Drop ceiling tiles were removed in the entire gym and office spaces below the affected. Vital Structures prepared a partial as-built floor and roof framing plan, discussed with the joist connector plate manufacturer, and performed a gravity load analysis using STAAD.Pro. The evaluation concluded the following:
- The failed joists appeared to have been installed upside-down.
- The steel beam was overstressed with respect to lateral torsional buckling failure, apparently due to loss of lateral buckling restraint at the top flange along the row of failed joists.
- Limited low roof joists were found to be overstressed.
- The steel beam web blocking which secured the low roof joists and floor joists to the beam was questionably attached to the beam.
- Top mounted joist hangers were fastened solely into plywood subfloor, against the hanger manufacturers fastening requirements.