Q. Explain Strain compatibility in mini-piles?

In designing the axial capacity of mini-piles, grout can be taken into account in the contribution of axial load capacity. Though the total load capacity of min-piles can't be equivalent to the sum of individual capacity derived from grout and from steel H-section. Reason behind this is that vertical loads on mini-piles are shared among grout and steel sections based on their Young's modulus and areas. Essentially in order to comply with strain compatibility criterion, steel bars and grout will deform as a whole though they possess different stiffness. A case may occur in which the sharing of loads for grout can be too high that cracks the grout section and fails the mini-piles already before the whole pile section could obtain the full design load that is presumed to be the sum of individual capacities. Henceforth strain compatibility has to be checked in designing vertical capacity of min-piles.