18 Orinda Way
With an innovative, self-healing structure, an essential city facility stands ready to serve its community.
As the center of this municipal government’s operations, including the police department and other important services, Orinda City Hall had to fulfill “essential-use facility” design criteria and, as such, provided a unique opportunity to advance both sustainable and seismic design.
The structural system is a hybrid of wood and steel framing. Seismic loads are resisted by rocking braced frames that represent the latest generation of restorative systems. The frames remain rigid for moderately intense earthquakes that occur occasionally, protecting architectural elements from damage during these events. For large and rare earthquakes, the frames can rock as a rigid body rather than buckle braces as in conventional designs. Vertical post-tensioned cables provide restoring forces and re-align the structure while fusible elements at the bases of the frames absorb seismic energy. The structural fuses are low-cost steel angles that can then be unbolted and replaced after yielding; thus preserving the useful life of the building.
In addition to making the building safer, this advanced structural system is also more sustainable. Designing for seismic durability can reduce damage potential and repair cost over the life of the building. Additionally, fifty percent of the cement in the concrete was replaced with slag, an industrial waste product, thus dramatically reducing the building's carbon footprint. The project has received LEED Gold certification from the US Green Building Council, with two innovation points for the rocking-frame structure and high-slag concrete.
Executed as Tipping Mar
2007 SEAOC Excellence in Structural Engineering, Small Project Excellence Award
2006 NCSEA Excellence in Structural Engineering, Outstanding Project Award
2006 SEAONC Excellence in Structural Engineering, Award of Excellence: Best Use of New Technology in New Construction