I-Beam Mounted Trolley

[shteve]

I am a Mechanical/Automotive Engineer, though I have recently been given some structural work. I will try to keep this as short as possible. My company purchased a new CMM machine which came with an I-beam mounted trolley for loading. The max load on the trolley is 2000 lbs. The I-beam is to be mounted underneath an existing 3" thick concrete floor. The floor joists are 3 ft. apart and are I believe 4" wide I-beam. The I-beam will be simply supported at one end by an outside concrete wall, and than welded to each floor joist. The other end of the beam will overhang the last joist by approximately 3 feet to gain the necessary travel of the crane. The question is, what type of deflection am I allowed at the overhanging end of the beam? There are no standards for this application that I know of. Also, what type of deflection would be allowed on the flange of the I-beam due to the mounting of the crane? Any help will be greatly appreciated.

Thanks in Advance

Steve

 

[jheidt2543]

I wouldn't be as worried about the monorail beam as I would the existing floor and joist you are attaching to. You should check the joist for the hanging point load of the hoist. With the joist only 3' appart, you could spread the 2,000 lb. load across three joist to help carry it. The 2,000 lbs. on the monorail beam spanning 3' or 6' will not have much deflection. Also, don't forget to check the impact load of the starting and stopping of the 2,000 lb. load.

 

[Ginger]

The approach used in UK is the Britsh Standard BS 2853 The Design & Testing Of Steel Overhead Runway Beams.

To quote the British Standard:- Clause 4; section k.

"The maximum measured deflection of runway beams under the safe working load shall not exceed 1/500 of the span. For cantilever beams the maximum measured deflection under the safe working load shall not exceed 1/250 of the span."

Hope this helps

 

[shteve]

Thanks alot guys, very helpful. I finally found what I was looking for about ten minutes before you posted ginger. l/500 is the suggested deflection for this case. A W10 beam will work just fine.

Thanks again