seismic design philosophy by swati pandey (Structural engineering student)

1. Chhattisgarh Swami Vivekanand technical university,UTD, bhilai (C.G.)
Presentation on – Seismic design philosophy
on buildings.
Presented by – Swati Pandey
Mtech/1st year/2nd SEM/structural engg./utd

2. Content
 Importance of seismic codes
 The earthquake problems
 Design philosophy

3. Indian seismic codes
IS 1893-2002, Indian Standard Criteriafor Earthquake Resistant
Design of Structures (5th Revision)
IS 4326-1993, Indian Standard Code of Practice for Earthquake
Resistant Design and Construction of Buildings (2nd Revision)
IS 13920-1993, Indian Standard Code of Practice for Ductile
Detailing of Reinforced Concrete Structures Subjected to Seismic
Forces

4. Importance of seismic codes
 IS 1893 (Criteriafor Earthquake ResistantDesignof Structures).
-It is divided into five different parts.
1.Part 1 Presents provisions that are general in nature and it provides
specifications related to buildings only.
2.Part 2 cover liquid retaining structures including elevated and
ground supported structures. Guidance is also provided on seismic
design of buried tanks.
3.Part 3 deals with bridge and retaining walls.
4.Part 4 contains industrial structures including stack like structures.
5.Part 5 provide design and construction guidance on dams and
embankments.

5.  IS 4326 (Code of Practice for Earthquake Design ResistantDesignand
Construction of Buildings).
1.This code covers general principles for earthquake resistant buildings.
2.It deals with the selection of materials and special features of design and
construction for different types of buildings such as timber constructions and
masonry constructions.
 IS 13920 (Code of Practice for Ductile Detailing of ReinforcedConcrete
Structures Subjected to SeismicForces).
1.This standardprovides requirements for designing and detailing of reinforced
concrete structures in order to equip them with adequate toughness and ductility to
withstand serious earthquake shocks without collapse.
2.The provisions for reinforced concrete construction given in this standard apply
specifically to monolithic reinforced concrete construction.
3.Precastand/or prestressed concrete members may be used only if they can
provide the same level of ductility as that of a monolithic reinforced concrete
construction during or after an earthquake.

6. The Earthquake Problem
Severity of ground shaking at a given locationduring an earthquake can be
minor,moderate and strong. Relatively speaking, minor shaking occurs
frequently, moderate shaking occasionally and strong shaking rarely. For
instance, on average annually about 800 earthquakes of magnitude 5.0-5.9
occur in the world while the number is only about 18 for magnitude range 7.0-
7.9.

8. Cases
CASE 1 : UNDER MINOR BUT FREQUENT SHAKING :
Beams and columns or any other main member (like shear
walls)carries vertical and horizontal forces successfully,
howeverbuildings may suffer repairable
damage.
• CASE 2 : UNDER MODERATE BUT OCCASIONAL SHAKING :
a. Main members may undergo repairable damage
b. Other membersmay be replaced
• CASE 3: UNDER STRONG BUT RARE SHAKING :
a. Main members may suffer severe and irreparable damage
but the building should not collapse

9. Philosophy is based on following fact
1. Earthquake proof construction is partially
impossible
2. Structures to resis most severe shaking are too
expensive to build
3. Most severe earthquakes are not frequent .

10. Earthquake-resistant design
philosophy
is based on dual design philosophy
• Safety-level design : Safety of structure (or its
occupants) should not be compromised under
extreme earthquake events
• Serviceability level design : Serviceability (utility) of
structure should not be unexpectedly Disrupted
under more regularly occurring Earthquake events
Design codes endeavour to satisfy both performance
requirements through a combination of analysis,
design and detailing specifications

11. Key Strategy:
Ductile Elements at key locations (load resisting locations) of the structure,
protects non-ductile elements from getting over stressed. This inelastic
response, tends to increase the effective period of the structure, resulting in
reduction in the strength demand, to deal with wind and earthquake forces,
as most of the earthquake forces go in overcoming the damped structure
due to inelastic response.

13. Thank you