4 Methods to Achieve Earthquake Resistant Buildings
Buildings are built to withstand gravity and the vertical forces thrusted upon it. But during an earthquake, seismic waves are emitted in all directions, causing the building to vibrate. If the building succumbs, being unable to withstand these vibrations, it collapses, causing severe damages to life and property. The amount of money required to compensate and repair the damage is very high.
In recent years, there has been significant developments and importance given to this particular field in architecture. Here are some of the ways in which we can earthquake-proof a building.
Making foundations strong and resistant to earthquakes
Use earthquake resistant materials for construction
Damping
Transferring the vibrations and energy safely to the ground
1. Foundations
Since vibrations start from ground up, making foundations earthquake-resistant significantly helps in reducing them from affecting the superstructure.
Avoid Separation
One easy solution is to build one single structure from the foundation level.
Earthquakes knock buildings sideways, breaking it away from its foundation. By building a single unit, the risk of breaking and consequently, the building collapsing is significantly reduced.
Base Isolation
However, the best method to earthquake-proof a building through foundations is base separation.
This involves floating a building above its foundation using bearings, springs and cylinders.
Most commonly, lead-rubber combination is used for the bearing. The core of the bearing is made of steel which makes it strong in the vertical direction. The core is wrapped in alternating layers of rubber and steel, making it flexible in the horizontal direction.
Plates are then used to attach the bearing to the foundation and superstructure. So when the earthquake hits, the foundation moves without disturbing the superstructure above it, causing reduction in the damage that might occur.
2. Materials
The choice of building materials plays a crucial role in a building resisting earthquakes. Traditionally, materials like wood and bamboo were used in places which were prone to earthquakes. Nowadays, new materials are being innovated too.
Steel
Be it a bridge or high-rise building, steel has proven to be the number one choice of material when it comes to earthquake-resistant construction.
Steel has high ductility.
It is strong but can also bend without breaking. This particular property makes it a good material for resisting violent vibrations.
Among the various grades, high grade Tmt steel bars are the best. It can take massive amounts of stress and vibrations without breaking.
Wood
Wood is also another highly earthquake resistant building material.
It is ductile and has high strength in comparison to its weight.
It is also highly elastic, making it able to withstand vibrations.
Even if these structures collapse, due to its lightweight, less damage to life and property is observed. This is why highly earthquake prone areas like Japan traditionally use wood for construction.
Reinforced Concrete
Reinforced concrete is concrete with reinforced steel bars.
This reinforcement makes the low ductile concrete into a highly ductile material.
Additionally, it is also strong and stiff.
RCC is also used to cyclone-proof buildings.
Bamboo
Bamboo is another effective material for earthquake resistance.
It is highly tensile and flexible, making it resistant to tremors.
This makes bamboo an excellent option since it is also affordable and sustainable.
3. Damping
Dampers are used to absorb shock or vibration. These are usually used in doors or packaging to reduce damage. Using the same technique, damping devices are also kept in between floors or columns and beams to reduce shock due to earthquakes.
Vibration reducing pistons
Vibration dampers have pistons that are filled with oil in them.
These dampers are placed on each floor in between columns and beams.
When an earthquake occurs, the vibrations are transferred into these pistons, pushing against the oil. This helps in dissipating the vibrations, thereby protecting the building.
4. Transfer of Energy
A building collapses when it is unable to withstand the vibrations caused by the earthquake. If these vibrations are safely transmitted to the ground, then the risk of collapse of the building is reduced.
Cross Braces
Cross braces are trusses built into walls and other supports in order to provide extra support.
These braces also effectively transfer vibrations safely to the ground.
Diaphragm
Diaphragms are horizontal structures which help pass on the tension from the floors to the vertical structures- walls, columns etc.
This helps pass on the energy to the ground without affecting the building.
Designing buildings should always be done with the user's safety in mind. Since India has several seismic zones, especially in the North and North-eastern parts, it is crucial to keep in mind the dangers of the building collapsing while designing.
