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RE: Contact loads from moving loads

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What you have is essentially a crane stop for an overhead electric crane.  There is a good discussion of crane stops in AISC Design Guide 7 "Industrial Buildings Roofs to Column Anchorage" by Jim Fisher.  The procedure is predicated on the same physics as some of the other responses already posted, but it also gives some good rules of thumb to get started. 


Fisher also presents bumper blocks made of wood and rubber where in the absence of specific data, the designer assumes the bumper force to be the greater of:

1.                   Twice the tractive force, or

2.                   Ten percent of the entire crane weight.


Other references for calculating crane stop forces:

Whiting Crane Handbook

ANSI Standard B30.2.0-1976 Part G Section VII

Harold O. Sprague

-----Original Message-----
From: Joseph Grill [mailto:j.grill(--nospam--at)]
Tuesday, October 07, 2003 10:07 PM
Subject: Contact loads from moving loads


Gentlemen and ladies of this fine list,



I know I am taking you California engineers away from the election this evening, but I need to ask a question that I am not too familiar with.  I have a situation where a 6200# log is moving along a support driven by chains.  The log will contact a stop mechanism which is supposed to stop the log.  The log will be moving at 200 ft/min.  I need to calculate the force on the stop.  Can you give me any help or send me to a reference that I hope I have that may explain what I need to do.  I have been looking at a 25 year old dynamics book from college, but to be honest it isn't helping me very much.  It is a little late this evening, but I need to get going on it in the morning.  I can scratch out some numbers which I think will be pretty conservative, but would like some other input if I can get it.  The stop mechanism needs to be designed after the force is determined.



Joseph R. Grill