Why This Bridge Is Suddenly Everywhere - Cheddar Explains

all across america old bridges are being destroyed [Applause] and you could probably guess what's replacing them the cable stayed bridge has become the bridge of choice for american architects and engineers over the last 30 years and although they may look modern the design has existed since the 16th century ultimately the design lost out to the truss or suspension bridges of the 19th and 20th centuries but now the cable stayed bridge is back [Music] the first cable state bridge design is credited to venetian inventor fausto varangio who published his model in his 1595 book machinai novae his design allowed for a bridge to cover greater distances by transmitting the load from the bridge deck itself through the cables directly to the tower as opposed to a suspension design in which the weight of the deck is supported by vertical cables suspended from larger cables that run between towers but the first cable state bridge wouldn't be actualized until the 19th century and when they were finally built early versions were plagued by tragic failure the dryburg abbey bridge in scotland one of the earliest cable state bridges collapsed in january 1818 just six months after it opened then there was the zale river bridge in germany on december 6th 1824 300 people were marching across the bridge when vibrations of the bridge deck caused one of the iron rods to snap this led to a second rod failure causing an entire section of the bridge to collapse plunging the marchers into the water below killing 55 people after those collapses cable state bridges were just not looked at again for a very long time instead truss and suspension bridges became the bridge of choice for more than 100 years especially in the u.s there's always certainly you know what's tried and true here in the us as opposed to somewhere else and you know there's there's a level of comfort there is an engineering tradition in every country and truth be told the u.s was ahead when it came to the design of suspension bridges and other types of bridge but elsewhere architects were getting a bit more experimental in 1955 the strom sound bridge was completed in strom sound jampelin sweden it was the first successful modern cable stay bridge since the early 19th century failures the bridge was constructed by german civil engineer franz dischinker who used a slide roll a mechanical analog computer to effectively calculate the forces on the bridge this jinger used high strength steels in the cables instead of iron used in previous bridges lastly he devised a new external pre-stressing technique for tensioning cables allowing engineers to tension the cables appropriately throughout the bridge deck that's why we call it the first modern cable state bridge because we basically apply the same uh ideas to most of the cable state bridges we design and build nowadays the one thing that has progressed which allows us to make much more complex cable state bridges is the computer technology so we don't need to use slide rules anymore and make assumptions cable stay bridges quickly rose in popularity in europe and asia as modernizing countries were hitting a similar infrastructure boom that occurred in the u.s decades before architects of these nations chose cable-stayed bridges over suspension or trust bridges because of their cost-effective nature and visually pleasing aesthetic the role of aesthetics in in bridge type or bridge design uh has really become i i would say a major factor early on it was really all about functionality you know get me from point a to point b don't really care how much what what it looks like so you know so much but uh just make sure it's safe of course aesthetics have a major role always in the selection of a particular type of bridge and i think a lot of people appreciate normally the aesthetics of cable state bridges which is often why they're chosen or for other types of bridge ideally you'd like to have aesthetics and structural efficiency and reasonable costs that would be the ideal situation but in the u.s cable state bridges were slow to take hold you know if you look at new york other parts of the northeast of the united states there were many suspension bridges that had been built in the late 1800s and early 1900s before anywhere ever any modern ones at least were ever built in asia or europe other countries that didn't have the infrastructure that the united states had needed to build their infrastructure and the cable state bridge came along at that time when they needed to build up their infrastructure so a lot of their bridges ended up being cable state bridges but back in the u.s our bridges are getting old most long us bridges were built in the late 1800s to mid 1900s and the average lifespan of a bridge built in that period was predicted to be roughly 50 years as yeah the bridges of the 1900s mid-1900s you know certain point maintenance becomes more expensive than replacement so cable stay are very economical today the average age of a u.s bridge is 42 years old and these bridges are very costly to maintain on top of that more people than ever are using these old bridges the u.s population is expected to grow from 327 million people today to more than 400 million by 2060. as bridges begin to deteriorate and need replacement cable stay is is definitely going to be for those mid span ranges will be the go-to bridge design they're inexpensive per square meter in relation to other bridges to construct they work very well they have a very good structural performance currently there are nearly 40 cable-stayed bridges in the u.s three more are in the process of being constructed and at least four others have been proposed [Music] but this does not mean our traditional truss or suspension bridges will disappear completely everything really comes down to the span length uh as far as what is the most economical type of bridge to build and cable stay are very economical for spans between say 800 feet and maybe up to 3 000 feet if it's less than 800 feet really a cable stay uh you know you're better off using some other type of bridge uh you know a lot less expensive they're very good bridge but you have to understand that every bridge is appropriate for a certain span length and cable state bridges are not appropriate for all span lengths and so if you look at the super long span bridges nowadays the ones that have either been built or that are on the drawing board they're all suspension bridges they're not cable state bridges because of this limitation thanks for watching so what do you think about cable state bridges comment below and if you like the video be sure to check out the channel and subscribe

Channel: Cheddar

Views: 506,164

Rating: 4.8852024 out of 5

Keywords: Cheddar, cheddar explains, cheddar explores, explainer, cable-stayed bridge, suspension bridge, engineering, bridge collapse, architecture, city planning, bridge, bridges, zakim bridge, truss bridge, transportation, design, urban planning, cable bridge, SUTONG BRIDGE, STONECUTTERS BRIDGE, brooklyn bridge, american bridges, infrastructure, roads, american infrastructure, streets, highways, cars, Sunshine Skyway Bridge, Penobscot Narrows Bridge, new bridge

Id: W8_wRcGUud4

Length: 8min 6sec (486 seconds)

Published: Tue Oct 27 2020

Reddit Comments

[u/hperron01]

Really interested but can't watch rn... Could anyone tl;dw?

[u/moomooland]

really enjoyed this video, i only wish there were more stars regarding the bridge