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THE COVER Vertical Construction in the Middle East – story on page 10
CHANNELS ENVIRONMENTAL + SUSTAINABILITY
12 Opportunities and Threats in Utility-Scale Solar Construction 13 Achieving Sustainability by Utilizing Migratory Corrosion Inhibitor Technology STRUCTURES + BUILDINGS 16 BauGrid® Reinforcement Enables the World’s Second Tallest Building to Soar into the Skies of Kuala Lumpur 20 Reinventing the Past: Timber is Making a Comeback 22 Optimizing Indoor Sports and Recreation with Cutting- Edge Fabric Facilities 24 5 Innovative Materials and Techniques for Vertical Buildings 26 Salesforce Tower Chicago, IL 28 Investing in Innovation: The Ion WATER + STORMWATER 29 Landfill or Stormwater Detention? BUSINESS NEWS 31 Using Geospatial Data to Mitigate the Spread of Disease SOFTWARE + TECH 32 Sustainability in Facility Management 36 Giving teachers the tools to prepare students for 21st Century SURVEYING 39 Seeing the Forest for the Trees 41 SAIDEL Engineering Designs First Residential Building above Subway Tunnels in West Bucharest 43 Lighting the Way
departments 8 Events 46 Reader Index Columns 5 Onwards and Upwards Christy Zweig Niehues 6 Looking Back, Moving Forward: Mesas, Cliffs, and the
Ancestral Pueblo Luke Carothers
VOLUME 7 ISSUE 11 csengineermag.com
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Onwards and Upwards Christina Zweig Niehues
The past year and a half has been a time of transformation for the AEC industry – we’ve all adjusted to new scenarios in the way we work, develop business, and manage and lead projects and people. The work engineers do in shaping the built environment is not exempt from this – new technology and new needs from the population have also ushered in what will be a new era for design. We’ve covered some of these amazing projects in this issue – check out methods of vertical construction in the Middle East – and others such as Washington DC’s first mass timber overbuild project and the Salesforce Tower in Chicago. One of these big changes and one of the most controversial topics right now is centered on remote and flexible work policies. Zweig Group’s most recent survey, AEC Workplace of the Future , found that on average, just 47 percent of a firm’s workforce is back in the office full time – but those who are working in the office vs remote are becoming an increasingly homogenous group. More men than women are back in the office (54 percent vs 41 percent), and there’s a straight-line correlation between age and work preference – 72 percent of individuals aged 65+ are in the office, but just 17 percent of those between the ages of 25 and 34. Feelings of productivity were also heavily impacted by the work situation. Those working remotely were seven times more likely to say they felt more productive than pre-pandemic when compared with those working full-time in the office, and 4x more likely to report feeling “more creative and motivated.” Firms looking to alter their policies need to do so carefully – 20 percent of Zweig Group’s survey respondents said they would consider looking for a new job at a different firm in order to retain their ability to work remote, and 10 percent of respondents said they would consider leaving the industry in order to keep this option. It’s clear that remote and flexible work policies are creating more than just a cultural divide in the AEC industry – diversity and the long term viability of firms in our industry is going to be dependent on firm leaders making choices that both support building community, culture, and teamwork among their employees, as well as supporting their desire for workplace flexibility and remote options. With recruitment and retention remaining one of the top challenges for firm leaders, and the vast majority reporting record backlog and demand for their firm’s services, it’s going to be more important than ever to maintain creativity and productivity among every single person working in the AEC industry. Although it’s harder to track than simple utilization rates, as an industry we need to find ways to assess and reward innovative ideas, efficiency, and the other intangibles that lead to great design and a positive work environment. After all, these are the things that make people want to enter (and remain) in this industry, and ultimately produce work that makes our world a better place and take our industry to new heights.
CHRISTY ZWEIG NIEHUES is director of Research & ECommerce at Zweig Group. She can be reached at email@example.com.
looking back, moving forward Mesas, Cliffs, and the Ancestral Pueblo
Located in the American Southwest, some of the world’s most impressive early examples of vertical engineering can be found perched on the walls of deep canyons and along the face of steep mesas. Built by the Ancestral Pueblo, who are also sometimes known as the Anasazi, these structures were complex construction projects that served as apartment-like housing for the population as well as sites for significant religious events. These dwellings were often multiple stories and, in the largest example, could contain up to 800 individual rooms. Earlier in their history, the Ancestral Pueblo were a nomadic, hunter-gatherer society, but by 750 CE the culture had shifted towards a focus on agricultural products like cotton. In turn, larger communities and villages began to form throughout the region. During this period, the Ancestral Pueblo also developed stone masonry, which allowed them to build community structures, known as pueblos, with dozens of adjoining rooms. The development of stone masonry also allowed the Ancestral Pueblo to create larger structures both vertically, in the form of great houses, as well as downward in the form of kivas. By around 1000 CE the Ancestral Pueblo began to build bigger structures to support a growing population. In this pursuit, they turned their eyes downward from their mesas towards the cliffs high above the canyon floor. It is believed that this movement was also a form of defense against raiding parties from neighboringApache and Navajo tribes. Rather than building defensive structures around their cities, the cliff dwellings relied on a single means of egress, a ladder or rope, that could be pulled up in the event of an attack. Their agriculture assets would also be protected high on the cliffs. It is also theorized that this move to the cliffs was done as a way to shelter from wind in the winter and draw heat from the sun. While their exact reasoning for building settlements on what seems like precarious footing will likely never be known, it is clear that these structures were capable of supporting large populations at one time. The Ancestral Pueblo cliff dwellings were made primarily with hand cut blocks and plastered with adobe mortar. Built in a stepped fashion with the highest floors built against the stoneface, many of these cliff dwellings were designed to have terraces on each floor. To create floors and rooms, the Ancestral Pueblo again turned to adobe mortar. The process began with installing large crossbeams followed by smaller branches to fill in the gaps. This structure would be repeatedly plastered over with adobe mortar until it was solid enough to serve as a roof. The largest of these Ancestral Pueblo cliff dwellings is Pueblo Bonito, which is located in modern day New Mexico. In an area of roughly 3 acres, Ancestral Pueblo were able to construct more than 800 individual rooms. Another notable site of these cliff dwellings is the Mesa Verde area, which now forms Mesa Verde National Park. The Ancestral Pueblo inhabited Mesa Verde from around 500 CE to 1300 CE when they were forced out by drought. During this time, the area’s inhabitants created hundreds of dwellings, from the earliest single story clusters of semi subterranean structures along the mesa’s top to the iconic Cliff Palace, which features 217 individual rooms. Archaeological evidence suggests thatmost of the region inhabited by theAncestral Pueblo experienced a severe drought that lasted several decades at the end of the 13th century. This in turn made the traditional method of mesa-top farming unsustainable for the Ancestral Pueblo, and they were forced to abandon their cliff dwellings and seek wetter areas elsewhere. While the Ancestral Pueblo moved to find more suitable living environments and eventually broke into the modern Pueblo tribes, these Ancestral Pueblo left behind an incredible testament to their engineering and architectural prowess, a feat that was not replicated by their descendants following the abandonment of the cliff dwellings.
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 firstname.lastname@example.org.
events + virtual Events
solution led products and services. https://www.b2bmarketingexpo.co.uk/welcome December 2021
business of automated mobility forum november 2-3
AUVSI and SAE have teamed up to host the Business of Automated Mobility Forum: Flight Path to UAM with a very clear purpose: helping companies that are building the future of mobility create an actionable roadmap to success. In support of this evolution, SAE and AUVSI are partnering to host the Business of Automated Mobility: Flight Path to UAM, November 2–3, 2021. This virtual event will equip attendees with the most current regulatory and operational updates about UAM. Topics facing industry and government leaders include vehicle development and production, vehicle management and operations, Unmanned Aircraft System Traffic Management (UTM), safety and security, as well as remote pilot technology and autonomy. https://bam-forum.org/home The first Summit on Drone Geophysics held in November 2020, was by all accounts, a huge success. The more than 130 registered attendees learned about the latest developments in the quickly evolving world of drone enabled magnetometry, electromagnetics, and ground penetrating, along with issues associated with acquiring geophysical data with a drone, and application use cases of drone geophysics technology. The upcoming Summit on Drone Geophysics will build and expand on the themes expressed in the first workshop by placing emphasis on drone geophysical applications. https://seg.org/Events/Summit-on-Drone-Geophysics-2021 Summit on Drone Geophysics 2021 november 2-5 Zweig Group has decided that the annual in-person ElevateAEC Awards Gala will return in 2021. Due to recent guidance from the CDC as well as loosening guidelines from the State of Colorado, the 2021 ElevateAEC Conference and Awards Gala is opening up registrations and restoring the full agenda for the annual in-person conference in Denver, November 3-5. This includes bringing back the iconic black-tie awards gala celebrating the 2021 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. https://www.zweiggroup.com/2021-inperson-elevate-aec-conf-gala/ Welcome to Europe’s leading marketing event, connecting the most proactive marketing professionals with the tools, techniques and innovations they need to be at the forefront of the ever-evolving world of marketing. Research the market, learn about new innovations and discover the latest strategies and trends to progress and develop your marketing in our unique educational programme, consisting of expert- led seminars and panel debates, live demos of the latest technology, as well as industry leading companies equipped with the industry’s finest ElevateAEC Conference & Awards Gala november 3-5 – denver, co b2b marketing expo November 16-17– london
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 archconf software architecture conference december 13-16 – Clearwater, fl ArchConf 2021 is a one of a kind education event for software TECHLEADER SUMMIT 2021 december 8-10 – Clearwater, fl
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, 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 We’re excited to define the next iteration of Geo Week: the coming together of the SPAR 3D Expo & Conference, AEC Next and the International Lidar Mapping Forum (ILMF), as an integrated event covering the intersection of geospatial and the built world. From digital twin technologies to automation, the technologies that allow us to better understand our world are helping professionals across a wide variety of industries to get better and more actionable data quicker than ever before. While Geo Week will explore how these markets, technologies and solutions overlap, anyone seeking updates on the latest AEC technologies will still find them within our event and digital offerings. In a combined conference, you can explore content specific to the AEC Amsterdam Drone Week january 18-20 – amsterdam International LiDAR Mapping Forum 2022 february 6-8 – denver, co
industry and its evolution towards digitization, and also look ahead to where overlap exists. https://www.geo-week.com/
Leadership Skills for AEC Professionals february 17-18 – New Orleans, la
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 march 2022 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. Project Management & Advanced PM for AEC Professionals march 10-11 – tampa, fl https://shop.zweiggroup.com/collections/seminars/products/ excellence-in-project-management?variant=34602103013527
Led by cities like Dubai, the Middle East has seen an enormous growth in large scale construction projects over the last twenty years, particu - larly in the realm of skyscrapers. Iconic structures such as the Burj Khalifa in Dubai and the Ethiad Towers in Abu Dhabi have become synonymous with the vertical expansion of Middle Eastern skylines. Abdo Kardous, President of Hill International Middle East, says the increase in tall building projects in the area is a result of two factors: population growth and wealth gained from oil. In recent decades, several cities in the region have exploded in popula - tion, particularly in the United Arab Emirates (UAE). In 2000, Dubai was home to less than 900,000 people; today, Dubai is home to more than 3.3 million people. Kardous also points out that, unlike in places like the United States and China, there is little to no developed rural land surrounding these cities. Whereas in China, the US, and other similar countries populations migrate from rural areas for work, the working population of many Middle Eastern cities is located within the city itself. This places an even greater emphasis on housing de - velopment within the larger cities, which is a viable use for high rise structures in urban areas. Combined with capital from the oil industry, population growth is fuel - ing an expansion of real estate investment within the region. This in - flux of real estate development is further influenced by the availability of buildable land, the lack of which has driven the price of land steadily upward. According to Kardous, this has caused developers to develop their properties vertically to maximize the available space. In addition, thin, vertical structures are a viable option because there are little to no seismic considerations that have to be made. Even in the areas where there is seismic activity, it is to a much lesser degree than areas such as the West Coast of the United States. Kardous also believes there is another aspect coming into play that is fueling vertical expansion beyond what the economic factors dictate–prestige. The desire to create a landmark structure is demonstrated by projects like the aforementioned Burj Khalifa, which is almost 200 meters taller than the second tallest building in the world, Merdeka 118 in Kuala Lumpur. The construction of the Burj Khalifa, despite numerous setbacks, resulted in an iconic landmark at a staggering price. Aside from cost, there is also instability in some of these projects as a result of shifts in international markets. If international economic markets experience low or stagnant rates, these projects are often affected by way of project delays and cancellations. In addition, there are several considerable challenges associated with construction in hot climates that projects must contend with while Building Towards the Sun: Vertical Construction in the Middle East By Luke Carothers
remaining safe and on-schedule. According to Kardous, the use of concrete is among the most important considerations for high rise projects in the Middle East. Projects must find ways to keep their ready-mix concrete below a certain temperature. One of the more cre- ative solutions includes using ice to cool the water that mixes with the concrete. To ensure that these solutions are practical, there is consider - able logistical planning that needs to take place. This means planning to ensure that there is sufficient time to transport the concrete from the production facility to the construction site as well as enough time to pour the concrete. This becomes critical when it comes to pouring concrete to the project’s upper stories. As such, Kardous notes that the efficient planning not only places the production facility as close to the construction site as possible, but also that the concrete’s transportation route avoids delays from cities and densely trafficked areas. Once the concrete reaches the construction site, these logistical considerations must also contend with the further challenge of pumping concrete higher and higher as the building extends vertically. The extra time af - forded by this planning is especially crucial for projects that reach 300 meters or higher, where Kardous notes that additives must be mixed in with the concrete to keep it malleable. Another challenge to tall construction projects is the vertical transpor - tation of both workers and materials, which can become one of the biggest time consumers on these construction projects. Again, this involves considerable logistical planning to ensure that construction activities such as inspections and maintenance are ordered in such a way that they do not require multiple trips up and down the structure. When it comes to the vertical transportation of materials, Kardous says there are never enough tower cranes and hoists for the project, but, by optimizing their usage, materials can be efficiently transported to their appropriate levels. This optimization usually comes by extend - ing the usage cycle of the lifting equipment from a standard 8-hour work window to a full 24 hours. While this results in longer hours for contractors and workers, it ensures that materials are moved efficiently and the project is completed on time. However, even with potential complications with these prestige- driven projects as well as challenges building in the hot climate, more and more tall buildings are being constructed throughout the Middle East. Led in part by firms such as Hill International, tall buildings
such as the Silhouette Tower in Doha, Qatar where they provided construction and project management services. Kadous believes that this trend will only continue. Currently, the UAE is leading the way in terms of vertical building with both Dubai and Abu Dhabi leading the way for the Gulf Region. Kardous believes that in order for this trend to continue, there needs to be an emphasis on both safety and fire protection. To place a stricter emphasis on safety, there are a few smaller categories into which the subject is divided. Life safety focuses on the means of egress for the occupants of any building or project. This means paying attention to the distance between occupants and their means of escaping in the event of fire or structural damage; it also means including design ele- ments such as refuge floors into buildings. According to Kardous, life safety is directly tied to both the building codes of each country as well as the capacity of the local authorities. Wherever a high-rise building is proposed, the local fire department must have the ability to help the people on the highest floors in the event of a fire. In some places, this greatly limits the available height of new building projects. Once a focus on life safety is established, then the next area of focus becomes protecting the building and its systems. Once all the occupants are safely evacuated, the emphasis becomes protecting the structure, sys - tems, and installations within the building. Although there is a focus on these safety elements during the occupation of the building, Kardous believes that there needs to be a greater emphasis on providing fire safety during the construction phase where there are additional dangers from things like welding and electrical work. There appears to be no slowing down when it comes to the pace of new vertical construction projects in the Middle East. As more projects are scheduled and completed, there will not only be challenges associated with construction and logistics, but also with the use of these build - ings. How this challenge is met will define the landscape of how these projects are handled in the coming years.
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 email@example.com.
November 2021 csengineermag.com
Opportunities and Threats in Utility-Scale Solar Construction By Gene F. Rash and Steven J. Stuart
It is no secret that the current presidential administration’s pursuit of 100 percent clean energy by 2050 should be a boon for the already growing solar industry. Estimates vary with some analysts predicting unprecedented growth rates for any industry. Increasingly, there will be more opportunities in both the public and private sectors, with cor - related risks to companies serving the sector. Aside from the growing number of utility-scale solar facilities, several legislative initiatives will help ensure the success of smaller new con - struction and retrofit opportunities. Each project-type has unique legal considerations. Due to each of these author’s respective involvement in a wide variety of power plant projects, this article highlights specific opportunities and threats inherent with constructing solar facilities given the investment push in solar energy. The Substantial Completion Deadline is an Expensive One to Miss For either a photovoltaic (“PV”) or concentrating solar thermal (“CST”) power project, construction work itself can proceed rapidly and often must because of the involved tax credits, investment terms and loan guarantees that are central assumptions to business cases justifying the construction of a large facility. Typically, an EPC (engineer, procure, construct) contract arrangement is utilized by project owners. Solar project investors and owners prefer the EPC arrangement in large part because the EPC contractor manages the entire project’s design and construction. Accordingly, the EPC contractor and the subcontractors carry large amounts of risk under tight timelines in exchange for the contract price. Sophisticated contractors are accustomed to managing long-lead items within the normal climate of the construction industry. But contin - gency plans for failed equipment such as PV modules, actuators, or electrical substation components must also be implemented. Early emphasis on understanding and planning for SCADA requirements rather than awaiting the end of the project to address the same is a typical best practice. Managing risk has become even more difficult with the current climate of material escalation, manpower shortages, and production delays. Sizeable liquidated damages associated with failing to meet substantial completion are a common hazard. Not surprisingly, substantial completion typically drives the project’s critical path. Substantial completion is often tied to the facility’s ability to produce power and connect to the power grid – both dates being their own important milestones carrying discrete subtasks. Like with
all contracts, the words matter. How substantial completion is mea- sured and defined is critical for the project team to understand and work towards. Often, substantial completion does not require completion of the entire project site’s civil scope of work. This can mean that important compo - nents of civil work remain after substantial completion, and, depending on the remaining civil scope and necessary modifications to the same during construction, perhaps due to changed conditions, the remaining civil work can carry substantial cost. It is much more expensive to perform civil work after array installation and initial operation of the facility. It is exceptionally more expensive where significant grading and retrofit applications, such as adding stormwater pumping systems or redirecting stormwater through other means, are required for ulti- mate operation and maintenance of the facility. Proactive, consistent collaboration, communication, and management of expectations are central tenets of a successful solar project. Each Project Site Is Unique Due in part to the sheer size of utility-scale solar facilities, local condi- tions often spawn issues. These range from the abilities, quantity and cost of skilled workers to variables such as the soil conditions at the site. The contractor’s means and methods should account for the unique site access and soil conditions onsite while maintaining productivity and installation tolerances of completed components. For example, in dual- use agrivoltaic facilities, the EPC team must be careful to not overly compact the native soil during construction because of the negative effects on planned crop growth. The spacing below and between the trackers is also critical for the dual-use function. In closed basin site locations, native infiltration rates may be the relied on means for surface water management. Sloppy earthwork operations or lack of stormwater management during construction – and many other factors – can severely impact the assumed native soil infiltration rates, increasing the risk of flooding within the solar plant site itself, particularly in closed basin sites, or downstream in open basin sites. In open basin site locations, water runoff and erosion control must be actively managed. In either type of basin, absent an easement or other legal mechanism, it is typically required by the pertinent jurisdictional authority for post-development surface water runoff to not exceed pre-
development surface water runoff. Over the course of several hundred acres, a slight deviation in slope or stormwater infiltration rate can have enormous impacts on surface water management. Perimeter and interior access roads also often cause challenges. It may seem simple, but the project team should agree on the width of the roads early on – critical for equipment to clean panels in arid conditions and maintain vegetative growth in other conditions. Likewise, the project team should agree early on the required surface of the roads – whether they are gravel or native soils, for example. Within the context of meet - ing the seemingly more complex power generation requirements for substantial completion, site grading, maintenance, and operations can evolve into an expensive afterthought. Like all construction projects, cohesiveness between owner-provided documents and contractor-generated documents helps ensure mutually acceptable final conditions and payment. An owner should expect a contractor to rely on owner-provided geotechnical reports and bor- ing reports. These are valuable documents but limited by their innate sample-sizing. Rock, structurally inadequate soils, high groundwater, and existing infrastructure are not uncommon to incur during foundation and pile installation. Like retroactive grading after substantial completion, The request for long-term concrete structures without premature need for maintenance and repairs is growing rapidly all over the world. Clients have asked for structures, tunnels, or bridges to be designed to satisfy a specified service life, usually around 100 years and sometimes even 200 years. This surpasses the design life of traditionally used codes and standards. Usually, the durability is ensured by adopting rules and standards such as Eurocode, AASHTO LRDF, BS, or DIN. Unfortunately, these rules that are based on experience and research have many faults and can very often result in durability design that is not adequate. Codes and standards that we use today are too often insufficient, and we cannot rely just on those standards. The term ‘du- rability’ started being considered just as important as ‘structural safety’ about 40 years ago. Engineers, contractors, and owners had to learn Achieving Sustainability by Utilizing Migratory Corrosion Inhibitor Technology
retrofitting or remediating inadequate foundations and piles late in the project can be very expensive. Owners and EPC contractors must have fair contractual mechanisms, like differing site conditions or changes clauses, to equitably address the unforeseen and to progress with the project. In Closing Due to the unique characteristics of solar power generation facili- ties, along with the rapid improvements in technology and speed of construction, solar is attractive in many areas with favorable condi - tions. This includes both fast developing countries and the United States. Aside from innate climate characteristics such as cloudy or rainy days, solar offers a predictable output of power that benefits investors, owners, users and ultimately spurs economic growth. The coming years will further prove out solar power’s immense benefits and capabilities, so long as the industry mitigates the risks inherent with the anticipated growth. GENE F. RASH AND STEVEN J. STUART are partners with Smith Currie & Hancock, LLP, a leading nationally ranked construction law firm. Their practices include contract drafting and litigating large-scale utility and infrastructure projects throughout the United States and abroad. They can be reached at firstname.lastname@example.org and email@example.com, respectively. Learn more: www.smithcurrie.com. more about the fact that environmental impacts are irreversible and they worsen with time. This happens, for example, because of the ac - cumulation of chloride ions in concrete exposed to salts or sea water. How to approach durability design? Most standards as well as design codes for concrete structures have a “wish-to-satisfy” approach to the design and specification of reinforced concrete in various exposure environments, including exposure to chlorides. Design life has not been included as a consideration except the obvious time-dependent nature of the risk of concrete deterioration such as reinforcement corrosion. Today, design for the durability of new reinforced concrete structures is based on a prescriptive approach. Environmental impacts are characterized in exposure classes in EN 206 and the resistance of the structure to these impacts is defined by a set of requirements, e.g., concrete strength class, w/c ratio, cement content cover depth, crack width needed to achieve the required ser- vice life without major repair work (for bridges, usually 100 years). The design, construction, and planned maintenance of a concrete structure have to lead to the intended level of safety and serviceabil - ity throughout its entire service life. It is very important for designers to understand the basic deterioration mechanisms and the potential types and rates of damage development. For example, different types of corrosion cause very different damage developments, some of which reduce structural safety.
November 2021 csengineermag.com
According to certain engineering regulations, the durability and de - sign of structural lifetime is often around 50 years. It can be greatly extended with regular maintenance; otherwise the structure should be demolished and rebuilt. By using MCI® Technology in severely corrosive environments, structures will have a stronger resistance to corrosion and therefore longer durability. Increased durability means fewer repairs, enhanced structural integrity, and a longer service life, all leading to greater sustainability. To put it more simply, maintenance is essential to avoid fatal tragedies like the one we witnessed when a residential building in Florida suddenly collapsed. Structural engineers were shocked that this would happen to a building that had stood for decades. Engineers are conducting a preliminary review in order to help understand the collapse. Such a failure suggested a foundation- related matter—potentially corrosion or other damage at a lower level. Corrosion is the deterioration of materials over time. It is a serious problem for engineers who use metal products in their structures, be - cause it can be a huge safety hazard. Ignoring this powerful force can have tragic consequences. The three major potential consequences of corrosion are 1. Life threatening accidents resulting in loss of life 2. Economic costs involved in rectifying the corrosion damage 3. Environmental damage threatening the ecosystem How to Build and Maintain Durable Structures During the last two decades there have been huge advances in technol - ogy to extend the lifespan of structures and avoid possible tragedies. Patented MCI® Technology was designed to protect reinforcing metal in concrete from corrosion and is widely used around the globe. The application of MCI® products has experienced rapid growth in recent years due to a number of factors such as proven efficiency and envi- ronmental advantages. By using this technology, corrosion initiation is delayed, and the lifecycle of structures is significantly extended. One of the most efficient uses of Migrating Corrosion Inhibitors (MCI®) is when applied directly during the construction phase as well as being used as a part of the maintenance repair system in existing structures. Sustainable construction has become a goal for owners across the globe. Often overlooked is the aspect of durability and service life for the final structure. However, this is undoubtedly one of the main factors influ- encing structural sustainability. Many MCI® inhibitors are made from a renewable raw material, enabling users to earn certain LEED credits.
Corrosion Protection of Coto del Rey – El Vendrell Water Tank The Consorci D’Aigües De Tarragona (C.A.T.) needed to construct a 25,000 m³ capacity regulating water tank in the Coto del Rey area in El Vendrell , Spain in order to increase the supply and security of their water source. Given previous problems in other C.A.T. facilities, they decided to add corrosion protection to each of the reinforced concrete elements included in the project. The tank at Coto del Rey is rectan - gular: 88 m long, 63 m wide, and 5 m high. Once the problem and potability considerations had been established, Cortec’s MCI®-2005 coating was selected for admixing into 3,800 m³ of concrete containing 289,000 kg of corrugated steel reinforcement. MCI®-2005 dosage rate was 0.6 L/m³. C.A.T. had previous experience using MCI®-2005 for water structures in 2003 and 2016 and chose it once again in 2021. A key factor in their decision was the admixture’s certification to meet NSF Standard 61 for use in large potable water structures. MCI®-2005 will be an important protective measure against attack by chlorides and carbonation in order to extend the durability and service life of the new water tank now and in years to come. Repairing and Extending Service Life of Höganäs County Water Tower The water tower in Höganäs County, Sweden was built in 1978 and was designed for at least 50 years of service. The height of the tower
Croatian Overpass Preservation The customer required protection to prevent against future corrosion- and to create a better appearance of the overpass.The concrete surface was water blasted to remove dirt, oil, and grease. Once dry, MCI®- 2020 Powder was applied by brush tothe surface and allowed to dry for 24 hours. Then MCI® Architectural Coating RAL 7035 (Gray) was applied as additional corrosionprotec- tion and a more appealing appearance within thelandscape. Cortec® provided an innovative solution to protect the overpass against future corrosion and provided an additional protective coating that offered a more natural look. The Spanish government requested renovation of the Leon bridge in Ruitelan, Spain. The goal of the project was to protect the highway bridge form corrosion. Corrosion protection of the concrete against chloride ions was conducted on of surface:8.800m2. After that passiv - ating grout was applied followed by repair mortar. Finally MCI-2020 was applied onto the surface. Rebar Preservation at Prince Mohammed Bin Abdulaziz Medical City Another project was facing construction delays after the majority of concrete work had been completed. The main issue was corrosion on exposed rebars of a significant number of in-fill beams and expansion joints that needed protection from the corrosive environment during the delay. Two stages of protection were conducted: Rusted rebars were treated with CorrVerter® MCI® Rust Primer and MCI® CorShield® was then applied on all exposed reinforcement to provide the neces - sary outdoor exposure protection during the construction delays. This provided an economical and efficient solution to preserve exposed reinforcement and satisfied the requirements of all parties involved in the project. Durability in the exploitation of reinforced concrete structures is the basis for the preservation of structures long-term. The durability of structures depends on a good and professional choice of materials that help to avoid damage. If damage occurs, rehabilitation should be ap - proached with great care and responsibility and selection of a product that is compatible with material used during construction, in order to avoid major damage or demolition of the building itself. Cortec® has a wide range of products that can help to achieve greater durability and, above all, safer structures.
is approximately 45 meters (49 yd), and the total façade area is ap- proximately 3,000 square meters (3588 yd²). The water tower’s frame is made up of six externally reinforced concrete pillars that have a U- shaped cross section. These pillars stand around a larger central pillar of reinforced concrete that houses stairs, an elevator, water pipes, and electricity installations. On top of these seven pillars is the water reser - voir. The reservoir is built of reinforced concrete with 14 tension cables running through rings in the outer walls. On the outside of the reser - voir, there are six pilasters, two of which serve as anchoring points for the tension cables. The concrete had been breaking down, with pieces falling off in several areas where the concrete covering the reinforce - ment had been consumed. The presence of chlorides in conjunction with concrete carbonation (which reduced the natural protective quali- ties of the concrete) had caused reinforcement corrosion. Fortunately, splint injuries had not become extensive enough to affect the bearing capacity to a greater extent. The damages were limited in size but relatively numerous. The situation was still serious because such large areas had high levels of chlorides and because concrete damage can develop at a rapid pace—especially in areas around the fastenings of the tension cables. The investigation also showed damage to fastenings of the tension cables that could affect bearing capacity. It was therefore important to slow down the development of claims in good time. The municipality wanted a repair method that would extend the structure’s durability by at least 20 years.
Old broken concrete on small areas was removed and Surfaces were cleaned
November 2021 csengineermag.com
In 2015, when the project team was confronted with the complex con - structability challenges and confinement reinforcement design issues for the construction of the world’s 2nd tallest building, they turned to BauGrid Reinforcement for solution. This extraordinary project, Merdeka PNB-118 (aka PNB-118), is a 118-story, 644 m (2,113 ft) tall Skyscraper that is nearing completion in Kuala Lumpur, Malaysia. It is currently the tallest building under construction in the world. The structure with its exclusive spire was inspired by and resembles a unique silhouette of Malaysia’s then Prime Minister, raising his hand during the 1957 assembly at this site, while chanting “Merdeka” (which means “Independence”), marking their independence from Great Britain. The designers of super tall concrete structures who need to provide for resistance to high axial compressive forces, strong cyclone or typhoon winds, and blast forces, must consider the balance of strength and duc - tility in their design approach. Increasingly, engineers are specifying higher strength concrete while the ductility is maintained through care - ful detailing of the reinforcing. When properly designed and detailed, it is the transverse reinforcement that provides the concrete with ductil - ity through enhanced confinement of the longitudinal reinforcing steel. Since early last century, this has been achieved by using closely spaced hoops, stirrups, and crossties. However, today’s mega tall structures, designed in accordance with the more stringent code requirements for this century, require rebar bends, hooks, and hook extensions in their transverse assemblies that, quite often, result in labor-intensive construc- tion, reinforcement congestion, and concrete placement challenges. BauGrid®Reinforcement Enables the World’s Second Tallest Building to Soar into the Skies of Kuala Lumpur By Al Anvari, P.E.
One-piece BauGrid reinforcement can replace the many pieces of conventional transverse reinforcement. The resistance-welded inter- sections replace cumbersome end hooks and provide a more exact and efficient system for placement of longitudinal and confinement reinforcement. The system significantly improves forming and con- crete placement, enhancing concrete consolidation and increasing construction speed. The Design Engineers and Construction Team for PNB-118 Tower se- lected BauGrid Reinforcement in the most congested column sections of the core wall, at the lower levels of the structure. Many large U.S. and international engineering and construction companies had already discovered the benefits of this transverse reinforcement system by completing many important projects, such as the 60-story residential tower in San Francisco to mark the tallest reinforced concrete structure in California, USA; the world’s tallest precast concrete structure in the region of highest seismicity in San Francisco, USA; and the world’s tallest tunnel form structure, built in the most severe earthquake zone,
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