Welcome, everyone. Good afternoon, I believe, for almost everybody that's listening. Hopefully, you're all here to hear about the content and the updates for the 8th edition of the Design Handbook. If you're here, you probably know what the learning objectives are, but to just recap them real quick, we're going to take a walk through the PCI Design Handbook, trying to identify some of the content and reference standard updates that have occurred transitioning from the 7th edition to the 8th edition. We're going to talk about some of the new component and connection design concepts and then also describe some of the new information included in the appendices. The 8th edition of the Handbook just started shipping. I don't know if everybody out there has received their copy yet. If you have, you know that it's roughly about two and a half inches thick, so if you can imagine trying to get through all the content that's in a book that thick in about an hour is a pretty good task. So, I've tried to distill this presentation down to primarily just the updates and then the rather important ones that I could recall during the time of the committee to try and distill it down into just an hour on what's really changed within it. So, just a quick recap, what is the Handbook? Most people here probably know that it's a collection of knowledge in the industry, not just on the design of the components or the structures, but also fabrication and construction. It goes through handling and erection, and it covers both architectural and structural precast and pre-stressed concrete products. The 7th edition there was published in 2010, and if you've got your new copy, that's a picture of the cover. It's a bright blue published now in 2000, just at the end of 2017. So, just a quick recap of the process that we use when we're updating the Handbook. First, of course, with anything you form the committee, each edition has a new committee that's formed. We're just getting started on the 9th edition now, forming that committee. Then, you determine what content and updates that you want to incorporate into the Handbook, what's happened over the last time period that maybe you didn't get into the last edition. Develop a subcommittee for each of the different chapters. One thing the Handbook does is use the technical editor, just due to the volume of comments and the volume of material that there is to take care of, somebody that's solely dedicated to doing this work, a technical editor, instead of relying on volunteer contributions from everybody on the committee. And, of course, you develop your updates, ballot it through the committee. We had about 100 total ballots this last cycle. After the committee gets done with it, it goes to the Technical Activities Committee of PCI for an additional review from another collection of individuals, experts in the precast industry. Then, kind of the last step, a lot of our standards nowadays go out for a public review period, 318, AISC, a lot of those, AISC 7. They all go out for a public review period. Instead of doing that, PCI assembles what they call a Blue Ribbon Review Committee. It's a group of 10, 15, 20 individuals that are all very knowledgeable in precast, that that's part of their day-to-day business. So, they ask them to kind of serve as that public or that peer review group to take one final review of the Handbook in totality, just to make sure that everything is complete and ready for publication. So, what do we update? It's going from the 7th edition to the 8th edition. So, the 7th edition was based off the 2006 IBC, and it also referenced AISC 705 and 318.05. Included in Appendix A of that was how you could apply the concepts in the Handbook to 318.08, the different things that changed between 318.05 and 318.08, and what effect that had on the design of precast and prestressed products. Updating now to the 8th edition, we've gone to comply with the 2015 edition of the International Building Code, which then references ASC 710. When we originally started our work of the committee, it was unclear whether 318 would complete their update that they were embarking upon with the reorganization. And so, we initially started updating the Handbook to ACI 318.11. Once 318.14 was official, became available, we went ahead and decided that let's go ahead and update the Handbook to meet 318.14, since that was a standard that was going to be referenced in IBC 2015. So, that probably set actual publication of the Handbook back a year, maybe 18 months, not entirely sure. Just going through every chapter, again, anything that references 318 needed to be confirmed that the right section was still updated. Went through a few other iterations, just to make sure that we were meeting the updated 318 and its content. So, not just standards, we're not just updating the Handbook to meet the current standards. There's also new research, the industry sponsors a lot of research, and we want to try to incorporate that to improve practices of a lot of our manufacturers. And then, just how industry practices have changed, which you'll see as we get here through some of the slides. Overall content, the chapters of the Handbook have essentially remained the same from the 7th to the 8th edition. Chapters 1 through 9 are the same. You get into 3s, kind of your preliminary design, just how you go about sizing general components or structural systems, 4s, kind of the overall building, 5 gets into the individual components, and then 6 starts to get into the connection between those components. Then you start getting into some of the more specialized topics in the industry where they're talking about architectural, the handling and erection, like I mentioned, materials. Going through the rest of the chapters, 315 are still, again, essentially the same, some of the more specific aspects applicable to the industry. There at the bottom, you'll see three appendices that are highlighted. These are all brand new to the Handbook. The first one is on blast-resistant design. Second one is on design for both structural integrity that the general building code would require you to comply with for most buildings, and then some additional discussion on disproportionate collapse as you start getting into government facilities, some buildings where there's an increased risk for loss of a load-bearing component that you want to design that building to resist a disproportionate large collapse of the remaining part of the building. Then the last appendix is the diaphragm seismic design methodology that's actually in ASC 716, but this was a pretty comprehensive research program that PCI sponsored, and we wanted to get that information out to the design community as fast as we could. We'll cover each of those in a little bit more detail toward the end of the presentation. I'm going to skip chapters one and two. There's really not a lot of technical updates in either of those. One's your general precast systems, and a lot of the design award winners, two gets into your notation. Three is really where the technical updates start to occur. Your preliminary design chapter kind of goes through general systems that you can achieve with precast, but then also most people know those tables that we have in there for your typical components, your double Ts, your beams, hollow core components, all the different types, just the general tables that give you a general component size and reinforcing that you might need. So what do we do in chapter 13? We've updated some of the tables, figures, and photos, as we'll see, and then one thing we constantly tried to do through the process of the eighth edition was not just continually add material, add material, add material. If there was something that nobody on the committee really felt was providing value anymore, no producers were producing those types of products, maybe, anything like that, we tried to consciously remove material from the handbook. You can see here, nobody really felt that double T wall panels were a common element anymore. Nobody was really purposely producing them, so that was one of the components that we went ahead and decided to pull out of this edition of the handbook. So to try and give folks that might not be as familiar with precast, kind of how you can achieve an entire building, a total precast type solution, we have a lot of these types of figures. This one currently was the one in the seventh edition, and you can see it's a little fuzzy. It may not be clear. It usually gives a good depiction of how you can achieve a total precast concrete building, so with each of these kind of graphic depictions, we tried to use updated software and try to update some of those figures, so just to highlight some of the different component types better. So each of the different ones, this is an exterior shear wall, there's an interior shear wall, a moment frame, some of the different types of buildings, we tried to update those. In addition, there's photos of different types of precast concrete construction. This is, again, one that was in the seventh edition, a multi-story bearing wall. So the lay designer looking at this, an architect might say, I don't quite see where the precast is in this building. I don't know how you achieve this building out of precast, so to help facilitate that, we've now got photos of the building actually during construction. You can start to see the load-bearing wall panels, the floor components, all the different components that are actually precast that ended up achieving the final goal that they were looking for in the aesthetic of this building. Another photo from the seventh edition of a single-story beam column construction. Again, this is another one that wasn't – a lot of the community didn't think was truly showing the capabilities of precast, so we tried to update that with a nice multi-story beam column type building, another five-story total precast type solution. You can see the columns, the beams, and the double-T panels that are starting to erect this building. Another one that we had in the seventh edition of what was labeled as a moment-resisting frame. Again, you kind of look at this photo, you see some gravity columns and what might be some gravity spandrels. You don't necessarily see a moment-resisting frame from this photo. You can't quite tell what causes this to be a moment-resisting frame. Again, we tried to update that to more current practices. These are some H and F type frames that are then – you have an infill that's cast between them to create the true moment-resisting frame out of a partial precast solution. Again, just trying to highlight some of the capabilities there. Some of the other updates in Chapter 3 were on the double-T load tables. Again, we don't just trust all the numbers that the previous edition had. We checked, verified, and updated all of them where necessary, kind of like the double-T wall panels. Not a lot of producers were making eight-foot-wide double-Ts anymore. They were fairly – been out of the industry, I think, for a few years, and so we went ahead and decided to remove those from the handbook. The 7th edition used a cast-in-place topping on top double-Ts of two inches, and kind of standard throughout the industry has made that into a three-inch topping, so we went ahead and updated all the tables to that three-inch topping, and then some additional clarifying information on the strength and the unit weight for the different components. So, this is kind of a general view. The whole view of the page that you might be familiar with is there on the left side, kind of showing a typical double-T, a 12-foot-wide by 28-inch-deep double-T. The top part of that table is the pre-top T, and the bottom part is the field-top T. So, highlighted in yellow are a lot of where the content actually changed on these tables, just giving us as an example, just so we can try to clarify some of the information. Chapter 4 then gets into the analysis of the whole structural system, so when we get into this chapter, then we start talking about updating our reference standards that we talked about before. We added a couple new examples and modified some of the design aids. As I was mentioning, we have a new appendix both on BLAST and structural integrity, so there was previously a smaller section within Chapter 4 on each of those different topics, so now we just have a small paragraph that gives a quick introduction and then a reference back to those two appendices for more comprehensive discussion on each of those two topics. Looking at some of the specific changes that have happened in the load standards that we've had to incorporate in updating the handbook, the easy one that's pretty straightforward, but the vehicle load impact for your perimeter walls in a parking garage in Oak 5, we just designed that at 18 inches above the driving surface, and now ESC 710 has us apply that concentrated load anywhere between 18 and 27 inches above the driving surface, but really the more comprehensive change that affected the whole building was a change in our wind speed from service-level forces in ASC 705 to now strength-level forces in ASC 710, so going from just that one chapter in 05 to now six chapters in 710 was a pretty comprehensive change that we had to incorporate in the update. Seismic systems are covered pretty extensively in chapter four of the handbook, and based on a survey of most producers in the room trying to find something that was generally applicable across the industry, across the country, for all seismic systems, we decided to treat intermediate precast concrete shear walls the most extensively. That was the one that had the most applicability for something generally seismic design category C or so, so that was the one that we had the largest discussion on. We touch on each of them, both ordinary and special, a little bit, but that's the one that's covered most extensively, and again, we get into moment-resisting frames a little bit as well, talk a little bit if you have a shear wall frame interaction, and then the big discussion in the handbook's really on diaphragms. You know, we all hollow-core double-Ts, not just in a total precast building, but in another load-bearing-type building that would have those as their floor elements. We still use those as the diaphragms, so we treat that quite a bit here in chapter four on the traditional sense, and then when we get into Appendix C on the new methodology that we use. You can see there at the bottom, we have that discussion on shear walls, whether you're going to treat those as all coupled together and how they respond to the lateral force or if you're treating those as individual panels resisting that seismic force. One of the things that was discussed quite a bit in the committee and now in the handbook is the yielding element of seismic connections. There's really two requirements that are pertinent to this topic. First is what 318.14 requires, where you need to restrict your yielding to a steel element or reinforcement part of that connection, so it has to be one of the plates or reinforcement that crosses the joint, something that's connecting those two concrete components. It needs to be a steel component that is your yielding element, and anything else that connects to that element needs to develop at least 1.5 times the strength of that element, so that's a requirement in 318. IBC has another layer to it that you need to maintain 80 percent of the strength at your design displacement. So we go through in the handbook discussing each of those different requirements, and then we discuss how you can determine what that deformation demand is from the code and what kind of strain levels you should anticipate to design for so that you can satisfy both the strength requirements from 318.14 and the displacement strain requirements from the 2015 IBC. There's a detailed, pretty comprehensive example of a five-level, two-bay parking structure in seismic design category C. It was previously a three-level, three-bay, so we've increased our height a little bit. It goes through kind of the general seismic design with your approximate period and your Raleigh period, doing the conjugate beam. It goes through a stability and a quick P-delta check. It evaluates whether wind or seismic in both directions is the controlling load combination, which one is more relevant. And then the real result of this is, again, that diaphragm analysis and determining your cord and your collector reinforcement for the diaphragm of this building. It doesn't actually get into designing the individual lateral force-resistant components. That kind of gets into Chapter 5, where we start talking about components. This is more on the whole entire structural system and not the individual component level. So this is an overview of the building. You can see it's about five stories tall. The primary lateral force-resisting system, you can see here we've got two small shear walls in the short direction, kind of each end of the diaphragm, and then a longitudinal long shear wall right through the middle of the building of this two-bay structure, resisting lateral forces in that direction. Like I was saying, the real result is the diaphragm design. And here you can see the results, the collector and the cord reinforcement requirements for that diaphragm, so that we can deliver all those forces back to those lateral load-resisting elements. Chapter 5, then, gets into the design of components. Again, it covers both just general reinforced, I think conventionally reinforced, and those pre-stressed components, of course. It refers fairly regularly to the PCI standard design practice that's essentially an interpretation of how you would apply general ACI 318 requirements to a precast-type products. Not everything in 318 is directly applicable to precast and pre-stressed products that are manufactured off-site and have different requirements. So where there's a slight difference in the industry, where the industry has interpreted 318 slightly differently, that's usually included in the standard design practice, and then we reference that in Chapter 5 as part of our design process for each of those components. I think on, if you got the handout, it might say there was 19 work examples. I think that was updated to 40 total work examples in the chapter. It also includes some information that is not in 318 specifically. One of those, 318 actually references the design handbook for the design methodology and the requirements, and that is in Section 9547 for the torsion of solid precast sections with an aspect ratio of greater than 4.5. So here you're essentially talking about spandrel beams, those that are 12, 14 or so inches wide and four and a half, five feet deep, so that you have a really high aspect ratio and that you start to get a slightly different behavior than your traditional torsional behavior that you would assume in a traditional design of a one-sided loaded beam. The other things, reinforced concrete bearing, you don't see bearing connections as often in general concrete construction. They're fairly common in precast where we'll reinforce that bearing with a bearing plate and some reinforcement there to help confine that bearing area, and so there's a treatment in the handbook on reinforced concrete bearing. And like all the other chapters, there's updates to meet the current codes, revisions to meet current industry practices, and then a new research that we're trying to incorporate. As I was mentioning, of course, we've updated it to HCI 318.14, which essentially took all the provisions that we previously referenced in the 7th edition and moved them around, reorganized them as 318 was, and so we went through the chapter and confirmed the correct reference section for that new provision, and so we went and updated all the references that are in there too as well to follow that. In general, the organization of chapter 5 in the handbook has remained unchanged. If you're familiar back with chapter 22 in 318.14, one of the ones they call the toolbox chapter, it kind of walks through the different load effects, you know, it talks about flexure, it talks about shear, it talks about axial force. It goes through the different effects that you have from your loads. And our handbook chapter kind of follows that method already. We go through those different effects on designing a component. So we didn't feel that reorganizing our chapter was necessary at this time. But to help anybody that wasn't necessarily familiar with 318, we went and prepared a design procedure, a flowchart essentially, for a typical prestressed concrete beam, something like a double T maybe, how you would go about designing that component to comply with 318.14, the different sections that you would need to reference. So it's a fairly straightforward flowchart. It walks through the different sections, primarily in chapter nine, where the design for beams is included in 318. And then it has all the other toolbox or other chapters that we reference to go back and find other information that we need to as part of that design. So there's just a simple two-page flowchart that we have. Similar to the other, back in chapter three and four, there was tables and design aids that were rarely used or obsolete. We went ahead and deleted those. There was a shear reinforcement design aid that I remember that none of the designers in the room really used anymore with our computer-based technology. And so we went ahead and deleted that. There was another one or two design aids that most of the committee just didn't feel were necessary anymore. So we went ahead and eliminated those. We've updated all those examples to the current practice. So back when we were talking about preliminary design, we've updated our topping thickness to three inches. So now in chapter five, when we're designing a component, a double T with a topping, we've updated the topping thickness to three inches to match that practice to try and ensure some consistency throughout the handbook. When you're trying to calculate the moment of inertia of a crack section, there's a step where you calculate the decompression force as part of that process. And no matter how many times people read this, I'm not quite sure how many editions this has been through, eventually somebody sees that and says that there's something missing there. And so we've updated that calculation for the decompression force as part of that example following an old math paper. And then if you are familiar with the design of ledge beams and particularly inverted T's that have a ledge on both sides, you're going through the design process for that ledge and you get to a point where you need to calculate the hanger reinforcement that you put kind of in the body of the section. There's an M factor that's used in that calculation to determine the amount of hanger reinforcement that you need. And it wasn't entirely clear the method for calculating the M factor for an inverted T. The example was given for a ledge beam with a ledge on one side. So now we've updated that and we've got an example, a clear term for the M factor on an inverted T now as well. Some of the new information. Like I was saying, ACF 318 references the handbook for slender spandrel design. So generally the design is applicable for a simply supported spandrel with lobes evenly spaced. Almost, you know, usually talking about something like a double T sitting on a spandrel beam. It's laterally strained at two points at each end and it's got a fairly large aspect ratio of 4.5. Not uncommon for most precast spandrel beams in parking garages and other similar structures. So in the end, the design methodology is akin to something like plate bending instead of a true torsional behavior. You don't get a true torsional crack forming. You don't get that kind of response out of this component because of the depth of it. And so you no longer need continuous hoop reinforcing. In this type of element, when you have that kind of aspect ratio, you need just your flexural reinforcement and some nominal reinforcement on the opposite face. You know, it depends on what region you're in. If you're in the end region where there's higher shear and a higher potential for torsion, then you got to the transition in the flexure region. And so the main requirement is that you no longer need that continuous hoop reinforcement to resist the torsion on these one-side loaded spandrel beams. Some additional new research is DAPTNs of thin stem members, eight inches or less. So again, we're primarily talking about double Ts. So this was a pretty comprehensive program done down at NC State, which included both full-scale testing and some analytical modeling. Several different reinforcement configurations were tested to try and optimize some of the reinforcement for the rest of the industry. If you're talking about a DAPTN in a beam larger than eight inches, just a general rectangular maybe type beam, the design process really hasn't changed. The methods that are currently in the handbook still apply. This is really only for those thin stem or double T type members. There's one additional check in that extended nib above the DAPT. There's additional shear check that you have to make in that region as part of the process. And then there's some additional requirements for a cover over the hanger reinforcement and some of the bend requirements at the different points where the reinforcement transitions. So of course with this, we've got some new configurations and so we've got complete design examples for some of those configurations. So this is what the six tested configurations, preferred configurations look like. The two examples that are included, the one that most producers in the room preferred with this vertical L-shaped reinforcing scheme, kind of your traditional DAPT type reinforcement with the hanger reinforcement that comes down and then turns out longitudinally along the beam. And then this inclined L-shaped reinforcement. This was a pretty well performing reinforcing scheme for the behavior at the end of this beam where the DAPT is. And so this was the other example that we included as part of the handbook. But all six of these are recommended configurations from the research. Some additional research is the ledge design of L-shaped beams. Following on the project on the slender spandrel research, they identified some deficiencies in the ledge design. So essentially the current equations, the equations in the former edition of the handbook were unconservative for punching shear. So essentially when you have that point load on that ledge, you get a punching shear failure through the bottom of the ledge. So what was found is that strength is a function of the global stress in the beam. You can see an example there in one of the numerical models where you have the global flexural and bending of that spandrel beam, and then she has some increased stresses in the bottom flanges. The bottom is in tension, pulling apart, so you get a reduced punching shear capacity at that point. And so the new design process requires evaluation in multiple locations along the beam, whether you're talking about the end region with high shear or the middle region with higher moment. Here in general, it's a new design process comparing the seventh to the eighth edition. So kind of just stepping through the different terms that we have in the equation, if we start kind of in the brackets, we have two times BL minus B. So this term here in the parentheses essentially gets you the length of the projection. So we have two times the length of the projection, BT is the width of your bearing, HL is the height of your ledge. Those essentially defined your punching shear perimeter. So if we look here at the second term, we have BT is still the width of your bearing, two times the length of the projection. You still have that going from the face out to the edge of the ledge, so that's still your shear perimeter. Now you can see we have two times the height of the ledge. The research found that you get a breakout failure that is similar to a concrete breakout, a slightly shallower angle than your traditional 45 degree breakout. And so we are engaging more of the ledge in this resistance. So we can engage two times the width of the height of the ledge as part of our punching shear perimeter. Looking outside the bracket now, the height of the ledge, that defines your punching shear area, and the square root of F prime C, that's consistent across both. Then at the front, you can see where the major change is. One's going from three in the seventh edition, if you're talking about the general area. This is the second equations when you get closer to the end. If we go now to the eighth edition, we eliminated a three and now we have a gamma and a beta. Here these are the terms that we defined, so we have an additional term to calculate. Those are shown down here at the bottom. If you're familiar with the ZSU method for torsion design, gamma is the same term from that method. It's essentially related to the effective pre-stress on that section, so you have one plus the effective pre-stress divided by the compressive strength of your concrete is your gamma term, how much effective compression you have on your section. And then beta is related to what location you're on the beam and what load you are resisting at that section. You start with calculating what we call an R, which is the larger of the ultimate shear to the nominal shear and the ultimate moment to the nominal moment. You calculate both of these ratios, determine which one's larger, that determines what your R is. When you get out towards the end, you have a high moment, you're going to be usually above 0.6. When you're at the end, you have a high shear, you're going to be above 0.6 on that ratio. Here your beta becomes one. When you get kind of in that third point where you're not in a high shear zone and you're not in a high moment zone, if it gets down below 0.2, if you've got a lot of excess capacity there, your beta can increase all the way up to two. So depending on where you are on the beam, this beta factor will change. And so both of those two equations feed back into this equation on calculating your ledge capacity. So this is where the effect of the global member behavior is incorporated into each of the two equations. So just taking a quick comparison between the two methods using the same example, the same properties of a typical ledge beam, you can see the results down there from the two different additions. We have a slight decrease in capacity, even though we've increased our punching shear error because we've engaged more, we have less resistance for punching shear because of the tensile effects of resisting moment or shear at the end of the beam. So we have a net reduction in punching shear or ledge capacity because of that. An additional update was the effective width of double T flanges for concentrated loads. So again, based off testing research, observing crack patterns under concentrated loads, we took from the seventh edition at 60 degrees and we've updated that to roughly a three to one or about 71 degrees now, just based off observing and testing. And then in addition, it discusses some other ways that you could go about designing the ledge. If you don't want to design for that critical section at the face of the stem using the three to one distribution, you can use Leo Lines, Pucher's influence charts, and a couple of other different methods. Chapter six now gets into the design of connections. Of course, this is stuff that's necessary for precast. There was a previous diaphragm overstrength table with a side factor that was included. We've eliminated that because now you just use the regular overstrength factor for the code. Deformed bar anchor. So any type of deformed reinforcing, whether it's a reinforcing bar, another type of bar with the deformations along it that are welded to the back of the plate, how you develop that at that section and what strength does it have at that section. So if we're talking about just direct tension or compression, we have equations right there. It's just the number of bars, times their area, times their yield strength with slightly different feed factors. If you're talking about shear friction, we recommend you just go back and look at the shear friction design provisions. Anybody that is familiar with ACI 3.18.05 and also ACI 3.18.14, or 11 for that matter, knows the vast difference in appendix D, if you're in that method, or chapter 14 now, the design and the treatment of post-installed anchors in 3.18. So with that, we've had, went and updated chapter six of the handbook to incorporate all of the new information, the new technology, the new processes, the new design that you have for post-installed anchors as part of your design. And so we cover all expansion adhesive grouted type anchors. We even touch a little bit on concrete screw type anchors that aren't necessarily included in 3.18 yet. They're trying to get those included, but they're not included quite yet. And then we have a complete design example going through both the shear capacity of an expansion and the tension capacity of an adhesive anchor. So instead of most designers that might just pull up one of the manufacturer software, you know, Healthy Profits or Powers or ITW or any of the other manufacturers, pull up their software, calculate your capacity, and move along, we try and give kind of a general design. We go through, you know, more typical bond strengths. We don't give any specific manufacturer bond strengths. We just kind of make the whole process more general to help educate somebody as part of their anchor design. Embedded plates with headed studs. We would have traditionally considered these as pin-pinned at each of those studs. We've added a new consideration if you want to consider that fixed-fixed at the studs, which also means you need to consider the prying action on those studs due to the fixity. So now we have a design example that considers that plate both pinned and fixed. And so you can see the comparison between the steps necessary to design that plate and that connection and just the different capacities you can get out of those two considerations. We treat steel design a little bit in the handbook, both sections and torsion or un-stiffened connections angles along a wall or something that's trying to support another horizontal precast type component. The one larger thing that changed regarding steel design is stiffeners, un-stiffened connections. And so between additions of the AISC manual between the handbook, they updated their design methodology. You can see a figure of it there. You calculate some resultant forces along a plane that goes from the intersection of the vertical to the horizontal bearing plate, and there's a resultant plane there that you calculate a normal, a shear force in a moment along, and you design your plate to resist those forces. So we've updated our methodology now in the handbook to mirror that included in the AISC steel manual. Most of our examples are pretty comprehensive. They try and consider all modes to determine that controlling element. Here you can see one, it's a typical wall component attached to a foundation. It's got an expansion anchor and an angle and an embedded plate, but you can see the table there at the bottom. It goes through all the different possible elements that could be the controlling element. One example is without prying action. One is with prying action. You can see the different capacities you can get. So we try and step through the process to help educate the designer in doing the various design connections. We discussed welds. Of course, we have exposed connections, so we're going to have welds. We go through the different types and how you can weld reinforcement to develop it, whether it's lapping the reinforcement and welding it, welding it to a plate, perpendicular or longitudinal to a plate, all the different ways you can develop reinforcement. We talk about weld groups and the different ways you can analyze that weld group, whether it's elastic vector, the instantaneous center, and then we have an example that goes through the process for the same connection, and you can see the different design strengths we get from each of those methods versus what would the tabulated solution from the AASC manual be. We've even tried a comparison between the seventh and the eighth. We had an example for if you're doing the elastic vector method, probably a little less common for most folks. We had a figure here on the side that you had a vector kind of going in each direction for each of these different forces. It didn't quite make sense why they weren't coinciding, so now we have an example where all the vectors coincide at one point, what the eccentricity is to this node on this two-line weld that we are designing for so we can determine what the elastic stress is on that part of the weld. Connections. It goes through some of the more specialized connections to precast corbels, lube hangers, Kazali hangers, bearing pads, column bases, some of the different types. Kazali hangers, I wanted to mention specifically, they have what are called hanger reinforcement. You can see them here in this beam. So we have the hanger that comes down, connects to this bottom bar, and there's this hanger reinforcement that is taking some of the stress and forcing this bar and bringing it back up to the top of our component. Some research found that where your component is shallow enough that you can't provide that hanger reinforcement, that the design method was now unconservative if you did not or you could not provide that hanger reinforcement. We have an additional step if you have a shallow component where you're not providing that. You essentially get concrete breakouts at 35 degrees, might look familiar. You have a breakout cone that develops at the bottom of the hanger and then transitions up at that angle. The terms over here on these equations look similar to our typical concrete breakout equations, so there's just an additional step for that type of hanger if you're using it in your components. The diaphragm shear connector, general play with two bars welded off at roughly 45 degrees. Previous to the seventh edition, they used a feed factor of 0.9 for all the forces on these different elements. During the development of the seventh edition, they updated that to a feed factor of 0.9 for tension and 0.65 for compression, generally trying to align with the 318 building code for those different modes. When you take a look and try and visualize design strength equilibrium, if you're using different feed factors and your area and your yield strength is the same, you no longer have really design strength equilibrium, which as engineers, we love everything in equilibrium. That didn't quite sit well with everyone, so after much discussion, should we just go back to 0.9, should we take everything down to 0.65, we said, well, strut and tie would have us use a feed factor of 0.75 for both of them. That seems logical. It's essentially breaking it down to a strut and tie. If you do the comparison using a feed of 0.75, you'd get roughly the same capacity as you would from using a feed of 0.9 and 0.65. Tying back to the discussion we had back in chapter four on the shear wall base connection, a seismic connection with one of the connections needing to be the yielding element and everything else providing a strength of at least 1.5 times the strength of that element. Here we have a shear wall base connection where we've determined that the connection plate or this jumper plate here is the yielding element, and so we've designed everything else, the embedded plate and the reinforcement, the base plate here and the reinforcement, developing that into the foundation for 1.5 times the strength of that yielding element. Fillet walls, we've expanded some of the design needs in chapter six. This was the previous table in the seventh edition. It really only covered these 70 electrodes. Now we've gone all the way up to the 110 electrodes to try and give you some more easy quick reference information for the strength of the fillet wall for various sizes. Similar for bolts and threaded rods, ASTM developed a new specification F1554 for threaded rods since the seventh edition. You have a lot of similar strengths, similar grades of bolts and fasteners, but now we've updated this table to include some additional grades all the way up to 125 KSI type fasteners, and so what the different tension and shear capacities you can get out of the various size fasteners that you could use there, both for the older ASTM standards, the 36, the 325s that we're familiar with, or all the way up to the 1554s. That's kind of getting through the basic information that most designers would be familiar with. Through the rest of the presentation, we're going to cover some more of those specific topics. So the first one is Chapter 7 on Architectural Precasts or the Structural Design Considerations for Architectural Precasts. So really, the main update here was trying to illustrate or highlight some of the information that the overall building structural engineer of record needs to provide to the structural engineer of record or the engineer of record for the architectural precast in the contract document so they can design their component appropriately. So you need the building codes, loads, and design criteria, of course, where you can connect back to the structure and if there's any special considerations that you might need. Chapter 8 gets into Handling an Erection. So again, this is most things that happen either in the site or in the plant or on the site prior to the building getting finished. So the first one is if you have maybe a scrap piece of pre-stressing steel and you bend it over into a hairpin and you embed it into your concrete component to use it as a lifting loop, the capacity in the 7th edition was at 8 kips and reviewing some research that was performed, reviewing the design limits, the embedment limits, and some of the other requirements, we went ahead and updated that to a 10 kip capacity for that type of loop. The swivel plate you can see over here on the right side. You can imagine you get 25 to 30 engineers in the room, you'd be surprised how many different ways you could come up to analyze a swivel plate like this, but we discussed this pretty extensively in finalizing our design process for this and what the appropriate consideration, kind of that prying action that you would get on the insert and some of the different forces that you have on the swivel plate. There's again some clarifications related to an erection stability. One thing the quality side of the industry is trying to highlight is if you're using any type of coil product, whether they're coil inserts you can see with the swivel plate, coil nuts that you might weld on the backside of the plate to thread into later, coil rods, coil bolts, anything, is the compatibility between different manufacturers. Each manufacturer has a slight difference in the way they make those coil products. Just ensuring that you're using the same externally threaded product with the same internally threaded product because otherwise you could end up with less capacity than what you might believe that connection to have. So they want to have compatibility between those so you're using the same product and the same manufacturer. Additional figure updated to rapid panel tripping. So here you have a wall panel sitting on the truck. You need to get that oriented vertically so you can erect it as part of the building. So we've added a new figure here and quite a few cautions regarding this type of method because it can lead to some uncontrolled rolling and other concerns related to stress reversals. And so we've got some cautions included in the text. We've got some information included right there on the figure on the sling length and some other information just to highlight anybody that might be involved in determining the rigging for the erection process. Chapter nine gets into materials. So it's kind of just a general discussion of concrete, steel, all the various materials that we use as part of precast concrete construction, some of the fresh and some of the hardened properties. Talks about strand bond. It's working its way through the industry. It's got some discussion and caution on structural bolts. So if you're talking about some of the higher strength structural bolts, they're essentially you can't weld them once they get above certain grades and even at some of the intermediate grades you have to have supplementary requirements on some of the chemical compositions to make sure that that type of fastener is still weldable. So we try to add some discussion and highlight there on the different types of fasteners that are commonly used in the industry, both your traditional 307, 325, and 490 bolts and that new ASDM specification on 1554 on which types of grades of bolts you could weld. You might need special requirements to weld or that you're really not recommended or just not even permitted to weld those types of fasteners anymore due to their composition. Chapter 10 gets into fire resistance, which is primarily a reference to MNL-124, designed for fire resistance manual. It goes through the different processes for designing by cover or a more rational design and even has some discussion on post-fire examination. Chapter 11 is thermal and acoustical. Again it's a quick discussion on some of those topics. Chapter 12 gets into vibration. It goes through kind of the whole process on vibration design, some of the different causes. It has some discussion on damping devices if you have a component that is in place in a building and you find it to be deflection sensitive and you need to try and damp that out, how you can go about doing that. It really follows kind of two standards in the industry, both ATC Design Guide 1 and the AISC Steel Design Guide for vibration. So those are kind of the two standards that it follows. Chapter 13 gets into tolerances. So there between the 7th and the 8th edition there was a new publication, the ACI ITG or Innovative Task Group 7 in 2009 published a specification for tolerances for precast concrete. So ACI realized that 117 really doesn't provide any tolerances for precast and prestressed concrete. So they wanted to develop some additional specifications for that and so essentially a group of industry experts was assembled and they developed a specification with tolerances that are essentially similar to those in MNL 135. So the content, the types of tolerances that are used are fairly similar. Kind of the path moving forward for each of these documents is a little unclear whether ACI is going to incorporate ITG 7 into 117 and maintain the tolerances on their side or whether it's going to come back to PCI and reside in 135 or another type of standard. But we discuss all those different types of tolerances and the sources for those tolerances and the various product direction and interfacing tolerances. Chapter 14 is specs and standard practice. So it kind of goes through some of the discussion and the terminology for the various project participants. It goes through what you would typically do as part of a contract, whether you're required to provide shop drawings, test and inspections, who's responsible for what during erection, what when that product arrives on site is still on the truck, who's responsible for it, if there's any warranties as part of the construction. Kind of the big discussion is on the responsibility of the various design parties going all the way from the owner of the building or the developer all the way down to the specialty engineer who's usually just working for the precast so they don't have any relationship with any of the other parties. And so what each of those different parties going through the whole process from architect, structural engineer, contractor, all the way down, what each of those parties has as part of developing and achieving the vision that the eventual owner will have for that project. One note, the PCI standard design practice that I mentioned for back in chapter five, it has not been published yet. There's a different committee in charge of developing the standard design practice and they're still working on that. So it's not included in chapter 14 like it has been in previous editions. But that's a document that's yet to be published. Chapter 15 is just a nice collection of design aids, both design information, shear moment diagrams, material properties, different other information on section properties. The one thing I like to note for anybody that has not taken either the PE or the SE exam, this is a good reference to have. It has a lot of good information, quick and easy reference that you can tab and highlight and pull out as part of that exam. Just as an example, the table on the right, along the top you have your support conditions. On the left-hand side you have your loads and so those are all the different types of beams. We have design equations right in the handbook for towards being on the right side. Getting into some of the new material, the first one is Appendix A on blast-resistant design. And this full appendix has actually been published already in the PCI Journal back in the winter of 2014. There was a push in the industry at the time to get some information out to the rest of the design community and even some of the government entities on the capabilities and how you would go about designing a precast and pre-stress component for blast resistance. So instead of waiting for the handbook to get finalized, we went ahead and through the Blast Resistance Instructional Integrity Committee, went ahead and published Appendix A as a standalone document. It's really a condensed version of another document that PCI has on blast-resistant design. It tries to summarize it all in a quick, condensed format for that quick information. So of course, if you're familiar with blast-resistant design, you're usually talking about government entities, the GSA physical security criteria, some of the United Facilities criteria for the various departments of defense, some of the Department of State information. There's a lot of different government-type facilities here. It goes through kind of the process of doing blast-resistant design. So we go from taking a real system, you have some sort of component subjected to a blast load that is going to deflect. We take that and we determine some shape functions for that component, whether we're talking about its elastic response to that blast load or its inelastic response when it has yielded and a plastic hinge at the center at the maximum deflection, or our shape functions, so that we get into our generalized single degree of freedom system, that spring mass, then we have our equation of motion that everybody sits around and solves by hand nowadays. So we go through that, how you go about doing this as part of your design. Of course, everybody uses software, there's a variety of different softwares out there that most people use as part of their blast-resistant design, but we kind of try and take you through the process of how you do that as part of your design process. Design examples, there's three examples in Appendix A. The first one is on a solid wall panel, so you go and you determine your stiffness and your resistance function so that you can plug them into your single degree of freedom system, and you can get what's down here on the left side, your displacement history response to that blast demand, so you have some initial displacement and then it starts to damp out over time, and you can see what your residual displacement of that wall component is after that blast effect. So then we take that same example, and now we have determined what the reaction forces that you need to design for. So there's some discussion in the handbook on what is an appropriate factor for those design reactions. The component responding inelastically to a blast isn't necessarily a bad thing, you've got to be able to absorb some of that energy, but we don't want our connections to fracture. We don't want that component to fly into the inside of the building or fall off the outside of the building. We don't want any of those things to happen, so we want to make our connections more redundant as part of that design, so we have some of that discussion here in the handbook. And then the last one, a lot of the research that PCI was doing was on insulated wall panels and their response to blast effects. You're usually talking about a sandwich wall panel, where both Ys are resisting that blast load. And so we go through an example where you determine how many Y connectors you need, both for a kind of a distributed type Y connector that you have, both of these photos are a more discrete type connector that you might use as part of your design. Try to not be manufacturer specific, but more general on a sandwich wall panel. So it goes through the same process that we did for the solid wall. Now it's just talking about a sandwich panel or an insulated wall panel. Appendix B gets into structural integrity and progressive collapse, so it goes through a lot of the historical developments and how design has evolved for that, discusses the building code criteria, which is usually the structural integrity aspect of it, and then the additional criteria for government facilities, which is a disproportionate collapse aspect of it. And then we talk about some different design strategies that you might use to achieve disproportionate collapse resistance in your structure. So kind of the history of that, the Ronan Point failure back in, I think, 1968 or so timeframe, a blast occurred on one of the higher floors, blew out one of the load bearing panels and you got a sandwich effect going down the rest of the building. Following that, PCA did some research and determined some of the minimum requirements for these types of vertical ties, the perimeter ties, longitudinal ties, and transverse ties that you have to provide some minimal integrity, some minimal reinforcement, kind of tying the rest of that structure together to prevent something like Ronan Point from happening again. So kind of design approaches when you start talking about it, there's a couple of different ways you can go through what's more of a direct design method. So the first one is an alternative load path method where you're essentially just considering a column removal scenario. So you have a model of your building, a 3D model, you go along one of the sides and you remove one of the interior columns. How does that affect the rest of the building? Does the entire bay or multiple bays above collapse in or is it just the loss of that one element, maybe the floor above? How does the rest of the building respond is kind of your alternative load path method. The next one is specific local resistance. So you're really trying to harden or increase the resistance in a localized area to those effects, the blast effects or the event, the abnormal load that might cause disproportionate collapse. The other way is to go through an indirect design. Here usually is essentially equivalent to what structural integrity is doing in the general building code. So you're providing some minimum connection, some minimum force transfer between vertical and lateral load resisting elements so that you can transfer forces that were resisted by one component back to the rest of the structure in case of a loss of that element. So kind of talking about design strategies, there's kind of two ways. You can either do component robustness as you can see in the figure here on the right. We started with a more conventional framing. We had just simple span spandrel beams, column coming down, we had a loss of the column down here. How is this structure going to respond? Some testing in NIST confirmed that you'll typically overload these types of the traditional types of connections and won't be able to resist vertical forces from above. The one way you can achieve some robustness is to use dual-span members. You have a spandrel beam now that spans over that, so it will likely be capable of resisting this column load from above. And if you happen to be at where you lose it at a connection, now you have a cantilever type situation where the cantilever action of the spandrel beam should be able to resist that force from above instead of trying to use a true cantonary type action through these connections up here. The other one is connection robustness, so that goes back to this type of connection up here. We'd have to really make this connection robust, usually use some high-strength 150 KSI type reinforcement to really improve the strength of that connection. The last appendix to talk about is the diaphragm seismic design. This was a 10-year research project, co-sponsored in part by the Precast Concrete Institute. It went through an entire both analytical study and some actual testing of approximately three full-scale type buildings out in UC San Diego using various types of diaphragm component types, both hollow core and double T type components. So when most people start to get into it initially, the design appears a little bit more difficult. There's a couple more steps that you have to do. But with a slight improvement in our analysis, if we innovate and develop some improved connection details and we are a little more proactive in our system layout, generally the structural system will help improve system performance. And the real goal is in some of our more higher seismic design categories, it was difficult to demonstrate appropriate behavior to use precast concrete diaphragms without a topping, without calling it a cast-in-place diaphragm on top of a precast system, just because of the nature of precast that has all these discrete connections and points of yielding. So as part of this, now you can start to use total precast concrete diaphragms without a topping in higher seismic design categories. So kind of the two main changes are one change to the core force levels. So we're modifying the forces that we're designing our diaphragms for. And then we'll also have some additional qualification requirements for those connections between two adjacent components. So to run through kind of the different processes, there's really three different ways you can design your diaphragm under this method. The first one is the elastic design option, where you are going to design your diaphragm to remain elastic in both the design and the maximum considered earthquake. Since we're staying elastic, we have the highest force, and we can use pretty much any connection we want, because we're designing our entire diaphragm to remain elastic as part of that process. The next one is getting into the basic design option, where we're going to start permitting some inelastic behavior to occur when we get into the maximum considered earthquake, because we want to start having some of that energy absorption. Because of that, we have a lower force that we need to design for since we're going to be dissipating that energy. But with that now, we need to make sure our connections can accommodate those types of displacements. So now we need either moderate or high deformability elements so that they can accommodate the strains that you would have with those connections. The last option, the option that's the most beneficial in our higher seismic design categories is now the reduced design option, where we are going to allow some yielding in both the design and the maximum considered earthquake. Again, since we're allowing that energy dissipation, we have a lower force that we need to design our diaphragm for now. Because we are allowing the yielding, the inelastic behavior, we need our connections to be able to accommodate those strains. So now we have high deformation elements that we need to use as part of the connection. And current technologies that are available, high deformation element is essentially limited to reinforcement crossing a joint now. So that's pretty much what you're limited to. Kind of a quick summary. Just looking here in the middle of the table is kind of the main information from ASC 716. We're talking about elastic, basic, or reduced. We have an R factor. In seismic design, our R factors are always in the denominator. So we're dividing by these numbers. So when we're elastic, we're dividing by 0.7. So we're factoring up the force we're designing for. When we get to the reduced design option, we're dividing by 1.4. So we're reducing that force as part of our design. So kind of the general steps that you use are determine what demand you have on that diaphragm. It's similar to a seismic design category. ASC gives you some guidance on which one, the elastic, basic, or reduced, would be recommended for your structure. With that, you can determine which classification you fall into, whether it's low, moderate, or high deformability. Design your forces, determine your strengths, and design your connections, of course. So you don't just have to wait until your jurisdiction adopts ASC 716 to use this new methodology. The CCI approached ICC to get this evaluation service report 3010, which permits essentially the same process that we just went through, the process of ASC 716, to be used with both the 2012 and the 2015 International Building Code. And then there's also a recent NEHR seismic design technical brief out there that is available discussing seismic design of precast concrete diaphragms and the diaphragm seismic design methodology. So the last thing I wanted to do was thank all the members of the committee. You can see the main committee members and the consulting members here on the screen. Those in bold are folks that helped prepare versions of this presentation at various points of time at other venues, and so I wanted to thank all of them for their help in preparing this slide talk as well. And with that, I went a bit over, but I think I covered it all. Thank you all for your attendance and participation. I think Brenda might take a question or two.

8th edition

Design Handbook

precast concrete structures

committee

load standards

seismic systems

component design

appendices

engineers