When MEDA and co-developer Chinatown Community Development Center (Chinatown CDC) set out to build 94 units of housing for seniors, it sought to ensure that these vulnerable San Franciscans had not just affordable housing, but quality housing.
That effort was recently recognized by the United States Resiliency Council (USRC), which awarded Casa Adelante – 1296 Shotwell a Gold Rating. USRC’s mission is “to establish and implement meaningful rating systems that describe the performance of buildings during earthquakes and other natural hazard events, to educate the general public to understand these risks and to thereby improve societal resilience.”
Casa Adelante – 1296 Shotwell is just one of 34 buildings worldwide to garner this acclaim — and it is the first-ever multifamily, 100 percent affordable-housing development to be so honored.
“MEDA is proud that our efforts to keep our future senior residents, who will be moving in at year’s end, will have as safe a structure as possible,” explains MEDA Project Manager Serena Li, who is overseeing the structure’s completion in conjunction with Chinatown CDC.
Echoes Chinatown CDC Director of Housing Development Whitney Jones, “Living in an earthquake zone, we’re glad to ensure as much as possible that we have a building safe from disruption. We want our seniors to not have to worry that their housing is at risk when an earthquake happens.”
Think of these USRC ratings as similar to vehicle ratings for safety, gas mileage, etc.; however, in this case it is for earthquake hazards, the rating based on the building’s expected performance, using USRC adopted technical methodologies, in seismic events similar to those used in building codes and standards for the design of new structures.
The main questions are:
How long to repair the building?
How long for residents to get back in the building?
The Casa Adelante – 1296 Shotwell Gold Rating, which is applicable for five years, is broken down as follows:
- Safety: 5 stars out of 5
Injuries and blocking of exit paths unlikely: Expected performance results in conditions unlikely to cause injuries or to keep people from exiting the building.
- Damage: 4 stars out of 5
Moderate damage: Repair cost likely less than 10 percent of building replacement cost.
- Recovery: 4 stars out of 5
Within days to weeks: The expected performance may result in delay of minimum operational use for days to weeks , excluding external factors.
The building was designed by Mar Structural Design, with that firm’s David Mar and Sandesh Aher working with USRC over the past year to review and rate Casa Adelante – 1296 Shotwell. The innovative strategy included the use of seismic dampers (video).
In contemplating the need for shelter after a natural disaster, Mar Structural Design wanted to harness the benefits of high-performance design and structural resilience for the residents of Casa Adelente. As a structural engineer, Mar was acutely aware that conventional buildings designed per code, while life-safe, may not be functional after a major earthquake, as it can be devastating to lose one’s home for an extensive period during earthquake repairs. The residents of Casa Adelente – 1296 Shotwell are especially vulnerable since most do not have the resources to weather the aftermath of a major earthquake, given that 100 percent of the units are affordable, and 20 percent are slated for formerly homeless seniors.
“Our goal was to design a building that is substantially more resilient than a conventional structure, while having similar construction costs. We achieved high-performance by tuning the concrete walls to rock and re-align. During a major earthquake, the tilting walls activate flexure and yielding within the foundation and floor slabs. Special lead-extrusion dampers embedded in the foundation improve performance. The building’s own weight helps it re-center during the rocking response. This effort required a special team. Professor Geoffrey Rodgers of the University of Canterbury, designed, oversaw manufacture and tested the lead-extrusion dampers. Professor Greg Deierlein of Stanford University performed the expert peer review. These efforts by Geoff and Greg were performed pro bono, to support resilient design for folks who may need it the most.” explains Structural Engineer David Mar.
“The San Francisco Mayor’s Office of Housing and Community Development (MOHCD) is proud that Casa Adelante – 1296 Shotwell, a 100 percent affordable senior housing development, received the USRC Gold Rating for its enhanced structural design to ensure the building will not only continue to stand, but also remain safely occupied after a major earthquake event,” says Dan Adams, MOHCD Acting Director. “This protects our lowest-income senior residents and prevents displacement in the aftermath of an earthquake, while also reducing the impact on our City emergency response and shelter systems.”
“MEDA is so grateful for the vision of David Mar and his team for the safety of Casa Adelante – 1296 Shotwell, especially being that we are in earthquake-prone California. The design is unique and definitely deserves the kudos it has now received,” concludes MEDA’s Li.