Pipe held up by a chain

I've got a question that I've been struggling with for a while...
I've got a pipe held up by a chain. Picture a pipe bent into an arch,
held up by a chain suspended below. I've put a gif of this on my
website: . Periodically, there are
struts from the pipe to the chain that hold the shape together and hold
the pipe above the chain. The entire structure is supported vertically
only, so the ends are free to move.
I've done the analysis using both a catenary and a parabola; the results
are essentially the same for both.
I am unclear as to the end conditions. The pipe arch is flatter than
the chain, so the horizontal reactions are greater than the chain. I
figure that some of the horizontal reactions go into raising the pipe,
thus reducing the stress in the chain and increasing bending moment on
the pipe....
Direct measurements indicate that the tension in the chain is about 1/3
of that predicted by a parabola/catenary, and I am at a loss to explain
this amount of discrepancy....
Any thoughts, discussion, suggestions?