The steel beam shown is subjected to a uniformly distributed load () with mean = 3 kip/ft
and coefficient of variation (c.o.v.) of 0.20. The mean yield stress of the steel is = 47 ksi and the c.o.v. is
0.12. The section modulus () equals 50 in3
. What is the probability of failure by plastic collapse, assunung
that the load and yield strength both have (a) normal distributions and (b) lognormal distributions? [Answer:
(a) pF = 0.0015, (b) pF = 0.0023]