Look at the edges of the paired hexagonal gusset plates midway between the diagonal and the upper box beam. Those edges (both plates in both photos) are "kinked" about halfway between the diagonal and the upper beam.
And they were bent at as least as far in the past as ca 2003...
I see what you refer to now. The deflection appears to be at least 1X gusset thickness. It shows a decreasing angle between U9-U10, and L9-U10. (Those probably are the strain sensors referred to in post 45, if so, yes, that could easily be the U10 gusset.) How the gusset deflection got that way, and what having it like that did for the bridge, structurally are problematic, at least.
But your third image appears to show that critical evidence has been tampered with, THE gusset that failed the bridge, altered, SINCE the collapse.
Where did that image come from?
“Look at the edges of the paired hexagonal gusset plates midway between the diagonal and the upper box beam. Those edges (both plates in both photos) are “kinked” about halfway between the diagonal and the upper beam.
And they were bent at as least as far in the past as ca 2003...”
I’m not an engineer (nor did I sleep at a Holiday Inn) but that kinky gusset picture is nothing if not third-degree alarm bells going off. As you say, those plates are clearly showing forces acting both in vector and in amount the gussets are/were inadequate to counter. It doesn’t get any simpler.