Continuous Beam Design 2

[KelvinChung]

Hi there, i would like to ask how to design different level of beams (or) different size beam as continuous beam?

For example:
1. Span 1 Span 2 Span 3
250 x 450 250 x 600 250 x 750 (beam size)


2. Span 1 Span 2 Span 3
+450 +400 +350 (beam level)

Example 1 is beams with different sizes (bottom level of beam is same)

Example 2 is beams with same sizes but different level.

Thank you =)

 

[ishvaaag]

As long as you have enough strength, there's nothing that prevents doing so; detailing may however dictate the need of some transition zone, to properly transfer the forces. Yo may need be particularly careful with kinks that might try to cause spalling, an effect that needs be restrained; the more common way in such corners is to provide straight splice lengths beyond such the vertex of such obtuse angles.

When detailing the joints, the effects of the disposed rebar must be inspected to further ensure (usually by strut and tie) that not unbearable/adverse effect develops.

When you have RC column supports monolithic to the beams you may have facilitated the transfer through its existence, then avoid transition corbels. The corbels when used and if needed more properly should be accounting when analyzing the structure, but sometimes as non consequential their presence is ignored in analyses.

 

[MiketheEngineer]

Hire an engineer or go back to your Structures and Materials books

 

[dik]

Determine your positive and negative moments for the span.

For beam span 1, 2 and 3 use the +ve design moment for the bottom and determine the area of steel required. You may want to keep some common bars.

For the negative moment between span 1 and 2 use the smaller depth to determine the area of steel. For the negative moment between span 2 and 3, use the area of steel determined for span 2.

Check for deflection and shear and you're done like a dinner...

I don't understand what your second beam is...

Dik

 

[shobroco]

Hey Dik, I think the "done like dinner" line is the definitive one...

 

[msquared48]

Invest in BeamPro, after you learn structures...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[rb1957]

make sure you splice the different height beams together to transfer moment stresses from one cap to the other,

else three simply supported spans