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pr beam connection--what is the slope formula

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发表于 2009-9-15 14:00:39 | 显示全部楼层 |阅读模式
pr beam connection--what is the slope formula?
i work for a small storage rack manufacturer and have the joy of updating our capacity spreadsheets (based on 3rd ed. lrfd).  however, the formulas used have no reference as to where they came from.  some are self explanatory such as those found in the aisc book but others look like they are from a mechanics of materials book.
in one of the formulas, it appears that the beam is assumed to have partially restrained connections and that the rotation/slope is (1/2) of ml/ei.  in the mom book, for a cantilevered beam with one end fixed and dist loading, the rotation/slope is ml/ei.  therefore, is the slope of a beam with a dist load and both ends having partially restrained connections 1/2 of that of a cant beam?
if anybody has any clue as to what the slope formula is and can clue me in, i would appreciate it.  some of this engineering stuff is having a hard time coming back to me; i spent 10 yrs in the military and never once used my ce degree!
thanks for your time and in search for next cold one,
near beer

it depends on the moment-rotation curve of the connection.  blodgett has a discussion on this and a rational approach for the moment-rotation curves of plates for pr connections (section 5.5 and 5.6).  if the pr connections are top and bottom angles, there are several papers which address this, but don't give a rational approach.  they do however give some tables/charts.
section 5.5 and 5.6 of what reference?  thanks for your response.
/r,
near beer
for a simply supported beam with moments m applied at both ends of the beam the slope at each end is m l/(2 e i)...
hope that helps
ed.r.
edr:  thank you very much!  can you humor me and give me a specific textbook/reference where that formula can be found?  my mech of mat. book does not have formulas for beams with both end fixed, just can beams.  this exercise is turning into a documentation goat rope; the only books i have to work with are my old mom book and the 3rd ed. of lrfd...thankfully the company is going to reimburse me for ordering the updated stuff!
again, many thanks...near beer
the reference for my first post is blodgett's "design of welded structures"
i'm not sure how the slope for an end moment only on a simple beam is all that useful. how would you use that?  
to determine the true deflection at the tip of the cantilever, so one can see if material will tend to slide off the end of the storage racks?
mike mccann
mmc engineering
gentlemen:
a bunch of you have misread my post.....the formula is for a "simply" supported beam (pinned at one end and rollered at the other) with a concentrated moment (m) applied at each support and has nothing to do with a cantilever (unless you are superimposing a group of load cases for a more complicated loading situation...re  
but my question is what good is the end slope for a simply supported beam with end moments only?  what is that telling you in the way of pr connections?
     good information!  i have attached the spreadsheet that i am working off of and someone's handwritten notes that was used a reference for the spreadsheet so that you can have an idea of what i am doing.  unfortunately, our engineer doesn't re
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