Q$3)(30$P$)$ Consider the structure shown in Figure. The distributed load, w$,$ is random variable with mean value $=6\mathrm{.}5\frac{k}{f}t$ and COV$=0\mathrm{.}18.$ Assume other loads can be neglected. Both members are made of perfectly ductile material. For beam AC$,$ consider only the negative moment at point $B($do not consider the maximum positive moment between A and $B).$ The mean$-$moment carrying capacity at B$,$ RAC, is $100k-ft$ and its COV is $18$ percent. Tension member DB is made up of two parallel bars, each with the mean tensile strength of $60k$ and COV$=0\mathrm{.}10.$ Calculate the system reliability index assuming that all members are uncorrelated.