Not only one of the greenest buildings in the area: the David Brower Center

Post-tensioned concrete walls for seismic resistance

http://www.tippingmar.com/projects/project_details/19

(go ahead on the arrows 1-9, especially n. 4/9 and 7/9)

CASE STUDY:

http://www.tippingmar.com/uploads/documents/publication/PTwalls_PTI_Journal.pdf

This mixed-use complex located in the heart of downtown Berkeley provides a unique environment that promotes and embodies an agenda of environmental health, justice, and advocacy. The David Brower Center, named for the Sierra Club’s first executive director, incorporates work and gathering space: offices for various nonprofit organizations, a theater, a restaurant, and event facilities. The adjacent Oxford Plaza offers a hundred units of market-rate and affordable housing set above retail, further enriching the center’s community. Although well served by transit, the complex includes some below-grade parking.

Fittingly, the Brower Center will be a model of integrated sustainable design expected to receive LEED Platinum certification. Sustainable features include natural ventilation, incorporation of sophisticated, natural day-lighting strategies, photovoltaic panels, and rainwater collection. High-slag concrete was used to replace cement by seventy percent in the foundations and fifty percent in the superstructure. The use of slag, an industrial byproduct, will reduce the embodied energy and carbon footprint of the building on the order of forty percent. This is the first Bay Area project to use high-slag concrete on such a large scale.

The Brower Center’s lateral structural system reflects the Tipping Mar philosophy of integrating sustainable design and high-performance engineering. The system uses post-tensioning cables in flexural walls and frames to create a highly damage-resistant structure. While conventional reinforced-concrete structures are expected to yield and displace permanently under large seismic events, the post-tensioning cables used in the lateral system act as springs, allowing the building to flex, then pull back to its original alignment. This re-centering behavior should allow the Brower Center to remain usable after a seismic event, whereas a more typical structure would require costly repair.

Both the high-slag concrete and the self-healing structure are being proposed for LEED innovation credits.

More information on the system:

http://www.tippingmar.com/uploads/documents/publication/PTwalls_Concrete_Intl.pdf

http://www.tippingmar.com/uploads/documents/publication/PTwalls_PTI_Journal.pdf