## Strip foundation problem

## Strip foundation problem

(OP)

Using the shear stress for strip footings per the CERM it seems that negative stresses are frequently calculated. They give no reference for the equation, is there something I'm missing?

The equation is Vu=(qu/d)*((B-t)/2-d) where (B) is the footing width, (t) is the wall thickness and (d) is the critical depth.

The equation is Vu=(qu/d)*((B-t)/2-d) where (B) is the footing width, (t) is the wall thickness and (d) is the critical depth.

## RE: Strip foundation problem

What is Vu?

What is qu?

BA

## RE: Strip foundation problem

I’ve gotta tell you, I’ve given up even trying to participate in half the questions here on E-Tips, because you have to guess at what the real question and real problem are, and may be wasting your time at that. Then you probably don’t have the latest Ed. of the code or the software that they are plucking the obscure equation or nomenclature symbols from, even though the design of strip footings has been going on long before that Ed. of the code was foisted upon us, and some of those structures are still standing too. I often wonder if it makes any difference if they don’t understand some obscure formula, when there is every evidence that they don’t understand the fundamentals of the problem, by the nature of the way the question has been asked, without being able to define the problem.

## RE: Strip foundation problem

Most US soil texts, I believe, will use the term q for the maximum calculated soil pressure in the footing. With the u subscript referring to the fact that this term was calcualted at ultimate strength force levels. That's not quite so widely accepted, but common enough that I would think most currently practicing engineers in the US would get it.

However, I do not know what CERM refers to.

## RE: Strip foundation problem

Mike McCann

MMC Engineering

http://mmcengineering.tripod.com

## RE: Strip foundation problem

EIT

www.HowToEngineer.com

## RE: Strip foundation problem

EIT

www.HowToEngineer.com

## RE: Strip foundation problem

I would have expected Vu (using capital V) to be a shear, but the units don't make sense. In this case, the OP probably means v

_{u}, meaning a shear stress in the strip footing.If he is getting negative values, it means that d>(B-t)/2 which would suggest shear is not an issue.

BA

## RE: Strip foundation problem

BA

## RE: Strip foundation problem

I am amused, the spell checker doesn't like "formulae" it wants "formulas", my old English teachers must be rolling in their graves.

Michael.

Timing has a lot to do with the outcome of a rain dance.

## RE: Strip foundation problem

## RE: Strip foundation problem

## RE: Strip foundation problem

## RE: Strip foundation problem

For example vu and qu in psf; B, t, and d in feet. The same thing applies to eqn. 55-8.

@spats - I concur