I have to analyze the behaviour of piles under tension loads (settlements...). For the skin friction I have to consider, may I use the same parameters as for the compression loads, or does the fenomenon change so that I have to use coefficients or a completely different model? Thank you in advance,
In Cementation’s experience, with relatively low strains and typical pile geometries, skin friction under static loading conditions appears to behave in the same manner and magnitude whether a pile is moving upwards or downwards.
One does need to be cautious about the loading history of any pile tested in tension. For example, a previous compression loading test will have locked in stresses between the base and the shaft and the subsequent friction in tension is reduced accordingly.
A further caution with concrete piles is that the concrete may crack when the stresses exceed 2-4N/mm2, this causes a change to the elastic behaviour of the pile.