Email #57 – Flashback: A Tie Back Story On the Dec. 19 tour of Architecture Hall, M.Arch. student Karen Esswein asked how the seismic reinforcing concrete walls are tied-in to the historic brick walls. Since the walls had long since been shotcreted, I tried to explain verbally how L-shaped rebar tiebacks were first inserted long-side-into the brick wall with the short parts sticking out. Luckily I knew that because last fall I had asked the very same question of Mortensen Project Engineer Holly Higgins, who explained it all very well. Now, for some visual evidence, I looked through my archive and selected these pictures taken last September on the day before the shotcrete crew started on the first floor. In the left photo one tieback is visible protruding from the west wall of the South Wing. The depth of the window formwork is the depth of the new shear wall. The right photo was taken in the SE corner of the first floor. In this photo I found ten tiebacks and colored them yellow in Photoshop to pop out the pattern. Cool... I learned something too. Presumably there's at least one more pair of tiebacks above the scaffolding, but I didn't photograph the wall up there. I was looking at light and structure that day, but not counting tiebacks. Note the plastic wrap on the scaffolding legs in the right photo. That's because the shotcrete application is pig sloppy, and the stuff dries fast. It's easier to wrap the scaffolding before shotcreting than to clean the scaffolding afterwards. There are still eight openings for the next tour of Architecture Hall on Tuesday Jan. 2 at 2:30 pm. Email me if interested. Those who went on the Dec. 19 tour have to fly standby. John Stamets See also #16a and #25 |