U.S. Courthouse senior project manager Brian Murray and architect Michael Johnson explained the details of the new courthouse’s high-tech composition to members of the Federal Bar Association during Tuesday’s luncheon at the Omni.
“This project will be a stepping stone for projects [like this] down the road,” said Johnson of KBJ Architects.
The foundation includes over three times the pounds per square inch resistance of residential slabs and 3,000 tons of rebar or reinforced steel in its base. Attention to high water tables was addressed by the implementation of internal water-proof membranes to prevent mildew.
“We de-watered the whole site,” said Johnson. “We got to keep those [water] pumps going long enough because it would actually float the building up so we had to get enough mass to keep it down.”
Currently, the outer skin of the building is being installed.
“It’s important to note that if they ever do demolish this building, poor demolition contractor,” said Murray. “People are going to lose teeth trying to chip on this. The local insurance firm testing the strength [of the foundation] did not have a machine to break the concrete.”
The precast (the skin) of the building is designed to be blast-resistant according to specifications from a certified blast consultant. The Jacksonville courthouse is only the second courthouse in the country designed after the Oklahoma City bombing; the first was in Las Vegas.
A progressive collapse design led to the demise of the Oklahoma City building. The Jacksonville courthouse was designed to eliminate that flaw.
“Concrete takes compression and steel takes tension, so you use the two together. A good way to do that is to use steel cables to stretch them,” said Johnson. “The problem is once those cables let loose, it starts to collapse and then the next one hits the next one and it progressively goes down. One of the things is that we designed against that in this building. We could actually lose structural support and it will stay. We could lose columns and the span would still stand between them. Our rebar runs from side to side all the way across.”
Another feature of the building, which was topped out in January, will be the placement of cooling towers and a generator on the roof to impede unwanted access.
The curtain wall system utilized adds aesthetics with a curved front that reflects the surrounding skyline. Don’t be fooled by appearances though; the shape harbors extra-long supports, which are there for safety precautions more than anything else.
The project is slated to be complete by next October.