Earthquake related presentation for seminar.pptx

EQ related presentation for seminar.pptx

1. B.KANDAVEL M.E-STRUCTURAL IRTT GUIDELINES FOR PLANNING AND DESIGN FOR EARTHQUAKE RESISTANT BUILDINGS

2. 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.

3. 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

4. Shape – Horizontal Layout BUILDING CONFIGURATION

5. PLAN OF BUILDING (Asymmetry should be avoided) Asymmetric buildings undergo torsion and the extreme corners of asymmetric buildings are subjected to very large earthquake forces

6. Shape – Horizontal Layout BUILDING CONFIGURATION Failure Mode

7. Shape – Vertical Configuration BUILDING CONFIGURATION

8. Shape – Adjacent Buildings BUILDING CONFIGURATION

9. Shape – Adjacent Buildings BUILDING CONFIGURATION

10. BUILDINGS HUGGING TO-GETHER

11. Soft-Storey Effect: STRUCTURAL SIGNIFICANCE

12. Soft-Storey Effect: STRUCTURAL SIGNIFICANCE

13. STRUCTURAL SIGNIFICANCE Soft-Storey Effect:

14. Strong Column – Weak Beam STRUCTURAL SIGNIFICANCE

15. A WEAK COLUMN - STRONG BEAM SYSTEM

16. WEAK COLUMN - STRONG BEAM SYSTEM

17. A WEAK COLUMN - STRONG ROOF SYSTEM

18. Most RC buildings with open ground storeys that collapsed showed a very common practice of poor detailing; 6mm diameter lateral ties in the columns with 90 o hooks and longitudinal spacing as large as 30cm. This did not provide the required confinement to the core concrete

19. GENERAL SHAPE OF BUILDING Very slender buildings should be avoided Inverted pendulum type buildings are unstable

20. Sudden change in lateral stiffness should be avoided GENERAL SHAPE OF BUILDING

21. Projections and large overhangs Avoid long projected balcony Large projections should be avoided

22. Floating columns Large overhangs, projections and floating columns attract large earthquake force and therefore likely to damage/ collapse due to instability

23. Separation of dissimilar buildings To avoid collision, adjacent dissimilar buildings should be separated by a minimum gap Type of construction Min. gap per Storey (mm) Load Bearing Building 15 RCC Frame Building 20 Steel Frame Building 30

24. Minimum depth of foundation Plinth band is not required for foundation on rock and hard soil

25. Attachments and Overhangs All the attachments, fittings, equipments and artifacts should be properly fixed to the ceiling/wall so that they withstand severe vibrations Parapet wall should be properly secured Reinfor -cement in parapet wall

26. Heavy mass at the top should be avoided Large water tanks should be avoided. Small water tanks, if provided should be properly connected with the framing system

27. EXCESSIVE TOP CANTILEVERS

28. HEAVY MASS ON TOP: WATER TANK COLLAPSE WHIPPING EFFECT

29. LOCATION OF A HEAVY MASS ON TOP: WRONGLY DETAILED

30. Collapse of one-half of the 14-storey RC frame residential apartment building in Ahmedabad ; the collapsed portion had a swimming pool on the roof, unlike the other half that is standing

31. Numerous cases of dislodging of the weakly connected overhead storage water tanks were observed in the entire earthquake affected area. Picture shows dislodging of water tank appendages from atop unfinished and finished RC frame buildings in Bhuj Dislodging of water tank appendages from atop unfinished and finished RC frame buildings in Bhuj

32. Avoid long walls Depending upon functional requirements, either buttresses or cross walls can be used to reduce the unsupported length

33. Rubble masonry To avoid splitting of rubble masonry walls, through stones should be provided in sufficient number

34. Minimum distance between openings and corners Openings in masonry walls weaken the walls The openings should be small as far as possible and should be provided away from the corners and each other To compensate the loss of strength due to openings, 6 mm bar encased in concrete or 1:3 cement sand mortar should atleast be provided around the openings

35. WITH A WISH TO DESIGN AND BUILD SAFE HIGH RISED BUILDINGS One of the RC frame multistorey buildings at Ahmedabad that withstood the earthquake shaking with only minor cracking in the masonry infill walls

36. Based On the above Planning Configurations Building design should be done and also resist from the earthquake forces. CONCLUSION

37. Thank You.