Statnamic Load Tests on Model Piles and Their 3D-Elastoplastic FEM Analyses.

Abstract

During the past ten years, the Statnamic load test has drawn attention from the piling community as one of the most economical methods for pile load testing. However, almost all of the research and development have been based on data from field tests. A consistent interpretation is difficult to achieve with such data due to the uncertainty and the complexity of the ground. To overcome this deficiency, the first objective of this research is to develop a system whereby Statnamic load tests can be performed under one constant condition. A small-scale Statnamic loading device for model tests has been developed whereby pre-compressed air is applied instead of gas from an explosion. In this study, two types of piles, friction piles and end bearing piles, are modeled and are loaded with two levels of forces, namely, small loads and large loads. The former loads are for determining the initial stiffness of piles and the latter for determining the ultimate capacity. The second objective of this study is to develop a 3D-FEM program that can analyze various types of loading. For a dynamic analysis, the solution is determined by the direct integration in time domain. The experimental results show the possibility of producing a loading curve similar to that in the original Statnamic load test. The analysis also shows that the force distributions in piles under Statnamic loading are similar to those under static loading.