As we have seen in the last several years, earthquakes can happen at any time and any place, not just close to a major fault line. Many old commercial facilities are dangerously unprepared to withstand the force of even very small tremors. An earthquake retrofit provides current structures with more strength to withstand the powerful forces of an earthquake. In buildings, this process typically includes strengthening inadequate connectors found in roof-to-wall connections, shear walls, continuity ties, and the roof diaphragm.
Commercial buildings, manufacturing facilities, and warehouses that were built prior to the beginning of this century most likely need to be strengthened with an earthquake retrofit. Past commercial building codes were not as strict as they are today, therefore it is a sound practice to inspect commercial-type buildings constructed prior to 2000, as they were built before the current structural codes/requirements were developed. In fact, many types of structures may benefit from an earthquake retrofit, including a variety of buildings, bridges, dams, etc. Buildings on the west coast, including in the Bay Area, are diverse in their design and style, therefore special considerations may need to be made before being reinforced.
- Un-reinforced Masonry (URM) – Adding roof and floor wall anchors and continuity ties will typically be necessary for an earthquake retrofit for any buildings with un-reinforced masonry. In some cases, there may be too many openings, such as a large open window, which requires special reinforcement to resist the shear loads. Some URM’s have walls that are too thin and will therefore require special work to strengthen them.
- Concrete Tilt-Up & Reinforced Masonry (CMU) – An earthquake retrofit for buildings like this usually involves adding anchors that interconnect the roof and floor framing to the walls, along with adding continuity ties throughout the building. Depending on the shape and size of the building, steel brace frames may be needed for additional reinforcement. The concrete tilt-up and masonry walls used in commercial properties are very heavy and when shaken in an earthquake, they exert tremendous force. The major reason for completing an earthquake retrofit for these buildings is to keep the heavy walls from pulling away from the roof and floor framing which it supports.
- “Tuck Under” Apartment Buildings – These are buildings that have an open first floor (such as ground level parking or subterranean parking) with another floor above (such as living or business space). Because these buildings do not have the ability to resist the lateral forces along these open elevations, they typically do not fare well during an earthquake. An earthquake retrofit to strengthen these buildings usually includes adding a steel moment frame, concrete footing and drag lines to ensure that the lower level does not rotate and collapse. In addition, shear walls are commonly added to the existing walls on the interior areas of the parking stalls of apartment buildings to give added reinforcement.
- Concrete Buildings with two or more stories – These buildings exert a great deal of force, simply due to their extreme weight. An earthquake retrofit to reinforce multi-story buildings may include several types of strengthening systems. A combination of concrete shear walls, gunite, fiber wrapping, and steel collectors may be used to reinforce this type of building.
While earthquake retrofitting may be done for many different reasons, the most typical reason is to ensure the safety and security of a building’s employees, machinery, and inventory. The reality is simply this: many buildings in danger zones were not built to withstand the force of earthquake activity. To find out more about whether your commercial property in the Bay Area should be strengthened and reinforced to withstand the impact of an earthquake, call Saunders Commercial Earthquake Retrofit Bay Area today!