A steel cantilevered I-beam is welded to a wall has some load applied at the end. Where would it fail?

Mechanical Engineering Cantilever Beams
1

  1. A steel cantilevered I-beam is welded (fixed) to a wall and has some load applied at the end. Where would it fail?

  2. (Spoiler to No.1) Would it fail at the top or the bottom weld?

3.If it fails at the bottom of the beam, what kind of failure would you expect?

  1. What is the equation for the bending stress of the beam?

  2. For a fixed length, how would you alter the cross section of the beam to most efficiently double the load it can take?

MY ANSWERS BELOW

Answers:

  1. At the fixed end at the welds. 2. I said that I guessed that the top weld would fail since it is in tension and the bottom weld would be in compression. (Guy said that he could see failing at either but seemed happy with my response.) 3. I would expect buckling at the flanges of the I-beam 4. sigma = M * y / I 5. I would always change the height of the beam first as the mass moment of inertia scales with the cube of the height. (From I = 1/3 * b * h^3)