Ali Philips 2022-10-03 12:20:30
Stadia Magazine talks to engineering experts to discuss the biggest challenges faced during the process of designing and constructing a stadium and the solutions they use to overcome them
Participants:
Ed Bosco, managing principal, ME Engineers
Russ Murdock, venue sector technical director, Henderson Engineers
Budgets and time frames are the bottom line of stadium delivery. How can they shape a build and what methods or technologies do you employ to keep on top of them?
EB: Budgets and construction durations are impacted when system requirements are identified or changed late in the design process or in the construction phase. A confirmed understanding of the project’s requirements and limitations early in the design process allows the freedom to employ solutions that represent the best mix of performance and cost. As such, advanced planning is always more effective than late reactions.
“A confirmed understanding of the project’s requirements and limitations early in the design process allows the freedom to employ solutions that represent the best mix of performance and cost” Ed Bosco, managing principal, ME Engineers
RM: Stadiums used to afford us the ability to have longer lead times since they take years from conception to completion, but it’s increasingly less predictable given the ongoing inflation and supply chain hurdles. We’re consequently fine tuning on the fly. Most of our larger scale projects are utilizing some type of cost estimation or cost control strategy (or partner) at the onset of design, and that strategy is designed to react to and inform design decisions and progress. While design and construction teams are making great progress with parallel design/cost estimating workflows, there still tends to be a delay between when design decisions are required, and when reliable cost information is available to help inform those important decisions. The result is a process that is still more reactionary than team members aspire to, and one that for certain has room for refinement.
What type of terrain/groundwork is the hardest to build on and what solutions are required to carry out the project?
EB: Unstable soils and unpredictable ground water levels create challenges during and after construction. Unstable soils drive additional foundation complexity and may require additional area for foundation construction, which can make some complex buildings impossible to construct. Unpredictable ground water and the risk of storm surges create restrictions on the location of infrastructure in lower levels of buildings. Forcing infrastructure into the occupied floors above grade can impact the design of the upper floors.
“One innovative approach is using materials for nontraditional purposes to offset costs in other aspects of a project. For instance, we’ve incorporated architectural mass walls into our mechanical design approach to help absorb and retain cool temperatures or heat” Russ Murdock, venue sector technical director, Henderson Engineers
RM: From a building systems perspective, it’s soil bearing capacity and fill conditions, especially where fill will fall away and the mechanical, electrical, plumbing, fire protection, and technology systems under slab on grade must all be supported from the slab. This can impact what we plan to put underground, what systems should be planned for ongrade, and can even create advantages for larger equipment to be elevated. Furthermore, as venues are increasingly built near lakes and rivers, there’s growing pressure to place event floors and sub-basements farther below ground. This adds the need for serious attention to de-watering as well as strategies to protect building systems infrastructure or materials from those adjacent water tables and sources.
How much of an impact is the rising cost of materials to projects?
EB: Over the past 15 years an increased focus on sustainability has produced buildings where investments in envelope and equipment performance allow buildings to operate more efficiently and at lower cost during their lifetime. With operating and maintenance costs running 4-5 times the cost of the original construction cost, an investment in a high performing building has the potential to recover its costs many times over.
RM: Like virtually every other industry, the rising cost of materials is the biggest challenge we’re faced with now. We’re taking a variety of steps to mitigate the issue, often in collaboration with architects. One innovative approach is using materials for nontraditional purposes to offset costs in other aspects of a project. For instance, we’ve incorporated architectural mass walls into our mechanical design approach to help absorb and retain cool temperatures or heat. By using the natural properties of the walls to boost comfort, we offset costs on the mechanical side because the number of materials needed for the HVAC and so forth are lessened.
Design for manufacturing and assembly (DfMA) is growing in adoption and most of our trade partners are often pushing for it on projects. DfMA is a cost-saver because we design standardized building system components that are easy to manufacture and partially assemble at a factory, which makes it seamless to construct once on site. It’s prefabrication in simplified terms, and that saves time and money. You also have the added benefit of limiting waste since a lot of the systems are pre-built.
“Thoughtful and clearly written building codes and standards can actually improve the construction process by defining specific targets for owners and their construction teams” Ed Bosco, managing principal, ME Engineers
Our experts are also increasingly flexible with our material and equipment selections, regularly choosing alternatives that are high performing but budget conscious. Opting for PVC pipe instead of cast iron when it makes sense is a great example. Sourcing products locally is also a much safer bet.
In what ways do building regulations and building control impact your role, and how challenging can it be to adapt to new codes and standards?
EB: Advancements in technology, safety and sustainability have accelerated the evolution of building codes. Thoughtful and clearly written building codes and standards can actually improve the construction process by defining specific targets for owners and their construction teams. A code requirement that appears to be a huge challenge when first identified may become a common construction practice when proven and optimized.
RM: When it comes to adapting to new codes, we have a leg up at Henderson Engineers and Henderson Building Solutions in that we have technical directors on staff who are focused on monitoring upcoming changes to codes and regulations and keeping our firm and clients up to date. Large scale stadia projects can take four-to-six years from design to completion. We’re therefore usually faced with at least two code cycles during a project. It isn’t rare to design according to one code and then go back to the drawing board to adhere to new regulations a few months later. A mitigating strategy that we’ve frequently adopted with success is negotiating to lock in a code cycle once we submit a permit request. So, even when codes are updated, our designs are insulated from those changes, which saves time and money.
As engineers, we endeavor to come up with new, creative solutions to meet modern regulations. A great example is energy codes, which increasingly lean toward sustainability, and operational outcomes. Features like autonomous building controls and controlled receptacles are now a standard way of conserving energy. This autonomous nature of systems can be challenging to understand and maintain, especially for professionals who have managed stadia for decades and are accustomed to practices such as leaving lights on for long durations because it was the most efficient option from an operations standpoint. Our role has evolved to now include educating end users and operators on the why behind our code-related design decisions and the how of making everything work seamlessly.
With stadium architecture getting more advanced, such as creatively shaped roofing or trends for ways to enhance fan experience, what examples can you give of these causing headaches and how was it solved?
EB: Long span structures like stadia create opportunities for the creative use of fabric roofing materials such as PTFE. Modern materials are long lasting and deliver a wide range of insulating and light transmission properties. These materials can be matched to the climate and indoor requirements to deliver protection from weather while providing significant natural light when this is beneficial. The variety of materials can be mixed and layered to deliver a performance specific to the climate, season of operation and planned building use.
The strength of long span fabric roofing materials is improved when the materials are kept in tension and supported at intervals. High pitched roof shapes improve drainage from roof surfaces and reduce the build-up of snow. The architectural creativity that produces these interesting structural shapes is aligned with the structural engineers efforts to deliver a strong and reliable structure. The avoidance of low points in the long span structure reduces the need for traditional roof drains and piping which require support, obstruct views and create shadows.
“The increased use of operable openings and PTFE/ETFE assemblies to bring the outside in has recently been a big, but welcome, challenge for our experts” Russ Murdock, venue sector technical director, Henderson Engineers
RM: I agree. The increased use of operable openings and PTFE/ETFE assemblies to bring the outside in has recently been a big – but welcome – challenge for our experts. These features help venues stand out and boost flexibility in how the facility can be used. On the other hand, with such a setup comes balancing space comfort with first cost/energy, potential limitation of material choices including insulation type/performance as well as building finishes, and operational/control considerations to mitigate potential spectator comfort issues and damage to materials. We overcome these hurdles by educating owners, operators, and architects on best practices for minimizing both real and perceived negative impacts on the facility’s energy usage, spectator comfort, and materials.
The integration of ground-breaking technology is another trend in stadium design. How difficult is it to accommodate the likes of super-sized videoboards and center-hung systems, which seem to get bigger every year?
RM: Controls system integration and smart building technology have recently been a part of most of our major venue project goals and aspirations, both from our clients, and from our technical staff. How to get systems talking to one another and utilizing that capability to reduce energy usage, create better fan experiences, and help with venue operations are some of our top priorities and targets.
Along with more technology and larger video boards come requirements for larger and more dense rack rooms to support those systems. Utilizing hot aisle/cold aisle setups, dedicated HVAC/CRAC units, and implementing economizer/free cooling, similar to large data centers, is beginning to become the norm for large venues.
Has there been one famously tricky build that you’ve worked on you can discuss?
EB: In 2016, construction work was completed on an operable roof over the Arthur Ashe Stadium at the US Open Tennis campus. The structural capacity of the existing building and the surrounding soil made many traditional approaches impossible, leading to a 10-year effort to find a solution that could be deployed over the existing stadium. The final solution delivered the roof as a completely independent freestanding structure spanning over the existing building but sharing none of its structure.
RM: SoFi Stadium in Inglewood, California, home of the NFL’s LA Rams and LA Chargers, is perhaps the most famously tricky build that we’ve been involved in. We were the lead engineer on the project and its surrounding 298-acre Hollywood Park mixed use development. Los Angeles International Airport (LAX) is located less than four miles away from SoFi, so the field is positioned 90ft [27m] below ground level to ensure the stadium adheres to aviation-related height restrictions. Significant portions of the venue also fall between two and five levels below grade for this reason. It’s challenging to move air in and out of these recessed areas for air conditioning or to exhaust environmental air from kitchens, restrooms, and other areas. We therefore had to get creative. Given the seismic conditions in California, SoFi has a standard gap between the building wall and grade wall to allow for tectonic shifts. A seismic moat, if you will. We chose to utilize that traditionally unused space as pathway to transport air in and out of the structure. Whether we opted for ducts or not depended on where the air was coming from or heading to. It was an innovative solution that was both aesthetically and functionally astute.
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ENGINEERING ISSUES
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