Now that you have your beams built, it's time to test them! Start by making
sure the end supports are 20 inches apart. Then lay the beam down across the
opening between the supports like a simple bridge. Now lay the spreader block
on the beam lengthwise, and the short board perpendicular to the beam on
top
of the block. Now add the long spreader board parallel to the beam. Your
beam should now be supporting about 18 lbs.
Be sure that you record how much weight your beam is supporting everytime you add weight to it. Once you have the spreader board down, start adding weights to the beam, beginning with the lightest weight available.
Try to add to the load as slowly as possible. For example, if you had 3 1lb weights, 2 2lb weights, and 1 5lb weight, you would start by placing a 1lb weight. Then you would take that off and put down a 2lb weight. Then you would add in the 1lb again. The next step would be to remove the 1lb weight and add the other 2lb weight, and so on.
Note that for low section moduli, that both the short and long boards might overload the beam too early. If you are testing a beam with a low section modulus S, just use the spreader block in the middle of the beam, and then add your weights onto that.
When your beam gets to its failure point, due to deformation or breakage, be sure you record the total weight it was holding when it broke, as you will need that later in the lesson to see the differences between the beams.
click here to see the loading sequence
click here to see the loading sequence for an
I beam