What Are the Effects of Earthquakes on Buildings? Dangers, Facts & FAQ
Earthquakes are dangerous natural phenomena that can cause a considerable amount of damage to homes and other structures. If you are in an area that experiences many earthquakes or live along the coastline, you are likely concerned about the effects of earthquakes on buildings. Keep reading as we provide you with information that will help you avoid shoddy construction practices and other problems when choosing a home, so it will take less damage in the event of an earthquake.
How Does an Earthquake Affect a Structure?
The 10 Things to Consider When Choosing a House in an Earthquake-Prone Area
1. Soft-Story Buildings
A soft-story building has less resistance or stiffness on the lower floors than on the floors above it due to longer or fewer columns adding support. Many times, this occurs when there is a parking garage on the lower levels of an office building. Many dance halls and similar businesses will have an open first floor with apartments or offices upstairs, creating a soft-story building, especially when the ceiling on the first floor is higher than on the other building levels.
2. Short Columns
Short columns are usually a part of a non-bearing brick wall and restrict lateral displacement of the frame and increase rigidity.
3. Inadequate Reinforcement Detailing
Reinforcement-detailing mistakes can cause damage to buildings in earthquake-prone areas. Improper spacing and bar size of the rebar inside cement columns and other parts of the building can cause weak spots that fail when an earthquake occurs, which enables the cement beams to crack, shear, or buckle, possibly resulting in the collapse of the building.
4. Nonstructural Damage
While nonstructural damage shouldn’t endanger the stability of a building and isn’t a big cause for concern, it can create other dangers, like falling walls or plaster. For instance, a small earthquake might crack a wall in a bedroom. It might stay that way for many years before suddenly falling and leaving a large hole that you need to repair.
5. A Discontinuous Force-Resisting System
A discontinuous force-resisting system has support columns that don’t extend to the foundation. All vertical elements that support the lateral force of a building must continue to the foundation, or extreme damage can occur during an earthquake, often resulting in the complete collapse of the first floor and any floors that don’t have adequate support.
6. A Strong Beam But Weak Column
When you have support columns weaker than the beams, they will fail first in the event of an earthquake, which can lead to the collapse of a building. If the column is stronger than the beam, the beam will collapse first, which will cause damage to the floor but leave the building standing in many cases.
7. Inadequate Detailing
Inadequate drainage provisions, expansion joints, and other items can cause significant damage during an earthquake. Expansion joints, which often hold new additions to an older structure, are especially prone to breaking and might even result in the addition falling away, which might damage other structures.
8. Poor-Quality Concrete
Low-quality concrete without much tensile and shear strength is especially prone to damage during an earthquake, as it will easily shatter and crumble even when the reinforcing rebar is adequate, resulting in more damage.
9. Inferior Materials
Besides concrete, many other materials used in construction must be of good quality, especially in an earthquake-prone area. Items like dirt and rock foundations, cinder blocks, and clay bricks must be high quality, or they will be more prone to failure during an earthquake. The proper installation of these items is also essential.
10. Densely Populated Areas
Living in a densely populated area is another risk in an earthquake-prone area, as other buildings might fall and damage yours. The denser the population, the more you need to worry about properties that you have no control over.
Where Do Most Earthquakes Occur?
Most people associate earthquakes with California and the west coast, and while many earthquakes do occur here, they can occur almost anywhere in the country. Utah, Colorado, Wyoming, Idaho, and Montana all experience frequent earthquakes on the western side of the U.S. Oklahoma is a central state that receives several hundred small earthquakes each year. Eastern states that receive earthquakes include Arkansas, Missouri, Illinois, Kentucky, South Carolina, New York, and Maine.
How Are We Improving Buildings to Survive an Earthquake?
The USGS National Strong Motion Project has outfitted more than 250 structures with seismic sensory devices to study the effects that earthquakes have on them to help improve building techniques in the future. The data that these devices can detect includes the earthquake’s strength, the building’s movement and type, and the location of any damage. These devices demonstrate what kind of damage occurs most frequently, so we can take steps to add support in these areas.
What Happens After an Earthquake Occurs?
The effects of an earthquake on buildings can be devastating. Inertia and other forces can tear apart a building, especially if it uses low-quality building materials. Structures with a soft story or short columns will take more damage if an earthquake occurs. Programs like the USGS National Strong Motion Project are working to study the effect of earthquakes on structures so building techniques can improve. This means we should see less damage occurring in the future. Remember that earthquakes can occur almost anywhere in the country. Always research the area where you are looking to buy to see if earthquakes occur there, and look into the history of a building before you purchase it to see if it has already suffered damage that might make it weaker if another earthquake occurs.
Featured Image Credit: cobain86, Pixabay