According to scientists, there may be more earthquakes than usual in 2018. As part of the Geophysical Research Letters presented at the Geological Society of America, scientists tracked major earthquakes with a magnitude greater than 7 from 1900 to 2017. They found distinct and repetitive intervals at which the average number of earthquakes per year was much higher than other years. These intervals coincide with the Earth’s regular, recurring periods of slower rotation, when the law of inertia causes the molten core of the earth to ooze out towards the surface. After a while, the built-up pressure erupts on the Earth’s surface, compromising the structural integrity of homes, buildings and structures.
Scientists predict 2018 may be a tumultuous year for earthquakes. (Source: Take Two)
As structural damage is the leading cause of injury and deaths during an earthquake, architects, engineers and builders need to make sure buildings are built with the right materials and design.
SEE ALSO: What it Takes to Build a Natural-Disaster-Proof House
The Materials
The most dangerous type of earthquakes are ones that trigger horizontal movements, because tall buildings are better at resisting vertical loads than horizontal ones. These ground motions can damage building foundations in a matter of minutes, causing severe injuries and deaths. Building a structure to withstand seismic waves starts with the right materials with the right properties, and steel is by far the most widely used material for building earthquake-resistant buildings.
According to the World Steel Association, ductile buildings are safer as they dissipate energy from seismic waves. A building will typically have ductile parts that can undergo plastic deformations without complete structural failure during an earthquake. Steel is the most common type of material for such parts.
Moreover, due to the law of inertia, the lighter the building, the less force seismic waves will exert on the building. That’s why it’s important, especially for taller buildings, to be made of light and flexible materials such as steel that can “bend” with the movement of earthquakes. On average, multi-story steel buildings are 60 to 70 percent lighter and 10 times stronger than concrete-framed buildings of the same size.
The Design
With steel, builders can add vital designs and reinforcements to keep the structure standing through an earthquake. Here’s some of the most widely-used measures.
Cross braces transfer the force of an earthquake to the ground. (Source: Earthquakes in India)
The structural integrity of buildings can be reinforced with steel cross braces that frame the exterior of a building in an x-shape. Ultimately cross braces can transfer the force of seismic waves back down to the ground, instead of letting the building take the hit. Builders can also reinforce the walls of buildings with additional vertical walls, or shear walls, that add stiffness to the frame of the building, allowing it to resist swaying or horizontal movements.
Base isolators absorb much of the shock of seismic waves. (Source: Embelton)
Base isolation involves separating the building from the foundation so that the isolators to absorb shock from the earthquake. The isolators allow the building to move at a slower pace because they dissolve a large part of the shock. Moment-resisting frames also effectively dissipate energy from floors and roofs to the building’s foundation and the stiff yet flexible frames can change shape during an earthquake. Although more costly, moment-resisting frames enable buildings to withstand an earthquake with excessive horizontal movement.
Putting it into practice with POSCO’s Steel House
In September 2017, Young Bae Kim’s home in Gyeongju province, Korea was hit with a 5.8 magnitude earthquake, just 8.9 km from where the earthquake started. Surprisingly, Kim’s home was unscathed. “I could feel the ground shake, but the house was completely under control.” Kim expressed.
Kim lives in one of the Steel Houses built by POSCO employees who volunteer to build homes and bridges for communities in need. Each Steel House is made with POSCO’s lightweight structural steel known for its durability, fire resistance and vibration resistance. The homes also incorporate PosMAC, a specialized galvanized steel that is 5 to 10 times more corrosion-resistant than standard steel and is more durable and affordable.
POSCO Employees volunteer their time to build steel houses in rural communities.
Because all the Steel Houses survived the Gyeongju earthquake while other homes were damaged, more and more people in Korea are choosing steel for their homes over traditional building materials such as wood and concrete. The same trend can be observed in Japan, where earthquakes are much more frequent. In order to build more earthquake-resistant buildings, steel is still the best solution available.
Cover photo courtesy of CNN.
FAQs
What is the best building shape for earthquake resistance? ›
According to the University of British Columbia, the dome is by far the best shape for earthquake resistance. On the “shake table,” a test method used to simulate earthquakes' effect on certain building designs, the dome outperformed conventionally-structured houses.
Why is steel used in earthquake-proof buildings? ›Steel construction is lighter in weight than concrete, without compromising strength. It has less mass – and therefore less force – to damage itself under seismic shaking. It requires less earthquake resistance to be built into the superstructure and into the foundation, potentially lowering construction costs, too.
What are the 4 ways to make buildings more earthquake-resistant? ›- An Appropriate Foundation. Creating a flexible foundation for a building could help it stay standing during an earthquake. ...
- Seismic Dampers. Earthquake-resistant buildings also need features to help absorb shocks. ...
- A Drainage Mechanism. ...
- Structural Reinforcement. ...
- Material With Adequate Ductility.
As a high resistance and ductile material, steel is the indisputable choice for seismic-resistant construction. Even when it comes to the most demanding projects, such as high-rise buildings or long span bridges, steel frame construction has demonstrated its capacity to resist severe seismic events.
Which kind of building is most likely to survive an earthquake? ›Wood and steel have more give than stucco, unreinforced concrete, or masonry, and they are favored materials for building in fault zones. Skyscrapers everywhere must be reinforced to withstand strong forces from high winds, but in quake zones, there are additional considerations.
Are steel buildings good for earthquakes? ›Building a structure to withstand seismic waves starts with the right materials with the right properties, and steel is by far the most widely used material for building earthquake-resistant buildings. According to the World Steel Association, ductile buildings are safer as they dissipate energy from seismic waves.
How do steel structures withstand earthquakes? ›Steel structures are known to be earthquake proof as they are made of steel components that come in a variety of shapes, such as angles, plates, and beams. Steel offers the highest ductility and allows the resistant building steel structures to bend considerably without breaking.
Can steel withstand earthquakes? ›Cold-formed steel is the ideal material for buildings design to withstand seismic forces for two key reason: high ductility and light weight. Steel is considered a ductile material because it has the ability to bend or stretch without breaking when a force is applied.
Why are Japanese buildings earthquake-proof? ›Common earthquake-proof features in Japanese buildings
The use of a steel frame in the building's core – as opposed to the reinforced concrete core common in Western structures. The use of diagonal dampers, steel beams and columns rather than concrete columns. Pendulums in the core or on the roof of the building.
Soft-story Buildings: Extremely popular as a means of conserving space, these structures with open ground floors used for parking have been proven to be vulnerable because they lack the support to withstand lateral forces that push the building from side to side.
What are 3 features of an earthquake-proof building? ›
- Diaphragms. A diaphragm is a structural element – typically horizontal – that transmits lateral loads to the vertical resisting elements of a structure. ...
- Shear Walls. ...
- Cross-Bracing. ...
- Trusses. ...
- Moment-Resisting Frames.
The best type of steel bars to buy for construction of earthquake resistant buildings are TMT bars. They are made using a specialized process called Thermo Mechanical Treatment (TMT) and are high in tensile strength and ductility. TMT bars are of various grades - Fe-415/500/550, Fe-415D, Fe500D, Fe550D, and Fe-600.
What makes a building not earthquake-proof? ›If the building shakes too much, structural elements, including beams, columns, walls and braces, can be damaged, rendering the building nonfunctional. Base isolators are like shock absorbers between the building and the ground motion, letting a building slide back and forth while remaining upright during a quake.
What material is earthquake-proof building? ›Earthquake resistant concrete
EDCC combines cement with polymer-based fibres, fly ash and other industrial additives, making it highly resilient, according to UBC civil engineering professor Nemy Banthia, who supervised the work.
If it's a wood-frame house, as most houses in the Northwest are, it probably would not collapse, although your brick chimney might topple over. If your house is made of brick or concrete block, unreinforced by steel rebar, then the entire house might collapse.
Which building structure is least likely to be damaged in a strong earthquake? ›| A | B |
|---|---|
| NAME THE STRUCTURE LEAST LIKELY TO BE DAMAGED IN A MAJOR EARTHQUAKE | steel-frame building |
| describe LIQUIFACTION | during an earthquake, loosely consolidated sediments saturated with water can turn into a liquid that cannot support buildings, thus collapsing |
Earthquake resistant houses and buildings are designed to move with the quake, rather than collapsing or injuring those inside. Japan also hosts an integrated disaster prevention system. The government has issued extensive guidelines which include assembling an emergency kit in advance of a disaster.
Is steel or wood better in earthquakes? ›Steel has a significantly higher strength-to-weight ratio than wood. A steel frame is typically one-third the weight of a wood frame. Consequently, damage through "inertia" will be significantly reduced since there is less weight to move during an earthquake, and less weight that must stop.
What buildings are most at risk in earthquakes? ›Non-ductile concrete buildings have concrete floors and/or roofs supported by concrete walls, columns and/or frames. Due to their rigid construction and limited capacity to absorb the energy of strong ground-shaking, these structures are at risk of collapse in an earthquake.
Why do steel structures collapse? ›The collapse mechanism of steel structures exposed to fire depends on many influencing factors such as load ratios, strength of beams and columns, connections, slabs, fire scenarios, bracing systems, fire protections and their inter- action.
How do engineers build buildings to withstand earthquakes? ›
To help resistance swaying forces, engineers use vertical walls, known as shear walls, to stiffen the structural frame of the building. These can be used in place of braced frames or in addition to them.
How does China make their buildings earthquake-proof? ›The 'dougong' system consists of a series of interlocking beams cut to precise measurements, that when compressed under the weight of the buildings' heavy timber roofs, enable the buildings to be flexible yet strong enough to withstand earthquakes. The pieces are fitted together without using nails or glue.
What is the famous built to withstand the natural disasters? ›Crystal Bridges Museum of American Art, United States
The structure's roof is supported by cables, giving an illusion of a suspended bridge. So, the project does not break the flow of water but harmoniously stands the natural flow.
Built according to good practices, concrete homes can be among the safest and most durable types of structures during an earthquake. Homes built with reinforced concrete walls have a record of surviving earthquakes intact, structurally sound and largely unblemished.
What is the safest structure in an earthquake? ›Wood and steel are better than brick, stone, and adobe, which are brittle and will break. Larger buildings must sway, but not so much that they touch nearby buildings. Counterweights and diagonal steel beams are used to hold down sway. Large buildings can be placed on rollers so that they move with the ground.
What floor is most likely to survive building collapse? ›When a building does collapse, the safest place to be is on the top floor, and the most dangerous is the ground level.
What type of building construction is most likely to collapse? ›Type II Construction: Non-Combustible
Though these structures typically contain fire suppression systems, they are not often protected with fire-resistive coatings and are prone to collapse.
California has more earthquakes that cause damage than any other state. Alaska and California have the most earthquakes (not human-induced).
What is the difference between an earthquake-resistant building and an earthquake-proof building? ›An earthquake-resistant building is reinforced so that it doesn't crumble into rubble (which allows people to escape); an earthquake-proof structure has additional features designed to protect it during sideways shifting.
Why is steel used in high rise buildings? ›Due to its strength and load bearing capacity to weight ratio, steel is the undisputed material of choice for high-rise building structures.
Why is steel used to support buildings? ›
Strength. Due to its high strength-to-weight ratio, less steel is needed in a single support or beam, reducing material costs and improving its sustainable nature. It can withstand strong physical impacts and forces, keeping building occupants safe, but won't wear away or need to be replaced afterwards.
What is the major advantage of using steel as a building material? ›Steel has a unique combination of properties that make it an ideal building material. Steel's advantages in construction include speed, safety, optimal cost, reliability, light weight and design adaptability.
Why is wood and steel good for earthquakes? ›as a natural material, wood is much lighter than steel and concrete and has intrinsic flexibility, making it more resilient to earthquake loading; and. the redundancy in light-framed wood building load paths makes it very robust against collapse.
Are steel buildings stronger than wood? ›Stronger Than Wood
Steel buildings are more durable than wood, and more resistant to water damage. Steel will not warp or expand like wood does, and it does not rot, so it will be less likely to attract fungus. Termites and other insects who eat wood will also steer clear of a steel home.
Steel buildings are almost half the weight of a comparable wooden structure because steel has a higher strength to weight ratio than wood. This makes steel buildings stronger and more durable than wood, brick or concrete, despite their light weight.
Which type of building will benefit the most from steel construction? ›If you're planning to make a high-rise building or long-span structure, then structural steel is the material for you. Countless tall commercial buildings, long bridges, and more are made of structural steel. This is because structures are sturdy and reliable, and can be reinforced with steel plate girders or trusses.
What are the disadvantages of building with steel? ›The Cons of Steel Construction
Unlike concrete and wood materials, steel is notorious for rusting in certain environments. Consequently, the costs of painting and maintaining a steel structure can be high. Steel can also be a conductor of heat, which means it needs to be adequately fireproofed.
Steel has a high expansion rate with changing temperatures. This can be detrimental to the overall structure.
Do Steel Buildings need foundations? ›Do steel buildings need a foundation? Steel frames can, in extreme weather, be susceptible to wind uplift; however, this can be mitigated by securing the steel structure to an appropriate foundation.
How long do steel buildings last? ›Steel buildings face fewer issues with deterioration and corrosion than concrete or wood, and can out live other structures when properly built and maintained. Most steel buildings last anywhere from 50 to 100 years.
What are the disadvantages of high strength steel? ›
The disadvantages of high strength steels are primarily their high densities and susceptibility to brittle fracture. At a density of around 0.29lb/in 3, steel alloys are considerably heavier than other structural materials such as aluminum (0.1lb/in. 3) and titanium (0.16lb/in 3).
What are the disadvantages of steel reinforcement? ›High Cost: Steel is expensive and considerably increases the cost of structure. High Temperatures: Steel show tendency to melt in extremely high temperatures. This is also one of the reasons; steel is tied and not welded.
What material is earthquake proof building? ›Earthquake resistant concrete
EDCC combines cement with polymer-based fibres, fly ash and other industrial additives, making it highly resilient, according to UBC civil engineering professor Nemy Banthia, who supervised the work.
Structures made out of concrete and wood offer different resilience to earthquakes. For concrete buildings, it is recommended use concrete slabs or steel. On the other hand, wood structures should be bolted down at their foundations.