When Denver made the decision to replace the iconic Mile High Stadium with a modern stadium, the city wanted a structure that would last. And because the Front Range of Colorado experiences some of the highest non-hurricane winds in the country, the stadium’s architect, HNTB, entrusted CPP with ensuring that the new stadium would serve the Denver Broncos and their fans for years to come.
We were tasked with determining wind pressures and structural loads on what was at the time known as Invesco Field at Mile High (now Sports Authority Field at Mile High). We also evaluated pedestrian comfort issues and tested the stadium for potential snow drifting and loading issues, a very real concern during football season in the Mile High City.
Our technicians designed and built a 1:500 scale model of the stadium and created a detailed model of all surrounding buildings and terrain within 2,300 feet (700 meters) of the development site. Our model of the stadium featured more than 700 individual pressure taps for measuring peak surface pressures during high wind events. The test article was designed to permit removal of the nearby McNichols Arena, which was to be demolished but would remain standing for a brief period as the new stadium entered service.
Our pressure study included special attention for features unique to the stadium environment:
- Stadium lighting
- Pedestrian ramps
- A proposed visor not included in the final design
Based on the results of our pressure study, the stadium’s architects and structural engineers were able to ensure that the design would stand up to the project site’s design wind speed.
We designated more than 60 locations to study for pedestrian wind concerns and measured wind speeds at those locations using hot-film anemometers. Combining the results of these measurements with statistics of the local climate, we showed that while the upper west stands could experience high wind speeds on windy days, the stadium was, in general, a comfortable environment that wouldn’t require mitigation measures.
Finally, we subjected our model of the stadium to a snow study that combined the wind tunnel environment with a material that behaves like snow at model scale. Testing the conditions known to produce the greatest combination of wind and heavy snow, we found that the stadium would not appreciably accumulate drifting snow, except for certain ramp tower canopies and at entrances on the north side of the structure. In both cases, we recommended mitigation solutions to prevent problems down the road.
In its 15 years of operation, Sports Authority Field at Mile High has hosted football games, concerts, and President Obama’s nomination as a candidate in 2008. Thanks to CPP’s expertise, designers were able to ensure that the stadium is, for all its guests, safe, comfortable, and efficient.