C+S December 2021 Vol. 7 Issue 12 (web)

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THE COVER Gondor to Dubai: Chainmail as a Structural Solution – story on page 8 CHANNELS STRUCTURES + BUILDINGS 11 Future Proof 13 Structural Bearings Support Stadium Beam Joints 14 Centene Corporation East Coast Headquarters Charlotte, NC 16 Learning from Roman Concrete 17 Modular Bridging Solutions TRANSPORTATION + INFRASTRUCTURE 18 A Growing Demand for Community-Based Transportation 20 Light Rail Expansion in Seattle 21 To Rehabilitate or Replace: Merchants Bridge WATER + STORMWATER 22 Rebuilding an Underfunded Community in Houston 23 Lane Construction Constructs Storage Reservoir for Everglades Restoration 25 UMA Goes Deep to Anchor Georgia Pump Station 27 A Holistic Approach to Managing Flood Water 29 Wastewater Plant Develops New System With Power from an Old Source BUSINESS NEWS 31 2022 Key Trends to Keep Engineers a Step Ahead SOFTWARE + TECH 33 The Center-Hub of Data Integration 36 The Autonomous Site of the Future is Closer than We Realize; the Time to Embrace it is Now UNMANNED SYSTEMS 38 Engineering Experts Help Communities Prepare for Wicked Weather SURVEYING 40 Survey and Monitoring Tools Enhance Site Safety 41 Into the Woods 43 Generation’s Technical Workforce departments 6 Events 44 Reader Index Columns 5 Engineering Front Line: We Didn't Start this Fire Earlier Tom Godin






VOLUME 7 ISSUE 12 csengineermag.com

publisher Chad Clinehens, P.E. | 479.856.6097 | cclinehens@zweiggroup.com media manager Anna Finley | 479.435.6850 | afinley@zweiggroup.com ART director Maisie Johnson | 417.572.4561 | mjohnson@zweiggroup.com Editor Luke Carothers | lcarothers@zweiggroup.com

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Civil +Structural Engineer (ISSN23726717) ispublishedmonthlybyZweigGroup, Fayetteville, AR. Telephone: 800.466.6275. Copyright© 2021, Zweig Group. Articles not be reproduced in whole or in part without the written permission of the publisher. Opinions expressed in this publication are not necessarily those of Zweig Group. Unsolicited manuscripts will not be returned unless accompanied by a stamped, self-addressed envelope. Subscriptions: Annual digital subscription is free. To subscribe or update your subscription information, please visit our website www.csengineermag.com/subscribe/ or call 800.466.6275.

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WeDidn’t Start this Fire Either

Tom Godin

“… You might enjoy some madness for a while" – from “You May Be Right,” 1980 We don’t know how long these good times will roll. Our advice? Keep hustling. Do everything you can to make your firm a best place to work so that you hold on to what you’ve got. Look for innovative ways to make technology work to your benefit. Our Society “Social justice, DEI, climate change and cleaner skies” When we get busy, we stop doing the “important but not urgent” things on our lists. Marketing, training, mentoring, celebrations – these get pushed aside by AEC firms. “I'd love to stay but there's bills to pay, So I just don't have the time” - from “The Entertainer”, 1974 Don’t manifest this lyric. Not as it relates to marketing or employee experience. Not as it relates to the two defining movements of our time. There is all the work to be done in our industry as it relates to diversity, equity, and inclusion. DEI needs to be on every management team’s agenda in 2022. ElevateHER is an initiative – started by Zweig Group – to better the future of the AEC industry. It is a commitment to embrace, promote, and ensure equal opportunities for everyone in the AEC industry regardless of gender, race, age, sexual orientation, or ethnicity. ElevateHER’s website – has resources that every firm will find useful. The program is also actively recruiting its next cohort. Your energy and effort are necessary. Please engage with this important initiative. Along with DEI, and in fact closely linked with it – our planet and its environment need to be top of mind for our industry too. Worldwide we are hearing intense conversations around Net Zero. The IIA is full of projects meant to combat climate change. Sustainable design and building techniques are inmost firm’s repertoires now and AEC firms need to continue to stay abreast of leading-edge research and engineering developments. At Zweig Group, we intend to make this an area of emphasis in 2022. Ayear ago, Zweig Group Managing Principal Jamie Claire Kiser urged readers of this magazine to “Find your ElevateHER. Respond to your own call to action, whatever it may be. Leave your profession better than you found it.” I can’t improve on that advice for 2022. The voices aren’t going to pass by. Open the door.

Everything I know about the second half of the 20th century I learned from Billy Joel and his 1989 hit “We Didn’t Start the Fire.” In the space of four minutes, he chronicled four decades of world events. With apologies to one of my favorite artists, here is a look back on just one year – 2021. Within Billy Joel’s other lyrics we can also find inspiration for 2022. The Pandemic Pfizer and Moderna, variants and mutant strains. Second wave, third wave, booster shots and mask mandates When this magazine went to press a year ago, a Covid tsunami was breaking. Then case numbers plunged throughout the spring and early summer, helped by vaccines and social measures. By June, it felt like we were approaching a "return to normal". Cue the Delta variant. Cases spiked again in August and September. As I write this, Omicron is dominating headlines. We’ve been living with a persistent undercurrent of existential dread for almost two years now. AEC firms have done a remarkable job adapting, and business by and large has been very good. These are still not normal times, however, as tempting as it is to think otherwise. “I took the good times; I'll take the bad times; I'll take you just the way you are" – from “Just The Way You Are,” 1977 Zweig Group surveysAEC employees for its annual Best Firms toWork For Award. 2020 results represented the high-water mark for positive employee sentiment of their firms’ communications efforts. Our 2021 survey results were clear that employers retreated to old habits. We continue to beat our drum on this topic. Frequent, consistent, insightful communication about the state of affairs may have been “extra necessary” in 2020. It is no less important today than it was a year ago. To the firm leaders reading this: Don't take your foot off the communication pedal. Keep talking to your company. The Industry Return to office, Zoom fatigue, record backlog, steady fees. Talent shortage, rising costs, infrastructure bill proceeds. AEC firms will record excellent year-end financial results. Projects moved forward in 2021, across the United States and in all sectors. Backlog figures are breaking records. Merger and acquisition activity is brisk. The industry is experiencing full employment. Recruiting and retention of staff remains the top priority and concern of AEC managers. The recent passage of the Infrastructure and Investment Act (IIA) will push backlog numbers even higher and put more pressure on staff.

TOM GODIN is an advisor of Strategic Planning at Zweig Group. He can be reached at tgodin@zweiggroup.com.




events + virtual Events

December 2021

Microservices, Cloud Native Architecture, AWS, Machine Learning, Big Data, Enterprise Security, Soft Skills, Measuring and Profiling, Distributed Teams. https://archconf.com/ january 2022 As drones move from being optional extras to essential tools, benchmarking the value associated with creating and maintaining a commercial drone program is critical. Professionals need to understand how drones have proven to enable countless tasks to be performed in faster, cheaper and safer ways that can sometimes vary from region to region all across Europe. At Commercial UAV Expo Europe, we carefully develop conference topics in cooperation with an Advisory Board of esteemed professionals to focus on these kinds of real-world results. We thoroughly vet prospective presenters to ensure they are the best in their topic area and region. The goal: to provide outstanding, actionable information on the critical issues industrial users face integrating or operating UAS to showcase what innovations are making a bottom-line difference today while also providing a glimpse at what’s coming next for UAS across the entire continent and beyond. https://www.expouav.com/europe/ Commercial UAV Expo Europe january 18-20 – amsterdam Amsterdam Drone Week is the global platform for sharing knowledge on current air solutions, potential innovations and vital regulations. A top-level meeting point where all key players, big and small, commercial and non-commercial, from various industries, knowledge institutes and authorities, gather to co-create and co-operate. Creating urban air solutions together. https://www.amsterdamdroneweek.com/ february 2022 Imagine a single powerhouse event that champions the coming together of geospatial technologies and the built environment. Where professionals from a range of disciplines network and gain insight into the increasing confluence of their worlds. Where cutting-edge technology offers new possibilities, improved efficiencies, and better outcomes. And where education opens the door to the future just ahead. AEC Next Technology Expo & Conference, International Lidar Mapping Forum, and SPAR 3D Expo & Conference, along with partner events ASPRS Annual Conference and USIBDAnnual Symposium, are coming together in 2022. https://www.geo-week.com/ Amsterdam Drone Week january 18-20 – amsterdam geo week february 6-8 – denver, co The5th International ConferenceonMaterials EngineeringandApplications february 12-14 – Nha Trang, Vietnam

ENGINEER 2021 december 1-4 – malaysia

ENGINEER is the newest trade exhibition presented by C.I.S jointly organised with Malaysia’s official professional organisation for the engineering fraternity – The Institution of Engineers (IEM). This industry trade event is aimed towards providing engineering professionals in Malaysia and the region with an exciting and unique platform to gain an insight into cutting-edge solutions and advanced engineering technologies by international leading manufacturers. ENGINEER offers invaluable opportunities to network, collaborate and exchange ideas over the four-day event. https://engineermalaysia.com.my/ Enterprise Integration Summit december 9 Digital Transformation - Trends in APIs, iPaaS, Microservices Learn how API Management and cloud-based integration deliver smarter, scalable, easy-to-provision business apps & data. Low-Code Integration - Empower the Citizen Integrator See how 'drag-and-drop' integration empowers self-service for the 'citizen developer' and helps experienced integrators deliver projects faster. Hybrid Integration - Unlock End-to-End Solutions For many large enterprises, legacy apps and data remain the core of business value. Learn the proven mission-critical tools and techniques for connecting on-prem, cloud and mobile. RPA & Integration Automation - Bring Intelligence To Processes F2000s are enjoying big ROI for their analytics, big data, data lake and streaming data architectures – thanks to integration. See why. Security as a Service - Integration Secures the Digital Enterprise The distributed enterprise is stressing traditional security. Learn how top firms use integration for always-on, always updated security with authentication, visibility and control. https://www.idevnews.com/registration/?event_id=522&code=23356 At Tech Leader Summit you'll learn about the latest technologies, hiring methodologies and organizational practices that can help earn a competitive advantage for both you and your organization. Tech Leader Summit is an educational event for Engineering Management and Technical Leaders. Presented to you by No Fluff Just Stuff. Topics Include: Software Engineering Management, Leadership, Talent Acquisition and Training, Agile Methods. https://techleadersummit.io/app/ticket/event/514 TECHLEADER SUMMIT 2021 december 8-10 – Clearwater, fl

archconf software architecture conference december 13-16 – Clearwater, fl

ArchConf 2021 is a one of a kind education event for software architects and technical leads/developers. Presented to you by the No Fluff Just Stuff Software Symposium Series. Topics Include: Software Architecture, Domain Driven Design, Kubernetes, Containers,




It provides an opportunity for the delegates to meet, interact and exchange new ideas in the various areas of Materials Science especially on materials engineering and application. ICMEA 2022 aims in proclaim knowledge and share new ideas amongst the professionals, industrialists and students from research areas of materials engineering and application to share their research experiences and indulge in interactive discussions and special sessions at the event. http://www.icmea.org/ Practical leadership skills are vital to the health and success of every company in any industry. Effective leaders motivate their teams to achieve exceptional results, inspire others to be better than they thought possible, and create an environment where their team is focused and working towards a common vision. Zweig Group’s team of management experts – who have extensive experience working with AEC firms providing solutions to the challenges facing AEC firms today – deliver practical solutions that technical professionals can put to work immediately to lead their firms to success. Leadership Skills for AEC Professionals february 17-18 – New Orleans, la https://shop.zweiggroup.com/collections/seminars/products/ leadership-skills-for-aec-professionals?variant=34602098360471 6th International Conference on Sustainable Energy Engineering (ICSEE 2022) february 18-20 – Hobart (Tasmania), Australia 2022will offer an extensive programof interest to academia, government and industry. It will include several distinguished keynote speakers and three conference days full of papers, posters, etc. A series of exciting speeches to develop skills and advance awareness of requirements engineering practices are of particular interest to industry. http://www.icsee.org/ march 2022 Project Management & Advanced PM for AEC Professionals march 10-11 – tampa, fl This one-day training course covers the critical focus areas every AEC Industry project manager should be familiar with and is presented in lecture, tutorial, and case study workshop sessions. Attendees will leave armed with a comprehensive understanding of the characteristics, skills, and techniques successful project managers must have to flourish in their role. Each team member brings their own unique experiences and skillset to project teams. Effectively leveraging the talents of your team can optimize team effectiveness. Project Management for AEC Professionals provides people-focused, science-driven practical skills to help team leaders harness the power of their team. By addressing the most important aspects of any project – the people – this course will provide practical techniques that can be immediately implemented for a positive impact on any AEC team or business. https://shop.zweiggroup.com/collections/seminars/products/ excellence-in-project-management?variant=34602103013527

Elevating Doer-Sellers march 30-31 – scottsdale, az

Elevating Doer-Sellers: Intensive 2-Day Workshop is a two- day seminar specifically developed to help design and technical professionals in architecture, engineering, planning, and environmental firms become more comfortable managing clients and promoting the firm and its services. Led by two retired and current CEOs with extensive experience from the design desk to the board room, this one- of-a-kind seminar presents business development techniques proven to drive real growth and value in your AEC firm. Beyond the buzzword heavy, ra-ra approach of other business development and sales training seminars, Elevating Doer-Sellers: Intensive 2-Day Workshop focuses on what really works in today’s AEC firm utilizing practical and proven techniques that resonate across the organizational chart. https://shop.zweiggroup.com/collections/seminars/products/elevating- doer-sellers?variant=30892964577352 april 2022

elevateher kickoff april 6-7 – dallas, tx More information coming soon. https://zgelevateher.com/ CEO Roundtable april 21-22 – napa valley, ca

The CEO Roundtable Retreat is a unique opportunity for AEC firm leaders to engage and interact with industry peers to discuss current issues facing firms today, explore industry trends and next practices, and confront the biggest challenges they face leading their firms. Zweig Group’s CEO Chad Clinehens, PE, moderates the program guiding group conversations, encouraging integration and networking, and ensuring attendees gain valuable insight, new ideas and tools – and a new network of colleagues – to foster effective leadership at their respective firms. Come prepared to discuss your biggest challenges and successes during this highly interactive session. With you in control of the subject matter, roundtable discussions strike at the heart of what you need to effect change in your organization. https://shop.zweiggroup.com/collections/seminars/products/ceo-round table?variant=30872181014563




During the Iron Age (1200-300 BCE), nobility and royalty as well as their protectors began wearing shirts of interwoven metal rings to protect themselves. Known as chainmail, this technological improve- ment vastly improved the wearer’s chances of surviving a blow from a sharpened weapon. The earliest versions of chainmail were formed when leather or cloth shirts had overlapping rings of iron sewn onto them, but by the 10th century smiths were fashioning divided chain- mail suits that covered the head, neck, and torso while also facilitating use from horseback. In addition, improvements in industrial practices meant that chainmail was cheaper and easier to produce, meaning that it was no longer exclusively for nobility and their protectors. However, chainmail began to fall out of favor starting around the 14th century with the introduction of plate armor, and fell largely out of use until the late 20th century when it was found to be in- credibly useful when diving with sharks. Now, thanks to Kayne Horsham and his company Kaynemaile, chainmail is making its way back into the conversation. Horsham and his team at Kaynemaile, based in New Zealand, have developed a chainmail material made from lightweight polycarbonate that protects buildings as well as bodies; this update from the iron and steel of centuries past makes the material incredibly robust while still being lightweight. When Kaynemaile is used in place of steel sheets or mesh, it presents several key advantages. For example, Kaynemaile reduces the static load on buildings and cuts down on installation time and costs. Furthermore, Kaynemaile reduces the solar energy and sun- light entering a building, which has been one of its earliest applications in parking garages. Horsham first became familiar with chainmail when he served as an artistic director for the creatures, weapons, and armor department on the set of the iconic Lord of the Rings trilogy. When he was initially approached for the film, Horsham knew he had to not only make the materials look good on film, but also stand up to the rigors of moving to different filming locations over years of shooting. The first material they tried to use was steel, which looked beautiful, but weighed too much. Because the material was to be worn by actors and not battle hardened knights, Horsham knew he had to find a lighter material. Strict requirements set out by director Peter Jackson set aside the pos- sibility of using some sort of painted material. Horsham’s solution was to create a set of plastic rings then coat the rings with pure silver and copper using a process called electroform- ing. The resulting mesh very closely resembled the medieval chain- mail with the pure silver adding a necessary element of fantasy. While this product looked good on film, the labor of creating it was intensive. Each of the links were hand welded individually, which took thousands By Luke Carothers Gondor to Dubai: Chainmail as a Structural Solution

of hours for Horsham and his team. Additionally, because the material was used in all the stunts throughout the film, Horsham and the team constantly had to replace torn or broken pieces. It was during this time that Horsham began to think about ways to make his chainmail, dubbed “Kayne’s-maile” by actor Viggo Mortensen, both stronger and easier to manufacture. After filming wrapped, Horsham briefly worked in miniatures before he started working on a machine to assemble this material. Once this machine was assembled, it was fully automated to create the material, but it still took a lot of time and cost a lot of money. Coming to the realization that he was making chainmail the same way it had been made for thousands of years, Horsham changed direction and focused on creating the rings already assembled. Thus, the liquid state as- sembly (LSA) system was created. Horsham likens it to part printing rather than layered printing in that it “prints a part at a time in a desired position and [builds on] that.” According to Horsham, this paradigm shift in the assembly process alleviated quality control issues because he no longer had to worry




firm Woods Bagot who was familiar with the material from a number of projects throughout the United States as well as Mace Engineering. Woods Bagot was working with the Dubai World Trade Center on a project to create a new exhibition space. Part of this project involved the space between the train station and the new exhibition space. This space would not only need to capture the imagination of crowds enter- ing the exhibition space, but it also needed to shade users from the harsh desert sun. Woods Bagot and Mace had struggled to find a per - manent material to serve as a canopy for the space; they built three test structures using different materials, but none of the three traditional shading methods could stand up to the desert sun and wind. Based on their previous work, the teams decided to use Kaynes maile as the shading material for the project. Horsham traveled to Dubai and began working with the teams to fit the material to the specific designs necessary for the project. It soon became clear that Kaynes maile was able to outperform the other ma- terials due to its unique design and construction. Its seamless design allowed the material to respond to wind force smoothly as the rings are able to move independently from one another. This also means that no one area of the canopy is subject to more constant force than another. In addition, Kaynes maile has unique shading properties that made it the perfect material for the project. The material’s three dimensional

about the strength of each assembled link. With quality control as- sured, Horsham began experimenting with different materials to build the links with. Because of his previous work, he originally intended to use this new process and material in the fashion and costuming industry. Developing the world’s first liquid state assembly process allowed Horsham to develop his mail with modern materials such as polycarbonate, which has a high strength to weight ratio and could give the material applications in the architecture and engineering fields. Once Horsham and his team focused on the architecture and engineer- ing markets, the material applications of Kaynemaile soon became evident. After Kaynes maile became an established company in 2006, their lightweight polycarbonate mesh soon began to feature in art in- stallations and architectural designs. Kaynemaile also poses significant advantages from an environmental perspective. Unlike other materi- als, Kaynemaile is fully recyclable and is created using a “nil-waste” process. Due to this and other structural advantages, Kaynemaile is being used in projects across the world. A few years ago, the Kaynemaile team was approached by architecture


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design simultaneously creates shadow and circulates air, which allows it to function as a radiator and keep the entire structure cool. While this structure had to perform in the desert heat, it also needed to capture the imaginations of the people entering the exhibition space. In this regard, Kaynes maile stood out immediately. The over 120,000 square feet of material dazzles in four colors overhead the entrance to the expo. Wind moves through the overlaid mesh screens, causing shadows and light on the ground to move, breathing life into the space. Horsham and his team call this the “Wondercool Effect”. Kaynesmaile also worked with CD+M Lighting Design Group to use dramatic light- ing effects to further add to the sensory experience. Kaynemaile’s canopy structure is debuting at the Dubai World Expo 2020. This event, which was postponed due to the pandemic, fea- tures exhibits from 192 countries and only happens every five years. Kaynemaile also worked on the New Zealand pavilion for the World Expo. For the pavilion, which is located in the sustainability district, Horsham and his team conceptualized, designed, and created a living building facade. Horsham believes that the uses for Kaynemaile are only limited by the creativity of the user. For example, several parking garages throughout the United States have turned to Kaynemaile in part to combat the heat island effect. Furthermore, because each solution can be customized, Kaynemaile is a scalable solution for a variety of project sizes and needs. As exemplified by Kaynemaile’s selection as a shade canopy

for the Dubai expo space, the future uses of this material will be deter- mined by the problems architects and engineers seek to fix.


LUKE CAROTHERS is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at lcarothers@zweiggroup.com.




Future Proof molded polystyrene Geofoam pre-games construction challenges as airports expand By Sean O’Keefe

Ask any construction professional about their work and most will say they enjoy that every day is a little different. Even after more than 37 years of hands-on experience, Matt Outsen still feels that way. Outsen specializes in complex concrete structural frames for buildings and infrastructure. For the last 12 years, he has been a Superintendent with Ralph L. Wadsworth Construction Company (RLW) of Draper, UT where complex, high-stakes projects are the norm. “Working for one of Utah’s largest builders of heavy highway and mass transit systems puts me in constant contact with challenging construction situations,” shares Outsen. Founded in 1975, RLW specializes in innova- tive approaches to large, complex projects for both public and private sector clients. As a self-performing general contractor, RLW often takes the reins on piling, shoring, drilling, paving, structural steel, and struc- tural concrete on infrastructure, buildings, roads, and bridges to ensure quality and value in many of any project’s most critical elements. “Our greatest strengths are our people and our processes,” continues Outsen. “We are dedicated to safely building the best work possible through a commitment to innovation and continuous improvement.” In the realm of challenging assignments, Outsen has seen his fair share and takes pride in RLW’s reputation for delivering excellence on proj- ects with difficult logistics and tight timelines. One such example is the firm’s recent work at the Salt Lake City International Airport (SLC). The massive redevelopment program intends to right-size the airport for its next generation of life as a flexible, user-friendly, operationally efficient travel hub. The work includes a new terminal and concourses that will have state-of-the-art functionality for users on the inside and significantly more room for aircraft to be maneuvered on the outside. RLW’s work at SLC has included constructing numerous tunnels, foot- ings, concrete slabs, and decks for the Terminal, South ConcourseWest, Gateway Buildings, and associated components. A multi-contract, multi-phase assignment, Outsen has been building structural concrete solutions at the airport for more than five years already and expects to be working there for another two at least. In the area of thinking ahead, for Outsen one of the more unusual concrete elements he has built at the airport so far was a train station in waiting. “The airport’s next step will be to build another concourse, at which time they will add an Automated People Mover system on rails un - derground,” says Outsen. “As part of our concrete scope, we built an underground vault that will one day become the loading platform for the People Mover.” Building a train platform 28 feet below grade within the structural foundation of the new terminal building presented a significant void- fill challenge that RLW had to overcome economically. Carrying the

anticipated live loads of passengers across the sizeable train platform was accomplished through a combination of reinforced concrete and molded polystyrene Geofoam from Atlas Molded Products. “The structural platform consists of six-inch concrete walls every six feet with Geofoam blocks filling in the voids between walls,” says Outsen of the future platform’s slab assembly. Molded polystyrene is a cellular plastic material Atlas molds into blocks as large as 40 x 72 x 288”. A versatile building material that can be stacked, shaped, and even sculpted, Atlas Geofoam economically responds to the archi- tectural specification for a lightweight structural material that can be easily maneuvered in tight spaces. “We dropped the Geofoam down to the site using the opening for the future escalator walkouts with a crane,” says Outsen of the challenging access. “Once it was down there, it was very easy to customize with a hot-wire cutter and put in place by hand.” Outsen has previous experience working with Atlas Geofoam on a variety of architectural and infrastructure challenges and appreciates the company’s willingness to facilitate material orders and deliveries around construction sequencing and logistics. “Atlas will cut blocks to specific sizes based on the drawings. They will organize, stack, and label material orders, and then facilitate a


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for DIA’s existing Automated Guided Transit System, which will one day connect to future Concourses D and E. “The use of Geofoam was as a long-term but still temporary fill mate - rial within the future opening of the new tunnel,” says Heekin of the need for a lightweight yet structurally stable material that could be cost-effectively installed now and removed at a much later date. At approximately 1/100th of the weight of soil, Geofoam’s dimensional stability makes material behavior resolutely predictable. Atlas manu- facturers Geofoam blocks in compressive resistances ranging from 2.2 – 18.6 psi at one percent deformation. “We installed 940 Geofoam blocks that were eight feet long basically by hand. There were very few waste cuts,” continues Heekin. While the logistics of accessibility were similar to those faced at SLC, the big difference on the DIA project is the Geofoam blocks are intended to be removed in the eventual next phase of tunnel construction. “Right now, the Geofoam is sitting on a ten-inch structural slab. When the tunnel extension continues, all the Geofoam blocks will be taken back out completely intact and could even be reused,” says Heekin. Like his contemporary in Utah, Heekin has experience working with Atlas Geofoam to address a wide range of architectural challenges on projects of many sorts and understands the possibilities are virtually endless. “We have used Geofoam to create exterior terraces, outdoor seating, stair configurations, and lots of other applications requiring a light - weight fill,” finishes Heekin. “In commercial construction, new and challenging situations arise almost every day. Atlas Geofoam is a dy- namic building material that cost-effectively solves a lot of architecture and engineering challenges.”

just-in-time delivery whenever needed,” says Outsen of the company’s capacity to support projects with practical logistical assistance. At SLC, once the Geofoam block and rebar grid were in place, Outsen and the RLWteam poured the concrete walls directly within the Geofoam formwork, which remains structurally integral to the finished platform. Justin Heekin also enjoys a challenge. He is a project manager with GH Phipps Construction Companies in Denver, CO, focused on concrete for much of his 25-year career. A Front Range Colorado and Wyoming Contractor, GH Phipps has deep roots in public projects spanning from education to transportation and many in between including recent work at Denver International Airport (DIA). “GH Phipps is committed to building relationships and giving back to the community in everything we do,” says Heekin. In addition to self- performing concrete on all their projects, GH Phipps also frequently subcontracts concrete services to other local, non-competitive contrac- tors. “Our work at DIA reflects our expertise and versatility in concrete. We are providing concrete services on four different concourses as a subcontractor to two different teams of general contractors.” Like their contemporaries in Utah, DIA is also thinking ahead and using molded polystyrene Geofoam fromAtlas to help future-proof facilities. As part of the closing stages of work on the existing Concourse AWest, Heekin and the GH Phipps team built the entrance to a tunnel extension




A time-lapse video proves that Vesconite Superlube low-friction, high- load-carrying bearings perform as well as sliding bearings in large structures, including soccer stadiums. The video starts shortly after 7pm and shows structural movement throughout the evening, when the stadium concrete beams contract due to cooling, and continues past mid-day, when higher temperatures result in expansion. These subtle movements, when allowed by a bearing, ensure the safety and the structural stability of the stadium and the continued support of the superstructure by the support columns’ substructure. Since the stadium was designed to have a capacity of 55,000 specta- tors, expandable to 75,000, engineering performance was paramount to ensure the stadium withstands temperature- and moisture-related contractions and expansions, as well as earthquake and wind loads. History of the stadium The stadium was built more than ten years ago, and has been used for large sporting eventsThe original bearings were a bitumen-im- pregnated cloth. The columns and beams were made from traditional concrete. However, after eight years of use, excessive wear was found to the concrete of the continuous support beams and to the supporting columns. The bitumen-impregnated cloth had been torn or ripped away in some cases, and pieces of concrete in the beams and columns had disintegrated at the corners. Engineers believed that an unfortunate congruency of design and build- ing errors, combined with a choice of original bearing materials not suited to the design, necessitated an urgent review of bearing materials and expansion gap designs. Problem 1 - Small expansion gap All materials shrink and expand as temperature varies, so an expansion gap is required. Concrete has a known expansion rate so it is important that designs cater for this expansion. In this stadium in which Vesconite Superlube was eventually installed, the original bearings, made from bitumen-impregnated cloth, were employed at the expansion gap to prevent the columns from bonding with the continuous beam placed on top of them. The original contractors poured the column first and then used the bitumen- impregnated cloth to separate the column from the continuous beams. For a joint that doesn’t move much this would have been suitable. But, in the case of the stadium, the gap size and the material speci- fied proved inadequate and concrete was ripped out adjacent to the provided-for gaps. Structural bearings support stadium beam joints

Problem2 - Inadequate steel reinforcement and concrete cover Since concrete is good in compression but not in tension, many struc- tures, including bridges, have steel reinforcement to resist tensile forces. The steel tends to follow the contour of beams and columns with a certain amount of concrete cover. This prevents corrosion of the steel and the spalling of the concrete that results from exposure to the environment. However, at the stadium, concrete beam and column corners were inadequately strengthened with steel, and the corners cracked off leaving an inadequate bearing surface. Some steel was badly positioned, possibly because of a lack of over- sight during construction. The poured concrete moved, and the steel was not close enough to the surface to keep the corners strong. The Vesconite Superlube solution The existing bitumen-impregnated cloth was replaced with Vesconite Superlube, which is a low-friction, high-load-carrying bearing material. Since Vesconite Superlube was to be used as a sliding bearing, the bearing material was contained within two stainless-steel plates, which would slide relative to each other to allow for translational movements in a horizontal direction. Unlike various other stainless steel sliding bearing designs, the engi- neering contractor chose a top metal plate that arched down to join the bottom plate so as to reduce the ingress of dirt. The bottom plate was also longer than those traditionally used in sliding bearings and had a lip at each side; the length maintained the horizontal rigidity of the bearing during installation. Since there were significant engineering, design, and maintenance problems in place at the site, installing the Vesconite Superlube bearing solution involved several measures to address existing structural issues: 1. Hydraulic jacks were brought in to lift beams off the support - ing columns. 2. Where concrete columns or beams had had extensive pieces of concrete ripped off them, these were repaired by putting in form work and pouring concrete to ensure that the corners were intact. 3. Saws with large cutting wheels were used to cut out the ledges on which the Vesconite Superlube bearings were to be placed. Since Vesconite Superlube was to be used as a sliding bearing, the bearing material was contained within two stainless-steel plates, which would slide relative to each other to allow for translational movements in a horizontal direction.


DECEMBER 2021 csengineermag.com

mark, the Vesconite structural engineer who was involved in the project. “That is why Vesconite Superlube could be used very effectively here. The benefit is very low fric-tion with wear resistance that is much bet - ter than PTFE,” he says. Another benefit of implementing Vesconite Superlube in this applica - tion was that a smaller bearing could be used, taking advantage of Vesconite Superlube's high load-carrying capacity. “If there is a space constraint, that is helpful to an engineer,” Utermark notes.

4. Epoxy bedding compound was placed on to the stainless steel top and bottom coverings of the Vesconite Superlube

bearing to create a level bearing surface. Vesconite Superlube in structural design

In structural design, vertical load is considered as well as horizontal load. These two loads are used to determine the required column base- strength and the amount of steel and concrete. If there is a bearing on top of the column, the horizontal force that needs to be taken into account depends on the amount of friction at the top of the column. If you have a lower-friction bearing, then an engineer can design for a lower lateral force, which means less steel and concrete is needed for the column. “You want those lateral forces to be minimised,” notes Thomas Uter-

Transforming Healthcare Centene Corporation, a leading multi-national healthcare enterprise, is establishing an East Coast headquarters in Charlotte, North Carolina. The 80-acre campus will accommodate 6,000 employees and will be comprised of one million square feet of office and meeting space, a corporate boardroom, childcare, dining, and a fitness center. A condensed 32-week concrete construction timeline and complex cantilever designs presented a wide array of challenges to construction crews charged with erecting the building. The team turned to PERI USA to deliver a custom-engineered formwork and shoring system on a tight turnaround that would keep them safe and on schedule for Phase 1, including the East tower and parking garage. Critical Support The building design featured cantilevers extending up to 60 feet off the main building without self-support until all floors were constructed. To provide backshoring support on the cantilever, PERI provided a custom solution to support six building floors using Heavy Duty VST Shoring towers until permanent angled metal support beams could be installed. PD5 shoring towers supported the tallest, 30-foot cantilevers. PD5 achieves a high load-bearing capacity 10,000 pounds per leg, even Centene Corporation East Coast Headquarters Charlotte, NC

when extended to a maximum height of 32 feet. Assembly, disman - tling, and transport of the system can be easily done by crane or trolley, and the continuous adjustment makes it applicable for all possibilities. VARIOKIT VST Heavy-Duty Shoring Towers were selected to with- stand the full backshoring loads of 1.5 million pounds on one single tower – a solution requiring a highly technical design and coordina- tion. VST serves as shoring for projects requiring the central transfer of large loads and can be quickly assembled as towers, main beams, or birdcage scaffolding. For the smaller cantilevers, HD 200 Heavy-Duty Props provided backshoring while SKYTABLE slab tables were stripped and flown to the next level in just 10 minutes without moving the props. HD 200 is PERI’s lightweight, stackable prop system comprised of individual prop sections with easy handling, assembly by hand, and flexible ap -




plication. SKYTABLE is a large format table featuring a three-point pick method, best for large slab areas and designed for each project’s building geometry. Product delays throughout the project – including delays in the de- livery of steel support beams – required last-minute adjustments to the shoring support to ensure each tower could hold the load for an extended period of time. PERI USA engineers worked on site with the concrete crew to change solutions on the fly and ensure the proj - ect could safely continue. In addition, the building footprint changed on each level, requiring changes to the formwork and slab systems for each new floor of the building. Each deck was designed as a complex grid with a high-level finish, leading to the decision to utilize the rentable, customized, and adjustable SKYTABLE forms for beams and slabs. The formwork systems also enabled the use of self-consolidating, colored concrete, a slower-drying concrete. This added time to the construction process and further required an easy-to-use and quick formwork and slab solution to speed up the process. Aggressive Demands PERI’s team faced an aggressive timeline and had to meet demands on multiple fronts with the construction of the Centene HQ building.

A typical project of this nature would require a month’s time to prepare after being awarded the work. Based on an aggressive construction timeline, the team had only two days to complete its prep work before the start of construction. A team of eight engineers from PERI USA designed the unique form- work and shoring solutions for the Centene Corporation Headquar- ters. The development of the solutions required a combined 3,000 work hours. In total, PERI USA shipped 250 orders from its facility to the project site, representing nearly $11 million of material in two months. More than half of the orders were shipped out on the same day the order was placed to keep construction moving forward without any delays, all of it occurring during PERI’s inventory season. Every truck to the site included a full system that could be erected immediately upon delivery due to limited holding space. On top of the shoring and formwork system deliveries, PERI coordi- nated the delivery of 18 full and seven partial truckloads of plywood – 6.25 football fields worth – to be used with shoring. With the cost of a single day of delay being $40,000 and to accommo- date the high volume of deliveries daily, Lithko increased the concrete crew to 150 people on site working on a two-shift schedule to keep construction moving for 22 hours each day. Phase One: Complete Construction on the Centene campus will occur in multiple phases over several years. Despite the fast timeline and turnaround time, concrete construction was completed a week ahead of schedule thanks to the collaboration of Lithko and PERI USA and the efficiency of the sys - tems used. PERI’s involvement on phase one began in November 2020 and was completed in June 2021. Phase two is expected to begin in 2024.

Architect: LS3P General Contractor: Clayco Customer: Lithko Contracting Location: Charlotte, NC Products: • PD5 Shoring System • HD 200 Heavy-Duty Prop • VARIOKIT VST Heavy-Duty Tower • SKYTABLE Slab Table • Uniportal • MULTIFLEX Girder Slab Formwork • TRIO Panel Formwork • Plywood


DECEMBER 2021 csengineermag.com

Learning from Roman Concrete By Luke Carothers

For years, engineers and laypeople alike have pondered over the great concrete structures of Ancient Rome, admiring their enduring beauty and awing at the strength and resilience the structures still possess. Buildings like the Parthenon, the Colosseum, and Caecillia Metella’s Tomb have endured conditions, such as earthquakes and fires, that would have caused the failure of modern concrete structures that use Portland cement. Moreover, Roman concrete, unlike its modern coun - terpart, seems to get stronger as time goes on. One of the researchers trying to uncover the secrets of Roman concrete is Dr. Marie Jackson at the University of Utah. Dr. Jackson and her colleagues are studying the tomb of a first century noblewoman named Caecillia Metella which is located along the Appian Way. While not much is known about Caecilia Metella’s life, her tomb has been a source of both inspiration and awe. On top of being one of the most visited antiquity sites in Rome, Caecilia’s tomb is one of the most well preserved. To study the substructure of the concrete in the tomb, Dr. Jackson traveled to Rome in 2006 to collect samples. Dr. Jackson also collected samples from and studied other Roman concrete structures such as Trajan’s Markets. There are several key differences between Portland and Roman con- crete that impact the trajectory of their structures. Portland cement is made by heating limestone and clay to form clinker, then grinding that clinker and adding a mixture of gypsum. When mixed with water and aggregate, it forms concrete. According to Dr. Jackson, Roman concrete was made using the “antithesis” of this process, meaning there is no cement in the material. Roman concrete was almost entirely composed of reactive rock (usually volcanic) and lime. The resulting reactions between the rock and lime, known as poz- zolanic reactions, give the Roman concrete its “unique framework”, according to Dr. Jackson. When Roman concrete was mixed and poured, these reactions resulted in a phase known as C-A-S-H bind- ing (calcium-aluminum-silicate-hydrate). This means that Roman concrete was intentionally designed to change and grow stronger over time. Concrete made from Portland cement is also capable of form- ing these C-A-S-H bonds if there are supplementary materials added, but Dr. Jackson points out that “most times when Portland concrete changes, that’s a bad sign.” When Dr. Jackson and her team analyzed the samples from Caecillia Metella’s tomb, they were initially focused on how the boundaries of the reactive aggregate changed over time and formed new minerals, but they also soon realized that the C-A-S-H bonds were undergoing significant changes. In their samples from Roman concrete structures, Dr. Jackson and her colleagues found that, contrary to previous re-

search, these C-A-S-H materials “dissolved, split, grew nanocrystals, and elongated.” This process was well understood by the Romans. Part of the work Dr. Jackson and her colleagues performed around the time of their first trip to Rome was a retranslation of de Architectura from the perspective of a geotechnical professional. In his famous tome de Architectura , Ro- man architect and intellectual Vitruvius spoke about refined concretes made from hydrated lime and volcanic ash mortar that bind over time around a rock framework, an insight revealed after this new translation was completed. This historical approach also reveals that much of the aggregate material used in these concrete structures comes from the same pyroclastic flow. While some classic Roman structures, such as the Theatre of Pompeii, were built using materials from the top part of this pyroclastic flow, the Tomb of Caecilia Metlla was built using ma - terials from the lower portion of the pyroclastic flow. This means there is a higher natural presence of the mineral leucite in the mortar used to build Caecillia Metella’s Tomb. Over the centuries, groundwater and rainwater have seeped into the substance, dissolving the leucite and releasing potassium into the structure. In a modern concrete building, such a flood of potassium would be bad news. In such a structure, a flood of potassium creates expansive gels, eventually leading to microcracks, spalling, and deterioration of the structure. However, in the case of Caecillia Metella’s Tomb, this potassium dissolved and reconfigured the C-A-S-H bonds, preventing cracks and microfractures. Dr. Jackson and her colleagues are hoping to apply their research to modern forms of concrete. They are currently working with the U.S. Department of Energy ARPA-e to develop modern concrete using the same principles as Roman concrete, replacing tephra with engineered cellular magmatics. This could prove a huge paradigm shift in terms of sustainability with a stated goal of reducing the energy emissions of concrete production and installation by 80 percent and improving the lifespan of marine concrete by four times. LUKE CAROTHERS is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at lcarothers@zweiggroup.com.




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