How can I fill white spaces in two column when I have minipage?

Question

I am writing an article in two column and I am using the minipage environment. The problem is that in the column where there is the minipage any text fills the white space ? Why this happens ? I tried to reduce the height of the minipage but I couldn't do it. I tried also with \vfill

\begin{figure}[!htbp]
    \begin{minipage}[c][6cm][t]{0.49\textwidth}
        \centering
        \resizebox{0.9\linewidth}{!}{
            \begin{tikzpicture}[]
                \node[draw=none,fill=none,scale=1.0] at (0,0)  {\input{figures/case1_macro.tikz}};
                \node[draw=none,fill=none,scale=0.4] at (0,-4) {\includegraphics[]{figures/case1_macro.pdf}};
            \end{tikzpicture}
        }
        \captionof{figure}{\label{fig:case_1}Example of a beam subjected to flexion solved with the FE$^2$ multi-scale method.}
    \end{minipage}
    \begin{minipage}[c][6cm][t]{0.49\textwidth}
        \vspace{1.5cm}
        \centering
        \resizebox{0.9\linewidth}{!}{
            \begin{tikzpicture}[]
                \node[draw=none,fill=none,scale=1.0] at (0,0)  {\input{figures/case1_micro.tikz}};
                \node[draw=none,fill=none,scale=0.2] at (0,-3) {\includegraphics[]{figures/case1_micro.pdf}};
            \end{tikzpicture}
        }
        \captionof{figure}{\label{fig:case_1}Example of a beam subjected to flexion solved with the FE$^2$ multi-scale method.}
    \end{minipage}
    \vfill
\end{figure}

Answer 1

The problem was the figure arguments. Setting :

\begin{figure}[!h] ... \end{figure}

Solves the problem.

Answer 2

Specify [t] floating, but also set the layout parameters so LaTeX will allow "top" floats to mostly fill the column, leaving very little text:

\renewcommand\topfraction{.9}
\renewcommand\textfraction{.1}% 1-\topfraction

The default parameters are unusually restrictive.

Using [h] placement leads to hassle where you have to keep manually editing the document to make the figure come out right.