Where’s the building? Is it a statue? Who is the artist responsible for this installation? These were among the many questions posed to Hoffman Construction in the early phases of Johnson Hall.
While in the first few weeks of summer it appeared construction merely consisted of five free-standing, 52-foot concrete walls supported solely by some poles, the crew was strategically navigating space limitations and employing cutting-edge technology to create the new home for the School of Chemical, Biological and Environmental Engineering.
Initially, the most visible and talked-about part of the construction site north of Ballard Extension Hall, between Southwest 26th Street and Southwest Park Terrace Place, was the shear walls. A structural system known for its resilience against lateral loads, shear walls are designed to withstand heavy winds and earthquakes. Space constraints on the jobsite, however, required these walls be erected before any steel, an impressive feat spurring many questions from onlookers.
“The shear walls were very challenging,” said Kevin Cady (’84, Civil Engineering), senior operations manager for Hoffman Construction. “The forms are big, heavy and cumbersome, and to jump those around in the tight area we are working in is probably the hardest thing we had to deal with — keeping the students safe, traffic moving, and having enough space to do the job.”
Temporary stabilizing braces against the walls – some on the interior, and some on the exterior — allow the shear walls to withstand up to 90-mph winds while the remainder of the building is constructed. Positioning the braces with limited space, while allowing construction to continue, is an intricate puzzle sequenced by project superintendent Chuck Burnett.
“We have to pour the roof deck and then pour level three, then we’ll take the braces down and pour level two,” said Burnett. “It’s a top-down approach, which is dictated by the braces. If all the braces were outside, we could have built level two, three and four like a normal building.”
Aside from the structural benefits, an additional advantage of using shear walls versus steel-framed bracing systems is the ability to pour windows into the walls. Steel-framed bracing systems can limit the size and location of windows, and having ample natural light is not only an energy efficiency, it lends itself to a more open, bright aesthetic. Creating a space that fosters collaboration and innovation has been at the forefront of design, and the placement of windows and use of daylight are integral to creating such an environment.
Erection of steel began mid-July, masking the awe of the shear walls and allowing a more traditional building shape to come into focus. Not visually evident to those following the progress, however, is the front-line technology aiding the creation of the building.
The team at Hoffman Construction is using building information modeling, or BIM, which allows the construction of Johnson Hall to be executed digitally prior to the physical construction. “Before we are out in the field we are building everything in a 3D computer model. Everything goes into the model and we run a clash detection report and see what’s hitting each other,” said Nathan Moore (’10, Civil and Construction Engineering), project manager.
Before BIM, 2D overlays of drawings were used to ensure things like ductwork, electrical conduits, fire sprinklers and alarms, and data cabling all fit together and work as planned. If there was an issue, it likely wasn’t discovered until installation.
With BIM, potential problems are identified in advance and can be addressed without the cost and time implications they used to carry.
“It’s really a collaborative effort and saves field labor tremendously,” said Moore.
BIM isn’t the only timesaving tool being used in the construction of Johnson Hall. Gone are the days of working off hard-copy blueprints — the team has now fully implemented the use of electronic blueprints.
“It’s real-time information to the field to build the building,” said Cady. “Just integration of the technology tools makes us more efficient.”
Projected to open fall 2016, the 58,000-square-foot Johnson Hall will be three stories high and will include a 125-seat lecture hall equipped with fume hoods, state-of-the-art laboratories, and an experimental learning classroom space for senior capstone projects. The first floor will include engineering student spaces for academic advising, student retention, engineering tours, a learning hub, and support for the diverse student population served in the College of Engineering.
Watch the shear walls go up through the construction time lapse on the Johnson Hall web cam, and read about lead donors Peter (’55, Chemical Engineering) and Rosalie Johnson.
— Krista Klinkhammer