Foundation, Concrete and Earthquake Engineering

What should be Working Stress of Concrete in Designing Pile Foundation?

Dear reader after long time, we are publishing back to foundation engineering. This post must worth be a part of foundation engineering but there have also some content on concrete engineering too. Dear reader so far you have realized that we are answering such questions which are known to all but not easy to understand or express. Now we are solving a question that is regarding working stress on pile or more precisely on single pile.

Do we know what working stress is? No we will not answer this question here. So come to the point –limiting working stress in different piles. Here different piles means materials that comprise a pile may be concrete, steel or timber piles. At first we will know about concrete piles.

Placing concrete in pile in Tremie method
The working stress must not exceed (0.25-.033) X f’c in cast-in-situ concrete piles. Where f’c means compressive strength of unconfined concrete test cylinders after curing properly through 28 days.

Now we are providing information for steel piles. Working stress, in case of steel piles, at the tips is generally limited to 12.6 Ksi.

We can explain to some extent in regarding concrete piles. For steel pile you have to wait. But for your kind information, we have published some post regarding steel piles. Of these, splices of steel piles and corrosion problems of steel piles become popular. You are invited to all those posts, especially these two. Now, earlier, we have provided a range of limit of working stress in concrete piles. The lower limit of range is for piles where placement difficulties of concrete are considerable. This situation may occur where:

A half section of heavily reinforced pile to be concreted a. Small diameter of the tip of piles where size is decreased with depth.

b. Batter piles.

c. Heavily reinforced piles

d. Irregularities in side walls of shell

Proper allowance must be provided for prestress, in case of prestressed piles. Dear reader we have to finish this post here. In the next post we will discuss about point bearing piles. Keep tuned with the latest post, we will be answering your questions.

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