Need help with factors affecting suspension bridge failures

[studenthelp10]

re jambaugh: i found this article on dampers http://science.howstuffworks.com/engineering/structural/smart-structure2.htm

I think i know what the dampers doing? i think that it is resisting the (tension) of the building being pulled outwards because the mr liquid turns solid and as the metal piece in the middle pull out - it has to go against the solid (friction) . This reduces the tension.

 

[studenthelp10]

i just wanted to know one more thing, i have to write a synopsis on physics involved in our spaghetti suspension bridge design and I am ok with all of them except for how youngs modulus of elasticity is applied to bridges.

my answer is : youngs modulus of elasticity applies to bridges because it gives us an idea of what materials to use to build the bridge. Youngs modulus tells us how rigid or flexible an object is, this is because it is based on stress/strain meaning how much stress (compression/tension) needs to be applied before the object changes shape "strains". For a bridge we want a bridge that can take a lot of stress without straining and losing its shape. If more stress is applied to an object and it doesn't change in shape much, this means it is very rigid and strong- this is the type of material needed for a suspension bridge.

 

[studenthelp10]

spaghetti is not very rigid or strong (youngs modulus), so we will need to group them up- . in numbers spaghetti is much stronger under stress, because the stress is distributed over the many spaghetti strands instead of 1 for example. This will mean that the spaghetti bridge will strain less under more stress (compression/tension). By adding more numbers of spaghetti to the bridge it should be more able to take the 4kg load we are putting on it.

is this good ? its my last question

Thanks everyone for youre help and for the group discussions i know know a lot more about bridge failures and why the tacoma fell down :) :D

 

[Travis_King]

The main thing that the new design had that the old one didn't was a trussed side. The original bridge had plating on the sides which created a body for the wind to act on, and forced creation of the vortices. The new bridges in it's place, if you look at them from the side, are trussed, allowing the wind to pass through; reducing the effective area for the wind to act on.

 

[tiny-tim]

… For a bridge we want a bridge that can take a lot of stress without straining and losing its shape. If more stress is applied to an object and it doesn't change in shape much, this means it is very rigid and strong- this is the type of material needed for a suspension bridge.

you're only considering the stiffness of a material, ie how much it bends

something can bend a lot without breaking, or break after very little bending …

so you also need to consider the hardness and the toughness of the material

look all three words up in wikipedia and on this forum ​