Reliability-Based Design Criterion for TLP Tendons

Abstract

This paper presents a Load and Resistance Factor Design (LRFD) criterion applied to the design of Tension Leg Platform (TLP) tendons in their intact condition. The design criterion considers the Ultimate Limit State (ULS) of any tendon section along its whole length taking into account both dynamic interactions of load effects and the statistics of its associated extreme response. The partial safety factors are calibrated through a long-term reliability-based methodology for the storm environmental conditions, like hurricanes and winter storms, in deep waters of the Campeche Bay, Mexico. In the reliability analysis, the uncertainties in the definition of load effects and analytic limit state models for calculation of tendon strength and randomness of material properties are included. The results show that the partial safety factors reflect both uncertainty content and the importance of the random variables in structural reliability analysis. When tendons are designed according to the developed LRFD criterion, a less scattered variation of reliability indexes is obtained for different tendon sections across a single or various TLP designs.