For concrete buildings in seismically active areas, a building’s lateral bracing system accounts for a large portion of total building costs and can impose significant architectural constraints on the building design. Tipping has done substantial research on recentering post-tensioned shear walls, a new type of hybrid concrete shear-wall system that employs unbonded, vertical post-tensioned tendons, coupled with the energy dissipation provided by the reinforcing bars. Performance advantages for this wall system include rocking behavior and the ability to recenter after a major earthquake, which makes it much more likely that people will be able to reoccupy the building. Avoiding demolition and reconstruction following a major seismic event translates into cost savings, material savings, and reduced environmental impact. More broadly, operable buildings will help communities rebound more quickly and effectively.  Learn more about post-tensioned walls.

During our work on the San Francisco Public Utilities Commission Headquarters, Tipping used a hybrid lateral system involving vertically post-tensioned concrete cores, which was adapted from bridge engineering and designed to return a structure to plumb after a significant earthquake. In redesigning the SFPUC headquarters in concrete, Tipping implemented the latest iteration in a series of “self-centering” walls, meeting the performance mandate and budget. Tipping’s design solutions delivered immediate occupancy performance, increased constructability, shortened construction time, reduced construction costs, and reduced greenhouse gas emissions. The structural design saved the project almost $30 million in direct, indirect, and downstream costs. Incorporating state of the art green concrete reduced the carbon footprint for the structure by fifty percent, a substantial contributor to the structure’s achievement as one of the greenest office buildings in North America and LEED Platinum certification.

Tipping uses seismic isolation to achieve enhanced seismic performance and minimize damage to a structure during earthquakes. This approach decouples the structure from earthquake ground motions through the use of specialized isolator bearings that allow the entire structure to move relative to the ground. While traditional base isolation systems require a “moat” at ground level to accommodate the seismic movements of several feet, Tipping’s research has identified less conventional approaches to seismic isolation that are equally as effective, often for significantly less cost. Learn more about seismic isolation.

Keeping in mind our goal of elevating the craft of structural engineering, Tipping’s design of our office at 1908 Shattuck located seismic isolators ten feet above grade, avoiding significant foundation cost and efforts that would be required for the typical below-grade application. The isolators are exposed and visible, allowing us to showcase the technology to the public visiting the ground-level brewery. Tipping’s highly resilient building both prioritizes seismic safety as principle, while also allowing our team to soon reoccupy the structure after a major seismic event, so we can begin work to help our community recover.