How a single phone call from a student helped uncover a flaw that nearly toppled Citicorp. Get an exclusive 15% discount on Saily data plans! Use code veritasium at checkout. Download Saily app or go to https://saily.com/veritasium If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV Correction: From construction images of Citicorp, sharp-eyed viewers might see that the mid-V columns are still there. Those columns help prevent buckling of the diagonal and the weight of people on the floor above, but do not take the majority of the gravity load. So we left them out of our diagram to clearly explain the load paths. See page 70 of this source for more details - https://drive.google.com/file/d/1ODFo66-_V7Y9vKANbj53mQ0z20RZ2Uai/view Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter ▀▀▀ 0:00 Why is the citicorp building on stilts? 4:44 How wind load works 7:49 Tuned Mass Dampers 11:17 The Anonymous Student 14:00 Quartering Winds 18:38 What were the odds of collapse? 20:31 How was the citicorp building fixed? 25:40 Hurricane Ella 27:00 TMDs Take Over The World 28:36 Conspiracies and Cover Ups ▀▀▀ A big thank you for the incredible people without whom we couldn't have done this! 🖤 To Michael Greenburg, author of The Great Miscalculation, for his insights that really brought the story and its context to life. He gave us a pre-copy of his upcoming book, and it is fantastic: https://ve42.co/Miscalc To Eric Hines for all his help with the technical details, fact-checking, and making sure we got the engineering right. To Michael J. Vardaro for helping us uncover the details of the story and the resources he provided. To Brock Hedegaard for helping us dive deep into the Citicorp structural analysis. Learn the fundamentals of structural analysis on his brilliant channel, @StructuresProfH, and see here for his analysis of the citicorp center; https://www.youtube.com/watch?v=lE_DspFE2ZM To Michele Barbato from UC Davis for his inputs on the load calculations. https://faculty.engineering.ucdavis.edu/barbato/ Matt from @mvvvc for talking us through his wind load analysis. To Prof. Chris Letchford who helped us understand the impact of wind on Citicorp's structure. To DongHun Yeo from NIST for discussing his research about wind effects on buildings similar to citicorp: https://ve42.co/WindLoad Finally, to Team Columbia —who built the epic TMD and ran wind tunnel experiments that made this story come alive. This includes the folks at the Mechanical Engineering Teaching Laboratory (Follow all the cool stuff they’re doing: @mechcu, @columbiaengineering or visit https://teachinglab.me/) Amanda Lombardo, Manager of Instructional Laboratories Daniela Durón García, Assistant Manager of Instructional Laboratories Jorge Casas, Machinist And the amazing seniors from the Columbia Space Initiative: (Support their awesome work here: columbiaspace.org/support-us/, Follow them: @columbiaspaceinitiative) Michael Sheehan Claudio Solano Jessica Bolar Kathryn Lampo ▀▀▀ References: Michael M. Greenburg. The Great Miscalculation via. nyupress.org - https://ve42.co/Miscalc Joe Morgenstern. The Fifty-Nine-Story Crisis via. The New Yorker - https://ve42.co/59Crisis National Academy of Engineering. William LeMessurier-The Fifty-Nine-Story Crisis: A Lesson in Professional Behavior - https://www.youtube.com/watch?v=um-7IlAdAtg Diane Lee Hartley. Implications of a Major Urban Office Complex: The Scientific, Social and Symbolic Meanings of Citicorp Center via. princeton.edu - https://ve42.co/CitiSymbol Addition References here: https://ve42.co/citiref ▀▀▀ Special thanks to our Patreon supporters: Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, Autodidactic Studios, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Greg Scopel, HydrochloRick, Jon Jamison, Juan Benet, Keith England, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Tj Steyn, TTST, Ubiquity Ventures, wolfee ▀▀▀ Written and Directed by Sulli Yost Edited by Trenton Oliver Additional Editing by Axel Oliver, James Horsley and Peter Nelson 3D Modeling by Maydelis Anaya Romero Animation by Mike Radjabov, Andrew Neet, Fabio Albertelli, Jakub Misiek, and Emma Wright Illustration by Jakub Misiek, Maria Gusakovich and Cainejan Esperanza Filmed by Sulli Yost, Henry van Dyck, Andrew Abballe, Derek Muller Produced by Sulli Yost, Derek Muller, Casper Mebius, Zoe Heron, Rob Beasley Spence and Tori Brittain Additional research by Geeta Thakur Thumbnail contributions by Ren Hurley and Ben Powell Additional video/photos supplied by Getty Images, Pond5, Axiom Images and Storyblocks Music from Epidemic Sound