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Precast Protects Life: Transportation and Infrastr ...
Precast Protects Life Transportation and Infrastru ...
Precast Protects Life Transportation and Infrastructure
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Good afternoon. Welcome to PCI's webinar series. Today's presentation is Precast Protects Life, Transportation and Infrastructure. I'm Royce Covington, Manager of Member Services at PCI, and I'll be your moderator for this session. Before I turn the controls over to your presenter today, I have a few introductory items to note. Earlier today, we sent an email to all registered attendees with a handout of today's presentation. The email also contained a webinar attendance sign-in sheet, a guide to downloading your Certificate of Continued Education, and a PDF of today's presentation. The handouts are also available now and can be found in the handout section located near the bottom of your webinar toolbox. If there are multiple listeners at your location, please circulate the attendance sheet and send the completed sign-in sheet back to PCI per the instructions on the form. The attendance sheet is only for use at locations with multiple listeners on the line. If you're the only listener at your location, there's no need to complete an attendance sheet as we already have your information. If you cannot download any of the handouts, please email PCI Marketing at marketing at pci.org as shown on your screen. Note that all attendee lines are muted. The GoToWebinar toolbox has an area for you to raise your hand. If you raise your hand, you will receive a private chat message from me. If you have a question regarding the subject material, please type it into the questions pane where I'll be keeping track of them to read during the Q&A period. Also, a pop-up survey will appear after the webinar ends. Today's presentation will be recorded and uploaded to the PCI eLearning Center. PCI has met the requirements of the AIA Continuing Education System and can offer one HSWLU for this presentation. We are a registered provider of AIA CES and today's presentation contains content that has been approved or endorsed by AIA. Any questions about the content of this webinar should be directed to PCI. Credit earned on completion of this program will be reported to CES records for AIA members. Questions related to specific products or publications will be addressed at the end of the presentation. With hundreds of attendees for our webinars, it's impractical to prepare individual certificates. As PCI has met the standards and requirements of the Registered Continuing Education Program, we will upload attendance data to www.rcep.net within 10 days where you can print your Certificates of Continuing Education. Your login name at www.rcep.net is your email address, so please do not leave that blank if you're completing the sign-in sheet. We need your email address to get you your certificate for this course. Our presenter for today is Jim Snyder, Executive Director of PCI Mountain States. I'll now hand the controls over so that we can begin our presentation. Thank you, Royce, and thank you, everybody, for joining. Let me just get my screen set up here. All right. Let's see. Okay. So, first of all, I am Jim Snyder. I'm, as Royce says, the Executive Director of PCI Mountain States, our chapter of PCI here in Colorado. Okay. So, today we're going to be talking about Precast Protects Life, Transportation, and Infrastructure. So, kind of the concept of Precast Protects Life is the idea that, you know, we're talking about not only physical life safety, like, you know, making sure to keep people and communities safe physically, but also to be able to support the lives and lifestyles and livelihoods of communities and the nation as a whole. So, that's kind of some of the thematic piece we're going to be talking about today and how Precast can contribute to that on the level of infrastructure and transportation. So, our learning objectives today, we're going to define resiliency and discuss its importance in designing the transportation infrastructure of the future, discuss ways in which resilient design and sustainable design intersect, learn about the ways that Precast pre-stressed concrete can be used in infrastructure projects that stand the test of time and protect lives, lifestyles, and livelihoods, and share case examples of safe and durable Precast concrete transportation and infrastructure projects. So, why resilient infrastructure? I mean, certainly we talk a lot about infrastructure, its importance, and why we all need it. And, you know, I think it's always important to reemphasize that point because it is truly what connects all of us and brings our nation together. And the structures that enable the transportation of people and goods that connect our communities and our nation together are vital to our way of life. With climate change bringing on ever stronger storms and harsher weather conditions, it's vital to ensure that our transportation infrastructure is durable and resilient. So certainly, as we are thinking about not only replacing and repairing infrastructure of the past so that it can meet our current and future needs, we want to make sure that it's strong, it's durable, it's resilient, it can hold up to what Mother Nature and humanity is going to be able to throw against it in the coming decades, so they can continue to service us well into the future. And, of course, infrastructure has a long history in this country. It's always been important since the nation's founding, but also always inspires debate over how much to invest in it, how to invest in it, and what it is. You know, it's kind of been one of those things that ever since the beginning has been a debate in opposing forces where it comes to public versus private investment in this country. Because, you know, it is a big, big number investment, often to build these roads, bridges, transportation centers, and things. And these problems in infrastructure policy drove Washington, Madison, and others to form our constitutional form of government in the beginning, so that we weren't just a collection of individual little states, but a federalized union that was able to work together on things that tie us together and build our economy. And this cuts across all different belief systems and political systems within the United States throughout its history. Pre-Civil War era, even a young John Calhoun urged his fellow congressmen to bind the republic together with a perfect system of roads and canals. During the Great Depression, of course, FDR designed a public works program to put more people to work, both directly on public works themselves and indirectly in the industries supplying material for these public works. And then, of course, in the 1950s, most of us are familiar with the interstate highway system that was brought into being by President Eisenhower during that time. Amid post-war peace and prosperity, Eisenhower urged a modern and efficient highway system is essential to meet the needs of our growing population, our expanding economy, and our national security. So the interstate highway system program initiated by Eisenhower remains a gold standard at showcasing the benefits of infrastructure investment. Anytime we're talking about the importance of infrastructure investment, it seems like we go back to that program as this real high watermark in the nation coming together and building something that we all use. It's not just about going to take a road trip to go see your family or something. This is the system that ties the country together, allows the transport of goods and services across those spaces. And so infrastructure today, unfortunately, it's a little bit of a mixed bag. We have lots of issues, as is probably well known throughout the system, lots of things that need to be updated, rebuilt, restored. So unfortunately, federal infrastructure policy and programs haven't really truly modernized to meet the five major challenges facing the U.S. transportation system. These challenges come from a report called the Reform Agenda for the U.S. Department of Transportation that came from the Center for American Progress. Five challenges they see are major injuries and fatalities. Of course, we want our roads and bridges to be safe for transportation. Climate change, which causes issues all throughout the system, congestion, unequal economic opportunity, and also crumbling facilities. And that can relate to things other than just roads and bridges, too. We're also talking about transit stations, airports, things of that nature. That's all part of the idea of infrastructure. This is a quote from the State of U.S. Infrastructure from the Council on Foreign Relations. The $20 trillion U.S. economy relies on a vast network of infrastructure from roads and bridges to freight rail and ports to electrical grids and Internet provision. But the systems currently in place were built decades ago, and economists say that delays in rising maintenance costs are holding economic performance back. Civil engineers raise safety concerns as well, warning that many bridges are structurally deficient and antiquated drinking water and wastewater systems pose risks to public health. Meanwhile, Americans' international peers enjoy more efficient and reliable services, and the U.S. lags behind other developed countries in infrastructure spending. So these are things that we are certainly on our minds as we're trying to move forward into some infrastructure investment. As you're probably aware, Congress passed a bipartisan infrastructure law into effect earlier this year. That is putting some investment back in the system that we can hopefully start to modernize our infrastructure and bring us to a place where we are more on level with other countries. But, of course, for today, we are struggling in a lot of these areas. You may be familiar with ASCE's annual infrastructure report card. This year, or last year, I should say, for 2021, the grade was C- as an aggregate. The report itself breaks down different areas and gets into different grades for different parts and pieces. But a few basic takeaways from it are growing wear and tear on our nation's roads. Our roads have left 43% of our public roadways in poor or mediocre condition. Nearly 231,000 bridges in all 50 states need repair and preservation work. And the largest portion of the investment needed at airports is for terminal buildings. This is something that is part of the whole infrastructure investment we're looking at as well. We need to also modernize airports and facilities surrounding them. So poor infrastructure can impose a large cost on the U.S. economy. It's not just that, oh, by not investing in infrastructure or having it as good as we'd like it to be, it doesn't, you know, it's not just a matter of optimizing our economy and our society. It creates an actual drag on it if we don't do it. In addition to the threat to human safety from catastrophic failures such as or dam breaches, inadequately maintained roads, trains, and waterways cost billions of dollars and lost economic productivity. The delays caused by traffic congestion alone in the economy cost us over $120 billion each year. Airports are another choke point, and we've been hearing plenty of this in the last couple months, too. We've been having issues with airlines and airline staffing and airport structures and things like that have caused us increased delays and different kinds of issues in air travel. And so air transportation services support 1.4 million in U.S. jobs, and international tourism brings in hundreds of billions of dollars of tax revenue. So when those aren't working properly, that causes an issue for us as well. Some studies have found that delays and avoided trips due to the poor state of the nation's airports cost the economy over $35 billion each year. So with all of this in mind, we really want to take the type of infrastructure investment that we're seeing coming forward and hopefully continue that forward and build for tomorrow. So all buildings and infrastructure that we're building today must stand up to potentially catastrophic conditions and protect users, occupants, and communities in the future. So we want to be sure to build things that are not just efficient and useful for today, but also are going to continue to serve their purpose in the future, and they're going to be strong enough to serve communities and the nation for decades, if not centuries. So we want to think about using the most durable building materials and systems possible, and this is where PRECAST can really contribute in the area of infrastructure. So, for example, some of the biggest stressors facing structures in the United States as a whole are earthquakes, storms, and fire. As an example, the National Oceanic and Atmospheric Administration reports there were 195 earthquakes of magnitude 5.5 or greater in developed countries from 1985 to 2015. Of these 195 large quakes, economic damage estimates are listed for only about a quarter of them, and those damage estimates, while large, only really represent the basic damage done to central structures and repair needed for that. What it doesn't really represent, because it's hard to calculate, is what kind of loss was there in lost productivity and business that couldn't go on, lives that were disrupted. So when you start to factor some of those things in, these costs become even larger. And the more complex society becomes, too, the bigger the impact when these things happen. It's not just damage to the structures, roads, bridges, and buildings. It's also the interruption to the lives of communities and the nation. Storms also are a major damage to life and property in the U.S. The impact and damage caused by storms is significant and appears to be on the rise. Between 1985 and 2015, hurricanes alone caused $515.4 billion in insured damage. NOAA again reports that 1,676 tornadoes occurred in 2018 and 2019, causing 21 deaths. This is all billions of dollars in insured losses from tornadoes and thunderstorms. So once again, there's economic damage that's done, there's life damage that's done. It really encourages us to think about durability when we're thinking about structures of all kinds. And wildfires is another issue. And certainly, you know, I live in Colorado, and we've had no share of some, you know, we've had our share, I should say, of some bad wildfires out here. It's certainly all over the West. And the threat and damage from those wildfires appears to be on the rise in lots of parts of the country. There were 58,985 wildfires in 2021, which affected 7.1 million acres compared to just 18,229 wildfires and 1.3 million acres lost in 1983 when official record keeping began. There was a 17% increase from 2019 to 2021 in wildfires in the U.S. And a 223% increase since 1983. So wildfires are indeed a really increasing problem in this country and all around the world, really. Humans cause as many as 90% of wildfires. 2020 wildfires in the U.S. caused $16.5 billion in damages, making it the third costliest year on record. 2017 was the highest at $24 billion, and 2018 a close second at $22 billion. Note again, these figures do not account for indirect damages that I was talking about earlier, which experts estimate costs around $150 billion for the record setting 2018 wildfire season. So these are all things we should be thinking about and planning against when we are designing the structures for tomorrow. The fact is climate change is here. You saw probably or heard about the IPCC report that came out last year. It came out through the UN that predicted that we're essentially already in the meat of what is some significant climate change, and it's going to be getting worse in the coming decades. And frankly, you just have to look to Europe in the past week to see that some of the things they are experiencing there, both in terms of temperatures and wildfires, are things that climate models didn't predict happening for another 20 years. So it's certainly a serious issue. We have to think about what we can do to best mitigate our risk against it and build things that can stand up to the stresses that climate change will bring. And that's weather, fire, all kinds of things. So it's more importantly than ever to build with both sustainability and resilience in mind. Those two things do go hand in hand. I mean, certainly we have to think about reducing our material and carbon impact, and there are ways to think about that with precast as well. But the other part of it is making sure that it's a structure that lasts for a long period of time, because then if you have a structure that lasts for 100 years or longer, you're using less material, less energy, less carbon than something that stands for half of that time, and you have to rebuild it multiple times over that century. So it's important to think beyond first costs and look holistically at the long life cycle. So life cycle perspective means making decisions that take into account long-term operating expenses, environmental impact, maintenance, and overall longevity. So I want to talk a little bit about resilience to start with. So resiliency is the ability of structures and communities to effectively adapt to changing conditions and maintain functionality in the face of stress, environmental change, or extreme events. Resilient communities are those with structures, systems, and infrastructure that are sufficiently durable and flexible to continue operation during or immediately following an extreme event or change. I think on one level, we talk about durability, which is the strength of a structure or material to basically be able to take a punch, to be able to stand up to a fire, to a storm, or whatever it might be. Resilience takes it another step forward and says, can it then continue to function, even after taking that punch? Can this structure continue to operate, continue to serve its community and its people after a severe storm, fire, or other event? Some advantages to resilient design and construction. Resilient structures deliver a long and effective service life. And certainly when we're thinking about transportation infrastructure, these are things that are vital to the operations of our cities, our communities, our states, our country. And we want them to operate well over a long period of time. So we want them to be strong, durable, and resilient. And provide safety and well-being to occupants and users. Again, we saw some of the negative impacts and danger that comes from bridges that are not well maintained or things that aren't doing so well over time. We want to make sure to keep our transportation system safe. Effectively resist hurricane and tornado force, wind, earthquakes, fire, blast incidents, minimize disruption, and reduce recovery time for individuals and communities. So again, that resilience piece is being able to pick up and continue, even after a severe event takes place. So PRECAST is resilient and safe. Resilient to extraordinary loading scenarios, quick to erect, causing minimal disruption, passive fire resistance, protection from multi-hazards such as storms, earthquakes, fires, blasts, etc., able to suffer little damage or quickly return to service after an event. And all of these factors are important for using PRECAST in all kinds of applications, but certainly when we're thinking about infrastructure and transportation structures, these are all extremely important. The thing about PRECAST is it's manufactured in, you know, PRECAST pre-stressed concrete is manufactured in PCI certified plants and under really controlled conditions using optimal mixes and pre-stressing strand gives it that additional strength. And so you're able to have these long spans that we see in bridges and other types of applications. It also is very fast and this is something I'm going to talk a little bit about in this presentation, you know, in that it's important to think about on the whole when we're thinking about infrastructure and transportation projects. It may not be the protects life piece of it, but if you're looking at, you know, all the attributes of PRECAST because we want to use it when we're thinking about transportation projects, speed certainly factors into it because it makes a big difference when you're doing a bridge replacement or some type of infrastructure project to be able to do something quickly so you minimize disruption to a community. That's part of the overall resilience equation too. Passive fire resistance, you know, we'll talk about that, and storms and everything else. So durable, you know, again PRECAST is a very strong, durable material. It's one of its main, PRECAST has many advantages when it comes to sustainability and usability over time, but a lot of it really does come down to its durability. It's very strong, it lasts for a really long time, it does a really powerful job, does it well with minimal maintenance for a very long period of time. So PRECAST is a strong, durable, flexible material that can deliver a hundred-year service life. Its environmental impact is spread out over a long period of time, and that's part of where its life cycle impact comes in too. Its impact is spread out over a long life. Deconstruction and construction are energy and material intensive processes, so the longer a building lasts, the more that impact is mitigated. So PRECAST concrete delivers a long service life. It is inherently protected against corrosion in most environments. Exposed concrete surfaces are hard and resistant to penetration. Concrete is resistant to winds, hurricanes, floods, earthquakes, and fires. It is flexible for refurbishment, retrofit, or change as well. So now we're going to spend some time and look at some case examples of different types of projects in sort of the infrastructure and transportation area that give some examples of benefits in these areas, or why they might have been selected for this. So one study on durability here is State Route 167, 70th Avenue East Bridge Replacement. This is in Olympia, Washington. So this is a project out west here. The 70th Avenue East Bridge Project in Fife, Washington replaced an outdated bridge that was delaying future construction on State Route 167. We can't hear you. Six projects to support, oh I'm sorry, can you hear me? Is there a question? Thank you. Oh sorry. It was the first of six projects to support the Puget Sound Gateway Program, which provides essential connections between the ports of Tacoma and Seattle, ensuring people and goods can move reliably through the region. Washington State Department of Transportation chose PRECAST for this project because the material is durable and cost-effective and accelerated the construction. During the design phase, WUSDOT worked closely with the design build contractors to make sure the final design was even more efficient. The original plan include pre-stressed concrete girders with intermediate piers, including one placed in the median of the heavily used Interstate 5. However, the team at Guy F. Atkinson Construction offered an alternative technical concept that would adjust the bridge alignment and lengthen the girders to span I-5 without the need for the intermediate bridge piers. So the final design features 10 of the longest PRECAST concrete girders ever used in bridge construction. The 220-foot, three-inch long girders were manufactured just a few miles from the bridge site by Concrete Technology Corporation using a high-strength, lightweight concrete mixture which allowed the transport loads to stay within maximum allowable vehicle vertical forces. The design choice was necessary to ensure the transportation of the bridge site would be possible on specialized variable axle trucks. This long-span approach saved months of construction and eliminated the need for multiple disruptive closures and realignment of I-5 during construction. The bridge spans five lanes in each direction and accommodates the ultimate build-out of the freeway in the future. In August 2020, the 10 girders were hoisted across I-5 to form the foundation of the new bridge during two overnight I-5 closures. And it did require some girder adjustments that were able to take place. It was flexible enough they were able to do that during the job and no enclosures were necessary to resolve any issues. And so it's been a successful project for WSDOT and PRECAST was in large part selected because of both its durability and speed here. So this is something that's a long-term investment in a really important transportation corridor there and something that is intended to last for many, many years. Another one on the other side of the country, this one is Little Island at Pier 55 in New York. So this is perched above the Hudson River on a bed of PRECAST flowers. It's a floating park that offers a new open space for New York City locals and tourists to revel in nature and the artistry of its makers. The initial goal of this project was to address costly maintenance of the decaying steel and timber piles on the Hudson River while also creating a new 2.4-acre park space. The solution had to be durable once again and it had to be striking enough to warrant a spot on New York City's famed waterway. The owners were very sensitive to the durability issue specifically on this project, which is what one of the big things that led them to select PRECAST. The project stakeholders knew PRECAST would provide a resilient structure that could withstand the brackish conditions of the Hudson River. They didn't just want another flat pier with a park on top of it, this had to be something special. So originally the owner envisioned the park as like a floating carpet with undulating platform PRECAST concrete that hovered over the river, but the team quickly determined the initial vision wasn't economically or structurally feasible. So after several iterations, the design eventually evolved into a series of blooming tulip shapes that emerged from slender PRECAST concrete stems of varying heights that act as piles in the river. Each stem is topped with a massive PRECAST concrete flower and together those flowers provide a base and structure for the park. The design allowed for consistent loads across the piles while still delivering undulating surface and compelling profile. The team worked closely with a PRECAST concrete producer in this case to figure out the best and most efficient way to create the stems, posts, and pedals to deliver design. So this is something that was built for its durability and also really for its, you know, aesthetic pop. It's got a really special look to it. This is a pretty creative use of PRECAST. Each of the 655 unique pedals and column heads was first developed by an architect and engineer using scripts and three-dimensional modeling. The PRECAST producer then used digital scripting to pull data from the models for shop drawings, reinforcing bar fabrication, and form fabrication. These models are uploaded to a five-axis computer, numerically controlled milling machine, to mill a negative shape of each pedal out of a foam material that could support the weight pressure of the wet concrete. To ensure the proper geometry, the PRECAST concrete producer either dry fitted or 3D scanned 40 of the 132 completed pots in the manufacturing facility. Once the PRECAST concrete pieces were created, they were shipped via flatbed truck to a river port where each pot was assembled using welded stainless steel connection plates. The heaviest one weighed about 88 tons. The pots were then shipped four at a time via barge 120 miles to the project site where they were installed over PRECAST concrete piles, which had already been driven into the riverbed. This carefully timed delivery minimized the needs for laydown space on the job site, which is located just a few feet from the busy Hudson River greenway walking path. From afar, the park appears to have bloomed out of the water atop a giant field of flowers. Visitors to the park can enjoy green space, flower beds, walking trails, and a waterside amphitheater. So this is something that, once again, is intended to be durable, last for a long period of time, and really contribute to this community, even in pretty harsh conditions like in the actual river, and it's making a real statement while doing it as well. Those are a couple of examples of some PRECAST being selected for durability in these types of projects, and next we'll talk about weather resistance. So PRECAST is a really durable material against really strong, difficult weather conditions, which is why we see it used in different parts of the country for that purpose. One example of both the strength and resilience of PRECAST in difficult weather conditions is you may remember the tornado that struck Joplin, Missouri back in 2011. This was a terrible F5 tornado, made national news that year, and pretty much destroyed most of that town. It was a really destructive tornado, 162 lives lost, and a really disastrous hit to this small community. Now one of the few buildings that did survive that storm was a PRECAST concrete big box space, a former Shopko building attached to a mall, and it was identified as one of the few standing buildings in Joplin at that time that had space enough to host an interim high school. It had been vacant for 10 years, but they were able to actually retrofit that building in 55 days so that it could serve as the new Joplin high school. So PRECAST in this case showed to be both durable enough to withstand the onslaught of that terrible tornado, also flexible enough to be able to be retrofitted in pretty short order so that it could be used as a school, and allow that community to continue that piece of its operation. So that is really kind of part of the preserving the life of the community, the lifestyles of the people in it, and having that resilience to be able to continue that piece of the community's function, have its kids go back to school when they're supposed to in the fall. So that's an example of how PRECAST can supply that type of strength, durability, and resilience. And so we see PRECAST used in lots of projects around the country that involve things like community safe rooms or storm shelters or things like that. Safe rooms are becoming more common in communities across the U.S. and are often built into gymnasiums or schools. FEMA requires all safe room building design to be set to requirements for occupancy density, debris missile impact, and suction, as well as be able to stand up to direct wind speeds of 250 miles an hour for an F5 rating. Community safe room systems designed for specific, excuse me, specific FEMA 361 standards create stability with sheer wall panels. This is designed on the requirements of ICC 500 standards for the design and construction of storm shelters. So a PRECAST safe room composed of structural concrete walls requires additional connections and reinforcement to meet required loads. Wall panels are designed for high lateral loads. I mean the strength of concrete goes into, or PRECAST goes into kind of dealing with wind uplift and things like that. A lateral load system consisting of floor and roof diaphragm transferring lateral forces to PRECAST concrete sheer walls and foundations. These safe rooms should be built as individual units. These are usually built maybe along with a school, but structurally they're independent of it because they need to be able to stand up on their own in the case of a severe storm or other event. Just as an example, this is a high school in Kansas that had a storm shelter built onto it. The school is located in an area prone to tornadoes, features a community safe room system designed for FEMA 361 standards made up of three separate safe rooms ranging from 5,300 to 7,600 square feet. Safe room system is comprised of eight inch thick gray structural PRECAST interior concrete walls and 13 inch insulated architectural concrete walls. Additional connections and reinforcement were needed. PRECAST is common in these FEMA projects and is an ideal material for storm shelter requirements. So really I'm kind of getting to all this because it just shows that PRECAST is a material that's really well suited to stand up to storms in all kinds of applications and this includes community safe rooms and shelters and schools and things like that as well as infrastructure projects as well. So PRECAST provides superior protection against physical abuse that can be doled out by severe weather events such as tornadoes, hurricanes, and floods. Inherently resilient provides excellent protection against high winds, storm surge, scour, and flying debris often used in FEMA shelters as well as residential institutional public, government, and other structures requiring extra protection from the elements. So just to show you an example of the durability of PRECAST in the event of storms, this is actually a wind cannon test that PCI performed a number of years ago shooting a two by four at about 100 miles an hour through a few different wall systems to see how they react. I mean obviously we don't see bridges or anything like that built out of these materials but you can see how different materials react to this type of windborne debris. As a vinyl and wood frame wall it goes right through. Brick and wood frame wall also goes right through. Again this is reminiscent of what you might see in like an F4 or F5 tornado when you're talking about windborne debris. So this is not unrealistic to what a structure might face. That's a brick and steel frame you can see that projectile still goes through that. And then there is a PRECAST sandwich wall panel and you can see that the projectile just bounces off of the PRECAST. So that shows you in pretty stark terms the strength and durability of PRECAST pre-stressed concrete. Why we see it used in structures that are intended to hold up against really severe wind and weather conditions. But of course there's other conditions to deal with with environmental weather conditions and various you know mother nature aspects that come against different structures. And we'll talk a couple of case studies here quick for some projects where PRECAST was selected for its ability to deal with environmental conditions and weather. One of these was Veterans Drive PRECAST seawall. This is in the U.S. Virgin Islands. And the goal here was to replace an aging seawall using PRECAST. So the Veterans Drive in St. Thomas Virgin Islands is a two-mile long seaside road that offers breathtaking views of the harbor and the sea and serves as an anchor point for the city of St. Thomas. In 2017 the American Bridge Company contacted WSP USA to provide a value engineering design service to improve a half-mile seawall portion of the road which was badly in need of repair. The project included road widening, pavement reconstruction, seawall construction related work as part of a larger revitalization of the St. Thomas waterfront and downtown Charlotte anomaly. The owner originally proposed a stacked PRECAST concrete block design but the team determined that a structure would be too risky and too expensive. Also the supply of materials at the time was undependable so after considering a few alternative options the team did ultimately select PRECAST concrete counterfort wall design that can be designed and transported from coastal PRECAST systems in Virginia. So the design features individual standard PRECAST concrete wall units composed of a tapered base slab, a wall stem, and single or double counterforts based on height of the soil retained. Some of the counterforts were as tall as 16 feet. The PRECAST concrete producer developed the piecewise layout of the units to ensure they would fit the exact alignment of the project site. The engineer worked with PRECAST concrete producers to define element shapes and sizes and provide input for fabrication, shipping, handling, and installation. To meet aesthetic goals the seawall pieces featured a pigmented base and trowel finish that was achieved through the inclusion of a special PRECAST concrete form liner. To meet the stringent design life and durability requirements PRECAST concrete producer used a high quality marine concrete mixture and stainless steel reinforcement. Once cast the bridges were shipped via ocean barge from Virginia to St. Thomas and placed for storage on the seabed in the vicinity of the final installed location. The use of full height units, the full height units counterfort wall pieces instead of quay wall blocks reduced the number of crane picks from 6,600 that it would have had to have been to only 251. This approach allowed them to reduce the wall installation time by nine months. It also eliminated the need for divers to set blocks which was deemed a significant safety issue. Instead the team used underwater GPS equipment attached to an excavator to guide the PRECAST concrete pieces to the correct height and alignment. First half of the wall required excavation of the existing foundation soils which were replaced with crushed gravel prior to placing the seawall footing. This excavation would have proved very difficult if they had used the original wall design as the risk of wall footing washing out prior to backfilling would have been a real concern. By using PRECAST counterfort wall option the crews were able to place the wall segments to full height with one crane pick followed immediately by backfilling. PRECAST concrete module concept was effective and elegant solution to the seawall design. The concept can be considered to be a viable option for shallow piers, wharves, and other shore protection projects where durability, resiliency, anesthetics are critical requirements. So all these things came into play in selecting this particular PRECAST solution to do this project. You know which again it saved them both time and also gives them the durability they wanted on this. Another one in weather is the Mark Bassinite bridge replacement of the Herbert C. Bonner bridge. This is in Raleigh or this is in North Carolina. All right here we go. The 252,000,002.8 mile long Mark Bassinite bridge spans the Oregon Inlet, one of the most dangerous channels on the Atlantic coast due to its treacherous currents constantly shifting depths and high winds. The condition meant that the original 130 foot wide steel girder span had to be dredged continuously to preserve the required 14 foot channel depth and was rapidly reaching the end of its life. That bridge acted as a lifeline for residents of North Carolina's barrier islands, which meant its replacement had to be reliable and extremely durable. Providing the required 100-year service life for a bridge subject to that extremely harsh saltwater environment was a major challenge. The requirement was met through the extensive use of precast concrete, providing a high-quality, economic, resilient, and low-maintenance structure that can resist 84 feet of erosion, hurricane-level winds, and impacts by the occasional passing ships. So this is a bridge that has to take some abuse, and that is part of the reason why precast was selected for this one. The decision to use precast occurs early in the pre-bid engineering phase, when the design-build team recognized that many of the benefits of the material lent to the project design. Using precast concrete improved quality and durability while reducing costs and shortening project timelines. It also minimized disruption of the environmentally vulnerable barrier islands and lessened the risk of impact of construction on the area's 20 legally protected species, which include manatees, bald eagles, peregrine falcons, and five species of turtles. The precast concrete design also helped to address one of the biggest challenges faced in the project, which is its location. The project site is remote, with limited access for material delivery, and the working conditions in the Oregon Inlet are subject to very fast currents, high winds and surf, storms, nor'easters, and hurricanes, making field work pretty difficult. By choosing precast over fresh concrete, the precaster was able to reliably deliver structural elements to the project site in a carefully timed sequence. Furthermore, using precast concrete elements facilitated much faster, safer, and higher quality construction in a harsh marine environment. To ensure durability in the extremely harsh environment, the pile's final depths are up to 140 feet below the seabed. This depth accommodates the anticipated scour or seafloor erosion, which is expected to remove as much as 84 feet of the seabed, while still providing sufficient embedment into the seafloor to maintain stability and strength. Throughout construction, the team took extensive measures to minimize consequences for the animals and plants throughout the project area. This included the use of a minimum number of driven precast, pre-stressed concrete cylinder piles into the approach structures to reduce impact on the submerged aquatic vegetation beds. They also leveraged a leapfrog approach to limit the length of their work trestle, pulling spans from the trawling end of the trestle and moving them to the leading end. As the construction of the bridge's northeast approach spans progressed from north to south, this greatly minimized temporary environmental impacts. Adding further environmental benefit, excuse me, the original mostly precast concrete bridge was broken down and deposited at several offshore artificial reef sites to provide new habitats for fish. This project met the owner's requirements and created a beautiful and sustainable structure that the community loves. So that's a little bit about weather and storms. Next, we're going to talk about fire, which is another major stressor on structures of all kinds. So fire safety design with precast, first of all, as a material, precast is non-combustible. It's a non-combustible material, fire resistant for that reason. It does perform well against fires, provides fire rated components. And fire resistance is also extremely important. I mean, we certainly talk about it quite a bit when it comes to office buildings and hospitals and other kinds of occupied structures, but it's certainly important when it comes to transportation as well. Durability against fire is extremely important for bridges and infrastructure. Life safety and resilience are the focus here as well. Many of the same advantages we talk about for building, it's non-combustible nature, it's ability to hold up well against fire, apply to bridges too. Some studies have shown precast to perform well against fire. There are a few considerations to take in mind with that though. For one, there was a study, precast highway bridges can encounter various extreme load events during the service life and the events of accidental or natural or manmade fire on bridges is one of the least investigated hazard types. To bridge this knowledge gap, a full scale pre-stressed concrete bridge was tested under combined hydrocarbon pool fire and simulated actual live load, believed to be the first of its kind in the world. The superstructure of this tested bridge comprised of three Texas standard girders, precast deck panels and a cast in place deck. It's conducted for 60 minutes and the fire temperature reaches high as 1,131 degrees Celsius. It was found that the girder deck interface was not impacted by temperatures at those locations. The precast deck panels sustained significant spalling on the fire exposed side and much higher than some of the cast in place overhangs because the form was made of a high strength concrete and the latter of normal strength concrete. So what this essentially means is that the precast, first of all, stood up really well against extreme temperatures and test that continued to function was still in working order. It did experience some spalling that can be mitigated. The bridge would maintain integrity and protect life in that fire situation. There is this issue of spalling with precast, which can create some long-term challenges. So that's something that, you know, other types of projects have looked at and worked to mitigate. One of those examples is our I-70 project right here in Colorado, actually. On the I-70 highway project in Colorado, PCI certified precast or Plum Creek structures participated in numerous tests to improve precast performance against spalling. Testing showed in this case that the use of a fiber mesh in the components and adjustment to the mix design helped to minimize the impact of spalling. Most people appreciate the tendency for explosive spalling to occur as far greater in high density concrete than it is in standard concrete because it's because there's no real escape for internal pressures induced by steam or vapor during the rapid heating of the concrete. So specific to this I-70 project, there are box beams that create the quarter mile long tunnel over I-70. These beams have the additional fire fibers in the bottom six inch lift of the concrete and the beams. Testing was done for these beams in particular and a simple explanation, the fibers allow the steam to escape if there were a fire and to help prevent major spalling and fire getting to pre-stressed wires and normal reinforcing. So that's one way that we can mitigate against the impact of fire on precast. And it still holds up well against it even under some pretty extreme conditions in some of those tests. Another example of, and hey, this is critical infrastructure too. You got to have latrines, right? Like these are in the national park service throughout the country. We have a precaster who makes these small structures that are used in the national parks out of precast. And we've had several that were shown to survive wildfires that took place in the area. Wildfire devastated an area around it and this precast latrine is the only building left standing. So it holds up even under those very severe conditions. We do have some guidance and documentation and publications on fire on pci.org if you're ever interested PCI 12418 is specification for fire resistance of precast pre-stressed concrete. So there's lots of information out there if you want to learn more about fire and fire mitigation with precast. And then I do want to talk a little bit about speed of construction because that does factor into some of these infrastructure projects. We might be thinking about, you know, getting precast selected because of its durability, its ability to stand up against fire weather. But often when we're talking about infrastructure projects, schedule is a big part of it too. So I'm going to talk just a couple examples of how that factor came into play on some of these. One here is the I-94 and Rawson Avenue infrastructure and bridge reconstruction. With the goal to reduce traffic congestion over and enhance overall safety to many of those who use I-94 and Rawson Avenue bridge as the daily commute, it's paramount that reconstruction took place on time. Completely rebuilding and redeveloping a bridge spanning a highly trafficked interstate takes great amount of ingenuity, planning, and preparation. During the reconstruction process for the Rawson Avenue bridge, which spans I-94 just northwest of Oak Creek, Wisconsin, the engineers and construction crews raced against the clock to build and install two new sections as quickly, carefully, and professionally as possible. Both bridge sections were assembled on the side of the road near the construction using Span Creek brand precast products to speed up the fabrication process while ensuring strength and enduring stability. Construction crews used a self-propelled modular transporter to move two bridge sections into position. This project is one of the first in Wisconsin to utilize that method. It was a race against time. Highly trafficked interstate was shut down for only 12 hours overnight for the movement and installation of the new bridge. This use of rapid bridge building model reduced the construction process from six months to just over 30 days, impacting the community with the ability to vastly decrease construction time. Taxpayer money was also saved considerably because of that. Another one is the University of California, San Diego, Mesa Housing, Pedestrian and Bicycle Bridge. The idea here, the University of California, San Diego, it's set in a breathtaking location. However, at the university center is a canyon that separates the main campus from student housing. And historically, the separation caused long travel times for pedestrians and bikers. This new Mesa Housing, Pedestrian and Bicycle Bridge solves that problem, improving acres between the neighborhood and campus. Several bridge types were considered for this project, including steel truss, steel girder, precast concrete girder, and stress ribbon. The designers ultimately settled on a three-span precast concrete spliced girder bridge with 190-foot long middle span. The designers selected for its combined aesthetics, durability, and cost-effectiveness. Use of precast was the option with the highest cost savings, resilience, and durability, and also the least maintenance. So this kind of ticks all of those boxes. And use of the precast girders allowed the additional of all the aesthetics that features that allowed them to make the structure they wanted to here. An extensive analysis of the precast concrete design demonstrated its constructability amid adjacent project construction and steep grades, and proved it could accommodate the environmental restrictions of the canyon, which is home to protected wetland and coastal sage scrub and other habitats. So that's another thing we've seen precast use in a couple of these projects in sensitive environmental areas, and it can be good for that as well. By bringing innovative ideas and solutions to the bridge design and construction process, the team here achieved the balance of safety, functionality, environmental sensitivity, community value, aesthetics, and cost savings. The bridge enhances access and connectivity between the university and the surrounding community, and encourage walking and biking by providing significantly shorter, safer route to almost every part of the campus. Project demonstrates how a precast girder bridge project can evoke a positive image of engineering excellence in terms of architectural design and structural feasibility. It's also a testimony to the fact that precast concrete girders with expanded, I'm going to get this right, extended span limit can be used for architecturally innovative bridge crossings over areas where conventional form work is not feasible or is just too costly. By bringing innovative ideas to the project, the team achieved the balance of safety, functionality, environmental sensitivity, community value, aesthetics, and cost savings. And finally, I want to talk a little bit about some other types of transit projects, because as I mentioned at the top, one of the things we're talking about when we're thinking about new infrastructure investment are things like airports. And so we have a few projects that have used precast in airports as well. In fact, there are quite a few, but we'll just touch on a couple real quickly here. This one is a Phoenix SkyTrain Stage 2. So this is an extensive project or was to connect Phoenix Sky Harbor International Airport's existed elevated train to its consolidated rental car center and new ground transportation center. The goal of the extension was to streamline transportation for passengers and support growth of the Arizona Airport, which is expected to serve 58 million travelers by 2024. It also helped meet the airport's sustainability goals by reducing the daily vehicle count by 20,000. The project included construction of more than 2.2 miles of elevated bridge along with two aircraft taxiway bridges that will carry future airplanes over the below-grade portions of the guideway. Precast concrete was selected as the original design material for all of the bridge superstructures because designers knew its use was the best way to meet the aggressive delivery schedule required for the 2022 opening. Precast concrete was cost-effective and met the aesthetic goals of matching earlier sections of the project. Most importantly, the speed at which precast could be constructed was a big factor here, again, because they were working in a constrained airport environment where maintaining operations is critical. You can't just shut down the airport to do this. You have to be able to continue operating around it. And, you know, obviously Phoenix is a growing metro area, so it needs this additional bandwidth in terms of its airport so this is a way to service that. To support the guideway bridge superstructure, precast concrete U-girders were placed on cast-in-place columns and caps. The taxiway bridges were designed using precast concrete voided rectangular box girders. The facilities access road bridge was also constructed using precast concrete voided slab girders. The U-girders maintain the overall aesthetic of the guideway structure while meeting all the structural and serviceability requirements. The precast concrete producer modified its forms to accommodate a deeper U-girder section, allowing for continuous spans up to 197 feet, eight inches, and to maintain the standard webbed slope with filler forms to increase the versatility of the forming system. Erecting the post-tension U-girder was the biggest obstacle the project team faced as the unit spanned over an active airport terminal building during construction. Spliced precast concrete girders were used to extend the spans and fit the site. The tight site conditions did not allow the team to use temporary falsework supports in the span adjacent to the terminal building, so the precast specialty engineer designed embedded corbel brackets to support the drop-in girders from the adjacent pier girders. The corbels allowed for vertical adjustment within the shim plates and a simple field connection of two bolts per corbel. This accelerated construction method, the girders could be erected in the four-hour time slots allotted for the work. Given the splice location and pier geometry, several of the post-tension pier girders did not have a large enough factor of safety against overturning during the immediate stages of construction prior to casting splices and applying post-tensioning. To ensure the girders remained stable and maintain worker safety, the precast concrete producer and precast specialty engineer worked together to design and cast temporary ballast blocks to sit inside the U-girders during the intermediate construction stages. The girders were erected with the ballast in place to ensure stability when the cranes were disengaged from the girders. After the cast-in-place splices were cast and the girder stability was ensured, ballast blocks were removed. To further accelerate delivery, the precast producer installed electrical conduits on the exterior girder webs at the precast plant before the girders were shipped. This allowed for easier access with the girders at the ground level and saved contractor weeks of field installation. Also created a safer work environment by eliminating the need to install thousands of feet of conduit, which would have required laborers tied off and manless to work in active traffic zone at the airport. And another one just finally here in my backyard in Denver. This is the DIA West Expansion Concourse C Southwest Airlines. So under a collaborative design build approach and a tight schedule, the precast producer completed an 80,000 square foot five gate expansion to the west side of Concourse C at Denver International Airport. Shrestha Khan worked with Wong Stotch Architects and Wunder White Construction Company to design, produce, and erect this total precast moment frame addition in 33 working days while the existing gates were in use. Southwest Airlines sold tickets for the new gate so the project absolutely had to be done on time. Project includes 565 precast pieces incorporated into post-tension moment frames as the primary lateral force resisting system, a unique lateral system in this region. This one won a safety award during construction and it was the first, this award was based on working nearly 67,000 labor hours without injury and zero incident and dark rate for that year. The producer averaged 35 employees on site per day at DIA. So this was all done in challenging weather conditions including negative 22 degree days. The precast portion of the project was completed ahead of schedule. So in summary, the infrastructure of tomorrow needs to be durable, flexible, and able to protect life and continue operation even in the face of severe weather, fire, seismic, and other events. Precast concrete is a long lasting, durable, efficient material that inherently provides the versatility and resiliency needed to meet the demands of the present and future. Also add that it's a fast material. So it's something that can meet today's needs and also tomorrow's. And we're thinking about infrastructure projects as has been noted in several of these, we're talking about bridges that need to be able to operate and get turned around quickly, or airport expansions where you need to have operations happening around and construction needs to happen quickly. So precast also does enable you to have that advantage while also having the long-term advantage of durability, the strength to stand up against storms, fires, and other types of stresses and continue operating well into the future and protecting the lifestyles and livelihoods of communities and the nation. The flexibility and longevity of precast infrastructure means structures can be used and reused for decades, providing excellent performance for generations. And that is all I've gotten. I know we are just about at time, but I do want to thank everybody for joining us today. And I don't know if there's any questions or if you want to send those along later. I thank you for the time. Thank you, Jim. We don't have any questions, but we do have a testimonial for one of the examples you used. Dwight Brinforder is from Joplin, and he says, the Home Depot and the SHOPCO building were both tilt-up construction with bar-joist roofs. Home Depot was in the tornado path and was destroyed. SHOPCO was not in the path and was unaffected by the tornado. So that is a firsthand testimonial firsthand testimonial. So on behalf of PCI, I'd like to thank you for a great presentation. And I'd like to thank all of our attendees for a great participation. If you have any other Q&A, any questions, please forward them to marketing at pci.org and stay safe. Thank you very much. Have a great day.
Video Summary
In this video, the speaker discusses the benefits of using precast concrete in infrastructure and transportation projects. They highlight the durability, resilience, and fire resistance of precast concrete, as well as its ability to withstand severe weather conditions such as storms and hurricanes. The speaker provides several case examples to illustrate the use of precast concrete in various projects, including bridge replacements, seawalls, and airport expansions. They emphasize the speed of construction that precast concrete allows for, which is particularly important in infrastructure projects where minimizing disruption is crucial. Overall, precast concrete is presented as a material that can protect life, support transportation and infrastructure needs, and provide long-term durability and sustainability.
Keywords
precast concrete
infrastructure
transportation
durability
resilience
fire resistance
severe weather conditions
bridge replacements
airport expansions
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