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Students Design Explorations of Precast for an Extreme Climate

Guest blog by Doug Noble and Karen Kensek

2017 PCI Foundation Studio in the School of Architecture at the University of Southern California continued the tradition of examining precast concrete in the context of Joshua Tree National Park. 

Fourth-year undergraduate architecture students were asked to design an entrance gate to the national park along with a restroom facility and small exhibition spaces.  Joshua Tree National Park is about a two-hour drive from downtown Los Angeles, and the location presents the students with special opportunities to take advantage of precast concrete. 

Students were challenged to design for the extreme climate, the distant construction location, the fragile condition of the natural landscape, a high-risk seismic zone, and the lack of easy access to normal utilities such as water and power.  Students were forbidden to respond to the difficult climate with standard mechanical equipment.

Joshua Tree National Park is a hot-dry extreme climate.  Wild temperature swings occur on the same day. Daytime temperatures routinely exceed 100 degrees, while nighttime temperatures regularly fall below freezing.  Joshua Tree is very large, and has different climate zones, all hot and dry.  Rainfall is typically less than five inches a year, but sudden rainfall and flash flooding also occur.  The high-mass properties of precast can be carefully designed to take advantage the temperature swings to store thermal energy. High-mass concrete walls and roof elements left exposed to cold temperatures at night can be designed to give that cooling back to the interior spaces during the heat of the day.  Similarly, precast exposed to high daytime temperatures can help keep a building warm at night.

The natural landscape is very slow to recover from damage.  Areas in the park that were impacted by construction more than 50 years ago still show the signs of this impact. Students were charged with absolutely minimizing construction yard work areas, and we emphasized the possibilities for plant-produced precast as a solution.

Joshua Tree National Park is a very high seismic zone (think San Andreas fault and many similar geologic conditions).  Students needed to understand how precast assemblies can be tuned for movement, and how high-mass and high-seismic are not always natural enemies.

The PCI Foundation studio at USC is supported locally by Clark Pacific and PCI West.  Students toured two Clark Pacific precast plants. One plant visit was to learn about structural concrete: columns, beams, double-T's, and hollow-core.  The other plant was for building envelopes.  For students who had not previously heard of precast, the tours were eye-openers.  Doug Mooradian and Ruth Lehmann from PCI West also supported the studio with lectures, desk-critiques, and studio reviews. 

This year we went beyond the standard walking tour and powerpoint presentations of precast plants and precast building case studies.  For the first time, our students actually got directly involved in physically making precast, including GFRC.  Led by Brad Williams and Sal Cruz from Clark Pacific, the USC Architecture students received safety training followed by a full direct exposure to all of the steps in making precast and GFRC.  Clark Pacific went well beyond any reasonable expectations and dedicated considerable staff resources.  Sal Cruz taught the students to wire-tie rebar, and Robert Villa added expert advice and demonstrated additional advanced wire-tie techniques.  Villa's hands were too fast, and he patiently slowed down his demonstration until the students could repeat it successfully using a training rebar frame.  Leni Garcia and his GFRC team demonstrated the techniques, and then had each student do the work themselves.  Rich Hundall and Alfred Toves were instrumental throughout the day as Williams kept up constant communication with his team by radio, always advising the Clark Pacific team as to what the USC group was doing and what was coming next.  The students moved from station to station always just in time for the next step, and the students learned that timing