  In this paper, we consider a biharmonic equation under the Navier boundary
condition and with a nearly critical exponent $(P_\epsilon):
\Delta^2u=u^{9-\epsilon}, u>0$ in $\Omega$ and $u=\Delta u=0$ on
$\partial\Omega$, where $\Omega$ is a smooth bounded domain in $\R^5$ and
$\epsilon >0$. We study the asymptotic behavior of solutions of $(P_\epsilon)$
which are minimizing for the Sobolev qutient as $\epsilon$ goes to zero. We
show that such solutions concentrate around a point $x_0\in\Omega$ as
$\epsilon\to 0$, moreover $x_0$ is a critical point of the Robin's function.
Conversely, we show that for any nondegenerate critical point $x_0$ of the
Robin's function, there exist solutions concentrating around $x_0$ as
$\epsilon$ goes to zero.
