PERFORMANCE-FACTOR FOR BEARING RESISTANCE OF BORED FRICTION PILES

This paper describes a method for evaluating the reliability of the ve rtical bearing resistance of bored friction piles, in which a semi-emp irical expression using the SPT-N value is focused on. Two uncertainti es, which are the spatial distribution of SPT-N value and the resistan ce coefficients in the bearing resistance expression, are quantitative ly evaluated by statistical analyses of various soil investigations an d loading test results. Based on these evaluations, a performance fact or for the Limit State Design is proposed for the design of bored fric tion piles. The performance factor proposed here is also applied to a bridge foundation design.