Earthquake

AR.PRAGYA GANGWAR

Introduction

Earthquakes constitute one of the worst natural hazards which often turn into disaster causing widespread destruction and loss to human life.

The effects of earthquake vary upon the magnitude and intensity. Earthquakes occur every now and then all round the world, except in some places where earthquakes occur rarely. The devastation of cities and towns is one of the effects of earthquake.

What is Earthquake?

An Earthquake is the result of a sudden release of energy in the earth's crust that creates seismic waves.

The seismic activity of an area refers to the frequency,type and size of arthquakes experienced over a period of time

Techniques to resist Earthquake

  • Active & Passive system
  • Bracing
  • Rollers
  • Light weight material
  • Others
  • Shear walls
  • Dampers
  • Isolation
  • Bands

Active System

Active control systems are devices integrated with real-time processing evaluators for improved service and safety.

Passive System

Passive control systems are conventional devices to resist or absorb the energy produced during Earthquake.

Cross Bracing

Waste Tire Pads

Light weight material

In recent times, many new systems and devices using nonconventional civil engineering materials have been developed, either to reduce the earthquake forces acting on a structure or to absorb part of seismic energy.

Earthquake resistant designs

  • Design - but it is analysis of forces - buildings due to loads acting on it.
  • If a building is enough to resist the earthquake, then such building is called Earthquake resistant structure.
  • Such design is called Earthquake resistant designs

Popular Earthquake resistant Techniques

  • Earthquake may not be able to damage entire building but it damages members of it.
  • So special techniques are adopted: Base Isolation Devices and Seismic Dampers.

Disaster picture from Kashmir earthquake 2005

Damage to high rise building in Bhuj

Bracing

Rollers

Isolation

Suggestions

  • Avoid weak column and strong beam design
  • Provide thick slab which will help as a rigid diaphragm
  • Provide cross walls which will stiffen the structures
  • Provide shear walls in a symmetrical fashionIncrease in the transverse (Shear) reinforcement
  • Horizontal lintel band should be provided
  • The building must be regular and symmetrical in shape
  • Reinforcing bars should be provided at the corners and the junctions of the walls
  • Earthquakes affect RCC structures too…
  • Slabs forces the beam to bend with it when horizontal forces act.