Is there a fiber bundle $(E,B, \mathbb{R}^{n})$, with typical fiber $\mathbb{R}^{n}$, such that there is no any $n$dimensional vector bundle structure on the pair $(E,B)$? That is there is no a continuous map $p:E \to B$ such that the triple $(E,B,P)$ would be a $n$ dimensional vector bundle.

$\begingroup$ You might want to look for the universal case $BTop(n)$ in the literature. $\endgroup$ – user95545 Oct 26 '16 at 14:05

$\begingroup$ see "Open and Closed Disk Bundles" by William Browder, jstor.org/stable/1970428. $\endgroup$ – Igor Belegradek Nov 23 '16 at 4:02
Such a fibre bundle does not exists if you suppose that it is endowed with a differentiable structure. Stewart has shown that the group of diffeomorphisms of $R^n$ retract to $O(n)$. So every $Diff(R^n)$bundle has an $O(n)$reduction.
Stewart, T. E. (1960). On groups of diffeomorphisms. Proceedings of the American Mathematical Society, 11(4), 559563.

$\begingroup$ Thank you very much for your interesting answer and helpful reference. $\endgroup$ – Ali Taghavi Oct 29 '16 at 7:11
Yes, there a lots of them.
The topological tangent bundle $\tau$ of any topological nonsmoothable manifold $M$ gives you an example since a vector bundle reduction of $\tau$ is by smoothing theory equivalent to a smoothing of $M$.

$\begingroup$ Thank you very much for your interesting answer. Unfortunately I can not accept two answers simultaneously. $\endgroup$ – Ali Taghavi Oct 29 '16 at 7:13