documentclass{article}
usepackage{amssymb,stackengine}
newcommandlbr{%
  ensurestackMath{stackengine{0pt}{lfloor}{lceil}{O}{c}{F}{F}{L}}}
newcommandrbr{%
  ensurestackMath{stackengine{0pt}{rfloor}{rceil}{O}{c}{F}{F}{L}}}
begin{document}
begin{equation}
lbr a rbr
end{equation}
end{document}