Calculating Fixed End Moments with Uneven Beam Heights?

[seamie]

Ok, so I have a problem as follows:

A beam is simply supported at joints A, B, C D and E.

there is a UDL acting on the BC member

The member is 6m long with a UDL of 60kn/m

However the tricky part is that this member is 1.2 times higher than the height of the members AB, CD, and DE.

So BC = 1.2h, AB = CD = DE = h

I need to calculate the FIXED END MOMENT of CB and BC - which I am taking to be WLsq./12 - however I am unsure how the height element effects the caluclations

the answer is not 180 - that does not fit with my MDM calculations - anyone got any ideas?

 

[PhanthomJay]

The member is I need to calculate the FIXED END MOMENT of CB and BC - which I am taking to be WLsq./12 - however I am unsure how the height element effects the caluclations

the answer is not 180 - that does not fit with my MDM calculations - anyone got any ideas?

The answer IS 180...plus at one end and minus at the other...the height doesn't come into play until you start calculating the stiffness factors for your MDM analysis.

 

[seamie]

Hi there,

In that case i am making a mistake with my EI calculations - what effect does raising the member have?

the exact layout is:

Fixed End @ A -------B Simply Supported C Simply Supported D ----E @ E is a cantilever

BC to C is raised by 1.2h

Am i not still using 4EI/l at member BC and CB

 

[PhanthomJay]

Hi there,

In that case i am making a mistake with my EI calculations - what effect does raising the member have?

it increases its moment of inertia, which makes it stiffer

the exact layout is:

Fixed End @ A -------B Simply Supported C Simply Supported D ----E @ E is a cantilever

BC to C is raised by 1.2h

Am i not still using 4EI/l at member BC and CB

Oh heck it's been a long time...see here:

http://en.wikipedia.org/wiki/Moment_distribution_method

 

[diflection1]

are you there?