  The bottomonium spectrum is far from being established. The structures of
higher vector states, including the $\Upsilon(10580)$, $\Upsilon(10860)$, and
$\Upsilon(11020)$ states, are still in dispute. In addition, whether the
$\Upsilon(10750)$ signal which was recently observed by the Belle Collaboration
is a normal $b\bar{b}$ state or not should be examined. Faced with such a
situation, we carried out a systematic investigation of the bottomonium
spectrum in the scheme of the relativistic flux tube (RFT) model. A
Chew-Frautschi like formula was derived analytically for the spin average mass
of bottomonium states. We further incorporated the spin-dependent interactions
and obtained a complete bottomonium spectrum. We found that the most
established bottomonium states can be explained in the RFT scheme. The
$\Upsilon(10750)$, $\Upsilon(10860)$, and $\Upsilon(11020)$ could be
predominantly the $3^3D_1$, $5^3S_1$, and $4^3D_1$ states, respectively. Our
predicted masses of $1F$ and $1G$ $b\bar{b}$ states are in agreement with the
results given by the method of lattice QCD, which can be tested by experiments
in future. We also compared the RFT model with the quark potential model in
detail. The differences of these two kinds of models were discussed.
