Welcome back to Filling the Gap, our series dedicated to educating you about expansion joint solutions. We talk a lot about movement at CS (as a matter of fact, here’s a shameless plug for the Mastering Movement™ Academy), and expansion joint systems help control building movement to preserve resilient structures. This is probably not news to you, but it is an important reminder as we delve into this month’s topic—projects after the fact—and retrospectively examine how our expansion joint solutions hold up over time.
In perhaps the most fun example of expansion joint resiliency, NHERI@UC San Diego allowed us to collect enough data for many earthquakes without having to wait years for them to actually occur. A full-scale, 10-story mass timber building was built on UC San Diego’s shake table (the largest outdoor shake table in the world) and then subjected to 88 earthquake motions, ranging in hazard from 43-year return period to MCER shaking intensities. CS was thrilled to be involved—in addition to our DriftReady™ Stairs, we provided expansion joint solutions both inside and out. On the facade, series XLS, SF, and SC were used, while interior applications used series FWF, AFW, and fire barrier.
How did our expansion joint solutions perform during the simulated earthquakes? All of the joints accommodated some movement, but, due to the test building design, greater slip and corresponding joint movement occurred in some locations more than others. On average, walls with the FWFC-600 exhibited noticeably more slip than walls without the joint. Model AFWC-400 separated the movement of the adjacent walls where it was used, but when subjected to larger drifts, the joint covers bent due to the torque demand from the bidirectional movement. Considering the intensity and number of earthquake simulations, we think it’s incredible to be able to report that all physical damage observed during the tests was readily repairable and characterized as minor damage. In the future, slight construction modifications may even mitigate this type of damage.
For a more traditional example, let’s take a look at California Memorial Stadium in Berkley, CA, which was the first facility to require 12” expansion, compression, and lateral movement. When CS got involved with this project more than 10 years ago, we had our work cut out for us—the stadium is located on the Hayward Fault, and seismic upgrades were necessary due to the fault’s creep producing numerous cracks, offsets, and gaps in the structure. Plus, the stadium is on the U.S. National Register of Historic Places so the facade needed to be preserved. We designed, tested, and fabricated custom tread and riser joint cover assemblies for the six seismic separations created through the stadium bowl to help reduce seismic risk and ensure safety in a major seismic event. Since the time of our installation, the stadium has shifted as anticipated. Also as anticipated, our expansion joint system is still helping to provide a safe walkway and access to stadium seats, which have moved about two inches. Take a look at some project photos below and don’t forget to watch the video update to see what has changed in a decade.
Finally, let’s visit The Cathedral of Christ the Light in Oakland, CA, where CS provided seismic moat covers more than 15 years ago. The church, which was designed to have a 300-year building life and survive a 1000-year earthquake, is radius-shaped and needed moat covers to match. Our SSR series expansion joint systems was used in the unique moat design because it’s capable of spanning the 33” moat while accommodating both the movement and aesthetic requirements. Take a peek at the video for an update. Spoiler alert: our expansion joint covers are still doing great.
As always, you can come to us with a problem and feel confident that we’ll do whatever it takes to help you solve it for the long term.
