During the semester Introductions Basics of earthquakes History and Recording Damaging Earthquakes and Understanding seismic exposure Undertaking loss assessment Seismic analysis; and design and detailing (RCC and Masonry)

We spoke Foundation weakness last now Structural Weakness

We weaken a Structure by weakening/introducing: Symmetry Regularity Openings Soft Storey effect Local eccentricity Pounding situations Other Items with a potential to fall. Such as- Long cantilevers, partition, badly fixed non-structural components Basics of Earthquake resistant Construction

Careful when introducing weakness Difference between Centre of Gravity and Geometry. Understand structural properties of – Stiffness – Mass – Strength – Ductility – Displacement / deflection Distinguish between Structural and Non- structural cracks Basics of Earthquake resistant Construction

List of Codes and standards related to Earthquake Engineering Internet Sources – – – – – – Recommended Reading

Basics of Earthquake resistant Construction Performance Levels and Ranges Performance based design is a new approach used in earthquake resistance design and construction. FEMA document FEMA356 has more details

Basics of Earthquake resistant Construction Performance Levels and Ranges S-1 Immediate Occupancy S-2 Damage Control Range S-3 Life Safety S-4 Limited Safety Range S-5 Collapse Prevention S-6 Not Considered

Basics of Earthquake resistant Construction Performance Levels and Ranges S-1 Immediate Occupancy Structure retains the pre-earthquake design strength and stiffness, and is safe to occupy. Some minor structural repairs may be appropriate but not necessary to make the building safe to occupy. S-2 Damage Control Range This range may be desirable to minimize downtime and repair time, to protect equipment that depends on the survival of the structure for its functionality, or to preserve historic features of the building when its too costly to design for the S-1 damage state. S-3Life Safety The building will retain at least some of its strength against collapse and should prevent loss of human life. However, there may be injuries and the building could potentially be damaged beyond the point of economical repair. Some business owners may desire to have a higher standard of design safety for their building. This is especially true in the case of business s that would suffer dramatically if business was interrupted after a seismic event. Obviously any building that collapses proposed significant risks to life safety and would not satisfy this design objective. S-4 Limited Safety Range The continuous range of damage states between the Life Safety Structural Performance Level (S-3) and the Collapse Prevention Structural Performance Level (S-5). S-5 Collapse Prevention The building experience damage to structural components that weaken it so that it retains little or no lateral resistance against collapse either in part or in full. However, it will still continue to support its own weight provided that there is no further ground motion. Aftershock activity could cause collapse, but the initial event did not bring down the building. S-6 Not Considered A building rehabilitation that does not address structural performance at all, but instead focuses entirely on non-structural hazards associated with the building such as anchoring equipment and preventing damage to tenant property and improvments.

Which performance level is delivered by the building you are looking at?

Basics of Earthquake resistant Construction Summary -Note different collapse modes -Note different damage modes -Property of Stiffness in addition to Strength and Ductility -Keep Soil – Structure interaction in mind

Basics of Earthquake resistant construction Structure Types Classify based on Horizontal Load Resisting System Common types are: – Frame – Frame with infill wall – Masonry – Reinforced Masonry – Tensile, Membrane, Igloo, and other special systems

Basics of Earthquake resistant Construction Structure Type: Frame Any height Materials : Steel, RCC, Timber, Any other tensile material Non structural Partition

Basics of Earthquake resistant Construction Structure Type: Frame with infill Common types have brick partition which influence structural behaviour Similarly Basement

Basics of Earthquake resistant Construction Structure Type: Masonry Lower in height Use was high in history when buildings were designed as compression structures Materials : Walling: Brick, Stone, Rubble, Cement Blocks Mortar: None, Mud, Lime, Cement Structural Integrity is important

Basics of Earthquake resistant Construction Structure Type: Reinforced Masonry Usually lower in height structures Many house owners unjustifiably use this because of fear or a misinformed choice that this will make their house stronger Recommended as Horizontal bands and in vertical direction in zones of high seismicity Reinforcing material is any highly tensile material such as RCC or steel. Historical use as timber

Discuss Coordinate visit to GSDMA (whole 3 rd year?) Share what one is reading- – Books – Book Reviews – Copies of codes such as IS 4326, and IS 13920, IS 1893