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

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]{0.49textwidth}
        centering
        resizebox{0.9linewidth}{!}{
            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]{0.49textwidth}
        vspace{1.5cm}
        centering
        resizebox{0.9linewidth}{!}{
            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}