C+S January 2022 Vol. 8 Issue 1 (web)

Accomplish a year’s worth of geospatial business in just one week by attending Geo Week 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 USIBD Annual Symposium, are coming together in 2022 to form Geo Week. Each event features its own unique conference programming and combines in a single exhibit hall and inclusive networking activities. Welcome to Geo Week! Use code SAVE100 for $100 off a conference pass or a free exhibit hall pass! The intersection of geospatial the built world

FEBRUARY 6-8, 2022 DENVER, CO - USA geo-week.com

Learn more! geo-week.com



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THE COVER A Celebration of Our 2021 Covers

CHANNELS ENVIRONMENTAL + SUSTAINABILITY 8 Climate Pledge Arena - May 2021 issue 10 Underwater Visualization Drives Timely, Successful Habitat Restoration Project - June 2021 issue STRUCTURES + BUILDINGS 12 Hudson Commons: Historic Foundation Meets Modern Engineering in an Innovative Manhattan Overbuild - January 2021 issue 15 Building Value into Sports Facilities - February 2021 issue 17 Engineering Titletown - February 2021 issue 19 Underground Arts Scene: Updating the Museum of Fine Arts, Houston - March 2021 issue 20 When Cranes Fly - September 2021 issue 21 Hernando de Soto Bridge Emergency Repairs: Critical, Complex, Collaborative - October 2021 issue 24 Building Towards the Sun: Vertical Construction in the Middle East - November 2021 issue 26 Gondor to Dubai: Chainmail as a Structural Solution - December 2021 issue TRANSPORTATION + INFRASTRUCTURE 28 Connecting Jacksonville with the Future - May 2021 issue 30 Reimagining Resident Transportation: NYC Ferry System - May 2021 issue 32 Chongqing and Guizhou Organizations Advance Construction of Taihong Yangtze River Bridge - October 2021 issue WATER + STORMWATER 34 Light at the End of the Tunnel: How Technical Innovation and Community Buy-In Turned a 5.6 km Microtunnelling Project into a Huge Success - March 2021 issue 36 Living with Water in New Orleans - April 2021 issue 37 Calling in the K-9 Unit for Water Loss: Tennessee Home to Nation’s First Private Water Leak Detection Dog for Hire - April 2021 issue 38 A Texas-Sized Endeavor - June 2021 issue 40 Washington Project Restores Water for Farmers - October 2021 issue 42 Landfill or Stormwater Detention? - November 2021 issue SOFTWARE + TECH 44 Design Automation is the Necessary Future for Civil Infrastructure - April 2021 issue UNMANNED SYSTEMS 46 Cutting the Cost and Time for Stockpile Surveys in Half with Drones - May 2021 issue 48 Precision and Storytelling: Reid Hu’s “After the Mudslide” Wins 2021 Engineering Drone Video of the Year - July 2021 issue 50 New Ways Contractors are Leveraging Drone Data for Jobsite Management - July 2021 issue SURVEYING 52 Engineering Experts Help Communities Prepare for Wicked Weather - December 2021 issue 54 Mapping the Smart Path to Happiness - August 2021 issue departments 6 Events 56 Reader Index Columns 5 From the Editor: A Celebration of 2021 Luke Carothers






VOLUME 8 ISSUE 1 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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Yearbook of Engineering Achievement (YEA) Award




A Celebration of 2021 Luke Carothers

When 2021 began, there were a lot of questions floating around the industry–questions about sustainabil - ity, questions about the ongoing pandemic, questions about digitization, and more. Our responses to these questions have shaped not only the current state of the AEC industry, but also its future. Projects like the Fayetteville North Carolina Solar Farm and habitat restoration in Minnesota’s Kings - bury Bay demonstrate a growing push in the industry to incorporate a sustainable mindset towards environmental resources. This push was also echoed in several of our stories about unmanned systems and drones, discussing the capability of drones to completely alter our approach design, construction, and stockpile management. However, this is but a fraction of the topics and projects covered by us in the last twelve months. To celebrate the thinkers that have shaped the AEC industry’s discourse over the past year, this issue features some of the best pieces from Civil+Structural Engineer Magazine. These projects and ideas are foundational to how we see and shape the world moving forward. It is our goal to both elevate the AEC industry and celebrate the people who design the world around us. From Dubai to Alaska and back again,this publication has spanned the globe, covering those tackling the problems our industry faces with ingenuity and collaboration. By looking back and curating the best of the past, it is our hope that this issue shines a light into the unknowing of a new year.

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.




events + virtual Events

january 2022 Commercial UAV Expo Europe january 18-20 – amsterdam

adopted in the fields of Civil and Construction Engineering https://waset.org/civil-and-construction-engineering-conference-in- january-2022-in-new-york february 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/ 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/ Amsterdam Drone Week january 18-20 – amsterdam Application Architecture Summit is a multi-vendor virtual event where experts explore application platforms, frameworks and tools for low- hassle and light-speed app development, testing, delivery and security. https://www.idevnews.com/registration/?event_id=523&code=23400 ICCCE 2022: 16. International Conference on Civil and Construction Engineering january 28-29 – new york, ny The International Research Conference is a federated organization dedicated to bringing together a significant number of diverse scholarly events for presentation within the conference program. Events will run over a span of time during the conference depending on the number and length of the presentations. With its high quality, it provides an exceptional value for students, academics and industry researchers. International Conference on Civil and Construction Engineering aims to bring together leading academic scientists, researchers and research scholars to exchange and share their experiences and research results on all aspects of Civil and Construction Engineering. It also provides a premier interdisciplinary platform for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns as well as practical challenges encountered and solutions Application Architecture Summit january 27 – Virtual

geo week february 6-8 – denver, co

Geo Week is the intersection of geospatial + the built world. The event brings together AEC Next Expo & Conference, SPAR 3D Expo & Conference and the International Lidar Mapping Forum into a single powerhouse event. Industries covered include Architecture, Engineering & Construction; Asset & Facility Management; Disaster & Emergency Response; Earth Observation & Satellite Applications; Energy & Utilities, Infrastructure & Transportation; Land & Natural Resource Management, Mining & Aggregates, Surveying & Mapping, and Urban Planning/Smart Cities. https://www.geo-week.com The5th International ConferenceonMaterials EngineeringandApplications february 12-14 – Nha Trang, Vietnam 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. 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/ Leadership Skills for AEC Professionals february 17-18 – New Orleans, la




march 2022

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

Commercial UAV expo september 6-8 – las vegas, nv

Commercial UAV Expo Americas is the definitive event for professionals integrating or operating commercial UAS. With top- notch education, thousands of attendees, and more exhibitors than any other commercial drone event, it’s the best opportunity of the year for anyone who needs to keep up with commercial UAS technology,

trends, and developments. https://www.expouav.com/

ElevateAEC Conference & Awards Gala september 14-16– las vegas, nv

The 2022 ElevateAEC Conference and Awards Gala registration is open for the annual in-person conference in Las Vegas, September 14-16. Celebrate the iconic black-tie awards gala 2022 winners of the Hot Firm list, Best Firms To Work For, Marketing Excellence, Rising Stars, Top New Ventures and the Jerry Allen Courage In Leadership Awards. Register now for the AEC industry’s top IN-PERSON learning and networking event of the year. https://zweiggroup.com/pages/annual-in-person-elevate- leadership-summit

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




Climate Pledge Arena An Environmental and Engineering Marvel By Greg Huber ENVIRONMENTAL + SUSTAINABILITY

It is the gold standard against which all others are measured. People from around the world use its regenerative design framework to create spaces that give more than they take. Structural Challenges The first major challenge was determining how to “recycle” the 44-mil - lion-pound historic roof (designed by Seattle architect Paul Thiry. Meanwhile, the construction crew excavated 600,000 cubic yards of dirt underneath to substitute for the arena’s Y-column and buttresses that held up the historic roof. This was held by seventy-two temporary roof support (TRS) steel columns; each founded 70 to 90 feet below the existing arena floor level. The TRS system also had to resist seismic loads and limit movement to a quarter inch. Mortenson used water jets to remove concrete from the base of the old columns which exposed the steel rebar to allow the team to safely cut and extend the column foundations that were supported nearly 100 feet below grade. The process occurred during most of 2019 and used nearly the amount of steel equal to a modern-day Major League Soccer stadium. Morten - son relied on intense team collaboration, top-down construction, and digital tools to simulate the built environment. And today, Climate Pledge Arena is standing on the original 20 Y-columns and four pronged-buttresses to hold up the roof, originally built for the 1962 Seattle World’s Fair. In addition to maintaining the roof, Mortenson was charged with sav - ing the iconic glass curtain wall that every fan, visitor, and Seattleite will see walking by Climate Pledge Arena, while preserving the view of the Space Needle, cityscape, and more. To accomplish this, each glass panel had to be carefully marked, catalogued, and stored before reinstallation in its original location.

Being chosen by Oak View Group, a Seattle public-private partner and de - veloper, to redevelop the former Key Arena into a brand-new, best-in- world venue and the future home of National Hockey League’s Seattle Kraken and Association’s Seattle Storm, all while keeping its historic landmarked roof intact, has been one of Mortenson’s most challenging and rewarding undertakings. As if this alone wasn’t enough of a challenge, a whole new bar was set when Jeff Bezos from Amazon tweeted in June 2020, “I’m excited to announce that Amazon has purchased the naming rights to the historic Seattle arena previously known as Key Arena. Instead of calling it Amazon Arena, we’re naming it Climate Pledge Arena as a regular reminder of the urgent need for climate action. It will be the first net zero carbon certified arena in the world, generate zero waste from operations and events, and unclaimed rainwater in the ice system to create the greenest ice in the NHL. #ClimatePledge.” At the time of that announcement, the project team had already care - fully planned every aspect of the arena. The structural foundations and building excavation were well on their way, the procurement team was ordering necessary construction components and discussions with local utility companies were underway about how to power the build - ing’s operational needs. Although sustain -

ability was always an important feature to be incorporated into the project, this new goal – to create the first net Zero Carbon certified arena in the world – was the big - gest challenge yet. Luckily, Mortenson and the entire team’s passion and competi - tive spirit drove them to determine how – not if – this could be done. The certification by the International Living Futures In - stitute is the most rigorous benchmark of sustainability in the building environment.




Working towards Net Zero Climate Pledge Arena is working to be the first net Zero Carbon arena in the world, powered exclusively by renewable energy rather than natural gas. The arena will run solely on electric power for daily operations, eliminating all fossil fuels from the building and utilizing the first all-electric dehumidification systems in the NHL. This meant Mortenson had to replace natural gas infrastructure with electrical systems. From kitchen systems and concessions, to air handling units, and building conditioning – all systems were changed to be served by electricity instead of natural gas. Overall water usage is critical to limiting energy use and sustainability goals. Rainwater will be stored in a 15,000 gallon below-grade cistern and filtered as needed for the “rain to rink system.” Waterless urinals and low flush fixtures were added to increase water usage efficiency. The mechanical, electrical and plumbing (MEP) system was also de - signed with efficiency in mind. Energy recovery ventilators, serving all the locker rooms, collect 100 percent of the air that is exhausted and use the captured energy to preheat or cool the incoming air streams. Changing out gas to electrical conversion substations almost doubled the amount of electricity coming into the building, requiring more electrical equipment. With equipment in order, immediate decisions were needed. Luckily important changes were able to be made at the fabrication stage, and the custom electrical equipment production stayed on schedule. Next, situating heavy electrical gear presented a real space utiliza - tion conundrum. Mortenson and the design team needed to determine where the equipment was going to live. Typically, it’s located on the first floor, but construction sequencing hindered that possibility. The entire construction and design team needed to find the best location that was cost and schedule efficient and required the least amount of rework, which resulted in a substation on an elevated metal deck. Renewable Energy The original 160,000 square-foot arena roof is historic and, as such, could not be used to host solar panels. Instead, solar panels are planned to be installed on the roof of the new atrium building entrance and on the facility parking garage. The energy generated by

the solar arrays will be used to power to arena alongside additional renewable energy sources. Project Delivery The construction and design team used several tools to ensure design, construction and marketing efforts dovetailed together to create a seamless project delivery. Mortenson used 4D building information modeling (BIM) as a basis for multi-trade coordination and scheduling. The entire building was constructed virtually to aid with major trade system coordination. For instance, the steel team could use the model to track fabrication and installation tasks. Color coding was used to aid schedulers while tracking procurement, upcoming tasks, and com - pleted work. Using the 4D model, the MEP systems were modeled to not only assist in clash detection (field installation coordination) but also in prefabrication efforts. Changing horses in midstream to create a net zero arena was a major effort by the entire team. Mechanical and electrical contractors were essential in giving their input, as were the architecture and engineer teams that jumped in to determine construction sequencing. Climate Pledge Arena will be a beacon of corporate responsibility across the sports landscape. Together, Mortenson and Oak View Group are setting new sustainable standards for the built environment and inviting others to join The Climate Pledge to reduce carbon emissions for a better future.

GREG HUBER is Project Executive at Mortenson.


DECEMBER 2021 csengineermag.com

The Minnesota Department of Natural Resources (DNR) is facilitating the multi-year, $18-million Kingsbury Bay – Grassy Point Habitat remediation and restoration, a site located in St. Louis County, Minne - sota. The goal of the project is to restore 240 acres of fish and wildlife habitat within a part of the St. Louis River Area of Concern (AOC). Critical to the project is to excavate and reuse excess sediment, remedi - ate and reuse legacy wood waste and remove non-native vegetation. Minnesota DNR contracted Barr Engineering Co. to manage the en - gineering and design, construction administration, and quality control oversight and Veit & Company, Inc. for the construction effort. Begun in 2019, the restoration effort includes: • The removal of invasive cattail from Kingsbury Bay to an offsite disposal location • The removal of legacy wood waste from Grassy Point and reuse of waste to construct small islands in the area • Sediment dredging from Kingsbury Bay and reuse of sediment to restore aquatic and upland habitat The Veit crews also installed in-water stream control structures at the inlets of Kingsbury and Keene Creek, with a little help from technology. Underwater Visualization Founded in 1928, Veit & Company, Inc. has long been a technology leader in the Upper Midwest’s site prep and civil works market seg - ment. Its technology-enabled fleet includes dozers, excavators, motor graders, and skid steers all equipped with 3D machine control systems, as well as rovers, base stations and total stations—all connected to the cloud, enabling the easy transfer of 3D project files to field crews. For the Kingsbury Bay – Grassy Point Habitat project, GPS-guided machine control on excavators was particularly valuable, especially when combined with a Trimble Marine Construction System to track underwater material removal in real time. One of the most challenging tasks in the marine construction environ - ment – whether for dredging, building, or demolition – is working in turbid water including suspended sediments and materials, making it impossible to accurately monitor progress. Conventional practice is for a contractor to estimate the approximate amount of material to be removed or placed on a given site based on experience and pre- construction hydrographic surveys. Once the operator has reached an estimated point of completion, they conduct a post-construction survey for verification and certification, and almost always, the operator must return to the site for rework. Underwater Visualization Drives Timely, Successful Habitat Restoration Project

The Trimble Marine Construction System can be integrated with a single beam echo sounder (SBES) to acquire pre-/post-dredge survey data from below the water and then quickly identify high and low spots, calculate progress volumes and send grid model updates to both the office and the dredge vessel. “We use the Trimble Marine Construction System to track the bucket location in real-time in 3D—a huge advantage in water,” said Britton Lawson, Director of Construction Technology at Veit. “Essentially, the 3D map created by Trimble is the only eyes for the excavator operators to know where they’ve been and where they need to go. Project man - agers are also able to track progress and material quantities moved.” Customer Profile: Veit & Company, Inc. is a leading, technology-progressive specialty contractor with corporate offices in Rogers, Minnesota. The company specializes in earthwork, utilities, foundations, demolition, dredging and industrial cleaning. With an annual revenue of more than $200 million and 100-120 projects running at any one time, approximately 75 percent of the company’s earthwork projects rely on technology including machine control, rovers, total stations and base stations. Business Challenge: Efficiently remove and reuse sediment, legacy wood waste and non- native vegetation to restore the Kingsbury Bay – Grassy Point Habitat. Solution • Trimble Marine Construction System • Trimble Earthworks Grade Control Platform • Trimble Business Center • Trimble TSC7 Controller/SPS986 Antenna • Trimble Siteworks Positioning System • Trimble Remote Assistant




Dredged with Accuracy For the Grassy Point job, Veit used two Liebherr excavators with clam - shell buckets on barge spreads. Each was equipped with the Trimble Earthworks Grade Control Platform using the Minnesota Department of Transportations’ MnCORS VRS Virtual reference station network for instant access to RTK positioning services. “One machine would excavate to design and load the material. Two tugboats moving four hopper barges were used to transport the material to the placement site. The other unit would unload the material, placing it on the seabed to a design grade. This was all achieved with Trimble guidance,” Lawson said. “We also had a Trimble Siteworks Positioning System with a TSC7 Controller that was performing quality control/ quality assurance checks behind both spreads.” The Veit team relied on a remote connectivity cloud platform to remotely manage the units. Bi-weekly as-built progress surveys were completed by survey crews using a single beam sonar. The subsequent surveys were then uploaded to the machines for reference. “The data from the single beam echo sounder was compiled in Trimble Business Center and sent out with plan sheets,” said Lawson. “We used aerial drones to gather topographic data of the island surface above the water and then combined those surveys with the machine mapping data. That process helped significantly to reduce rework. We never had to go back because it was field-verified right away.” The Trimble Marine Construction System makes the process much faster and more accurate. Lawson estimates that the initial excavation is about 50 percent quicker than traditional methods because operators know where the bucket has been and where it needs to go. Lawson added, “With the 3D visualization, we have greater assurance that cut depths are accurate as compared to a mark on the stick. Reducing the time spent returning to a site for rework is invaluable.” Enabled by technology, Veit crews worked 24-hours a day, Monday- Saturday, to complete the required tasks from June to September 2020. Summer 2021 will conclude the restoration project, finishing the cap on the Grassy Point islands using clean sediment removed from Kingsbury Bay, dredging remaining excess sediment from open water

portions of Kingsbury Bay, restoring Grassy Point wood removal ar - eas using sediment from Kingsbury Bay and restoring and reseeding disturbed areas. Lawson concluded, “I cannot imagine performing this project with - out 3D positioning technology. Using the Trimble workflow greatly contributed to our success and reduced our rework to almost none. We would not want to tackle this type of project without the 3D tools we had available to us from Trimble.”


DECEMBER 2021 csengineermag.com

What began in 1962 as a functional-but-unassuming eight-story ware - house on Manhattan’s West Side has become the foundation of one of the most unexpected and fascinating projects in New York City today – the 26-floor Hudson Commons building. Over the years, the cast-in-place concrete building at 441 Ninth Av - enue has been reimagined; notably in the 1980s when it was converted into an office building that retained most of the architectural character from its original era. But it never experienced anything quite like its most recent transformation. When Cove Property Group acquired the commercial property in 2016, they envisioned a vertical expansion of the site to capitalize on the 2005 rezoning of Manhattan’s west side. That left the developer with a decision to make on the fate of the former warehouse: Would they demolish the old building and rebuild from a clean slate, or would they find a way to reposition the existing structure to meet their needs? Early site investigations showed that the robust structure was in good structural condition making it suitable for reuse. Thus, after weighing their options, Cove selected the most cost-efficient solution that would achieve the maximum rentable area: the rehabilitation, retrofitting and reuse of the existing structure. The existing building would add 17 floors and 300,000 square feet of commercial space, creating a sleek new steel and concrete office tower. Now that its transformation is complete, Hudson Commons emerges as a 26-floor, LEED Platinum Class A property that provides 700,000 square feet of rentable office space, topping out at 421 feet. The architect of the renovation and addition is Kohn Pederson Fox As - sociates (KPF), with WSP USA serving as the engineer of record. Mue - ser Rutledge Consulting Engineers (MRCE) served as the geotechnical consultant. The construction manager is Pavarini McGovern (PMG). Best of Both Worlds For the project to succeed, several challenges had to be addressed, from precise demolition procedures without the use of interior shoring, Hudson Commons: Historic Foundation Meets Modern Engineering in an Innovative Manhattan Overbuild By Joseph Provenza, AIA, P.E., LEED AP BD+C; Jeffrey Smilow, P.E., F. ASCE; Yujia Zhai, P.E., Motaz Elfahal, Ph.D., P.E.; and Gerardo Aguilar, Ph.D.

and retrofitting of the existing columns, slabs and foundation systems; to the articulation of the new building core. Shoring can be costly, so it was important to the owner that the project included a plan for shoring-free demolition of a 125- by 25-foot area throughout the existing building to accommodate the new core. In lieu of shoring, the existing slabs were reinforced with a combination of temporary and permanent steel members that provided the required support of the structure. The original structure is comprised of two-way concrete slabs on a 24- by 28-foot grid with drop panels, “mushroom” capitals, and a ma - sonry core providing lateral stability. The low-rise, massive building is representative of the 1960s. The addition takes the form of a sleek modern office tower, which speaks to the 14-acre Hudson Yards megaproject development rising to the west of Hudson Commons. By contrast, the subtle renovation of the original building, which reuses the existing wrap-around brick façade while upgrading the structure to meet current design and construction codes, will keep the project grounded in the context of the neighbor - hood and its 1960s roots. WSP faced several unprecedented challenges that demanded highly in - novative structural solutions if the vision developed by Cove and KPF was to be realized. The existing cast-in-place columns and footings required sizeable retrofits for the gravity loads imposed by the new tower above, and the existing roof slab required extensive retrofitting to accommodate a heavily landscaped amenity space. The most invasive feature, however, was the addition of a new reinforced concrete core linking existing and new construction that would provide the required lateral stability and stiffness for the new taller building.




Photo: Copyright Neoscape, Inc. 2017

capacity to accommodate 17 additional floors. To achieve expansive column-free areas, large spans in the office tower – some reaching 48 feet – amplified the demands at the base of the building where higher loads go to fewer columns. Conversely, a smaller number of original columns required retrofitting for the project. The solution implemented by WSP was the retrofitting of existing con - crete columns employing new reinforced concrete jackets. The first task was the assessment of existing conditions and the study of available construction documents. Although some original drawings were available, core samples were extracted from various locations to determine the in-situ compressive strength of concrete. WSP provided 3D laser scanning services for the entire structure, yielding an accurate representation of as-built column dimensions and locations, the latter being critical to tie in the column grid of the tower above. To minimize potential compatibility problems, concrete compressive strength for the retrofitting jackets matched the one determined through the coring campaign (approximately 5,000 psi). Furthermore, to minimize the increase in column size, large diameter high-strength rebar was used. Reinforcement continuity was critical to maintaining a consistent load path. Ground Penetrating Radar scanning was performed around each column, allowing WSP to map and coordinate locations for holes to be drilled for reinforcement to pass through the existing slabs. Large diameter (#14 bars) and high-strength (Gr 75) reinforcement were used to maintain jacket thicknesses under 12 inches, resulting in 60-inch-maximum-diameter columns. Column capitals were removed to achieve the desired reinforcement continuity and full column bear - ing but were rebuilt during the cast operation to maintain the original aesthetic, which was important to KPF’s vision. The forming and casting of circular columns in the building’s con - strained environment presented a potentially costly and troublesome prospect, so shotcrete was used for columns and capitals. Concrete was placed, compacted and consolidated all at the same time due to the design pressure with which the shotcrete was sprayed.

A Solid Foundation Although the existing structure was bearing on the good-quality sub - strate typical of Midtown Manhattan, the geotechnical composition of the site and its existing foundation elements presented a significant engineering challenge. The bearing capacity of the structure ranged from 20 to 40 ton/ft2, and there was a steep drop-off throughout the site. In addition, the con - straints of working within the confines of an existing structure were immediately evident, particularly for the use of deep foundation ele - ments and the equipment required for their construction. The reinforced concrete core is supported by a new 48- to 72-inch- thick mat foundation bearing directly on sound bedrock. With the core walls in-line with existing columns, consideration of existing column foundations added another layer of complexity. While some column foundations were narrow piers reaching the bedrock, a few columns were supported by larger pile caps. The latter were treated as local interruptions in an otherwise continuous mat foundation with cold joints only. The small footprint of the new core in combination with its eccentric lo - cation translated to large overturning moments, which were addressed by providing 45 600-kip anchors socketed 45 feet into rock. MRCE specified 450-ton micropiles socketed 15 feet into sound bedrock to achieve the required load demand. From these constraints emerged the development of three types of foundation retrofits: • piers-to-rock encapsulating and tied into existing piers-to-rock, • new caisson caps encompassing existing piers-to-rock, and • enlarged caisson caps articulating existing pile caps. Concrete Jackets One major challenge was the original building columns insufficient The addition of a 17-story tower to the original building has resulted in Hudson Commons emerging as a 26-floor building with 700,000 square feet of rentable office space in Manhattan. Photo: ©2017 NEOSCAPE, INC.


DECEMBER 2021 csengineermag.com

The final layer of concrete was applied by a skilled technician using a hand trowel, an aesthetic treatment that left the final appearance indistin - guishable from traditional methods. This application by the construction team was a genuinely innovative feature of Hudson Commons. Lateral-Load Performance To provide stability to both the existing structure and the new tower, a full upgrade of the Hudson Commons lateral force resisting system was required. WSP collaborated closely with KPF on an architectural design that included a new circulation and mechanical core eccentri - cally placed along the north side of the property that would maximize the building’s rentable area. One notable feature of the building’s core is its prominence in the ar - chitectural expression of Hudson Commons as it rises above the exist - ing building. The new spine of the building uses exposed architectural concrete as a tribute to the historic architecture of the neighborhood. The new reinforced concrete core runs from foundation to the top of the building and is comprised of 10,000-psi concrete shear walls ranging from 12 to 24 inches in thickness. WSP envisioned a box-like configuration wrapping the entire mechanical and circulation program that would counteract the torsional effects associated with an eccentric core. In this closed-box layout, the core is placed along existing col - umn lines, and the existing columns create breaks in the shear walls analyzed by considering individual piers at the base building. One intrinsic benefit of this approach was the absence of link beams in the base building, which allowed maximum flexibility with regards to routing services out of the core. Above the existing roof, the walls were connected through reinforced concrete link beams to provide adequate lateral stiffness. Per industry standards, three-dimensional finite ele - ment analysis software was used to model both the existing and new structure, allowing for an optimized and efficient structural design. WSP’s retrofitting approach for the gravity system included the rein - forcement of existing concrete slabs with steel members around the perimeter of the area to be demolished for the new core. Steel members were installed above and below the slab following the bending mo - ment demand associated with gravity loads. Top steel members were removed after casting the core walls, while steel members below the slab were fitted with studs to trigger composite action and remained as permanent bracket connections between the new core walls and the existing slab. This innovative solution resulted in significant savings in terms of both Another feature included in the project is the potential to turn outdoor open areas on the ninth and 25th floors into green spaces for the tenants. The existing structure has been reinforced and designed to allow for landscaping that could include grass, trees and other green uses. It will be the decision of the tenants on those floors, but the structure cost and schedule. Green Showcase

has been designed to allow for the creation of something quite el - egant on those spaces. WSP worked closely with PMG (Construction Management) to deter - mine the most cost-effective approach to accommodate green spaces on the existing roof. The final structural solution was a secondary support system of steel beams installed under the existing slab to support the significant load of a fully landscaped area on the original building’s roof. The structural solution was detailed in such a way as to not penetrate the existing roof, which would have added significant cost to the project. New steel members were designed as non-composite sections to elimi - nate the need to perforate the roof for stud installation, while clips were installed along the beams to prevent lateral-torsional buckling. Nearly every level of the new building features terraces or balconies providing remarkable views of the city and river. Vertical integration between floors is promoted by the exposed stairway, which also al - lows for an exceptional naturally-illuminated interior. Floor-to-ceiling windows further welcomes daylight coverage on each floor. The green roof, daylighting architecture and plans for efficient energy and water systems are features that lead to Leadership in Energy and Environmental Design (LEED) Platinum certification from the U.S. Green Building Council, and Wired Platinum certification. Vertical Vision Hudson Commons was completed in March of 2020 and tenants are now occupying a building that challenged conventional engineering and construction practice. The building has become one of the most innovative adaptive-reuse projects in New York City. This reimagined commercial building demonstrates the potential for large-scale vertical expansion when innovative solutions are applied. With developers and cities striving towards sustainable solutions, the relevance of projects like Hudson Commons is clearly recognized. One rarely comes across a project like Hudson Commons, mixing steel and concrete in a way that perfectly blends the two, taking advantage of the benefits each material offers economically and in an engineer - ing sense. This project provides developers with a methodology and alternative cost-effective, sustainable solutions that could change the way existing structures are upgraded for future use.

JOSEPH PROVENZA is a senior associate at WSP USA Buildings Inc. and served as the firm’s project manager for Hudson Commons. JEFFREY SMILOW served as the principal-in-charge. YUJIA ZHAI was the project director. MOTAZ ELFAHAL served as the structural analysis manager.




We live in a world where spending power can create some pretty wide disparities. Gawdy mansions and luxury cars exist because somebody can afford them, even if most of us are quite comfortable and happy living in a family-friendly house and driving a reliable, modestly- priced vehicle. Similar gulfs in wealth are evident in the sports facility market, where professional franchises and the top major college athletic programs can rely on massive television contracts and booster funds to construct any type of building they deem necessary, with every bell and whistle included to play games, train athletes, or attract recruits. In most of the sporting world, there exists a similar goal of design - ing the best athletic facility money can buy – it’s just that the amount of money to actually work with is much lower. For the majority of universities, schools, communities, or recreation clubs in the process of procuring a new athletic facility, finding the best value is paramount. Cost-Effective Sports Architecture The conversation for many entities naturally begins with traditional brick-and-mortar buildings. This makes sense, since it’s the construction option with which most people are familiar, and there are usually very few question marks about how such a building would look and function. In reality, though, not everyone is in a financial position to spend mon - ey on traditional construction. Many organizations have instead turned toward more affordable alternatives, such as tension fabric buildings. However, even this building category alone offers some drastic differ - ences when it comes to engineering, quality, and longevity. First of all, it’s important to establish how fabric structure styles have evolved in the past decade. More than 10 years ago, Legacy Building Solutions introduced rigid-frame, structural steel engineering to fab - ric building design. Prior to this development, fabric structures were mostly built with web truss framing, a system still prevalent among many suppliers today. By utilizing I-beam frames, fabric buildings instantly achieved more universal credibility. From an engineering perspective, rigid-frame de - sign was a known and proven method. From an end user viewpoint, it essentially provided a conventional approach to building construction, just with fabric material as a more cost-effective cladding for the roof and sidewalls. Custom Fit Besides inspiring more structural confidence, rigid-frame design also opened up a new world of possibilities by providing much more design Building Value into Sports Facilities Rigid-frame fabric buildings offer a high-quality solution for budget-minded projects. By Shannon Humbert and Eric Donnay

flexibility, allowing users to customize their fabric buildings to the pre - cise dimensions necessary for the sports or activities taking place inside. When web-truss fabric buildings first became available to the athletics and recreation market – and even to this day – they were typically sup - plied in standard, pre-engineered sizes. Therefore, if a certain length and width were needed, for example, customers would have no choice but to go up to the nearest available standard size. Another feature of this build - ing style is its curved frames, which can create unusable space along the sidewalls. The end result is that users often have to find ways to fit their building, rather than designing the building to fit their actual needs. With structural steel design, purchasers can start out with a clean sheet and develop a custom building plan from the beginning of the process. If the plan calls for basketball or volleyball to be played near a side - wall, the wall and roof slope can be built high enough to accommodate that activity. If the plan calls for tennis courts, the structure can be designed to USTAguidelines for building peak height and allow for the necessary space around each court. Ultimately, the rigid-frame design provides the ability to value-engi - neer a fabric building. By having their exact specifications met, users can get the space they truly need without paying for excess space or construction materials. Of course, fieldhouses and practice facilities for sports like football and soccer typically do require a lot of space, another area where rigid- frame fabric buildings prove cost-effective. The inherent strength of these I-beam structures, combined with lightweight fabric cladding, allows for long clear span roofs with no support beams. Old-school fabric structures lack the true engineering integrity neces - sary for really long spans. Brick-and-mortar buildings are structurally sound, but the larger the building needs to be, the greater the price difference between traditional construction and rigid-frame fabric buildings, which can be installed at a fraction of the cost. Interior Environment Another construction option that has long been popular, due to its price tag, is steel buildings. While steel-sheeted structures can help fill a certain niche in the industry, their cost-saving advantage gradually disappears as the building dimensions become larger. And no matter


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what size structure is required, steel buildings tend to fail the aesthetics test, generally offering poor lighting and acoustics. By contrast, the interior environment inside a fabric building offers a softer feel, better acoustics with less echo, and much improved lighting due to the reflective properties of the fabric material. People who’ve never set foot inside a fabric sports structure often comment that the atmosphere exceeds their expectations. While having an attractive venue is certainly beneficial to those using or visiting the building, engineers and architects will also take notice that the same materials used to create that welcoming atmosphere are actually serving another purpose in helping to meet building codes. For projects where state or local energy codes must be met, a rigid-frame design allows building suppliers to easily apply insulation – typically with R values ranging from R-19 to R-30 – along the interior of the structure. The insulation is secured and then covered with a fabric liner that is actually the same type of fabric used for the exterior cladding. Polyvinyl chloride (PVC) has the been the primary fabric of choice for sports facilities for many years because of its durability. The fact that users can select different colors of fabric to match their team, school or organizational branding is also a selling point for fabric in general. Leg - acy Building Solutions offers a newer fabric called ExxoTec™ PVC that delivers more durability and a longer life expectancy, due to the added layers of primer and lacquer around its high-strength woven fabric. To install the fabric, Legacy relies on its patented fabric attachment system that uses half-inch diameter bolts to clamp a keder rail to the top flange of the structural steel frame. Fabric panels are then slid through the keder channel to connect to each beam. This process allows fabric panels to be pulled into place with the properly calculated horizontal and vertical tensions. Wider fabric panels are used for the interior than the exterior of the building, but otherwise the process is the same both outside and inside. With the interior liner tightly secured, maintenance concerns for the fabric cladding itself are practically nonexistent. Behind the Scenes For many industries, the I-beams in a fabric building are left exposed and may require some kind of treatment to protect the steel. Since the structural frames in most fabric-cladded sports facilities are encap - sulated by insulation and liners, typically a primer coating is all that needed to treat the beams. That said, building users in coastal locations or who experience high humidity conditions due to their facility application – such as a swim - ming pool – could consider epoxy paint for I-beam treatment to protect against corrosion. Because the steel beams are permanently out of view, some users might choose this option purely for the peace of mind of knowing that the structural frame is well protected. It is worth noting that the rigid frame building design allows for effective passive ventilation within the walls. Ridge and soffit vents use the natural movement of warm airs to help remove moisture from the insulation cav -

ity, another key piece in meeting building codes for a given environment. Hanging Tough Because of the airtight nature of a lined fabric building, air flow is very important, and passive ventilation alone is not enough for most athletic structures. Users will need some sort of mechanical means to at least move air, if not also heat or condition it. Often this means the inclusion of fans or an HVAC system suspended from the building frame above. For a rigid-frame design, supporting hanging loads like HVAC, fire sup - pression systems and lighting isn’t difficult, although it does need to be considered in the original design. Engineers use finite element analysis software to calculate the stresses for each individual I-beam, rather than over-engineering the entire structure and adding unnecessary cost. Likewise, many sports facilities need to accommodate items such as scoreboards, video platforms, court dividers and netting. Some will even need to add mezzanines for spectator seating. By working with the customer to account for every potential collateral load, building de - signers can simply modify the rigid frame to add the necessary strength for those loads. Added Touches While project managers may be primarily focused on getting the most bang for the buck from a fabric building, of course it’s also common to need to appease certain stakeholders with additional flourishes, such as exterior facades containing brick or stonework. While these elements will add cost, the straight sidewalls of a rigid-frame structure do make it possible to easily include these types of touches. Another possibility with I-beam design is adding a fabric-clad addition to the gabled end of an existing structure. Designers need to consider snow loads and rain runoff for the original building and new addition, among other compatibility factors, but for situations where expansion is a more cost-effective solution than new construction, it often can be done. Built Fast, Built Right Rigid-frame fabric buildings can also be completed in far less time from start to finish than traditional brick-and-mortar buildings. While the time to build the framework is similar for a fabric building and a metal-clad structure, fabric panels can be applied in one-third the time needed to screw down metal siding. A big reason for the overall reduction in fabric building lead time is that companies like Legacy are full-service suppliers who can handle every step in the process from start to finish. By employing their own design engineers, manufacturing fabric panels and I-beams in their own facilities, and sending their own in-house professional installation crews to every jobsite, these companies can ensure full quality control and constantly keep projects moving, without any of the unexpected delays experienced by those relying on outside vendors. All things considered, tension fabric structures offer exceptional value for sports venues large and small. From proven structural integrity to a high level of interior finish and craftsmanship, rigid-frame fabric buildings make it possible for any entity to obtain a facility they can be extremely proud of, without breaking the bank.




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