Use what we call gang forms. The gang forms I've used for similar pours are made up of 8-inch double channel strongbacks on 4-foot centers with LVL 4x4 studs on 12-inch centers sheathed with 1 layer of 1-inch HDO or two layers of 3/4-inch form ply. Tie the forms back to the existing structure...
A few years ago in the 80's I remember welding in the field and learning the differences in AC vrs. DC welding.
One day in the late 90's I was eating lunch with an Ironworker in Seattle and in our casual discussion of the days work I discovered I was sitting by a man who had helped to weld the...
If you are welding with a low hydrogen rod or wire you may want to check your welding procedure which should include pre-heating requirements. Also, from what you've described you may want to re-visit the weldment design. If you can increase the weld size to 5/16 or 3/8 using a more impact...
If applicable/available pile snow on top the area. The snow will insulate the earth limiting frost penetration to 2-3 feet which can be excavated through. Also, keep in mind that any area receiving vehicular or equipment traffic will freeze deeper than the normal frost depth level.
JAE,
The erector did indeed have a licensed engineer on the payroll who designed the required lateral bracing to support the structure.
I think re-sequencing the erection was a primary cause of the failure because the newly imposed load conditions were not fully addressed in the bracing...
JAE,
Thanks for your coorespondence. I have grappled with the question of responsibilty for this project gone bad almost daily for the last 6-years. Have you ever seen a 24-inch long knife plate (shear lug) zipped off of a column? The structure we were working on collapsed after a...
A few years ago I was involved with a hi-profile project that included structural steel erection of a new parking structure over an existing precast parking structure, which incidently was being used by the public while erection of the new structure took place. During the course of erecting the...