Some questions regarding just how the weld test piece was fixtured. Hopefully the following pictures can help answer these constraint questions.
The testpiece as viewed from above is "T" shaped. The loading
arm is attached to the top left corner of the the "T". The top right
corner of the "T" is bolted into the fixture as shown below.
(The bottom leg of the "T" is anchored to the baseplate in exactly the
same fashion as the top right.)
A more oblique view of the connection:
The geometry of the welded test fixture is shown below. Please note
that each plate is welded to the next and all three plates are welded
to the 1" thick baseplate.
A side view showing both the base plate and specimen in elevation. Please note that the lower bolt hole center is 4" above the base plate: