pystra.decision.targets.lognormal_ratio_failure_probability#

lognormal_ratio_failure_probability(design, resistance_cov, load_cov)[source]#

Return P(R - S <= 0) for independent lognormal resistance and load.

design is the ratio E[R] / E[S]. The expression is the closed-form reliability model used in the Rackwitz/JCSS target-reliability examples.