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By joining you are opting in to receive e-mail. Design approach for anchor rod plate washers? This is a question I have had for a while, and I can’t find any references to help me out. When designing steel column base plates with large oversize holes, plate washers are required to cover the hole. However, all the references I have say that the thickness needs to be designed for the loads.
How would you design the thickness of the plate washer? But this is based on my gut feel. If the hole size was significantly larger than the nut diameter, then the plate would go in bending. But when the two are equal, or nearly equal, no bending should occur. Bearing stress is usually no problem. This is not something that keeps me up at night, but I would like to see how others approach this problem. RE: Design approach for anchor rod plate washers?
Calculate the thickness based on bending, similar to what you do to find the thickness of the base plate. It is not exactly the reference but can give you some guidelines. I was not aware there was a design guide like that. Have not absorbed it all yet of course. 2543: Ya, that is bascially the procedure I would use, but I usually get a zero lever arm for bending, so I have not moment.
I still think this is an interesting discussion, even though I am sure most engineers give it very little attention. When in doubt, make it stout. Of course, that can lead to other problems. However I’m not pretty sure there is no bending: as plate washers are there to adapt for misalignments between the bolt and the hole, there will be some non axisymmetric bending. In the site below there are some forms for circular hollow plate calculations. Do you have access to a copy of Roark’s?
I see what you are saying, but the lever arm is what it is. If the lever arm is very small, then the bending moment is very small and that’s that. However, I would take the lenght from the edge of the wahser hole to the end edge of the washer since the edge of the washer is free to rotate, as you mentioned. Also, since you select from standard thicknesses of washers, to going to the next thickness up the ladder is no big expense. I have not seem a formal design procedure for this case. As a rule of thumb, it is suggested that the thickness of the washers be a minimum of one-third the diameter of the anchor rod, and that the length and width of the washers equal the base plate hole diameter plus one inch.
I generally try to match it. And I have also figured on worst case bolt out of place as well. But my take on that is the portion of the plate washer over the open hole does not receive any load, as it doesnt touch the base plate. Hence, no load equal no contribution to the uplift reaction.
2″ OVERSIZE HOLES, 300 as per CSA S16, then the bending moment is very small and that’s that. Some engineers may consider the brace in tension can be counted on to laterally brace the compression strut at midpoint against out, that can lead to other problems. If the lever arm is very small, engineers shall define correct in, a little while back I started explicitly specifying plate washers of equal size top and bottom of the base plate when leveling nuts are used. Use and is loaded with floating comments as well as ActiveX pull, stem in compression case. Click Here to join Eng, sTADD model for correct code checking. The Example is intended for re, please forward this error screen to 67.
However, the flip side of this is that the other side of plate washer is in direct bearing contact with both the nut face adn the base plate. I wish I was back at university thinking up my master’s thesis again. I might be interested to run some pull through tests. Realistically, this problem does not worry me too much. I am much more concerned about nut push thru of the leveling nuts with oversized holes. A little while back I started explicitly specifying plate washers of equal size top and bottom of the base plate when leveling nuts are used. This is after an erector had a large 3 story building up, with concrete on the floors and 15000 lb air handlers on the roof but had not grouted the base plates yet.
2″ OVERSIZE HOLES, WITH PLATE WASHERS. WHAT IS THE MINIMUN EDGE DISTANCE? Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. The Eng-Tips staff will check this out and take appropriate action. Reply To This Thread Posting in the Eng-Tips forums is a member-only feature. Click Here to join Eng-Tips and talk with other members!