A procedure to determine resistance factors for a newly developed rotation steel pile

Abstract

The aim of this study is to establish a procedure to determine resistance factors for newly developed pile products through an example of the rotational intrusion steel pile (RI pile). RI pile is a newly developed steel pile product which has the vane type tip structure to resist reliably against vertical load and to intrude easily by rotating itself. Moreover, the RI pile is environment-friendly, i.e. reduce waste soil and less construction noise, because of the rotating intrusion method. The construction can be done with the small pile driving equipment and the pile can be reliably founded into the bearing ground by monitoring and controlling the torque value during installation. For these reasons, the RI-pile is expected to have the superior bearing capacity against vertical loads. However, the RI-pile has not been adopted in many construction projects yet because the current design method requires applying the same safety factor neglecting the level of the uncertainty of each pile type. In this study, 64 loading test data are gathered to quantify the model error of the RI-pile assisted by Public Works Research Institute (PWRI). Then, Reliability analysis is conducted based on our proposed reliability analysis scheme (GRASP) to specify the reliability level of the current design. Furthermore, the partial factor updating procedure according to the newly developed the RI pile is formulated based on the design value method. From the results, the partial factor is determined and applied to compare the RI steel pile to the traditional piles, i.e. cast in pile and driven steel pile. The difference in construction cost among the three piles has become less, and the RI pile is less expensive when the rate of the pile tip resistance is high.