tie beam

[migs29]

We have to design two storey Office building, the architect ask me, at what depth should the TIE BEAM be located from NGL. I suggested that it can be located at the the midpoint of the portion of the column buried from NGL to its depth, I suggested also that it can support the masonry as masonry footing when there some situation that the masonry wall should be place over the tie beam... I'm not so sure with what I suggested but in my college day my instructor said that there is no such literature about footing tie beam. It can be designed in such way that the load consideration is from soil pressure acting upward or it can be designed that the load consideration is from soil pressure over the tie beam and load from walls supporting by this... It is my question up to now how to design properly the tie beam??.. what load to consider in designing tie beam???... at what depth should this be located from NGL.... Guys... can you give me tip about this.... Do yo know some reference about the tie beam that can you give me.... your input will be highly appreciated... thanks....

 

[msquared48]

Tie beams can have several functions, some being:

1. Keep the spread footings in their positions during seismic events;

2. Serve as grade beams to redistribute vertical loads through moment and shear in the event of differential settlement.

3. Serve as strip footings to support interior or exterior walls.

4. Serve as grade beams over a pile foundation to link the pilecaps and support the structure above.

What is your application? Any of these?

I generally place the top of the tie beams for 1, 2, and 3 flush with the top of the spread footings. For 4, The tie beam is placed over the pilecap.

Mike McCann
McCann Engineering

 

[haynewp]

Do you need a tie beam or just spread footings? Are there any special soil considerations?

 

[migs29]

Tnx for the input guys... Actually the architect design the tie beam since the building is an airport facility, its maybe because due to anticipated vibration effect on the building but there is no such soil consideration in designing the tie beam. Ok.. for example i consider the no. 2 and no. 3 function from the input of msquared48, what is the load should i consider?.. is it the soil pressure acting upward on the entire length of the tie beam or the load of the wall acting down ward, or the algebraic sum of all loads acting on it?... I confuse on how should the re bars be placed. should it beam top or bottom bars at the midspan and top or bottom bars at the right and left end support?....

 

[hokie66]

Just because an architect shows something in his drawings doesn't mean it is correct. The structural engineer need to determine what is required and advise him, rather than the other way around.