can be idealized as concentrated or
lumped mass “m” supported by a massless structures with stiffness “k” in the lateral direction.
simple structures
flexibility of the structure in lateral motion is provided entirely by the _____
columns
The process by which vibration steadily diminishes in amplitude
damping
the kinetic energy and strain energy of the vibrating system are dissipated by various mechanisms
damping
primary requirements for the preparation of earthquake loading codes, for determining the earthquake loadings for structure
study of seismic activities
geological or other consequential
hazards
- Fault displacement
- Subsidence (flooding)
- Liquefaction of cohesionless soils
- Failure of sensitive or quick clays
- Landslides
- Mudflows
- Dam failures
- Water waves
- Groundwater
Factors influencing the local modifications to the underlying motion
- Topography and nature of the bedrock
- Natural geometry of the depositional soils
may involve a depth of a kilometer or more, and an area within a horizontal distance of several kilometers from the site.
local
The topography of both the bedrock and the deposited soils has various effects on the incoming seismic waves such as
reflection, refraction, focusing and scattering
These are sometimes generated by earthquakes
Water waves
It is caused by vertical displacement of blocks of sea bed
tsunami
may also occur in the enclosed waters of lakes and harbours due to resonance effects or landslides.
seiches
occur after earthquakes, apparently due to changes in pore pressure.
Changes in ground water discharge
the probability that social or economic consequences of earthquakes will equal or exceed specified values at a site, at several sites, or in an area, during a specified exposure time.
Seismic risk
is any physical phenomenon (e.g. ground shaking, ground failure) associated with an earthquake that may produce adverse effects on human activities.
Seismic hazard
may either purely descriptive terms or qualitatively evaluated, depending on the needs of the situation.
Hazards
physical consequences of earthquakes for human beings
- Death and injury of human beings
- Damage to the constructed and natural environments
basic seismic design aims
- The reduction of loss of life in any earthquake, either through collapse or through secondary damage such as falling debris or earthquake-induced fire
- The reduction of the damage and loss of use of the constructed environment.
Post-earthquake economic consequences
- Cost of death and injury
- Cost of damage
- Losses of production and markets
- Insurance claims
