Bars $AB$ and $AC$ have cross$-$sectional area

$A=100mm2$

$,$ modulus of elasticity E $=70$

GPa, and are connected by pins at A$,$ B

and C $.$ If it is not desired that these two

bars experience a

normal stress greater than $270$ MPa $,$ what

is the maximum vertical force that can be

applied at E

$($Considering DBCE is rigid$)?$