Dtyjlui

I have created a timeline with ticzpicture which looks nice (and is working) but I was wondering if there was any way to put underbraces with text below it?
Here is a picture of what I mean:

This is my code:

    documentclass[12pt,a4paper]{article}



usepackage{tikz}



usetikzlibrary{timeline}



begin{document}



begin{tikzpicture}[timespan={}]



    timeline[custom interval=true]{bfseries 2014, bfseries 2015, bfseries 2016, bfseries 2017, bfseries 2018}



    begin{phases}



            %A 2014

            phase{between week=1 and 2 in -0.5,involvement degree=2.25cm}

            %C 2014

            phase{between week=1 and 2 in -0.1,involvement degree=2.25cm}

            %R 2014

            phase{between week=1 and 2 in 0.3,involvement degree=2.25cm}





            %A 2016

            phase{between week=2 and 3 in 0,involvement degree=2.25cm,phase color=blue!80!cyan}

            %C 2016

            phase{between week=2 and 3 in 0.4,involvement degree=2.25cm,phase color=blue!80!cyan}

            %R 2016

            phase{between week=3 and 4 in 0.05,involvement degree=2.25cm,phase color=blue!80!cyan}







            %A 2018

            phase{between week=3 and 4 in 0.5,involvement degree=2.25cm,phase color=green!50!black}

            %C 2018

            phase{between week=4 and 5 in -0.1,involvement degree=2.25cm,phase color=green!50!black}

            %R 2018

            phase{between week=4 and 5 in 1.4,involvement degree=2.25cm,phase color=green!50!black}





    end{phases}

    %2014

            addmilestone{at=phase-1.90,direction=90:3.5cm,text={Announcement},text options={above}}

            addmilestone{at=phase-1.270,direction=270:1.5cm,text={Date},text options={below}}





            addmilestone{at=phase-2.90,direction=90:2.5cm,text={Clarification},text options={above}}

            addmilestone{at=phase-2.270,direction=270:2.5cm,text={Date},text options={below}}





            addmilestone{at=phase-3.90,direction=90:1.5cm,text={Results},text options={above}}

            addmilestone{at=phase-3.270,direction=270:3.5cm,text={Date},text options={below}}







        %2016



            addmilestone{at=phase-4.90,direction=90:3.5cm,text={Announcement},text options={above}}

            addmilestone{at=phase-4.270,direction=270:1.5cm,text={Date},text options={below}}





            addmilestone{at=phase-5.90,direction=90:2.5cm,text={Clarification},text options={above}}

            addmilestone{at=phase-5.270,direction=270:2.5cm,text={Date},text options={below}}





            addmilestone{at=phase-6.90,direction=90:1.5cm,text={Results},text options={above}}

            addmilestone{at=phase-6.270,direction=270:3.5cm,text={Date},text options={below}}





        %2018



            addmilestone{at=phase-7.90,direction=90:3.5cm,text={Announcement},text options={above}}

            addmilestone{at=phase-7.270,direction=270:1.5cm,text={Date},text options={below}}





            addmilestone{at=phase-8.90,direction=90:2.5cm,text={Clarification},text options={above}}

            addmilestone{at=phase-8.270,direction=270:2.5cm,text={Date},text options={below}}





            addmilestone{at=phase-9.90,direction=90:1.5cm,text={Results},text options={above}}

            addmilestone{at=phase-9.270,direction=270:3.5cm,text={Date},text options={below}}



    end{tikzpicture}



end{document}

Any help is gladly appreciated!:) Thanks!

Something like this perhaps?

documentclass[border = 10pt]{standalone}

usepackage{tikz}

usetikzlibrary{timeline}

usetikzlibrary{decorations.pathreplacing}



begin{document}

begin{tikzpicture}[timespan={}]



timeline[custom interval=true]{bfseries 2014, bfseries 2015, bfseries 2016, bfseries 2017, bfseries 2018}



begin{phases}



    %A 2014

    phase{between week=1 and 2 in -0.5,involvement degree=2.25cm}

    %C 2014

    phase{between week=1 and 2 in -0.1,involvement degree=2.25cm}

    %R 2014

    phase{between week=1 and 2 in 0.3,involvement degree=2.25cm}





    %A 2016

    phase{between week=2 and 3 in 0,involvement degree=2.25cm,phase color=blue!80!cyan}

    %C 2016

    phase{between week=2 and 3 in 0.4,involvement degree=2.25cm,phase color=blue!80!cyan}

    %R 2016

    phase{between week=3 and 4 in 0.05,involvement degree=2.25cm,phase color=blue!80!cyan}







    %A 2018

    phase{between week=3 and 4 in 0.5,involvement degree=2.25cm,phase color=green!50!black}

    %C 2018

    phase{between week=4 and 5 in -0.1,involvement degree=2.25cm,phase color=green!50!black}

    %R 2018

    phase{between week=4 and 5 in 1.4,involvement degree=2.25cm,phase color=green!50!black}





end{phases}

%2014

    addmilestone{at=phase-1.90,direction=90:3.5cm,text={Announcement},text options={above}}

    addmilestone{at=phase-1.270,direction=270:1.5cm,text={Date},text options={below}}





    addmilestone{at=phase-2.90,direction=90:2.5cm,text={Clarification},text options={above}}

    addmilestone{at=phase-2.270,direction=270:2.5cm,text={Date},text options={below}}





    addmilestone{at=phase-3.90,direction=90:1.5cm,text={Results},text options={above}}

    addmilestone{at=phase-3.270,direction=270:3.5cm,text={Date},text options={below}}







%2016



    addmilestone{at=phase-4.90,direction=90:3.5cm,text={Announcement},text options={above}}

    addmilestone{at=phase-4.270,direction=270:1.5cm,text={Date},text options={below}}





    addmilestone{at=phase-5.90,direction=90:2.5cm,text={Clarification},text options={above}}

    addmilestone{at=phase-5.270,direction=270:2.5cm,text={Date},text options={below}}





    addmilestone{at=phase-6.90,direction=90:1.5cm,text={Results},text options={above}}

    addmilestone{at=phase-6.270,direction=270:3.5cm,text={Date},text options={below}}





%2018



    addmilestone{at=phase-7.90,direction=90:3.5cm,text={Announcement},text options={above}}

    addmilestone{at=phase-7.270,direction=270:1.5cm,text={Date},text options={below}}





    addmilestone{at=phase-8.90,direction=90:2.5cm,text={Clarification},text options={above}}

    addmilestone{at=phase-8.270,direction=270:2.5cm,text={Date},text options={below}}





    addmilestone{at=phase-9.90,direction=90:1.5cm,text={Results},text options={above}}

    addmilestone{at=phase-9.270,direction=270:3.5cm,text={Date},text options={below}}



    draw [decorate, blue, decoration = {brace, amplitude = 10pt, mirror, raise = 4pt}]

    ([yshift = -5cm]phase-1.180) -- ([yshift = -5cm]phase-3.0)

    node [black, midway, yshift = -0.5cm, align = center] {Some text \ with breaks};



    draw [decorate, red, decoration = {brace, amplitude = 10pt, mirror, raise = 4pt}]

    ([yshift = -5cm]phase-4.180) -- ([yshift = -5cm]phase-6.0)

    node [black, midway, yshift = -0.5cm, align = center] {extra text};



    draw [decorate, green!80!black, decoration = {brace, amplitude = 10pt, mirror, raise = 4pt}]

    ([yshift = -5cm]phase-7.180) -- ([yshift = -5cm]phase-9.0)

    node [black, midway, yshift = -0.5cm, align = center] {This phase is the best};





end{tikzpicture}

end{document}

Welcome to TeX.SE! The idea of this site is to exchange codes. In your post, unfortunately, the preamble is missing, meaning that those who are willing to answer have to speculate. So I guess you have downloaded the timeline library from here. Looking at the code, I have not seen any obvious way to add the braces in an elegant way without changing the library code. What one, however, always can do is to "hack" it by smuggling something into the code using every node/.append style and the like. Of course, this is more fragile than a solution that could emerge by writing the library in a different way.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{timeline,fit,decorations.pathreplacing}

newcounter{mynode}

tikzset{step node/.code={stepcounter{mynode}%typeout{themynode}

}}

begin{document}

begin{tikzpicture}[timespan={},every node/.append style={step node,

alias=mynode-themynode}]



timeline[custom interval=true]{bfseries 2014, bfseries 2015, bfseries 2016, bfseries 2017, bfseries 2018}



begin{phases}



        %A 2014

        phase{between week=1 and 2 in -0.5,involvement degree=2.25cm}

        %C 2014

        phase{between week=1 and 2 in -0.1,involvement degree=2.25cm}

        %R 2014

        phase{between week=1 and 2 in 0.3,involvement degree=2.25cm}





        %A 2016

        phase{between week=2 and 3 in 0,involvement degree=2.25cm,phase color=blue!80!cyan}

        %C 2016

        phase{between week=2 and 3 in 0.4,involvement degree=2.25cm,phase color=blue!80!cyan}

        %R 2016

        phase{between week=3 and 4 in 0.05,involvement degree=2.25cm,phase color=blue!80!cyan}







        %A 2018

        phase{between week=3 and 4 in 0.5,involvement degree=2.25cm,phase color=green!50!black}

        %C 2018

        phase{between week=4 and 5 in -0.1,involvement degree=2.25cm,phase color=green!50!black}

        %R 2018

        phase{between week=4 and 5 in 1.4,involvement degree=2.25cm,phase color=green!50!black}





end{phases}

%2014

        addmilestone{at=phase-1.90,direction=90:3.5cm,text={Announcement},text options={above}}

        addmilestone{at=phase-1.270,direction=270:1.5cm,text={Date},text options={below}}





        addmilestone{at=phase-2.90,direction=90:2.5cm,text={Clarification},text options={above}}

        addmilestone{at=phase-2.270,direction=270:2.5cm,text={Date},text options={below}}





        addmilestone{at=phase-3.90,direction=90:1.5cm,text={Results},text options={above}}

        addmilestone{at=phase-3.270,direction=270:3.5cm,text={Date},text options={below}}







    %2016



        addmilestone{at=phase-4.90,direction=90:3.5cm,text={Announcement},text options={above}}

        addmilestone{at=phase-4.270,direction=270:1.5cm,text={Date},text options={below}}





        addmilestone{at=phase-5.90,direction=90:2.5cm,text={Clarification},text options={above}}

        addmilestone{at=phase-5.270,direction=270:2.5cm,text={Date},text options={below}}





        addmilestone{at=phase-6.90,direction=90:1.5cm,text={Results},text options={above}}

        addmilestone{at=phase-6.270,direction=270:3.5cm,text={Date},text options={below}}





    %2018



        addmilestone{at=phase-7.90,direction=90:3.5cm,text={Announcement},text options={above}}

        addmilestone{at=phase-7.270,direction=270:1.5cm,text={Date},text options={below}}





        addmilestone{at=phase-8.90,direction=90:2.5cm,text={Clarification},text options={above}}

        addmilestone{at=phase-8.270,direction=270:2.5cm,text={Date},text options={below}}





        addmilestone{at=phase-9.90,direction=90:1.5cm,text={Results},text options={above}}

        addmilestone{at=phase-9.270,direction=270:3.5cm,text={Date},text options={below}}

node[fit=(mynode-17) (mynode-19) (mynode-21)] (f1){};

draw[decorate,decoration=brace,thick] (f1.south east) -- (f1.south west)

node[midway,below]{something};

node[fit=(mynode-23) (mynode-25) (mynode-27)] (f2){};

draw[decorate,decoration=brace,thick] (f2.south east) -- (f2.south west)

node[midway,below]{something else};

node[fit=(mynode-29) (mynode-31) (mynode-33)] (f3){};

draw[decorate,decoration=brace,thick] (f3.south east) -- (f3.south west)

node[midway,below]{hibernate};

end{tikzpicture}

end{document}

Another option, yielding the same result in a less fragile way, which however requires more typing, is

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{timeline,fit,decorations.pathreplacing}

begin{document}

begin{tikzpicture}[timespan={}]



timeline[custom interval=true]{bfseries 2014, bfseries 2015, bfseries 2016, bfseries 2017, bfseries 2018}



begin{phases}



        %A 2014

        phase{between week=1 and 2 in -0.5,involvement degree=2.25cm}

        %C 2014

        phase{between week=1 and 2 in -0.1,involvement degree=2.25cm}

        %R 2014

        phase{between week=1 and 2 in 0.3,involvement degree=2.25cm}





        %A 2016

        phase{between week=2 and 3 in 0,involvement degree=2.25cm,phase color=blue!80!cyan}

        %C 2016

        phase{between week=2 and 3 in 0.4,involvement degree=2.25cm,phase color=blue!80!cyan}

        %R 2016

        phase{between week=3 and 4 in 0.05,involvement degree=2.25cm,phase color=blue!80!cyan}







        %A 2018

        phase{between week=3 and 4 in 0.5,involvement degree=2.25cm,phase color=green!50!black}

        %C 2018

        phase{between week=4 and 5 in -0.1,involvement degree=2.25cm,phase color=green!50!black}

        %R 2018

        phase{between week=4 and 5 in 1.4,involvement degree=2.25cm,phase color=green!50!black}





end{phases}

%2014

        addmilestone{at=phase-1.90,direction=90:3.5cm,text={Announcement},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-1}]

        addmilestone{at=phase-1.270,direction=270:1.5cm,text={Date},text

        options={below}}

        end{scope}





        addmilestone{at=phase-2.90,direction=90:2.5cm,text={Clarification},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-2}]

        addmilestone{at=phase-2.270,direction=270:2.5cm,text={Date},text options={below}}

        end{scope}



        addmilestone{at=phase-3.90,direction=90:1.5cm,text={Results},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-3}]

        addmilestone{at=phase-3.270,direction=270:3.5cm,text={Date},text options={below}}

        end{scope}





    %2016



        addmilestone{at=phase-4.90,direction=90:3.5cm,text={Announcement},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-4}]

        addmilestone{at=phase-4.270,direction=270:1.5cm,text={Date},text options={below}}

        end{scope}



        addmilestone{at=phase-5.90,direction=90:2.5cm,text={Clarification},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-5}]

        addmilestone{at=phase-5.270,direction=270:2.5cm,text={Date},text options={below}}

        end{scope}



        addmilestone{at=phase-6.90,direction=90:1.5cm,text={Results},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-6}]

        addmilestone{at=phase-6.270,direction=270:3.5cm,text={Date},text options={below}}

        end{scope}



    %2018



        addmilestone{at=phase-7.90,direction=90:3.5cm,text={Announcement},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-7}]

        addmilestone{at=phase-7.270,direction=270:1.5cm,text={Date},text options={below}}

        end{scope}



        addmilestone{at=phase-8.90,direction=90:2.5cm,text={Clarification},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-8}]

        addmilestone{at=phase-8.270,direction=270:2.5cm,text={Date},text options={below}}

        end{scope}



        addmilestone{at=phase-9.90,direction=90:1.5cm,text={Results},text options={above}}

        begin{scope}[every node/.append style={alias=mynode-9}]

        addmilestone{at=phase-9.270,direction=270:3.5cm,text={Date},text options={below}}

        end{scope}



        node[fit=(mynode-1) (mynode-2) (mynode-3)] (f1){};

        draw[decorate,decoration=brace,thick] (f1.south east) -- (f1.south west)

        node[midway,below]{something};

        node[fit=(mynode-4) (mynode-5) (mynode-6)] (f2){};

        draw[decorate,decoration=brace,thick] (f2.south east) -- (f2.south west)

        node[midway,below]{something else};

        node[fit=(mynode-7) (mynode-8) (mynode-9)] (f3){};

        draw[decorate,decoration=brace,thick] (f3.south east) -- (f3.south west)

        node[midway,below]{hibernate};

end{tikzpicture}

end{document}