Lax goal problem

Our lacrosse goal has a problem - it won't stand up on its own because the right-angle turns have weakened. We're thinking of using 2x4 braces to hold it up.

Here (below) is how it should look, but it won't stand up without T holding it up.

Here's what happens if he let's go - it just crumples to the ground.

 Here we're zoomed in on one of the right-angle joints... it looks OK because T is holding it up.

Here's a picture of the same joint, but without T holding it up - it just folds over.

The metal tubes are about 1.5" in diameter.

Here's a sketch of our basic idea of using 2x4 braces.