THE EFFECT OF LOADS, STRUCTURAL STIFFNESS AND SOIL VARIABILITY ON THE RELIABILITY AND PERFORMANCE OF PILE FOUNDATION

ABSTRACT: In the settlement calculation, piles and piles groups are considered as isolated structural elements, neglecting their connection with other structural elements and the effect of the structural stiffness. This paper presents the results of a reliability analysis that considers the piles as part of a reinforced-concrete frame portal. The results are expressed in terms of the probability that differential settlements between piles supporting adjacent columns exceed the limiting values given in the National Building Code of Canada. The results indicate that the calculated reliability targets are much larger than those required by the codes. This confirms that the design practice is very robust to handle poor design practice and judgement. The results also stimulate a discussion on what a reasonable reliability target for geotechnical foundation systems should be, in order to ensure a balance between safety as well as design economy. Also, the current design methodology seems to be very punitive for good geotechnical engineering practice, triggering the question whether good practice should get rewarded by allowing more economical design.