Natural Calamities’ Ecological Impact and the Need for Efficient Engineering

The recent ecological devastations, coupled with internal tectonic plate movements of the earth’s crust have made a deadly impact on the surface. The earthquakes and tsunamis, be it in Japan, Haiti, Indonesia, Turkey, the Philippines or the Indian subcontinent have caused massive devastation.

These countries have suffered from loss of lives, economic loss of millions, and ecological devastation. The trend is not showing any signs of reversal, with such phenomena becoming more frequent.

The AEC industry has introduced new building materials and designs to empower the structures to withstand seismic activities. In this article, let’s shed light on how earthquake and tsunami-proof buildings are developed.

Impact of Earthquake on the Buildings

Delving into how seismic activity affects various structures is essential before learning how to build earthquake-resistant buildings. An earthquake sends shockwaves through the earth rapidly in a short period, extending in all directions.

Generally, buildings are equipped to withstand vertical forces from their weight and gravity. However, they are not capable of dealing with side-to-side forces emitted by quakes.

The horizontal movement causes vibration in floors, walls, columns, braces, and beams that hold the structure together. The building’s bottom experiences a difference in movement from the top, which causes extreme stress and ruptures the supporting frame. It leads the structure to collapse.

How to Design Earthquake-Proof Buildings

Lay a Flexible Foundation

Engineers use a method called base isolation to lift the building’s foundation above the ground. It is an effective way to resist ground forces. They raise a structure on top of flexible steel, lead, and rubber pads.

When an earthquake occurs, the isolators start vibrating ensuring steadiness in the structure. This way seismic waves are absorbed and cannot travel through the building.

Use Damping to Counter Forces

Shock absorbers are also prevalent in creating earthquake-proof buildings. Engineers utilize them to mitigate the magnitude of shockwaves, which helps reduce pressure on the structure. They use two ways to accomplish it: pendulum power and vibrational control devices.

Pendulum Power

Pendulum power is a common damping method and engineers use it while building skyscrapers. In this process, professionals use steel cables to suspend a large ball connecting to a hydraulic system, which is at the top of the structure.

If an earthquake occurs and the building sways, the ball moves in an opposing direction like a pendulum. Eventually, it stabilizes the building.

Vibrational Control Devices

In this method, civil engineers place dampers at every level of the structure between beams and columns. They fill every damper with a cylinder consisting of piston heads and silicon oil.

At the time of an earthquake, the building shifts the seismic energy onto the pistons and they start pushing against the oil. This process transforms energy into heat, dissipating the vibration forces.

Protect Buildings from Vibrations

Researchers are conducting studies to discover ways to deflect and reroute earthquake’s energy. In this innovative process, experts create a cloak of 100 concentric plastic and concrete rings. They bury it at least 3 feet under the building’s foundation.

On the occurrence of an earthquake, seismic waves enter the rings and they can easily move to outer rings. Thus, this method helps seismic waves channel away from the building and disappear into the ground.

Strengthen Building’s Structure

Redistributing the seismic energy caused by an earthquake is crucial to ensure the safety of a building. Experts use shear walls, diaphragms, cross braces, and moment-resisting frames to strengthen a structure.

Shear Walls

This building technology plays a significant role in transferring seismic forces. Multiple panels are used to make these walls and they empower a structure to keep its shape during an earthquake.

Professionals often support shear walls with diagonal cross braces made of steel. These beams support tension and compression, which pave the way for pushing forces and counteracting pressure.

Cross Braces

Engineers attach cross braces to a building’s frame. They set it in an X pattern to improve load capacity. This technique bolsters a building’s capability to withstand strong winds and seismic activity.

Moment-resisting Frames

These frames allow space for additional flexibility in the design of a building. Professionals place moment-resisting frames in the structure’s joints. As a result, columns and beams can bend easily while maintaining rigidity in the joints.

Diaphragms

Diaphragms are at the core of a building’s structure. They encompass a building’s roof, and floors, and have decks placed over them. Diaphragms divert the forces to the vertical structure of a building and eliminate tension from the floor.

Impact of Tsunami on the Buildings

Tsunamis are caused by a series of vibrations happening after a strong earthquake hits seas and oceans. This seismic activity in the ocean creates complex subsurface waves that can hit the shorelines running at the speed of several hundred miles per hour.

These waves are strong enough to fully or partially damage structures in the coastal regions. Tsunami waves also carry a substantial amount of debris, which can affect the roof or walls of a building.

Furthermore, tsunami waves coming forcefully onto the land and retreating to the ocean can cause erosion of building foundations.

How to Construct Tsunami-resistant Buildings

Protect Rough Ground Near Shorelines

Local communities living on the shorelines must preserve trees and plants on the beach. A rough ground can reduce the impact of a powerful tsunami wave. Mangrove swamps are the perfect natural buffer that can slow down the speed of tsunami waves.

Prohibiting the destruction of reefs for shipping channels can lead to mitigating the effects of waves.

Use Concrete for Construction

Wooden homes are more robust to withstand earthquakes as timber is a lightweight material. However, tsunamis can easily uproot wood, hence strong concrete or steel structures are ideal for such areas.

Implement Tsunami-resistant Designs

Multi-story buildings must have suspended floors/open. They can also have breakaway first and ground floors to let the forceful tsunami waves flow through these structures.

You can design a building with walls that lay at the ground to the first-floor level. Also, add robust frames to effectively support the floors above the first floor without relying on the help of walls.

In the sandy areas, set footings and bracing deep into the ground. Lay a concrete surface under the building floor to protect light soil from erosion. You can prevent tipping and scour by enclosing a grill of steel beams in a concrete floor adding moment connections to the columns at ground or below level. BIM can help you design such structures efficiently.

Position the Buildings Properly

Constructing buildings close to each other can cause significant damage. Hence, maintain gaps between the buildings to ensure water flows effectively at the time of tsunami occurrence.

Additionally, having walls directly facing tsunami waves makes a structure prone to damage. You can build structures diagonally to ensure pointed corners face the sea. It can help divert tsunami waves and reduce water pressure on the building.

Build Structures at a Safe Location

Creating buildings at a low level on the shoreline above a shallow and smooth beach is not ideal, specifically near canals/inlets as it can increase the force of tsunami waves.

Conclusion

Earthquakes and tsunamis are natural disasters and cannot be prevented. Also, taking these measures cannot ensure that a structure can endure the overwhelming power of nature. However, you must adhere to these construction guidelines to make sure the building has a chance to survive the effects of these calamities.

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