Question: How to plot a piecewise function?

Recently I wanted to create a simple 2D-plot representing this piecewise expression:

T1:=piecewise(x>=0, 3.5*x*13/3+13, x>=20, 3.4*x*13/3+13, x>=30, 3.25*x*13/3+13);

or alternatively: T1:=t->piecewise(t>=0, 3.5*t*13/3+13, t>=20, 3.4*t*13/3+13, t>=30, 3.25*t*13/3+13);

Unfortunately, no matter whether I entered it as a function or as an expression, I was not able to make Maple plotting this function correctly for a domain Dx of say [0,40].

Is there a trick to be known, or did I neglect something?

Thanks for answering.

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