Footing tie beam requiremets

[beamer]

Does anyone know of any code requirements that a building have tie beams between spread footings? We were asked recently why one of our buidlings didn't have tie beams between the spread footings by a reviewer. We moved past this issue too fast to talk about it, but it is one of the odd comments that comes out of a meeting that sticks with you. This building is located in Kansas City which is very low on seismic loading, but I wonder if it is a new seismic requirement in the 2000IBC or in ASCE. I am researching this on my own this afternoon, but any help you could lend me would be helpful.

 

[Focht3]

Describe your site and structure.

I haven't encountered this, but most of our structures are on piers or monolithic foundations - so tie beams wouldn't be appropriate.



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[beamer]

Single story conventional steel with spread footings. Soil is typically an expansive clay with the potential of sand layers. Bed rock is anywhere from 10 feet to 50 feet below the surface. Perimeter is supported by grade beams.

 

[JAE]

Tie beams are not required in an area like KC typically. They are usually required in high seismic areas between pile and pier type foundations as the lateral stability of pier/piles are highly compromised under a seismic event as the earth either significantly shifts or goes into liquifaction. In that case, you would have a serious stability issue as the pier/column connection is typically a pin, unable to transfer much moment, and therefore unable to resist lateral displacement at the top of the pier. Then, high P-delta forces develop that could initiate collapse.

But with spread footings in non-seismic area, this is not necessary.

 

[Taro]

See 2000 IBC Section 1805.4.2.2. Ties are required for high seismic design categories on soft or liquifiable soils.

 

[beamer]

Thanks. I found the section in the 2000IBC that requires tie beams or something with a load modification for seismic zones D, E and F. If we try really hard, we might be able to get to zone C, but nothing this high. I haven't found any other code requirements.