, you know, games you achieved. And then based on that, I'll pick up who's gonna be the mayor of war or something. But no, actually those types of, of interactions, I, I think there are critical, because as you said, you may have a very well functioning, uh. House, sorry. You may have structurally sound building after a wildfire, but if you don't have electricity, water, sewage, or anything else, it's not a great help. Right?

Negar Elhami-Khorasani 55:20

Exactly. And I think in the we side, our water network is really not designed for attacking or suppressing a, an intense fire line.

Wojciech 55:32

Yeah.

Negar Elhami-Khorasani 55:32

designed for individual structural fires and a couple of structural fires across neighborhood. Neighborhood, but not a whole block on fire. We can't really suppress because it's not designed for those conditions. so once we, I think on the buoy side again, so on the earthquake they can model these. uh, the question I will mention this, that, that there's always a question that, um. Where's the data to validate this? Some of it there, there have been validated because, you know, earthquake side, they do collect very good data, after earthquakes and try to go back to the models and see how they're doing. Some of it perhaps is less, validated verify, but, but to the extent they, they've been able to validate these, community level models, they've done it. Now on the UI side, number one, I think we, we need to start, uh, integrating this different infrastructure within the whole holistic approach. Uh, we have been, again, doing research, um, because it was needed. You have to start from, you can't start at times zero integrating everything. That's not the right thing to do. But once we advance and each infrastructure modeling and answering some of the questions, then we can start integrating them. To look at the problem or the community response more holistically and then look at, okay, so if we do some structure hardening, but we also think about our backup water system, because if we don't do any structure hardening, probably with an extreme fire, our water system is, will not have the flow and pressure needed. But if we lower the rate of fire spread and potentially, improve our water system, then there might be a solution there, right? Um, transportation evacuation, making sure that emergency response, teams can get to the location of the fire. All of those things, once we start integrating them, um, then we can tweak, or mitigate, at different levels, which potentially as a whole, then we reduce the overall losses. Justin.

Justin Moresco 57:36

Well, I, it's, it's a slightly different thought, but just, it, it's maybe just to, that I, I, I want to, I don't wanna lose sight of that. We, we've been talking about some pretty sophisticated concepts. Right. And,

Wojciech 57:50

Yeah.

Justin Moresco 57:50

and, and, and again, you know, we, one of the, the main points of discussion today has been looking at what earthquakes have done, uh, the, the field of earthquake engineering. And I, I just want to emphasize that I don't think we have to go all the way to the fully probabilistic, most sophisticated models and understanding to get benefits. From thinking about that risk framework. I think that just when I'm attending conferences or reading papers, I do see confusion out there. It seems in not always, but often in the way people are talking about these different components of risk. And so I think even just as a first step for people to start, um, if they're not already familiar, educating themselves on how other hazards have defined risk in these components that we've been talking about, and then trying to be as precise as they can in their, um, in their discussions and then in their, when they're developing their programs, to use these terms as accurately as they can. And hopefully we as a community can start building consensus around the way these terms are used and that that will help us to, to move forward. I think.

Wojciech 59:05

I'm, I'm gonna take the, the, the, the out, out of what we've been discussing, but I have a down to earth question. Does earthquake engineering deal with post earthquake fires as well? Is it a part of earthquake engineering or, thank you.

Justin Moresco 59:21

We shoulda said that, said that from the.

Wojciech 59:23

What? But

Negar Elhami-Khorasani 59:24

I did wanna say at some point I thought about it, but I said, earthquakes are bu I'm not gonna bring in the fires following earthquake.

Wojciech 59:31

yeah.

Negar Elhami-Khorasani 59:31

Um, it's, um, it falls under earthquakes. I would, I mean, it's between fires and earthquakes, but for me, very briefly, I would say that the difference, uh, between fire following earthquake versus wwe, there we are again dealing with individual ignitions across the community versus for wwe we have a full fire line

Wojciech 59:53

Mm

Negar Elhami-Khorasani 59:54

So that's the primary difference. The other difference is that after an earthquake, you get fires, but you already have a system that is damaged. So

Wojciech 1:00:03

mm.

Negar Elhami-Khorasani 1:00:03

structures, your life, your fire safety measures, your sprinklers Inside this, the. The building. So these are typically internal fires. Your supreme clears are probably damaged. So the, the fire department may not reach to the location of ignition in time because they're already, dealing with the chaos. and on the Wooey side, uh, we have an intact water system, but again, your water system may not necessarily be designed to have to, um, suppress that, um, intense, uh, fire line. So there are differences, uh, between the two, although they both are considered as far as inside the built environment. That's how I would categorize them.

Wojciech 1:00:49

So on this optimistic accent, I think we can wrap it up. So, so thank you very much for, for coming, uh, to the world of fire engineers and talking about experiences of earthquake engineers. I'm really happy that we can, uh, learn, uh, from each other.

Justin Moresco 1:01:04

Thank you so much. And I said, thank you for listening. Now the next thing I need is worked out examples to see how this, uh, methodology works in practice. In the show notes, you can find some papers linked and you can find the previous episodes of the podcast I've mentioned, uh, which help us work out. Uh, this is not the only framework that we have been discussing. In the Fire Science show, we also had Pascal Vaca some episodes ago. She talked about her approach, uh, that she applied in Catalonia to some wildfire communities. It's very nice that those things are peeled up and we get more and more tools that are useful in planning, resilience of communities planning. Preparedness of communities for potential wildfires. I liked the aspect that Justin brought up about testing for previous disastrous fires. This is very interesting where you can apply just a, a fire as a boundary condition, something that happened in the past. Now. Difficulty will be obviously that what is built influences that fire. So if, if you have rebuilt in a different way that it was built, uh, previously, then the outcomes will be different. But still, you could get a lot by simplifying the, this growth or just having a range of possible fires and just see what happens. That's a very, very powerful, way of looking at the problem and something I feel is quite possible for five safety engineers. I always say that. There is a job coming wildfire engineer, where we will be hired to do these things for communities and hopefully paid quite generosity for our good work. And, uh, I think, uh, yeah, approaches like that are, are one of the ways that, that we can help support those, uh, communities at risk. Um. I think that would be it for today's podcast episode. There was a lot of new stuff. I hope you've enjoyed a lot. It was quite new for me. I had never known the details of how earthquake engineering works. And frankly speaking, I like it a lot. A lot of those other engineering, uh, disciplines have such nice methods and, and some of them are so much transferable to fire science. We need to do more of that. So, uh, for this, uh, important effort, I am highly thankful to Justin, highly thankful to Nagar. And, uh, for you listener. I'm thankful for being here with me today. I hope you've enjoyed your. Weekly dose of fire science, and if you will be looking for more. Another episode is coming your way next Wednesday. See you there. Thank you. Bye.