Seismic Retrofit for Tilt-up Buildings in California Contributed by Frank Cambra, Civil Engineer The Northridge Earthquake of 1994 clearly demonstrated that tilt-up buildings designed and constructed to pre-existing codes and standards have a significant risk of sustaining life-threatening damage and severe economic loss, including partial or complete structural collapse given moderate-to-strong ground motions. A Structural Engineering Association of Northern California (SEAONC) task group concluded, "risk is primarily due to inadequate anchorage for walls into the horizontal roof diaphragms." A SEAONC report entitled Guidelines for Seismic Evaluation and Rehabilitation of Tilt-up Buildings and Other Rigid Wall/Flexible Diaphragm (RW/FD) Structures was authored in 2001. Concrete tilt-up structures with inadequate roof to wall connections collapse damaging their precious contents, often bankrupting unsuspecting businesses, forcing their owners to look for safer new buildings.
Establishing Seismic Strengthening Requirements for Tilt-Up Buildings.HCG Associates, Inc. recommends anyone owning, operating or occupying tilt-up or RW/FD buildings as described above arrange for a structural engineering inspection and report addressing concerns including, but not limited to: Out-of-plane Wall Anchors Wall Anchor Load Transfer into Diaphragm(s) Collectors and Load Transfer to Shear Walls Diaphragm Load Carrying Capacity, Chords and Openings Sub-diaphragm Load Carrying Capacity Wall Ledger-diaphragm conconnections In-plane Wall Capacity Out-of-plane Bending Capacity of Walls Foundation design and Wall Anchorage Panel-to-Panel Rigid-Body Wall Motions and Connections Mezzanine and Appurtenance Building/Sub-structure Interaction Material Warehousing and Industrial Equipment Services
While architectural configurations and construction details are many, HCG Associates, Inc. has successfully applied Mercalli XII structural components and systems for seismic retrofit. Recommended product applications include: In conclusion, seismic retrofit can most often be achieved for less cost and minimal disruption than one would guess. Let HCG help assess your risk today. Contact HCG for an inspection and assessment of your building. | 
