Calculating max load on bridge
I received the following question by email:
hi,
I'm a highschool senior and I need help in calculating the maximum load a bridge that I have designed and built can carry. How do you do that? I am trying to build it using balsa wood. I do not know nor do I understand the underlying mathematical formulae involved in the process. I am really interested in bridges and engineering, and I would really like to understand this concept. Please help me.
Thank you,
A.
Here is my response:
Dear A.,
thank you for your question. Calculating the maximum load a bridge can carry can be relatively easy or quite complicated, depending on the bridge type and bridge complexity. That's why bridge engineers typically study several years in college and then need to work several additional years under supervision of more experienced engineers before they can design bridges on their own.
But to directly answer your question, there are several types of bridges and each of them carries the load in a different way - basic bridge types website provides nice overview of the basic bridge types and how they carry the load. In your of building a balsa bridge, I would recommend you to visit active statics website with nice and interactive graphical solution for several representative bridge types. Hopefully this will help you to develop feeling how the bridge behaves and responds to loads and you can apply this to your balsa bridge design by making the most heavily loaded members the strongest.
Good luck!
-ok