Anchoring bookshelves to walls prevents them from falling over during an earthquake.
When there is an earthquake, seismic loading is the amount of force placed on buildings. It is what makes them shake. Retrofitting buildings, and the objects inside them, to handle seismic loading during an earthquake will help everything and everyone escape unscathed. Bookcases are nonstructural items, according to the Federal Emergency Management Agency, and it is up to homeowners to prepare the bookcases for disaster. The importance is not on how many books are on the shelves, but on making the bookcases sturdy to prevent them from falling during an earthquake. Does this Spark an idea?
Building Codes
The International Code Council created a list of safety codes for buildings. These codes are law in many states where earthquakes are frequent. Architects must follow these codes and have building plans approved by a structural engineer. When installing shelving for buildings, the installer must have a specific license. Homeowners, on the other hand, use the codes to install home bookcases and anchor them to the floor, walls or ceiling. While the codes are for bookcases 5 feet tall or higher, anchor any sized bookcase if living in areas with high seismic activity. The requirements for anchoring bookcases depend on location according to the National Hazard Seismic Map created by the United States Geological Survey.
Zone 4
Zone 4 on the seismic zone map has the highest risk for massive earthquake damage, as locations in this zone rest on fault lines. The force of an earthquake is measured by percentage of gravity and written as percent g. When the percentage of gravity is high, that means the earthquake is strong. Locations in zone 4 have earthquakes with forces of 48 percent gravity and up. Areas in zone 4 include the West Coast, the southern coast of Alaska, west Nevada, the eastern coast of South Carolina, as well as the corners of Illinois, Kentucky, Tennessee, Arkansas and Missouri. Bookcases and shelving inside buildings located in this zone require anchoring to the walls and floor, with one anchor for every other section of the bookcase. Any shelving taller than 5 feet requires brackets welded to the shelf.
Zone 3
Areas in zone 3 have a high risk for major damage caused by an earthquake, as they rest near major fault lines and are usually the areas around zone 4. The areas have a gravity percentage between 32 and 48 g. Locations include northern and central California, central Nevada, northern Washington, western Montana, central Idaho, northern Utah, central Alaska and parts of Hawaii. In this zone, bookcases require one anchor for every third section.
Zone 2B
While areas in zone 2B are not as likely to have earthquakes that cause major damage, the earthquakes do reach gravity percentages up to 32 percent g. Locations include central Washington, Utah, California, Nevada, Idaho, Oregon, as well as parts of Montana, northwestern Arizona, northern New York, South Carolina, Alaska and the lower Midwest. Place one anchor for every fourth section of the bookcase.
Anchor Installation
Bookcases need anchoring to the wall as well as to the ceiling or floor. If the wall is wood, locate studs on the wall using a stud finder and anchor the bookcases to the studs. Attach sway braces or steel angles using lag bolts that are 1/4 to 3/8 inch in diameter and long enough to reach at least 2 inches into the wall. Metal studs require sheet-metal screws. Walls made from drywall or concrete require anchor bolts installed in the wall before the screws or lag bolts for extra hold. For floors or ceilings, locate the beams or joists in the floor or ceiling and attach the brace using lag bolts or screws. If the bookcases are located in the center of a room, anchoring to the floor is necessary.
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