There are two approaches for design of  mini -piles:

(i)   In the first approach, the axial resistance provided by the grout is neglected and steel bars take up the design loads only. This approach is a conservative one which leads to the use of high strength bars e.g. Dywidag bar. One should note that bending moment is not designed to be taken up by mini-piles because of its slender geometry.

(ii)  The second approach considers loads to be taken up by both grout and steel bars together. In this  approach, strain compatibility requirement of grout and steel has to be satisfied.