Earthquake Resistant Structures

Earthquake means quick shaking of the ground due to the shift of rock and tectonic plates underground. The ground appears as solid, but the topmost crust of earth is deep and long periods of time produce pressure to develop among plates and fissures.

When the pressure is applied, seismic vibrations and fierce shaking reverberate to the surface which instantly impact miles of land. Once the initial quake hits, aftershocks happen to create further damage.

In areas where seismic activity is not too harsh, we can utilize these techniques to save money and complexity but make the building resistant to seismic activities.

Structure Stiffness: The most traditional way to fight quakes is to use stronger materials to construct the building. Stiffer or heavier members can be used to fight the lateral forces generated during seismic activities. While creating design for earthquake-resistant buildings, safety professionals suggest sufficient vertical and lateral stiffness and strength – specifically lateral. Structures are likely to deal with the vertical movement resulting from quakes superior to the lateral, or horizontal, movement.

Geometrical Absorption: The building can be planned in such a regular and special geometrical shape that it disperses the seismic forces evenly so that no particular member experiences excessive force. This naturally fares much better than a poorly-planned unsymmetrical building.

For existing buildings that are structurally asymmetrical, you can use seismic joints and expansion points in places where the forces are dispersed unevenly. Providing extra columns, shear walls, and framing can make the weaker section withstand the extra forces to a good level. Parking levels should have extra reinforced columns in order to negate the soft story effect.

Lateral Force Resistance: Using three types of lateral force resisting systems, we can try to negate much of the seismic forces. These are:

1. Moment Resisting Frame System: it is designed to resist all types of earthquake generated forces acting on the structure. They can be customized to fit the seismic activity scale of the region.

2. Building Frame System: these are designed to resist gravitational loads only, but they function excellently in that. A shear wall is added to resist the lateral forces acting on structure.

3. Dual Frame System: this is a combination of the above two systems. Shear walls along with moment resisting frames work excellently to fight off the vibrations and displacements from an earthquake. But, of course, they are more complex and costlier to build.

Non-Structural Parts: Much damage caused in buildings due to earthquakes comes from the collapse of non-structural elements, like walls or floors. We can negate that upto some extent if we reinforce them as well.

Building the masonry portions with hollow bricks is an excellent idea to resist seismic activity. Proper detailing and reinforcing of openings in the building will resist their collapse as well.

Base Isolation: It is a rather ambitious idea of placing the building on rollers. These rollers are as near friction-less as possible. The concept is that when the earthquake hits, the rollers will roll, but not transmit any of that energy to the structure. Therefore, the building will experience very little of the seismic forces. The base isolators, that is, the rollers or flexible pads need to be carefully placed and regularly maintained to keep them able to respond at a miliseconds notice