Resonance Explained: Physics and Architecture | Viral Stadium Video
Hey there! If you’ve been following any of the viral clips lately, you might have seen that crazy stadium video where the entire crowd is jumping up and down in perfect unison, causing the stands to sway like a hammock on a breezy summer day. It’s both thrilling and a bit concerning. Trust me, as an architect, I got chills thinking about what could be happening under those feet. (And if you’re an engineer, you’re probably either laughing or breaking into a cold sweat—or both.)
Below, you’ll find my embedded video/podcast episode where I break down exactly why this happens. But first, let’s get into the nitty-gritty of resonance, how it ties into architecture, and why you need to know about it (especially if you’re studying for the ARE 5.0).
What’s Going On in That Stadium?
The Viral Clip
In the clip (check it out in the video above), you see a packed stadium. Fans are jumping up and down in sync—cheering, chanting, living their best lives. The entire structure starts to move, and we’re not talking subtle vibrations. You can literally see the stands swaying side to side.
The Big Question
I’ve had so many people ask, “Is that safe? Will the stadium collapse?” The short answer: probably not—it’s usually designed to handle these loads. But the longer answer involves a fascinating (and sometimes scary) concept called resonance.
Resonance 101: The Physics of “Uh-Oh”
Resonance happens when a force—like a bunch of fans jumping—matches the natural frequency of a structure. Think of it like pushing someone on a swing: if you push at just the right rhythm, they go higher and higher. But if your timing’s off, you end up doing an awkward mini-push that barely moves them.
When crowd movement aligns with the stadium’s natural sway frequency, each jump adds a bit more energy, and the structure moves more and more. This is why you can see such dramatic side-to-side motion in that video. It’s not simply about weight; it’s about the frequency of that weight moving in unison.
Why Architects Should Care (Yes, YOU!)
Listen, I know some people might be thinking, “But wait, that’s the engineer’s job to worry about.” And you’d be right—structural engineers are the wizards calculating those loads. But as architects, we’re not off the hook. We still need to understand these concepts because:
Collaboration: We work hand-in-hand with structural engineers, and having a grasp of resonance and dynamic loading makes us better collaborators.
Code & Compliance: Ever heard of “health, safety, and welfare?” That’s on us, too. Architects have to ensure designs meet or exceed code requirements and occupant safety measures.
ARE 5.0 Prep: If you’re studying for the Architect Registration Examination, you’ll face questions on how live loads, dynamic loads, and occupant loads affect design decisions. You don’t have to solve every equation, but you do need to know what’s up.
Real-World Examples: Bridges & Soldiers
Bridge Failures (Hey, Tacoma Narrows!)
One of the most infamous resonance examples is the Tacoma Narrows Bridge. It literally twisted itself apart back in 1940 because wind-induced vibrations matched the bridge’s natural frequency. Cue dramatic footage of a bridge flopping around like a ribbon in the wind. Yikes.
Marching Soldiers
Ever wonder why soldiers “break stride” when crossing a bridge? Resonance is why. If everyone marched perfectly in sync, their collective footsteps could match the bridge’s natural frequency, leading to excessive (and dangerous) vibrations. Moral of the story: sometimes, you need to be a little out of step for safety’s sake.
The Millennium Bridge: Modern Example Gone Wobbly
In more recent times, we have the Millennium Bridge in London. Opened with great fanfare, and thousands of people walked across it on day one. Within a week, it was shut down because it started wobbling. Turns out, people naturally walked at about two steps per second—which happened to be the bridge’s frequency of 2Hz. The fix involved installing damping systems to counteract that rhythmic swaying. Lesson learned: match at your own risk.
Bringing It Back to the Stadium
Now, in that viral stadium video, you’ve got thousands of people jumping in perfect harmony. That’s basically the definition of a repeated rhythmic force. Over time, that collective force could match the stadium’s natural frequency. When it does, you get a serious show—even if it’s not necessarily dangerous every time.
But Is It Safe?
From what we can tell, most modern stadiums are designed with hefty safety margins. Engineers account for maximum occupancy and a whole bunch of “live load” scenarios (the fancy term for people and other moving loads). However, large resonant movement might exceed what was expected.
Could it lead to structural damage or even failure? Possibly—but it’s pretty rare. Still, seeing a stadium sway like that can be nerve-wracking, and it’s a good reminder that when people move in unison, interesting (and sometimes alarming) things can happen.
Resonance and the ARE 5.0
If you’re an aspiring architect, resonance and dynamic forces might pop up in the Project Planning & Design and Project Development & Documentation sections of the ARE 5.0. You might see questions about occupant loads, vibrations, and how to mitigate these issues in your design documents. You don’t need to do advanced math, but you do need to grasp:
Live vs. Dead Loads
Dynamic Loads (wind, seismic, rhythmic movement)
Coordination with Structural Engineers
Building Code & Safety Requirements
Basically, the exam wants to make sure you have enough knowledge to collaborate effectively and protect the public. And hey, if your stadium design ever appears on a viral video, you’ll know what’s really happening!
Final Thoughts
Resonance is everywhere—in bridges, stadiums, nature, and even within us when we sync up with others’ rhythms (hello, group dancing!). Understanding how it impacts our built environment is crucial for architects, engineers, and anyone else who loves geeking out on how buildings stand (and sometimes sway).
So next time you’re in a packed stadium, jumping and cheering with thousands of fans, take a moment to consider the physics at play. The structure might be swaying a bit more than you think—but don’t worry, that’s just the dance of resonance, reminding us of the awesome interplay between architecture and science.
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Comment below with any wild stadium experiences, or if you’ve got questions about resonance, the ARE 5.0, or anything else that makes your brain buzz.
Until next time, remember: stay curious, stay safe, and keep your stride just a little off when crossing that next bridge.
– Bryn
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