Optimum configuration of helical piles with material cost minimized by harmony search algorithm

Helical piles are a manufactured steel foundation composed of one or multiple helix plates affixed to a central shaft. A helical pile is installed by rotating the central shaft with hydraulic torque motors. There are three representative theoretical predictions for the bearing capacity of helical piles: individual bearing method, cylindrical shear method, and torque correlation method. The bearing capacity of helical piles is governed by the helical pile’s configuration, geologic conditions and penetration depth. The high variability of influence factors makes an optimum design for helical pile configuration difficult in practice. In this paper, the harmony search algorithm is adopted to minimize the material cost of helical piles by optimizing the components composing a helical pile based on the proposed bearing capacity prediction. The optimization process based on the combined prediction method with the aid of the harmony search algorithm leads to an economical design by saving about 27percent of the helical pile material cost.