Inspired by Calvin’s same question where his Dad answers “They drive bigger and bigger trucks over the bridge until it breaks. Then they weigh the last truck and rebuild the bridge,” how do engineers determine the actual load limit on bridges in the real world?
In: Engineering
His dad’s answer is in the right direction, it’s just missing something.
The ‘bigger and bigger trucks’ is instead stress testing, and it allows engineers to know how strong a material is. But this can be done without building a bridge; they just need to have a piece of the materials (which will include the connections), and then they can use other tools such as hydraulic presses to do the testing. They will also do erosion testing to see how the material will do after it’s been in use and in weather for a while.
Once they do this with a piece of the material they can plug the numbers they got into the shape of the bridge. This returns a number that will break the bridge, and then they use legal code calculations to determine how much smaller than the ‘break’ value they need to list the ‘load’ value.
So in short, they ‘drive’ pretend trucks over a ‘pretend bridge’ until it breaks and then write a smaller number on the bridge they actually build.
Latest Answers