Bridge Design

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Bridge Design....

I have a design exam on friday and I need some tips on revising for a particular question. We designed a bridge from aluminium angle and strip and tested it under a load to see what it could withstand before failure. I have been told by my lecturer that the question will ask 'comment on how you could improve the framework design of this bridge to withstand a heavier load'?

Where could i get information on this topic and what sort of things should I consider. I have an idea that the joint design is of importance but what are the others?

Thanks in advance for help this will be greatly appreciated guys :smile:
 
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  • #2
Danger
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Look into the stress distribution in various geometrical shapes such as triangles, hexagons, arches, etc.. Also what sort of attachment method is best for the material that you're using (ie: rivetting, welding, etc.). That's about all that I've got for you.
 
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  • #3
Astronuc
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Basically one has to figure out how to distributed the load and reduce the maximum stress or stress concentration. That can be accomplished by increasing the cross sectional areas (thickness or depth) of the members, or increasing the number of members, or selecting a higher strength material - all with increased cost.
 
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  • #4
turbo
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Astronuc said:
Basically one has to figure out how to distributed the load and reduce the maximum stress or stress concentration. That can be accomplished by increasing the cross sectional areas (thickness or depth) of the members, or increasing the number of members, or selecting a higher strength material - all with increased cost.
Some of these options will necessarily increase the load that the bridge's own mass contributes. If the load-bearing ability of the bridge does not increase faster than the mass of the bridge increases as you add materials, the load-bearing capacity of the bridge is actually going down. There is a game-like program called "Structural Engineering Challenge" that illustrates this. It's pretty fun!

http://www.tucows.com/preview/218291 [Broken]
 
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Also in any truss design, the more distance you have between the top chord and the bottom chord increases the load capacity for the same member. You can also calculate each member's force and determine which ones you need to increase or decrease the strength of the member.
 
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