Bridges

Suspension Bridge

World's Longest Suspension Bridge:

Akashi Kaikyō Bridge, Japan
AKA "Pearl Bridge"
1,991 meters = 1.24 miles
built to withstand typhoons, tsunamis, earthquakes, and corrosive salt-water environment

 Before the bridge, ferries were used to transport people across the Seto Inland Sea.


Siun Maru disaster

JNR (Japanese National Railway ferry "Uko Maru" collided with the Sium Maru ferry. 
Accident attributed to thick fog, and lack of radar. 
168 people killed including 100 elementary and junior high school students who were on a field trip.

Akashi bridge project was started to replace the dangerous ferry route.
10 years to build to build the bridge: 1988-1998

https://www.youtube.com/watch?v=N9fbRcRJY34


Bridge: Big-Bigger-Biggest, 2008

(Movie copyright: National Geographic, English subtitle prepared by ACUD.VN)

https://www.youtube.com/watch?v=lJIknkN7_84

https://www.youtube.com/watch?v=mjBuBEQmQzw

Leap 1: Material

Stone arches (max 30m span, larger bridges cannot hold up their own weight)
Cast Iron (too brittle)
First Iron bridge built in 1779 "Iron Bridge"
iron corrodes/rusts, needs maintenance. 

Leap 2: the suspension bridge
Rope bridges → iron chains→Cables
Need anchor

Leap 3: strong chains
Chains - only as strong as their weakest link
1845 - 79 people standing on a bridge watching a clown pulled in barrel by geese drown
Niagra Bridge

Leap 4: building underwater
Brooklyn Bridge: 140,000 vehicles per day
Sludge & silt→bedrock
Shallow water: People working in wood casons with air locks
Deeper water: steel cason

Leap 5: taller towers
Golden Gate:  Too much traffic for ferries
Ideal curve for a bridge - https://en.wikipedia.org/wiki/Catenary
Increase length = increase height to maintain ideal curve
Towers need to be strong enough to support cables, and ductile to bend when needed

Leap 6: wind
Longer decks = more twisting and bending = more susceptible to wind
Open Lattice box structure
open - allows wind to flow through bridge (rather than trying to divert wind)
box - keeps it from bending.

Leap 7: earth quake
Dampener Pendulums
Flexible materials



Bridge
Big-Bigger-Biggest
2008
https://www.youtube.com/watch?v=ZCrwIyfnyY0
Megastructure Longest Suspension Bridge In The World Construction Documentary  

Megastructures Lupu Arch Bridge China Construction
https://www.youtube.com/watch?v=JEwjB0eku8M
Longest arch bridge

Ponder the reasons to use twin arches that angle inwards..

The Ada Bridge

Arch bridges:

https://en.wikipedia.org/wiki/Arch_bridge

List of bridge failures:

https://en.wikipedia.org/wiki/List_of_bridge_failures



 

Bridge Competition

Bridge Competition

Bridge can only be made out of any kind of pasta (like spaghetti) and glue (any kind of glue) and string or fishing line.

It needs to span 2 feet, and have room to place a 5cm by 5cm by 2cm loading block on it. 

Score = weight it can hold up to 15 kg / weight of the bridge

Beam design:

https://www.quora.com/Why-is-an-I-section-commonly-used-in-beam-design

Truss structure:

Do an image search for "Truss Structures" 

→ Make it light weight, if it holds more than 15kg it's over-designed.  

Winner gets 100% on the final!

Bridges from past years:

wt: 404g, held 14,600g - 36.14

Beam design!

 wt:139 held 1750 - E 12.6

 Paper - wt:392g, held 5400   E 13.77

wt: 1048g  held>79,500  E>75.85

↑Unbreakable!↑

wt: 141  held 5,000   E 35.46 

 wt 244g, held 11,150  E: 45.7

wt: 552g, held 11450  E 20.87

wt 263  held 5000 E 19

Creative joints!

wt of bridge: 421, held 8.15kg, efficiency 19.35

Red bridge: 

Bridge weight was 421 g, held 4.4kg, efficiency of 10.45

Wt: 208g, held 2.1kg, efficiency 10.1

wt of bridge: 608g, held 2.35 kg, efficiency 3.86

Bridges from previous semesters:

Best Bridges of the AM section:

Grand prize winners! 

Quan N. 65.07g held 22,680 g - efficiency of 348 / or 15,000/65 = 230!!!

These top two bridges were so close, that we are now going to call it a tie:

42.15g, held 6.8 kg, efficiency of 161

Quang Le -

124



124

 90

82



Efficiency rating = Weight it can hold (up to 15 kg) / Weight of the bridge

Bridge HW Grade based on:

• 25% Design 
• Creativity (your own design? or just something from the internet?)
• Aesthetic appeal
•  Homogeneous distribution of weight

• 25% Use of materials (what material did you use, and why?)
• Cost efficiency (the cheaper the better)
• Strength/weight ratio
• bonding agents & designs

• 25% Efficiency rating
• Class weighted; Top 33% = A, next 33% = B, lowest 33% = C

• 25% Adhere to all of the rules
• It's long enough for the span?
• It is able to be loaded with the 5cm loading block?

Prize:
Person with the highest efficiency rating does not have to take the final.

Basic set-up:
A 5cm by 5cm by 2 cm wood block with a hook in the center will support the weight (see the top green arrow)

Weight will be added to your bridge by adding sand to a bucket suspended to your loading block. 




3feet span

** Your bridge will need to be slightly longer than what it needs to span!  Span = the distance between the tables your bridge will be resting on. 

Rules:

• The bridge will just rest on the table surface - you cannot anchor it with duct tape etc.

• Efficiency is determined by your bridge weight, so choose materials carefully!

• Failure will be defined by either the bridge breaking, or deforming more than 5 cm.  

• You will need to fully load your bridge in 8 minutes or less.  

Tips:

• Pay attention to your joints - make the connections solid!  

• Use clothespins, bent hairpins, paperclips, or small C-clamps (from the dollar store) to hold pieces together while it dries:

• Wax paper makes a great building surface - the glue won't stick to it.

• Build it in sections - don't try to build it all at once!

Competition:
TBD
if you are not able to come to the campus for the competition, you can make a video of testing it at home!

Simulation Bridge builder:
There are several online truss solvers - just google "truss solver" and see what comes up!  I cannot vouch for what any free software will do to your computer, so the risk is up to you if you want to try out some of the free codes people have posted online.  

http://engsci.stevenhe.com/trusssolver

http://mathonweb.com/truss.htm