Advanced Earthquake Resistant Design
Whenever there is an earthquake related disaster in the news with collapsed buildings &other structure all over the place, one may think that earthquake resistant design(EQRD) of structure are still in dark age. Thus we desperately need advanced earthquake resistant design to make structure less vulnerable to earthquake even for large earthquake.
Seismology is the branch of Geophysics concerned with the study and analysis of Earthquakes and the science of energy propagation through the Earth’s crust.Engineering Seismology is concerned with the solution of engineering problems connected with the Earthquakes. Seismology is extremely important because:
- Study of earthquakes gives us important clues about the earth’s interior
- Understanding earthquakes allows us to minimize the damage and loss of life
What is an earthquake?
- An earthquake is the vibration of Earth produced by the rapid release of accumulated energy in elastically strained rocks
- Energy released radiates in all directions from its source, the focus
- Energy propagates in the form of seismic waves
- Sensitive instruments around the world record the event
What causes an earthquake?
Movement of Tectonic Plates
Earth is divided into sections called Tectonic plates that float on the fluid-like interior of the Earth. Earthquakes are usually caused by sudden movement of earth plates
Rupture of rocks along a fault
Faults are localized areas of weakness in the surface of the Earth,sometimes the plate boundary itself
How Earthquake Causes Damage
- The severe shaking produced by seismic waves can damage or destroy building & bridges , topple utility poles & fracture gas and water mains.
- S wave can put stress on building to tear them apart. Also trigger landslide or avalanches.
- Base-isolation are designed in buildings . It is a building designed to reduce amount of energy that reaches the building during earthquake.
- Flexible joints and automatic shut off valves can be installed.
Protecting Against Earthquake Damage
- Prepare a Seismic Risk Map for the globe which identifies rock types, liquefaction potential, landslide potential.
- Extensive geologic surveying has to be done to identify all active faults, including hidden faults.
- Earthquake Resistant Design of Structures
- Enact building codes to design and build earthquake-resistant structures in high seismic risk areas. wood, steel and reinforced concrete are preferred as they tend to move with the shaking ground (unreinforced concrete and heavy masonry tend to move independently and in opposition to the shaking, battering one another until the structure collapses)
Earthquake resistant expansion joint(ERJ)
Buildings need to be designed and constructed as per the building by laws to withstand ground shaking. Architectural and engineering inputs need to be put together to improve building design and construction practices. The soil type needs to be analyzed before construction.
Building structures on soft soil should be avoided. Buildings on soft soil are more likely to get damaged even if the magnitude of the earthquake is not strong . Similar problems persist in the building constructed on the river banks which have alluvial soil.
In the coming years the work in the field of EQRD is very important to have safe structures which can take the effect of earthquake with less damage to the society.