Concrete tilt-up construction shaped much of Southern California’s built environment throughout the mid-twentieth century. Fast to erect and cost-effective, the method involves casting large concrete wall panels on-site and lifting them into place with a crane. What it did not always provide, however, was sufficient seismic resilience.
The core vulnerability in tilt-up buildings lies in the connection between heavy concrete wall panels and the roof or floor diaphragm. During an earthquake, the diaphragm behaves like a horizontal beam, transferring seismic forces to the walls. In many older buildings, these connections were underdesigned, with inadequate anchorage between the roof framing and concrete panels.
When those connections fail, the consequences are severe. Roof systems can separate from the walls, leading to partial or total structural collapse. This failure mode has been repeatedly observed in past California earthquakes and remains the primary focus of modern tilt-up seismic retrofits.
The University of California (UC) system enforces seismic performance standards that exceed those of the California Building Code. Any facility occupied by UC operations, regardless of ownership, must comply with these elevated requirements. Unlike typical commercial standards that prioritize life safety, UC criteria also emphasize post-event functionality, particularly for buildings supporting research, education, and critical operations.
As a result, UC occupancy triggers a formal seismic evaluation and upgrade process. Buildings that may otherwise be considered acceptable under standard code requirements must often undergo significant structural improvements before they can be occupied or remain in service.
On a recent project delivering laboratory space for University of California, Los Angeles in Culver City, our team executed a targeted seismic retrofit to meet these standards ahead of increased operational demand tied to the upcoming 2028 Summer Olympics.
The retrofit scope included the installation of new steel hold-down hardware and tension anchors at critical wall-to-roof connection points. These components, visible as galvanized steel plate connectors with threaded rod assemblies, are designed to transfer out-of-plane seismic forces from the wall panels through the roof framing and into the foundation. This effectively closes the failure path responsible for many historic tilt-up collapses.
In areas where existing wood framing was deteriorated or insufficient, supplemental members were added to restore structural capacity and ensure proper load transfer.
Execution required working above an existing suspended acoustical ceiling system, within a highly constrained plenum space. Our team navigated around active mechanical, electrical, and plumbing systems, including HVAC ductwork, conduit, and domestic water lines installed over decades of building use. Coordination was continuous, and sequencing was critical to maintain system integrity while completing the structural scope.
The completed retrofit brings the facility into full compliance with UC seismic performance standards, resolving a known life-safety vulnerability inherent to tilt-up construction of this era. UCLA can now occupy the space with confidence that the critical connection between wall and roof will perform as intended during a seismic event, supporting both occupant safety and continued operational use.
-By Charles Peterson
