CCC Job #3394

University of Michigan - Center for Innovation

STATEMENT OF PROBLEM:

Structural drawings call for embeds ~8' o.c. for each floor within the cast in place shear tower. The building had seven different levels with each level requiring a different number and size of embeds. Structural beams tie into these embeds and support the floor.  These embeds were installed off the shear wall working platform at each level and varied in size. The embed that was missed was 1'-4" x 2'-4". The task became repetitive and at first look the crew had thought they included all the required embeds. Additionally, some embeds were installed with the incorrect orientation.

ROOT CAUSE:

COURSE OF ACTION:

We submitted an RFI and the engineers had us cut the nelson studs off the embed and surface mount the embed with (12) 3/4" A36 threaded rods. Anchors needed to be embedded 8" and used with approved adhesive. We also had to take extra caution to not drill through any existing re-steel. It is helpful to use a marker and write the identification of every structural embed on the exposed face of the embed. 
 

LESSON FOR FUTURE PROJECTS:

Multiple people missed installing this embed. Our superintendent, foreman, two layout professionals, third party inspector, and General Contractor all missed this. Our superintendent came up with the idea of creating a cheat sheet that was laminated with all the embeds on it per level. The crew could use this as an quick reference guide to double check that all the embeds were installed per the plan. There were so many documents and changes that it made things hard for the crew to assure that they didn't overlook anything. Use a marker to write the identification for the structural embed on the exposed face, write thing like "top, bottom, east, west," and etc to ensure correct installation.