"Leuf" wrote in message
The weird
thing is the glass didn't break, except a small chip in one corner.
All 4 joints on the frame came apart though, which is sort of the
opposite of what I would have expected. They were splined miters with
the spline about 1 inch deep at the joint. It appears the splines
were either slightly too thin or I didn't use enough glue, as the
splines came loose with no damage at all to the frame or splines. I
test fitted one and it seemed like a proper fit to me. I'm a little
confused.

So here are my questions,

With the proper joinery should a frame survive a fall like this or
should it be expected to fail?

Should I be making the spline deeper or adding a key for additional
strength?

The frame protected the glass by absorbing the shock. Take a look at things
like the bumpers on your car, crumple zones, the foam packaging
appliances/electronics come in and what do they have in common? They all
absorb shock.

If you want the frame to absorb the shock of a 4' fall, it must be designed
into it. Strong materials do not always do the job as they transmit, not
absorb the energy. Frames, with purpose in mind, are made to look pretty,
hold pictures or mirrors, and provide support for hanging. Never has
falling come into the engineering.