Pile Load Test Results as a Basis for Reliability Calculation with Parabolic Response Surface

The paper will discuss a method of analysing head displacements of piles subjected to lateral load test that is suitable for reliability calculation. The obtained results will be used for writing down the serviceability limit state equation related to a pile representing the group of piles under investigation. The obtained set of displacements for the test piles will be a base for creating a response surface function which may be used for determining reliability index of a pile foundation by means of FORM, SORM or Monte Carlo methods proposed by structural reliability theory. A classic response surface has a form of a polynomial of degree two. Unfortunately, this type of response surface produces erroneous reliability indices. The discussed method of allowable pile load estimation, based on load test results and using a parabolic response surface without an independent term for structural reliability theory calculations, is characterized by the easiness of obtaining a response surface. It is very easy to obtain results for this type of response surfaces by using FORM and SORM methods