step footing for retaining wall replacement at existing stairs? 1

[SLTA]

The owner of the failed retaining wall decided today to replace the wall with a new poured wall. I've attached a picture here of the existing condition. She wants to keep the existing stairs as they are. Can the new wall have a stepped footing to follow grade, or do I need to dig all the way down?

This one little project has been such an "interesting" one, in the way that the purported Chinese curse says "May you live in interesting times".

 

[SLTA]

looks like attachments are working again (cheers Eng-Tips) so here's a closer picture too.

 

[SkiisAndBikes]

Stepped footings are possible to construct, however there are several items I would consider.

- the new footings should likely be placed below the frost level.
- the new footings should be placed on undisturbed soil, therefore, if the existing wall's footings extend all the way down, you will also have to go all the way down.
- depending on the depth of your excavation, what is going to keep the soil underneath the stairs in place while you excavate/form, etc... You are going to end up with either lost formwork or one sided formwork adjacent to the existing stairs.

 

[hokie66]

You could step the footings, but if it were mine, I would pull it all out and start over. That way, the walls can be cantilevered off the stair slab.

 

[Ron]

hokie's suggestion would be a lot less expensive and easier to implement.

This effort seems to be a bit imcompatible with the structure, unless perhaps the structure has some historical or architectural significance. I would probably concentrate on the wall by the sidewalk and do pier-supported wood steps to replace the concrete steps. Then you only need a small concrete boxed area at the beginning of the stairs, with piers installed upslope.

 

[msquared48]

I, too, agree with Hokie. Take 'er down.

Mike McCann
MMC Engineering