Uneven I beam centroid

[paulpatrick]

How do I find the centroid of an uneven I Beam at one end the flange is ten times bigger thatn the other....I looked at Efunda but keep getting a negative answer for it....I did the cumulative method of sectioned into smaller areas and I get answer that sounds better but its off a bit...

something is telling me its off.

 

[hokie66]

Just pick a point. Sum all the A x d (where d is distance from your point to centroid of that part), divide by sum of A, you have distance from your point to centroid of gross section.

 

[rb1957]

1) why divide the thickness by 10 ? (in your area calcs)
2) your calc 16.99 looks good to me
3) i think your efunda calc is off 'cause the thickness cells havn't been divided by ten

 

[IDS]

The centroid is 48.8 from the base of the wide flange.

Your spreadsheet would give the right answer if you just entered the actual dimensions, rather than dividing random numbers by 10.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[paulpatrick]

Sorry I spotted my mistake.. there was not a random division of thr numberd by it was a mistake in excel on my part it. the numbers were out by a factor of ten on the thicknesses.. thanks to all