Earthquake Resistant Design & Construction (Gujarat Institute - - PowerPoint PPT Presentation

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Earthquake Resistant Design & Construction (Gujarat Institute - - PowerPoint PPT Presentation

Mar 09, 2023 167 likes •822 views

Earthquake Resistant Design & Construction (Gujarat Institute of Disaster Management) (28-07-2020) by Professor APPLIED MECHANICS DEPARTMENT L D COLLEGE of ENGINEERING Ahmedabad Earthquake Engineering Practice Concept of Earthquake

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by Professor APPLIED MECHANICS DEPARTMENT L D COLLEGE of ENGINEERING Ahmedabad

Earthquake Resistant Design & Construction

(Gujarat Institute of Disaster Management) (28-07-2020)

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.

Earthquake Engineering Practice

Concept of Earthquake Resistant Design of RC structures Actual Construction Practice Construction practice - Beam, column, foundation, walls and roofs Geotechnical considerations

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– Earthquakes do not kill, unsafe buildings do – Earthquake is a manmade disaster – Solution lies in “buildings” & not in “earthquakes”

Challenge : Understanding

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2005 NPEEE Earthquake Design Concept : Lecture 1: Impact of Earthquakes 4/29

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Destruction of Human life.

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Structural Design

  • Life of Structures
  • Loads acting on civil engineering structures

Design Loads

  • Dead Load
  • Live Load
  • Wind Load
  • Earthquake Load
  • Many other types of loads
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Structural Design

  • Design for Gravity Loads : (DL+LL)
  • 1. Permanent load
  • 2. Factor of Safety
  • 3. No damage
  • Design for Lateral Load: (Wind + EQ)

Lateral forces create discomfort to structures

  • 1. Wind Force – frequent - No damage
  • 2. EQ Force - ??? (Max effective time 2 minutes)
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Dead Load + Live Load +Wind or EQ Load

DL + LL + WL or EQ

Earthquake Force F = mass x acceleration = ma Wind Force F = Intensity of wind x Area of Obstruction

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Cyclone Resistant Design

  • No damage condition

Earthquake Resistant Design - ???????

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Design Philosophy for Earthquake

Which design philosophy should we follow? Earthquake Proof Design OR Earthquake Resistant Design

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Philosophy of earthquake resistant structure

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During an earthquake, lighter the building and the roof, the better is the performance of the house. Lighter roof would not induce as much load on the walls, and the walls would be able to transfer the loads easily during an earthquake. On the other hand, during a cyclone, heavier the roof, the better is the performance of the house. It would resist strong loads due to the wind pressure, hold itself and the house in place.

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Cyclone Resistant Design

  • No damage allowed

Earthquake Resistant Design

  • Damages allowed but no collapse
  • We heavily rely on ductility
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IS 13920 – 2016 – Ductile Design & Detailing

  • f RC Structures subjected to Seismic Forces

– Code of Practice Ductility is defined as the ability

  • f

a structure to undergo inelastic deformations beyond the initial yield deformation without decrease in strength & stiffness

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Elastic Response Vs Inelastic Response

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Advantages of Ductility

  • 1. Absorbs lots of energy, therefore good performance

during

  • load reversals,
  • Impact
  • secondary stresses due to differential settlement
  • f foundation.
  • 2. Enough warning by showing large deformation

before failure - loss of life is minimized

  • 3. Yielding of steel reinforcement - assumptions in the

design of reinforced concrete structures by limit state method.

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WHY IS DUCTILTY REQUIRED?

TO PREVENT BRITTLE FAILURES.

  • SHEAR FAILURE
  • BOND FAILURE
  • COMPRESSION FAILURES (OVER REINFORCED

SECTIONS)

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VARIOUS CONVETIONAL LATERAL LOAD RESISTING SYSTEMS

  • COLUMNS
  • SHEAR WALLS
  • BRACING SYSTEMS
  • MOMENT RESISTING FRAME
  • TUBES
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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 22/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 23/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 24/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 25/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 26/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 27/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 28/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 29/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 30/23

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2005 NPEEE Earthquake Design Concept : Lecture 9: Overview

  • f EQ resistant Structural

Systems 31/23

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Learning from failures DEFICIENCIES IN BUILDINGS

  • LOCAL DEFICIENCIES
  • GLOBAL DEFICIENCIES
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LOCAL DEFICIENCIES IN BUILDINGS Failures of Flexural Members

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2005 NPEEE Earthquake Design Concept : Lecture 14: Ductility

  • f MRFs

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2005 NPEEE Earthquake Design Concept : Lecture 14: Ductility

  • f MRFs

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Confinement & Anchorage

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Confinement to increase strength Continuity & Anchorage for integral action

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Confinement to increase strength Continuity & Anchorage for integral action

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Anchorage for integral action

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135 degree bend

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LOCAL DEFICIENCIES IN BUILDINGS Failures of MEMBERS SUBJECTED TO BENDING & AXIAL LOAD

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Hinges

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FAILURES DUE TO INADEQUATE LINKS

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FAILURES DUE TO INADEQUATE LINKS

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When a column terminates into a footing or mat

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2005 NPEEE Earthquake Design Concept : Lecture 14: Ductility

  • f MRFs

49/37

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Thanks to well detailed confining reinforcement (Taiwan 1999)

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IS 13920 -2016

  • Design of Beam Column Joint
  • Design of shear wall
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MITIGATING GEOLOGICAL HAZARDS

  • Ground collapse
  • Liquefaction
  • Differential compaction
  • Landslide
  • Earthquake-induced flood
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ASSESS THE POTENTIAL FOR SOIL LIQUEFACTION

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The building sank evenly about 1 m due to soil

  • liquefaction. The

displaced soil caused a bulge in the road.

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This inclined building sank unevenly and leans against a neighbouring building

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The solid building tilted as a rigid body and the raft foundation rises above the ground. The building itself suffered only relatively minor damage.

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This tank is also tilted due to the liquefaction of the sandy artificial landfill.

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Mitigating Liquefaction

  • Foundation on bed rock
  • Vibro-floatation
  • Soil with stabilizing materials
  • Provision of drainage to release pore

pressure

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Factors for Good Seismic Performance

  • Architectural configuration
  • Simple and regular configuration
  • Structural design
  • Adequate lateral strength
  • Adequate stiffness
  • Adequate ductility
  • Integral Action
  • Non-structural elements
  • Quality of construction
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CONCLUSION For safety in future earthquakes, all provisions

  • f the codes should be followed in design &
  • construction. This should be a mandatory

provision in the Building Bylaws.

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Wish U All the Best

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Courtesy: Dr S K Jain Dr C V R M Murthy