Evaluation of Load and Resistance Factors of Armor Units on LRFD of Reliability Design Method

A design equation of LRFD of reliability design method has been formulated properly, and several load and resistance factors with respect to the target probabilities of failure on armor units of rubble-mound breakwaters and mound of composite-breakwaters have been suggested, which have been evaluated by both reliability analysis and application of design value method following strictly the process of code calibration defined in design procedure. Also, the mathematical models have been provided from the reliability functions, so that the characteristic values of the resistance function and load function can be calculated straightforwardly that must be applied to the design equation of LRFD of reliability design method. The existing sections of each type of breakwaters designed by traditional deterministic design method have been included as many as possible in the reliability analysis in order to consider the diverse ocean environmental-conditions according to the failure modes of armor units. Those results of reliability analysis have been necessary inevitably in applying the design value method by which each load and resistance factor according to each failure mode can be evaluated correctly. The load and resistance factors on the Hudson formula and Van der Meer formula for rock and TTP units of rubblemound breakwater have been compared with the load and resistance factors suggested by PIANC and CEM, in which the present results have been satisfactory in the same conditions of the target probabilities of failure. In addition, Tanimoto formula for armor units on mound of composite-breakwaters has been studied in this paper for the first time. The load and resistance factors of non-perforated and perforated composite-breakwaters have been evaluated and suggested according to the target probabilities of failure. Also, mathematical models of characteristic values of the resistance function and load function have been formulated from the reliability function of Tanimoto formula that must be applied to the design equation of LRFD of reliability design method. It has finally been seen that the qualitative trend of those load and resistance factors with respect to the target probabilities of failure on non-perforated and perforated composite-breakwaters has been in agreement with the behavior of those of other failure modes.