Earthquake Proof buildings are those buildings that have been specially designed to withstand the earthquake forces imposed to some extent. Despite the continuous efforts of constructing earthquake-proof structures, it is practically not possible to provide complete immunity to the buildings from earthquake due to its unpredictable intensity of occurrence. It may be said that the motive of constructing earthquake-proof buildings is to erect buildings that have better resistance to seismic forces during seismic activity. We will briefly discuss the features of earthquake proof buildings.
With the growing cities, the risk of collapsing of buildings during the earthquake has increased and due to this, constructing earthquake-resistant buildings have become a prime area of concern for engineers throughout the world leading to the development of a new field of engineering i.e. Earthquake Engineering. Several philosophies, methods and techniques have been developed to ensure such construction. Some of the important features of earthquake-proof buildings can be summarized as follows:
Features of Earthquake Proof Buildings
Some of the features of earthquake proof buildings are:
1. Strengthened Diaphragm:
The diaphragm is one of the important horizontal components of the building including floors. Earthquake-proof buildings have their diaphragms placed on their deck and strengthened horizontally to share the forces with vertical components.
2. Cross-Braced System:
Earthquake-proof buildings are designed with a set of properly braced columns, braces and beams to reverse the seismic forces back to the ground. Cross brace incorporates mainly two diagonal sections in an X like a shape.
3. Stronger Shear Walls:
To resist the sway during an earthquake, vertical walls known as shear walls are erected in earthquake-proof buildings. It helps to enhance the stiffness of the structural frame of the building. It is used in addition to the brace system.
4. Moment-Resisting Frames:
Earthquake-proof buildings may be designed with moment-resisting frames as an alternative to shear walls as shear walls somewhat limit the flexibility of the buildings.
Moment-resisting frames function same like the shear walls. In addition to this, moment-resisting frames allow more flexibility to the designers for constructing exterior walls, ceilings and also for the arrangement of various building components.
5. Lighter Roofs:
One of the prominent features of earthquake-proof buildings is that they have lighter roofs. Most of the designers use profiled steel cladding on light-gauge steel purlins or double skin with insulators and purlins.
This feature of earthquake-proof buildings is concerned with the movement of buildings in a lateral direction. It must be ensured that during the earthquake the building moves equally in both directions and dissipate equal forces on both the sides avoiding excessive force on a single side.
Earthquake proof buildings must have adequate vertical as well as lateral stiffness.
Redundancy is perhaps the most important feature of earthquake-proof buildings on account of safety. Redundancy ensures that during an earthquake even if one method of prevention fails, other alternative methods or strategies of safety come into play. Due to this reason, earthquake engineers focus on equally distributing the masses and strength throughout the building.
9. Stronger Foundation:
A strong and stable foundation is an important characteristic of earthquake-proof buildings. A strong foundation is vital for resisting the large earthquake forces as well as for the long life of buildings. In most of the earthquake-proof structures, foundations are well driven deeper into the ground i.e. deep pile foundations are used.
10. Continuous Load Path:
While designing the earthquake-resistant buildings, the designers must ensure that a continuous load path is maintained. The structural and non-structural components of the buildings must be tied together so that the inertial forces dissipate. If the structure is not properly tied, the components will move independently making the structure prone to collapse. Ensuring continuous load path is a must for dissipating large seismic forces.