Good afternoon. Welcome to PCI's webinar summer series. Today's presentation is the PCI 124 specification for fire resistance of precast, pre-stressed concrete. My name is Royce Covington, Manager of Member Services at PCI, and I'll be your moderator for this session. Before I turn the controls over to the presenters, I have a few introductory items to note. If you need anything, please feel free to contact me by replying to your registration confirmation or send an email to marketing at pci.org as shown on your screen. Earlier today, we sent an email containing handouts for today's presentation. The handouts are a PDF of the PowerPoint that will be shown, detailed instructions to access your certificate, and a webinar attendant sign-in sheet, which is only for locations with more than one person viewing. Please have all attendees at your location fill in the sign-in sheet and send to PCI per the instructions on the form. 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Any questions about the content of this webinar should be directed to PCI. Questions related to specific products or publications will be addressed at the end of the presentation. Our presenters for today are Steve Scalco, founder and principal of Stephen V. Scalco PE and Associates LLC. Mr. Scalco is a registered professional engineer in Georgia in both the fields of civil engineering and fire protection engineering. Mr. Scalco has over 40 years of experience in the application of construction and fire safety codes for buildings. He is the former building official and fire marshal for Macon-Bibb County, Georgia, previously served as regional manager of codes for the Portland Cement Association, and is now an independent consulting engineer. Mr. Scalco has provided numerous technical presentations, including application of the fire safety requirements and the international codes and NFPA codes and standards to designers, code officials, and contractors. Joining him is Matt Husslick, chief engineer at Coarse Lab Structures, Miami. Mr. Husslick is a registered engineer in multiple states. He has designed and precast concrete structures for the more than 20 years across multiple uses. Mr. Husslick was the PCI fire committee chair during the development of the PCI-124 fire specification, and is the past chair and is currently an active member on the PCI fire committee. I'll now turn the controls over to begin our presentation. Thank you, Royce, and folks, I'm glad that you were able to join us this afternoon. We have several learning objectives that we'd like to accomplish as we present the information on PCI-124. I think one of the first things we wanted to do is to give you a little bit of an evolution history behind the PCI-124, where the background to it came from, how it evolved over time to result in the document that we're now going to be talking about today. We also want to take a look at the format of PCI-124. It is structured in a way to make it easy and usable for the user in order to approach a fire resistant design of buildings, and so we want to give you a sense of how the document is structured. And then as part of that, we want to be able to give some examples, both using the prescriptive method, which is one of the options within the specification, and the other is to show some examples using the rational design method, which in our mind as presenters, we feel like is one of the especially beneficial features for 124. And then finally, one of the things we want to cover is some special considerations at the very end of the presentation. Whenever you do fire resistant design and you have assemblies, you have some challenges that may come through with regard to poke-throughs or how you connect it to other precast or other structural building elements. So, we're going to talk about PCI-124 specification for fire resistance. It's important to realize that the precast industry really started evolving with regard to fire resistance in the 1960s. During that time, there was a lot of testing that was done by the Portland Cement Association, as well as other organizations, on the capability of precast to resist the effects of fire. And through these fire tests and other forms of evaluation and research, it was able to establish some procedures for calculating fire resistance of precast elements. From that effort in the 60s, PCI put together a document in 1977. That document was in essence, a technical design manual for precast fire resistance. And when it was published, it was made available for use by the people in the industry. But one of the things that was very important at that time was to also begin to get it introduced into the building code processes around the country. Because a lot of times, some locations, people perhaps are hesitant to use some kind of a new document without knowing that it has some approvals given by code officials. So, also at the same time, it published the 1977 manual. And let me acknowledge it really is the front runner to what is now PCI-124. Although the design document didn't have a number actually designated at that time. It was also submitted for consideration by the International Conference of Building Officials to be considered for inclusion in the Uniform Building Code, which is one of the legacy codes that's a front runner to the International Building Code. As part of that process, there was a technical information that had to be submitted to ICBO for them to issue an evaluation report. And the purpose of the evaluation report was for them to do a detailed evaluation of all the technical material being used to document the technical background and the technical justifications that were in the PCI design manual for 1977. And of course, in conjunction with those two items, the 1977 edition of the design manual was in fact accepted as an alternate method for determining fire resistance for precast concrete construction in the Uniform Building Code. As the legacy codes evolved to join together the three legacy organizations to form the International Code Council, MNL-124, it was at that time when it was put into the UBC, it was given a designation MNL-124. It was carried along and placed into the 2000 edition of the International Building Code, which is the very first edition of that code. And of course, from then on, it has continued to evolve in what we're going to be talking about this morning. Important thing to realize in the International Building Code, both the 2000 edition and even today, is the fact that the code has a section dealing with alternate methods of doing fire resistance design. And one of the methods is the calculation method. You see it bolded on the screen at section 720. Note that was 720 in the 2000 edition of the IBC. It is now section 722 in the most recent editions, later editions of the IBC. That calculation method was considered an acceptable method for determining fire resistance for a number of materials, not just precast, but include cast-in-place concrete, steel, and wood construction. In particular, where it got placed was in a table, or excuse me, there was a table specifically in the 2000 edition of the IBC, table 720.2.2.2 that covered fire resistance for precast. In the section that you see on the screen, 720.2.3.1, told what had to be done with regard to slab cover of the minimum positive reinforcement in order to accomplish a certain amount of fire resistance. MNL124 was listed in that section and therefore associated with that table as an alternate for precast, pre-stressed slabs. But it was only that precast, pre-stressed slabs that it was indicated that it could be used for. It didn't mention it anywhere else in section 720 of the IBC that it could be used for alternate things such as beams and columns. Now the IBC, both the early edition and even the editions today, has an alternate materials and methods, or alternate materials designs and methods section. And the whole purpose of that section is to allow persons to come to the building official and propose an alternate ways to what is outlined or specified within the body of the building code itself. And so MNL124 wasn't necessarily precluded from being used for other than slabs as indicated in section 720. But lo and behold, it could be used for beams and columns, but you were subject to having to present technical information to the building official and to hopefully find that they would say, yes, I'll accept that. They were under no obligation to accept it as those alternates, but at least it had the option or possibility that it could be used in that manner. As the International Building Code evolved, PCI also wanted to have it made sure it was included in an evaluation report. This is basically the ESR report. It's called Evaluation Services Report 1997. That report is basically the front runner to it was the ICBO report that was previously issued back in 1977, ICBO report 3264. It evolved into evaluation report ESR 1997. And of course, ESR 1997 specifically referenced the third edition of MNL124 for use for design of precast, pre-stressed concrete construction. As far as in the body of the code itself is concerned, it still only referenced MNL124 for slabs, but this evaluation report would be prima facie evidence that you could submit to the building official or the building official could go and look it up and find out, lo and behold, that they could accept MNL124 even for columns and beams in determining fire resistance because it carried the evaluation report as part of that part of it. The downside to that though is every time there's a new edition of the code, there's a requirement within the evaluation process to have to resubmit to the International Code Council to get the evaluation report revised. At the time it was first issued, it was referenced for the 2006 edition of the IBC. PCI had it followed through several other editions, but each time you submit it, there's a certain amount of cost associated with it. And obviously that built-in cost, you know, creates an ongoing expense that when you didn't have any change to the requirements, it kind of makes you wonder why are we keep spending this money when we in fact didn't change anything with regard to MNL124. And so one of the things that PCI did was to go ahead and decide maybe we should start developing our own standards. And so PCI became a standards development organization in 2014. I want to say that MNL124 was one of the reasons for that, but there are a number of other documents, technical documents, that PCI produces that have also already been since then or are in the works now to become standards, acceptable standards developed according to the American National Standards Institute's procedures, which we call these an ANSI designated document. The reason that's important is because that allows it to then readily become referenced in the body of other standards and codes, including the IBC, without having to go through the process of having to get an evaluation report each year or each time you're doing any kind of change. So PCI set up a standards committee that that committee's responsibility is to in fact manage and monitor the processing of the standards to make sure they follow the ANSI requirements. PCI assigned MNL124 to the fire committee. That's the committee that Matt Hueslick was the chairman of at the time we went through the process to convert MNL124 from a manual for practice of fire resistance design into a design specification with only mandatory language. That is one of the requirements to be referenced in the IBC is that you have to have the portions that are to be enforced in mandatory language, which then gives the building official the ability to enforce it if there's a question whether something's required or not. Some of the language in MNL124 was more commentary in nature or may say some statement to the effect of that you may do this, but may do this doesn't mean you have to, whereas mandatory languages say you shall do this, which gives it the ability for the code official to enforce. And so we went through a process that the fire committee went through a process through developing the document into mandatory language, putting it out for public review, which was part of the requirements, seeking comments, resolving the comments, and then submitting it to the PCI standards committee for them to give its approval to lo and behold assert that we did follow the ANSI requirements. It got published in October of 2019 and has been designated as PCI 124. Now the important part of that was then we were able to take PCI 124 and actually submit it as a approved document in total, not just for slabs, but in total for precast concrete construction. In section 722.1 of the 2021 IBC, there are other standards for example, American Concrete Institute has standard 216.1 for concrete and masonry. The steel industry has ASCE standard 29. Primarily what's referenced is chapter 5 for steel construction, and then the wood industry has the American, the American Wood Council has the national design specification and chapter 16 covers determination of fire resistance for wood materials. Now with PCI 124 as a bona fide standard that's gone through the ANSI process, we were able to then submit it as a code change and have it directly referenced in the 2021 edition of the IBC. By being referenced in the code directly also eliminates the need to have to keep having a evaluation report. So let's talk about format real quickly. Basically chapter 1 covers scope, it covers precast and cast in place concrete. There's special definitions that apply only to this document that would be important standard technical notations and of course then any reference standards associated with the design parameters within the document. Chapter 2 covers material properties, it covers steel, concrete, it discusses restrained and under strain conditions that have an impact on the fire resistance of structural elements, and then it also identifies that there are two methods for approaching fire resistance in PCI 124. One is what's referred to as the prescriptive fire resistance design and the other is the rational method. Both methods you know will allow you to do fire resistance the prescriptive. Prescriptive usually means if you do it this way it will work, meaning that the testing that was done way back in the 60s helped document the parameters. The rational design allows you to provide a little bit more innovative design to the elements and you take into account some of the concrete and steel properties. In fact the graph you see on the slide is a graph out of chapter 2 simply talking about looking at the specifics of the characteristics of certain steels and their impact from temperature and their ability to carry load. Matt will touch on that a little bit later in his part of the presentation. Chapter 3 is just covers the prescriptive and rational design methods. Under the prescriptive method covers columns, beams, slabs, and walls, and then the rational method covers slabs and beams. We also have, though, in the document, Chapter 4. Chapter 4 is special considerations. Protection of openings is one thing. If you do a fire-resistant element, whether it be a wall or, let's say, a floor slab, if you poke a hole in it for some reason to pass, let's say, mechanical piping up through it, you put a hole in that fire-rated assembly. And when you do that, you have to do something to protect that assembly. When you connect assemblies, if you're using, let's say, steel brackets to mount a double T or a precast beam, you've got to do something to protect that steel in order to be consistent with the fire-resistance rating of structural elements. And we'll talk about that a little bit later. And then finally, we want to make the audience aware of our appendix chapter. Much of what was in MNL 124, that was the commentary-type language, was moved into an appendix, so we didn't lose it. It's still very valuable history and a body of knowledge. So the appendix contains the commentary, and it's been tied directly to each of the sections that are within Chapters 1 through 4, so that when you're looking at things within the document, if you want to see if there's perhaps a little more explanation, you can go to the appendix chapter and tie it directly to the section that you're wanting to have consideration to. And with that, let me turn it over to Matt, and Matt will begin to present to you the details of Chapters 2 and 3. Matt, you're muted if you're speaking. All right, I was halfway done. Good morning, or good afternoon, everybody. Okay, Section 2 covers the properties of concrete and steel at elevated temperatures. This section of PCI also has a discussion on the restrained and unrestrained conditions for floor and roof systems. Typically, the restrained systems will have a higher fire resistance using thinner elements and less concrete. Can you hear me now? Yes. Yes, we can. Okay, Section 2 covers the properties of concrete and steel at elevated temperatures. The section of the PCI-124 has a discussion on restrained and unrestrained elements, or floor and roof elements. The restrained elements typically can have a higher fire resistance using thinner elements and less concrete cover. All right, now let's begin with the specifics of Chapter 3, which starts with the prescriptive requirements determined for fire resistance of precast concrete elements. These requirements cover all the common structural elements, including columns, walls, beams, and slabs. We will begin looking at these elements individually in order as they go along in the code. Columns are the first precast concrete elements covered in the standard. For columns with a concrete strength less than 12,000 psi, Table 321 gives a minimum size for the columns in their least length dimension, or their least width dimension. Of equal importance is the concrete strength of the reinforced steel. Both parameters will affect the fire resistance. For columns that are designed with a concrete strength greater than 12,000, the Table 321 does not apply. These higher strength concrete columns are required to have a minimum 24-inch dimension in the smallest direction, and a minimum height of 12,000. In these cases, the type of aggregate doesn't matter. In fact, the size of column can accommodate a fire resistance of up to four hours, which is the maximum fire resistance that most building codes will prescribe. All columns are required to meet a minimum concrete cover on their main longitudinal reinforcement of one inch per hour of fire resistance. Of note, the maximum amount of cover required is two inches. As a practical matter, that means that a column with a desired fire resistance of one hour needs one inch of cover, and a column with a desired fire resistance of two or more hours needs two inches of cover. Like the column size, the spirals and tie reinforcement also have specific requirements for all high-strength concretes. Here we see the extra attention to detail for the termination ends. For solid precast walls, the parameters are similar to columns in that the fire resistance depends upon the type of aggregate used and the wall panel. The top table shown here is Table 322A. Like the column, the fire resistance depends upon the type of aggregate used and the top table shown here is Table 322A. Like the columns, let's assume that we want a wall panel that meets a two-hour fire resistance. Let's also assume, or in this case, we are using the sand lightweight aggregate or the concrete mix. These two chosen parameters, we see that we need a solid wall panel of at least 3.8 inches in thickness to meet the two-hour fire resistance. Thus, a nominal four-inch wall panel or thick wall panel made of sand lightweight aggregate will suffice to cover the fire resistance. Suppose you wanted to consider reduced wall panel thickness because of site limitations. In this case, we could consider reducing the concrete wall panel thickness by adding a layer of 5A type X gypsum board attached to the exposed base of the wall. Table 322B, well, with the same parameters in Table 322B, the actual wall panel thickness for sand lightweight aggregate is reduced down to 2.5 inches by adding the gypsum board. For non-solid wall panels such as hollow core walls that are not uniform in cross-section, the standard has provisions to account for this non-uniformity. A method is referred to as equivalent thickness method. For example, for a hollow core panel or panel case, the equivalent thickness is determined for the wall by dividing the net cross-sectional area of the panel by the panel width. The net cross-sectional area is the gross area minus all the internal voids. When divided by the panel width, you'll get the equivalent thickness. The equivalent thickness of value along with the aggregate type is entered into the previous tables we've shown in Table 322A to determine the fire resistance of the hollow core panels that can be expected. Note that if the hollow core voids are filled with expanded shale or clay or slate or another material that will absorb the heat, you can add that area into the equivalent thickness calculations. When you have a panel that has a non-uniform surface, we can do the same thing. We can calculate the equivalent thickness by taking the area of the panel and dividing it by the width. You just got to note that when you have some stems or whatever that are more than two times the minimum thickness, you've got to ignore the parts that are beyond that. If the wall panels are insulated, Table 322D may be used. It has 23 combinations of inner and outer vice of precast concrete sandwiching and insulation core where the fire resistance can be read directly from the table. Care must be taken to enter the table with the specific widths or vice thicknesses, types of aggregate, appropriate insulating core to determine the fire resistance. For example, if a precast wall panel is comprised of two-inch interior and exterior vice of salacious aggregate concrete, one inch of cellular polystyrene insulation, we see the expected fire resistance or endurance to be one and a half hours. Alternately, for insulated sandwich wall panels, Section 3223-4 of the standard has a calculation method that enables a user to determine the fire resistance for the wall panel by using values specific to the panel configuration. Equation 3224-1, shown here, uses the thermal resistance characteristic R of the different components to calculate the fire resistance that can be expected. Figure 3-2e is used to determine the appropriate R value or to the 0.59 power for each of the fire resistant components in the equation. Here we see an example using the method for determining fire resistance of a sandwich panel. Our sandwich panel parameters are two and a half inch outer width of concrete using salacious aggregate. The R value for the two and a half inches of concrete comes out to be eight. For a figure for next, the two and a half or two-inch inner concrete wide using salacious aggregate. The R value for two inches of concrete from the figure is 6.75. And then finally, the adjacent table to this figure in the code, you'll find the one inch of cellular foam insulation to be R of the 0.59 value of 2.57. Okay, using equation 3224-1 and the values from the figure in the table, we see our fire resistance rating of the sandwich panel to be slightly over two hours. Next in the standard are the provisions for precast beams. The user is required to determine if the beam is restrained or unrestrained in order to know which tables should be used. The standard addresses restrained conditions first with tables 3, 2, or 3, 2, 3, A, B, and C for pre-stressed beams eight inches wide or wider in all other widths, or for non-pre-stressed restrained beams. The purpose in these tables is to determine the thickness of the concrete cover for the reinforcement. Precast beams in an unrestrained condition have similar tables. They just fall right behind the restrained conditions. In determining the required concrete cover of an unrestrained pre-stressed concrete or pre-stressed precast beam with a design fire resistance aggregate type and beam width, the tables are entered in from the top and the side. Here we see a two-hour fire resistance of an eight-inch precast concrete beam composed of salacious aggregate. It needs two and a half hours for a two-hour precast concrete beam. And it needs two and a half hours, sorry, two and a half inches of cover on the reinforcing steel. The increased cover for unrestrained condition is due to the fire tests. Also note that a lot of these tables have footnotes underneath them that will affect how you use them. In addition, the standard specifies where to measure the minimum cover of pre-stressed tendons for the conditions of a single tendon and ungrouted ducts and for multiple tendons. Corner tendons with equal spacing to the bottom and sides need to have a minimum cover. The, sorry, the minimum cover for a corner tendon has to be at least one half of what the actual cover is. So when you find the cover in the tables, you need to basically double it for the corner tendons to meet the fire resistance requirements. For stem members, the minimum cover is measured from the centroid of the strand group to the bottom of the stems. For any one pre-stressed tendon, the minimum cover shall not be less than half of the smaller values of the cover, the values of the cover in the tables for the reinforcement, but also a minimum one inch. Note also that interpolation is permissible from the tables. Concrete cover for non-pre-stressed reinforcing bars are also covered in the standard, or including individual bars, the corner bars. Note the minimum cover of the corner bars used in the cover calculations for determining fire resistance must be one half the actual distance because of the fire exposure on both sides. For precast slab design, precast wall, the precast wall table 3-2-2-A is used, is used with the same, or with the, with the aggregate type and the desired fire resistance. To see the minimum thickness of the slab must be, in this example, we see the we see the minimum 4, or 4.6 inch slab is needed to achieve a three-hour fire resistance using the slant, or using sand lightweight aggregate for a concrete. For non-uniform slab thicknesses, we apply the equivalent thickness method we previously talked about in the wall panels. Besides slabs with gypsum board on the underside, the standard has figures to cover multi-course floor slabs. The figures are fairly self-explanatory. The standard also has figures to cover multi-course floor slabs. The standard also has figures to cover multi-course roof slabs using mineral board and fiber, or fiber board insulation. Besides establishing the minimum slab thickness, or to accomplish the desired fire resistance, like beams, the minimum cover, or minimum concrete cover for reinforcement and slabs must be determined. The tables 3-2-4-A and B are used for unrestrained slabs. For restrained slabs, a minimum of three-quarter inch cover is required for all, for all fire endurances and, and concrete types. Figure 3-2-4-F is used where an intermescent mastic, vermiculite, cementitious material, or spray-on mineral fiber is applied to the underside of the slabs. Using table 3-2-4-A and the previous precast concrete slab design, or with a three-hour fire resistance, the table is entered with the desired fire resistance and a sand lightweight aggregate type to see what the minimum concrete cover must be. In this example, we see that the minimum concrete cover required for sand lightweight aggregate, or concrete is two inches to achieve a three-hour fire rating. Up to this point, we've looked at the prescriptive provisions of PCI-124 for determining the fire resistance of precast columns, walls, beams, and slabs. One of the major advantages to using PCI-124 for fire resistance design for precast is the ability to apply the rational design approach for precast floor and roof systems. This approach permits the designer much more flexibility with the design of these components. The approach requires the designer to demonstrate that the sectional strength of the precast concrete element are taking into account the elevated temperatures of the concrete and steel is sufficient to meet the design loads the element is expected to resist. Note though, unless otherwise permitted by the building code, the floor and roof slabs still must have sufficient thickness to meet the thermal transmittance requirements in the prescriptive sections 3241 through 3243, as we just covered. The rational design can be used for spans that are simple spans and continuous spans and can be used for structural systems that are both restrained and unrestrained. Even with adequate structural capacity, a member can still fail to meet the fire resistance requirements if it is not thick enough to prevent the rise in temperature on its unexposed surface by an average of 250 degrees above the initial temperature. To prevent such an increase in temperature, minimum member dimensions must be met regardless of how much cover is provided on the reinforcement. These minimum dimensions have to be met as well even if the rational design method is used. Section 3221 to 3224 and 3241 to 3243 of the PCI specification are dedicated to meeting these criteria. Under elevated temperatures, the strength of the concrete needs to be evaluated. While heating concrete can increase the strength due to concrete hydration, once the temperature reaches around 900 degrees Fahrenheit, the strength will start to decrease. If the surface temperature exceeds 900 degrees in the compression phase of the concrete, the concrete strength needs to be reduced. Figures 2.2b to 2.2d provide concrete temperatures for slabs and wide beams while figures 2.2e through 2.2j provide concrete temperatures for thin-stem members. Also, the temperature for both mild reinforcement and pre-stressing reinforcement is calculated at the centroid of each type of reinforcement. Again, the same figures 2.2b through 2.2d provide temperatures for slabs and wide beams while figures 2.2e through 2.2j provide temperatures for thin stems are less than 10 inches wide. The temperature is used to calculate the residual strength of the materials. For unrestrained precast members, the strength at elevated temperatures needs to exceed the applied service loads at the section. The demand moment is the sum of all the service moments. The rational design method is a calculation analogy of the ASTM E119 fire test. In the fire test, all the service loads are applied directly to the top of the test specimen while the fire's being applied to the bottom. The loads are not modified by P factors or by strength reduction factors. Equations 3.3.2.1 through 3.3.2.3 are shown here on the screen and they're used to determine the capacity at elevated temperatures. Of note are the theta subscripts that denote the material properties is considered to be at the elevated temperature. So if you have, and this can change depending upon whether you have positive bending or negative bending and which face is being heated by the expected fire. For restrained systems, the material temperature is calculated at half the fire rating of the unrestrained system but not less than one hour. For example, if you have a slab that is restrained at a three hour or restrained three hour system, the designer would determine the concrete and steel temperatures at an hour and a half. And if the slab is restrained for an hour and a half system, the concrete and steel temperatures would need to be calculated at the minimum one hour. Beams and slabs that are continuous over supports follow the same requirements for determining the capacity as simple span members. Continuous members that are part of a restrained system also follow the requirements of section 3.33. And now I would like to pass it back over to Steve to talk about the special conditions. Thank you, Matt. I mentioned at the beginning that chapter four covers special considerations. Anytime you have either a probe through devices like electrical boxes within the slab, or if you have openings in the slab, or if you have joints in the precast elements, because you've got a fire rated element that you can't just ignore those, they do have to be accounted for. And that's what chapter four helps do under section 4.2. The other thing that I want to talk about is under section 4.2. The other item I mentioned earlier was the fact that if you're connecting precast elements, maybe through the use of steel brackets, that you have to address the fire resistance of the brackets themselves. And that's what the purpose of section 4.3 is. So let's look at these just a second. For the probe throughs, we have some tables, or excuse me, some figures. There's five of them using various materials, spray mineral fiber, vermiculite cementitious materials, perlite concrete shields, mineral insulation board, and mineral wool insulation. It is possible to place these elements in a certain thickness on the underside of the slab so that the embedded electrical box is protected in such a way that you don't have heat transmission up through the slab. But each of these figures depends on the particular material you use to handle the probe through. Here's the, apologies, my mouse was messing up. Here's an example using the probe through devices. And in this case, we're gonna protect it with spray mineral fiber using figure 4.2.a. Let's assume we have a two hour rated slab and that we're gonna have to have some amount of thickness applied to the underside of the slab. We would enter this figure with the two hour fire resistance rating on the vertical part of the graph. Coming across, we're dealing with a box type fitting that we're providing the protection for. And then we'll see as we come down the page along the horizontal part of the graph, you'll see that we need 1.3 inches of thickness of the spray material mineral fiber applied to the underside in order to establish or maintain the two hour fire resistance rating because of the presence of that electrical box. If you have joints in a fire rated element, the joints are required to be addressed. In some instances, a good example is an exterior wall. The exterior wall may be required to have a fire resistance rating. However, if the exterior wall in relation to some property line that's far enough away or another building that's on the property, if they're far enough away, the joints themselves don't have to be protected if the building code doesn't require openings in the wall to be protected, openings including things like windows. If the joints are required to be protected, then in fact, you would follow the procedures in chapter four for that requirement. Joints and slabs typically have to be protected unless they're in, I'll give you a good example, an open parking garage with open ramps running between floors. The code does acknowledge joints in those types of floors, even though the parking garage may be fire rated, the joints don't have to be protected. Whereas if you're in a building that's a fire resistant construction and the precast floor elements form the barrier from floor to floor, you would in fact have to protect the joints. And of course, some of the joints for walls are commonly used in the precast industry to take two stage cavity, two stage shiplap, sealant and backer rod joints or ceramic blanket joints. There are figures within chapter four in section 422 that will help say how to address them. Here's an example of the figure from section 422 for sealant backer rod joints with it saying, let's say we had a one hour fire resistance rating and we've got a four inch panel. Based on the four inch panel, then we're saying that the joint itself can be no more than a quarter of an inch and then you be able to provide some protection to it. Let's say if the panel was five inches, you'll notice that we go move across the figure. Now we find that lo and behold, we're allowed to have a little bit wider joint dimension for that five inch thick panel because the depth of the panel has increased. Slab joints, as I mentioned for open park garages are permitted to be unprotected when the building code allows it. And alternate if you do have to protect the joints on a precast slab, a one inch minimum concrete topping is considered acceptable for providing that protection or you can in fact grout the joints themselves to a minimum of one inch depth but to not less than one third of that slab thickness. If you do that, then you'll have accomplished what the code is expecting. When it comes to connections, if you have steel brackets that are exposed, those steel brackets obviously will react to fire temperatures while the concrete may be performing like it needs to, the steel temperature goes up, the steel loses its strength. So we have methods in chapter four using spray mineral fiber or vermiculite cementitious materials or intumescent mastics in some manner to protect the brackets. Here's an example. Let's say we've got a two hour fire resistance and we're using a five 16th inch steel bracket as supporting a spandrel beam. You'll notice as we come up, we come up to where the T, T being the thickness of the bracket and we're gonna protect this. We wanna see what the thickness of the, in this case, a spray mineral fiber or the vermiculite cementitious material. We find that we need at least an inch and a half of cover over that steel bracket completely enclosing it and enveloping it so that it in fact is not exposed to fire conditions. That'll keep the steel temperature at the proper level for it to still perform its structural function. Let's say we increase the bracket thickness to an inch and one 16th. And you'll notice if we look at now at the two hour fire resistance, now we find for those same materials, the spray mineral fiber of the vermiculite cementitious material, you'll find that you can reduce the amount of cover to three quarters of an inch. And the primary purpose that that happens is because the steel mass or density increased because you've got a thicker element. Therefore, it is less reactive to the temperatures as that versus the five 16th inch steel. And then we'll finally, one of the last things to mention is of course, in some cases, a lot of precast, you have ledges and pockets and corbels that are cast integral with the precast elements themselves. If in the precasting of those consideration was given to the fire resistance as it was for the structural element itself, then there is no reason to have to do any other special kind of fire resistance design. It's basically built into the product itself, which in my mind, that's one of the things that enhances with regard to the use of precast construction as one of the options for meeting fire resistance in the buildings. And then finally, I mentioned earlier, the appendix covers commentary. I wanted to, again, emphasize that to the audience so that you're aware there's a lot of explanation about information in particular, especially if you're doing rational design sections, C2.2 and C2.3, which covers steel and concrete properties. There's some good information in there that is supplementary to what's in the body of the standard itself that can be used for designs. I do want to comment that any information in the commentary is strictly commentary. What that means is somebody can't enforce it, meaning make you do something in the commentary. By the same token, you can't use what's in the commentary and force somebody to have to agree with some position you have when you're using the information within the body of a standard. It does serve, though, as a resource. It actually has technical explanation that can be used to help make your case. And with that, Royce, we can do questions and answers. Thank you, Steve and Matt, for a great presentation. We have quite a few questions. We'll try to get as many as we can in our allotted time. And those questions that we don't get answered, we will definitely forward over to our presenters and I'll get back to you. The first question we have is, does PCI-124 apply the same for unbonded post-tension pre-stressed concrete slabs as pre-tension slabs? So the unbonded post-tension slabs, you need to, ACI-216 covers those requirements. All right. Thank you. So the next question we have, it says, for slide 51, PCI-124 provides strength reduction factors. Is there any concern with losing pre-stressing concrete-to-steel composite action at elevated temperatures? The test method is, the rational design method was based on the fire tests and the assumption is that you need to, material needs to support it through that time period. So based on the fire tests, you would assume that you would have adequate bond until that time. The fee factors here, or the strength reduction factors here, or the amplification factors, you would say, are one to 1.0 instead of something larger to mimic that ASTM test. All right, thank you. We have time for hopefully a couple more questions. Are there plans to develop fire code language to address UHPC building elements? PCI has been discussing that, I think long range. And I can't speak directly for all that PCI's discussions. I haven't been involved in them, but I've been at least involved in the periphery, but they clearly have had that as part of the discussions. And so my comment to you is I think long-term, PCI is expecting to try to pursue that and see that it can be perhaps incorporated into building code requirements. I think like anything, you have to crawl before you can walk. And I think in the early stages of what's happening right now, there's a lot more information has to be collected and perhaps some research and testing done before it actually happens. But I think long-term, I would expect PCI to do that. Thank you. We have time for one more question. And that is, is there a code reference for minimum concrete cover on wall panel reinforcement? No, the short answer is no. The fire tests or typically wall panels have a failure in heat of transmission. And due to the concrete properties, typically we don't have a problem with axial load. All right. Well, it looks like that's all the time that we have. On behalf of PCI, I would like to thank our presenters for the great webinar and all attendees for your participation. As a reminder, certificates of continuing education will appear on your account at www.rcep.net within 10 days. And a recording of today's webinar will be uploaded to PCI's learning management system. A pop-up survey will appear immediately after this program ends. All questions that were unanswered will be forwarded to our presenters. If you have any further questions about today's webinar, please email marketing at pci.org with the title fire resistance. Thank you again. Have a great day and please stay safe.

PCI 124 specification

fire resistance

precast concrete

pre-stressed concrete

material properties

elevated temperatures

prescriptive requirements

rational design method

special considerations