Hello. I posted this message on th

Hello.
I posted this message on the Bridge Engineering Forum. But, did not get much respond to my last posting. I hope someone maybe able to respond to my question here.

The reference I am trying to follow is "Bridge Substructure and Foundation Design" by Petros Xanthakos, example 4-5 p. 261. Link:

http://www.buildabout.com/forum.php?action=display&&item_id=51

Specifically, I do not understand how the factor distribution was derived in the frame analysis for the bridge interior and exterior columns. Any help is much appreciated.

 

[Ingenuity]

vbridge,

There are few arithmatic/transposition errors in the distribution factors:

Assuming that the stiffness of the columns are indeed 0.058I, and the beams 0.083I, respectively, then the corrected DF values are:

DAD=0.083/(0.083+0.058)=0.59
DBE=0.058/(0.083+0.083+0.058)=0.26

I have not checked the moment distribution.

Is this want you wanted?

 

Ingenuity,
Thank you for your respond.
I don't know how to find the stiffness to the column and the beam. How do I go about in finding the stiffness for the column and the beam? Also, I don't know how to arrive at the numbers above the beam, i.e. 9.7, -23.6, etc..

 

[Ingenuity]

vbridge,

This is the MOMENT DISTRIBUTION technique which is a rapid, hand iterative method.

You calculate your fixed end moments (FEM's), your Stiffness factors, distribution factors, carry-over factors, then distribute the FEM etc.

It is a simple technique but a little cumbersome to explain on this firum. You will have to check out a STRUCTURAL ANALYSIS text - most basic texts will detail this very useful method.

HTH

 

Ingenuity,
I understand. Thanks for your help.