Today was my first day of job shadowing Mike Jonson at North Shore Mining. The first thing we did was drive to the dump building to take some measurements. Several levels below ground level, there was a broken jib. A jib is basically a beam that is hinged to the wall, and used to swing a load from one area to another. This particular jib was rated for 2 tons. Last week someone decided to use the jib to move a 10,000 pound load. This caused more force than the anchor bolts could handle, and pulled them out of the concrete wall. Our job was to find a way to re-attach the jib in the same place and make it more reliable. To do this, we decided we needed to bolt an I-beam to the wall, and fasten the jib to the I-beam. This meant we needed to do some beam analysis. We found what moment of inertia would be needed to support the load, then look through the beam bible to find the most efficient beam. We ended up picking a w6x15 beam because it was the smallest beam that could hold the load, with a factor of safety of 5. But then, Mike remembered that the bolt pattern on the jib was 8 inches. This caused us to look at the possibilities for an 8 inch beam. The smallest 8 inch beam was a w8x31, which was more than 5X stronger than the 6 inch beam. Also, it more than doubled the weight and cost of the beam, but eliminated the waste of man hours, fab costs, and material costs that would have been required to mate the jib to the 6 inch beam.
Throughout the day we looked at many projects and solved lots of problems. It was a good learning experience for the both of us, considering Mike had never seen a Voyage 200.
Proofed by: Cory Moran
No comments:
Post a Comment