Designing for differential settlements

[rkchalla]

I am working on a project which requires extensive modification in an existing historic building. The soil data indicates that the soil parameters are reasonable. However, most of the existing building is founded on pile foundations.

I am firmly convinced that the vibrations due to piling would weaken the existing structure and am trying to avoid using them. The extent of my work is minor relative to the structure. We did a geotech investigation and came with a max. differential settlements of about 1/2 an inch or so. We are going to specify the fill, soil stabilization etc. to ensure that we have good bearing.

Can anyone suggest a source for structural steel connections that would allow differential settlement?.

We are minimizing the amount of connection to the existing structure and are keeping most of the modifications away from the existing structure.

-RKC

 

[ishvaaag]

At 1/2 inch differential settlement much of the usual details in new construction should not give much problems. In Spain even 75 mm total -not differential- may be allowable if there's not structural disorganization ... obviously most buildings nor take nor are calculated fur such settlements.

So check your structure taking unto account the expected soil behaviour, but I think almost everything should work if you are careful about deflections and so on.

Also, you could make in-situ piles -micropiles for your case- that would attain commonnality of behaviour with the extant foundation.

Depending on what in the cellar if any or the extant foundation and depending upon the nbuilding's size you may add general rigidity to the foundation -grill?- that may help to cope with the general distortions caused by the added structure.