Japan’s skyline is known for its towering skyscrapers and concrete jungles. However, what sets Japan apart is its ability to build earthquake-proof structures that can withstand the most powerful earthquakes. This resilience is achieved through robust engineering that makes buildings appear immovable, even in the face of natural calamities like earthquakes. Pakistan can learn from Japan's example and adopt similar practices to make earthquake-proof buildings.



Earthquake Proof House Design: Setting the Benchmark


In light of the increasing frequency of earthquakes due to climate change, it is essential to ensure that buildings are structurally sound and resilient. Engineers designing earthquake-proof buildings consider two categories of resilience. Firstly, buildings are designed to withstand minor tremors without any damage that requires repair. Secondly, buildings are designed to withstand extreme earthquakes, with the priority being to save human lives rather than preserving the building.



Structural Design Aspects


Horizontal forces, such as earthquakes, are the main cause of disruptions in vertical housing. Walls that are not designed up to code are the reason why buildings collapse during earthquakes. An earthquake-proof building requires walls and roofs that can swing independently when faced with tremors. The best way to achieve this is to fix the walls firmly to the foundation or attach them to a system of posts where the weight is equally distributed.



Flexible Foundation


The "base isolation" method can be used to solidify a building's foundation. This technique involves raising the building from the ground using unique architectural designs and constructing it using flexible pads made of rubber, steel, and lead. During an earthquake, the vibrators move, but the building remains steady. By adopting similar practices, Pakistan can ensure that its buildings are resilient and able to withstand earthquakes.



Seismic Dampers:


An Overview Seismic dampers are a vital component of earthquake-resistant buildings. They function similarly to shock absorbers, mitigating the impact of seismic waves. This section discusses two primary methods of damping, namely, Vibrational Control Devices and Pendulum Power, and their functioning.



Vibrational Control Devices


Vibrational control devices are an effective way to incorporate damping in a building's design. They involve placing dampers on every level of the structure between columns and beams. These devices consist of a piston head inside a cylindrical object filled with silicone oil. During an earthquake, the energy from shock waves is transferred to the piston, pushing it against the oil, which dissipates the seismic energy as heat, preventing earthquake damage.


Pendulum Power


Pendulum Power is another damping method commonly used in skyscrapers. This technique involves suspending a large ball connected to steel cables. These cables are linked to a hydraulic system placed at the top of the building. When the building sways, the balls act as pendulums, oscillating in the opposite direction, stabilizing the building.



Shape of House:


Impact On Stability The shape of a house plan is crucial in determining its stability during an earthquake. This section highlights the significance of the shape of the plan in providing a safety net against shocks. Engineers prefer compact plans as they offer better stability against seismic waves. Additionally, the shape of the plan contributes to its structural strength, with square and circular plans being preferred over rectangular ones.


The University of Kassel's Study on Wall Shapes As part of a doctoral thesis, the University of Kassel conducted a test on the impact of wall shapes on a building's response to seismic waves. This section highlights the findings of the study, including the influence of the square plan and the earth house with a circular plan.


According to the test, the square plan demonstrated the first sign of crack after the second stroke and completely collapsed after four strokes. In contrast, the earth house with a circular plan showed the first signs of crack after three strokes and experienced minimal wall damage after six strokes.



Earthquake Proof Materials:


Building materials play a crucial role in ensuring a building's stability during an earthquake. This section discusses the significance of using earthquake-proof materials in construction, such as structural steel, wood, memory alloy, and bamboo.


Certain construction materials:


Perform better than others when exposed to seismic waves. These materials have the ability to resist stress and vibrate when subjected to different energy frequencies. Structural steel is increasingly used in modern construction as it allows buildings to bend without breaking. Similarly, wood has high ductility, making it resistant to stress. Futuristic materials like memory alloy and bamboo also offer excellent earthquake resistance properties.