Seismic Upgrades Required? How Your Renovation Can "Shake Up" Infrastructure and Experience
Earthquakes cost the nation an estimated $14.7 billion annually in building damage and associated losses, especially in hotspots like California, Alaska and Washington State. Buildings constructed before modern seismic codes—such as pre-1980 non-ductile concrete buildings and wood-framed “soft story” structures—are even more vulnerable to damage due to outdated construction methods. The solution? Seismic retrofitting. The process of strengthening a structure to make it more resistant to earthquakes, seismic retrofitting has gained momentum in recent years due to several policies and ordinances introduced at the state level to improve seismic safety, as well as a clearer and more precise understanding of seismic behavior.
In addition to making buildings safer and less prone to damage, seismic retrofitting also provides the opportunity to revive an outdated building, and can open the door for improvements in other areas without significantly increasing cost or disruption. Here, we explore how to determine whether your building is a good candidate for seismic retrofitting, as well as techniques and solutions that meet today’s standards while enhancing building performance, functionality and aesthetics.
Is Your Building in Need of Seismic Retrofitting?
While seismic retrofitting is almost always a smart idea, determining whether your building needs to be retrofitted and, if so, where to start can be tricky. Fortunately, a simple set of questions can help you assess if your building requires seismic upgrades.
Simply put, it’s advised that buildings in earthquake-prone areas that were designed and built before benchmark building codes and standards for life safety are assessed for seismic retrofit. If the building is found to be vulnerable according to an ASCE 41-23, retrofitting in compliance with current standards is a recommended next step.
However, even if your building has not been found hazardous according to current regulations but was built before 1977 in a high-hazard seismic area, it may still be recommended for seismic evaluation. In California in particular, there are many mandatory seismic upgrade programs—for example, the required seismic retrofit ordinance in Los Angeles targeting soft story wood-framed structures and nonductile concrete buildings built pre-1980, Senate Bill 1953 mandating the seismic upgrade of acute care hospital buildings, and the UCOP Seismic Safety Policy addressing the inventory of existing University of California facilities. Standards and recommendations are also continuously updated based on new knowledge and technical advancements.
If a seismic retrofit is recommended, your organization can then determine the most pertinent actions for retrofitting. Some of these actions may include adding structural support, adding shear walls or steel bracings, using base isolation, reinforcing the foundation or using fiber-reinforced polymers. It's also worth noting that retrofitting, while recommended in most cases, may not always be the right solution. If the cost value exceeds the cost of new construction, demoing and building new may be a better option.
Identify and Address Vulnerable Areas—Without Disrupting Operations
Though an important step in ensuring a building’s safety and longevity, seismic retrofitting can also disrupt a building’s daily operations as it often requires significant structural modifications to existing buildings. So, it’s important to think creatively about phasing and team coordination, as well as materials and processes.
For example, at UCLA’s Arthur Ashe Student Health and Wellness Center, the building’s pre-1994 steel moment frame—a lateral force-resisting featuring large entryways or openings—required targeted strengthening to improve its seismic resistance. A combination of structural reinforcement techniques such as bottom haunch retrofit details and reinforced diaphragm-to-roof connections allowed the team to address structural deficiencies, while phased construction and performing disruptive work during off hours minimized disruption to daily operations without the added cost of additional temporary structures to house users during the process.
At the University of California Los Angeles’ (UCLA) John Wooden Center, a student recreation center constructed in the early 1980s, NBBJ and KPFF were tasked with strengthening the metal deck roof diaphragm—a flat, structural element used to transfer lateral loads such as those caused by wind or earthquakes to the vertical elements of a building. By employing Fabric-Reinforced Cementitious Matrix (FRCM), a material typically used for reinforcing concrete and masonry, the team was able to reinforce the roof from above, avoiding the need to access the underside which would have required extensive scaffolding and significantly disrupted the facility's operations.
Improve Experience without Significantly Increasing Costs
Seismic retrofitting to address safety and legislative requirements—as described above—is often the most important priority. However, retrofitting can also provide opportunities for improved user experience without significantly increasing costs. And any additional costs incurred are often offset by the improved lifespan of the building and its systems.
With an eye toward the 2028 Los Angeles Olympics and UCLA’s desire to position the building as a symbol of excellence, the team also engaged in a redesign of the Wooden Center's existing interior and exterior spaces in parallel with the building’s seismic retrofit. An enclosed porch area between buildings now accommodates a variety of programs, attracting activity and fostering student involvement, while welcoming lounges create a comfortable atmosphere for students to relax and connect inside. The revamped exterior actively engages Bruin Plaza through shaded outdoor spaces and a more visible front entrance. By performing this work while the building was already under seismic construction, the team was able to reduce costs and construction timeline rather than embark on a separate, isolated project which would have been more expensive.
The design team used the required seismic upgrades at UCLA's Wooden Center as an opportunity for building improvement with limited added cost and construction time.
Seismic Safety in Healthcare—Going Beyond Standard Retrofitting Requirements
Seismic retrofitting is important regardless of building type, however, ensuring that healthcare buildings meet seismic requirements is critical as these facilities function as a lifeline for people and communities, especially in the case of a natural disaster.
In California, new regulations requiring hospitals to not only withstand a major tremor but continue providing service in its aftermath prompted the redesign of Loma Linda University Medical Center in Loma Linda, CA. As one of California's most critical Level 1 trauma centers, Loma Linda needed to accommodate both extreme medical emergencies and extreme seismic activity, while continuing to deliver the efficient, patient-centered care the hospital is known for.
Designed to move up to 42 inches in an earthquake, the hospital is supported by an innovative structural system with special expansion joints between buildings, allowing each to move independently during a seismic event. In addition, seismic dampening strategies include 126 base isolators using triple friction pendulum bearings and fluid viscous dampers. In addition to a reinforced concrete floor, the complex’s superstructure also includes a 25,000-ton steel frame to further reinforce the structure, making it North America’s heaviest building. Combined, these safety features are expected to give the project a life expectancy of at least 75 years.
Loma Linda University Medical Center is one of California's most critical Level 1 trauma centers.
Seismic upgrades are complex yet essential for preserving lives and communities, regardless of building type. Retrofitting offers an opportunity to not only improve future safety, but to create beautiful, functional buildings at little to no added cost. What’s more, by focusing on innovative materials, efficient construction methods, collaborative design, and creative solutions, investing in pre-existing buildings can reduce waste and enhance building performance and lifespan.
Editor's Note: This piece was co-authored by NBBJ Principal Andrzej Czech and Associate Sandra Lozano, and KPFF Principal Mark Hershberg and Associate Maikol Del Carpio.
