The panels are not structural, but they create a plenum for the extraction of stale air - that's the rel reason they are needed. They are heavy because they are designed against flutter and movement.
The bolts are imbedded in epoxy filled drilled holes in concrete. The bolts are NOT (as I understand it) j-bolts or other typical embedded bolts.
The bolts are essentially glued into the concrete, and then the panels are hung from them.
This whole idea gives me serious pucker.
Horrible.
I would have specified steel embedments in the concrete above...and steel embedments in the concrete panels and then specified that a certified welder weld the two together in the field. Then any exposed steel or welds would be covered by a concrete patching crew afterwards...If there were any at all.
Possibly more expensive but thats the way we did it at the company I worked for. Also, as an engineer, I would've had to review all drawings to ensure that the embedments in the tunnel in the one blue print matched up to the embedments in the other blu print for the panel castings.
Very tedious, but at least no one dies.
I would think that the time required to drill holes OVERHEAD in the field to glue the bolts into place would have ate up any savings they could possibly have realized by A: not designeing decent connections, B: not Taken time to place steel embedments and C: not checking for matching locations.
Have you ever personally drilled overhead into concrete??? Unless they had a special rig, it would take a full day for 1 guy to drill holes just for one panel!! Maybe even more time than that.
If someone had designed a connection at the plant I worked for that specified that much field work the prints would never have made it to the production floor. The autocad guys would have sent it right back to the engineer with notes about how stupid engineers are compared to regular working folks...except phrased politely of course.
LOL... the original explanation of the bolting apparatus they gave to the press sounded like it was for the absurdity of 'asthetics'. But this proves once again that careers... and money... beat out a human life every time.
This system has been used for years to anchor heavy equipment to FLOORS where there is relatively little tensile load on the joint and where you are assured that the epoxy is well contained while it sets up.
This would probably be the worst application for this type of a fastener in that a full bond could not be assured particularly given the field installation methods.
I cannot say what the design specification was in this application, but I would not feel comfortable with less than a 5X margin of safety (but then my supervisors have always deemed me to be conservative). Should one of them fail, the adjacent fasteners must take up the load. But given your description of the panel, it is more likely that several of the fasteners failed simultaneously over a period of time. I.e., a poorly designed application for a marginally installed product.