Integral Abutments

[teckert]

I have a question regarding integral abutments. I realize in the diaphragm portion rear face bars are designed to take passive earth pressure. However my question is the the bars that are between beams- what are they really doing other than temp and shrink steel- i get the argument from expansion and contraction forces but the beam moves the same as the deck and the bars all move at the same movments so essentially zero.

Please let me know what your thoughts are.

Attached is a picture

 

[Qshake]

No attachment is present.

The bars on the fill face of the diaphragm only act for negative moment due to passive earth pressure. The bars on the stream or roadway face and in-between the girders resist the positive moment.

Also the vertical bars from the beam to the diaphragm are to establish the resistance for horizontal shear thus making the diaphragm and beam composite for live load.

The most all of the reinforcing helps with temperature and shrinkage.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[teckert]

Qshake thanks for the reply.

I see on the fill side how the bars are resisting the negative moment but it seems that the on the stream side the thickness is usually 3 to 4 feet for an integral abutment that on the stream side and in between beams, those bars wouldn't be seeing alot but maybe i am wrong?

Do you have a sample calc for the bars on the stream side?

Alot of times DOT design the RF side then just use the same bar size for the front which is really conservative.

Thanks,
Tim

 

[msquared48]

Tim:

Still no attachment....

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[crossframe]

The attachment is in the Bridge Engineering forum.

The reason the front face reinforcement is the same as the rear face is that in continuous beams, the positive and negative moments have a way of evening themselves out. The thickness is the same either way.

The front face bars are usually continuous, passing through holes in the beams.