Calculating Fixed End Moments with Uneven Beam Heights?

AI Thread Summary
The discussion focuses on calculating the fixed end moments for a beam with uneven heights, specifically for members BC and CB. The beam is simply supported with a uniform distributed load (UDL) of 60 kN/m over a 6m span, where member BC is 1.2 times higher than members AB, CD, and DE. Participants clarify that the fixed end moment can be calculated using WL²/12, but the height affects the stiffness factors in moment distribution method (MDM) calculations. The height increases the moment of inertia, thus making the beam stiffer, which is crucial for accurate EI calculations. Ultimately, the correct fixed end moment values are confirmed to be 180, with variations at each end.
seamie
Messages
2
Reaction score
0
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?
 
Last edited:
Engineering news on Phys.org
seamie said:
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.
 
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
 
Last edited:
seamie said:
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
 
are you there?
 

Thread 'Query on Isentropic relationships (such as PV^gamma = constant)'

Hi all, I have a question. So from the derivation of the Isentropic process relationship PV^gamma = constant, there is a step dW = PdV, which can only be said for quasi-equilibrium (or reversible) processes. As such I believe PV^gamma = constant (and the family of equations) should not be applicable to just adiabatic processes? Ie, it should be applicable only for adiabatic + reversible = isentropic processes? However, I've seen couple of online notes/books, and...
View full post »
Thread 'How can I find the cleanout for my building drain?'

Thread 'How can I find the cleanout for my building drain?'

I am a long distance truck driver, but I recently completed a plumbing program with Stratford Career Institute. In the chapter of my textbook Repairing DWV Systems, the author says that if there is a clog in the building drain, one can clear out the clog by using a snake augur or maybe some other type of tool into the cleanout for the building drain. The author said that the cleanout for the building drain is usually near the stack. I live in a duplex townhouse. Just out of curiosity, I...
View full post »

Thread 'Dry sump pump issue'

I have an engine that uses a dry sump oiling system. The oil collection pan has three AN fittings to use for scavenging. Two of the fittings are approximately on the same level, the third is about 1/2 to 3/4 inch higher than the other two. The system ran for years with no problem using a three stage pump (one pressure and two scavenge stages). The two scavenge stages were connected at times to any two of the three AN fittings on the tank. Recently I tried an upgrade to a four stage pump...
View full post »

Similar threads

Can I Calculate Shear Force and Bending Moment for Partially Loaded Beams?
Replies
4
Views
3K
I Calculating Combined Loading Stress: Neutral Axis and Bending Moment at Point A
Replies
3
Views
1K
Engineering Combined loading, where is the neutral axis?
Replies
11
Views
3K
What Is the Difference Between Moment and Bending Moment in Beam Calculations?
Replies
3
Views
13K
Structures, Beams: Proof of formulas for a beam
Replies
2
Views
7K
Problem about Proof A simply supported beam
Replies
2
Views
2K
Finding moments in pedal (beam w/ rightangles)
Replies
7
Views
1K
Problem with values for a bending moment diagram
Replies
6
Views
2K
Calculating the bending stress of a simply supported beam
Replies
5
Views
6K
Moment Diagram of Cantilever Beam with Fixed End at Left hand side?
Replies
5
Views
6K

Hot Threads

Recent Insights

Back
Top