Design of tall buildings lecture-1-part-2-dr-shafiul-bari-sir

ANALYSIS AND DESIGN OF TALL
BUILDINGS (CE 6114)
Professor Dr. Shafiul Bari
Professor, Department of Civil Engineering
Bangladesh University of Engineering and Technology, BUET.
Professor Dr. Shafiul Bari
Professor, Department of Civil Engineering
Bangladesh University of Engineering and Technology, BUET.

BOOKS
Two Books (No 1 & 2) are Mandatory
1. B. Stafford & A. Coull (1991): Tall Building Structures: Analysis and Design , John
Wiley & Sons.
2. W. Schueller (1977): High Rise Building Structures , John Wiley & Sons.
3. BNBC: Bangladesh National Building Code-1993
4.The Council on Tall Buildings and Urban Habitat (1995): Structural Systems for Tall
Buildings, McGraw Hill.
5. Taranath, B. (1988): Structural Analysis and Design of Tall Buildings, 2nd. Ed.,
McGraw Hill.
6. White & Salmon, (1987): Building Structural Design Handbook, John Wiley & Sons.
7. Schueller (1996): The Design of Building Structures, Prentice Hall, New Jersey.
8. Nilson et el: Design of concrete structures .
9. Fintel: Handbook of concrete engineering
1. B. Stafford & A. Coull (1991): Tall Building Structures: Analysis and Design , John
Wiley & Sons.
2. W. Schueller (1977): High Rise Building Structures , John Wiley & Sons.
3. BNBC: Bangladesh National Building Code-1993
4.The Council on Tall Buildings and Urban Habitat (1995): Structural Systems for Tall
Buildings, McGraw Hill.
5. Taranath, B. (1988): Structural Analysis and Design of Tall Buildings, 2nd. Ed.,
McGraw Hill.
6. White & Salmon, (1987): Building Structural Design Handbook, John Wiley & Sons.
7. Schueller (1996): The Design of Building Structures, Prentice Hall, New Jersey.
8. Nilson et el: Design of concrete structures .
9. Fintel: Handbook of concrete engineering

Class Lectures
(Total 12 Nos)
• Lecture – 1 : Introduction
• Lecture – 2 : Tall Building Criteria and Loading , Structural Form
• Lecture – 3 : Architectural Planning (FAR) & HVAC system.
• Lecture – 4 : Floor System (Behavior Under Gravity Load)
• Lecture – 5 : Structural System (Behavior Under Lateral Load)
• Lecture – 6 : Structural Modeling and Analysis of Tall Buildings
• Lecture – 7 : Rigid Frame & Drift Control
• Lecture – 8 : Shear Wall & Coupled Shear Wall
• Lecture – 9 : Wall-Frame & Tubular System
• Lecture – 10 : Design of Structural Members & Foundation Design
• Lecture – 11 : Fire Safety Engineering
• Lecture – 12 : Construction and Project Management Aspects
• Lecture – 1 : Introduction
• Lecture – 2 : Tall Building Criteria and Loading , Structural Form
• Lecture – 3 : Architectural Planning (FAR) & HVAC system.
• Lecture – 4 : Floor System (Behavior Under Gravity Load)
• Lecture – 5 : Structural System (Behavior Under Lateral Load)
• Lecture – 6 : Structural Modeling and Analysis of Tall Buildings
• Lecture – 7 : Rigid Frame & Drift Control
• Lecture – 8 : Shear Wall & Coupled Shear Wall
• Lecture – 9 : Wall-Frame & Tubular System
• Lecture – 10 : Design of Structural Members & Foundation Design
• Lecture – 11 : Fire Safety Engineering
• Lecture – 12 : Construction and Project Management Aspects

Lecture - 1
• What is “Tall Building” ?
• Classification can be done in many ways:
– Based on total height
– Based on “Relative Height”
– Based on number of floors
– Based on structural response
• From Structural Point of View:
– Tall building is the one in which selection, behavior and design of
lateral load resisting system significantly effects the overall
design of the building
• What is “Tall Building” ?
• Classification can be done in many ways:
– Based on total height
– Based on “Relative Height”
– Based on number of floors
– Based on structural response
• From Structural Point of View:
– Tall building is the one in which selection, behavior and design of
lateral load resisting system significantly effects the overall
design of the building

Lecture - 1
• For any structural/floor systems, we will discuss:
– How to select the system
– What is the behavior of the system
– How to model the system for structural analysis
• How to integrate the systems and analyze the entire building model
• How to interpret the analysis results for system components
• How to design the components based on analysis results
• How to use ETABS for modeling, analysis and design of building
systems and components
• For any structural/floor systems, we will discuss:
– How to select the system
– What is the behavior of the system
– How to model the system for structural analysis
• How to integrate the systems and analyze the entire building model
• How to interpret the analysis results for system components
• How to design the components based on analysis results
• How to use ETABS for modeling, analysis and design of building
systems and components

Lecture - 1
Special Considerations
• Story Drift for Occupant Perception
• Axial Shortening of Columns
• Transfer Girders and Deep Beams
• Shear Wall Design and Detailing
• Construction Sequence Analysis
• Seismic Performance and Dynamic Analysis
Special Considerations
• Story Drift for Occupant Perception
• Axial Shortening of Columns
• Transfer Girders and Deep Beams
• Shear Wall Design and Detailing
• Construction Sequence Analysis
• Seismic Performance and Dynamic Analysis

Lecture - 1
Tall Building Systems
• Building is an assemblage of various Systems
– Basic Functional System
– Structural System
– HVAC System
– Plumbing and Drainage System
– Electrical, Electronic and Communication System
– Security System
– Other specialized systems
Tall Building Systems
• Building is an assemblage of various Systems
– Basic Functional System
– Structural System
– HVAC System
– Plumbing and Drainage System
– Electrical, Electronic and Communication System
– Security System
– Other specialized systems

Lecture - 1
The Building Structural System - Conceptual
• The Gravity Load Resisting System (GLRS)
– The structural system (beams, slab, girders, columns, etc)
that act primarily to support the gravity or vertical loads
• The Lateral Load Resisting System (LLRS)
– The structural system (columns, shear walls, bracing, etc)
that primarily acts to resist the lateral loads
• The Floor Diaphragm (FD)
– The structural system that transfers lateral loads to the
lateral load resisting system and provides in-plane floor
stiffness
The Building Structural System - Conceptual
• The Gravity Load Resisting System (GLRS)
– The structural system (beams, slab, girders, columns, etc)
that act primarily to support the gravity or vertical loads
• The Lateral Load Resisting System (LLRS)
– The structural system (columns, shear walls, bracing, etc)
that primarily acts to resist the lateral loads
• The Floor Diaphragm (FD)
– The structural system that transfers lateral loads to the
lateral load resisting system and provides in-plane floor
stiffness

Lecture - 1
Knowledge Model for System Selection
• Architecture
• Building Services
• Construction Eng.
• Value Eng.
• Aesthetics
• Ergonomics Eng.
• Structural Eng.
• Knowledge Eng.
• Economics
• Artificial Intelligence
• System Eng.
• Common Sense
Knowledge Model for System Selection
• Architecture
• Building Services
• Construction Eng.
• Value Eng.
• Aesthetics
• Ergonomics Eng.
• Structural Eng.
• Knowledge Eng.
• Economics
• Artificial Intelligence
• System Eng.
• Common Sense

Lecture - 1
Selection of Structural System
Function has considerable effect on the selection of structural system
Based on Function/Occupancy of Tall Buildings:
• Residential Buildings
– Apartments
– Hotels
– Dormitories
• Office and Commercial Buildings
• Mixed Occupancy – Commercial + Residential
• Industrial Buildings and Parking Garages
Selection of Structural System
Function has considerable effect on the selection of structural system
Based on Function/Occupancy of Tall Buildings:
• Residential Buildings
– Apartments
– Hotels
– Dormitories
• Office and Commercial Buildings
• Mixed Occupancy – Commercial + Residential
• Industrial Buildings and Parking Garages

Lecture - 1
Typical Characteristics of Residential Bldg
• Known location of partitions and their load
• Column lines generally matches architectural layout
• Typical spans 15-22 ft
• Tall buildings economy is achieved using the thinnest slab
• One way pre-cast or flat slab – popular
• Lateral load resistance provided by frame or shear walls
• More or less fixed M/E system layouts
Typical Characteristics of Residential Bldg
• Known location of partitions and their load
• Column lines generally matches architectural layout
• Tall buildings economy is achieved using the thinnest slab
• One way pre-cast or flat slab – popular
• Lateral load resistance provided by frame or shear walls
• More or less fixed M/E system layouts

Lecture - 1
Typical Characteristics of Office and Commercial Bldg
• Unknown location of partitions and their load
• Need for flexible M/E layouts
• Post-tension or ribbed and flat slab with drop panel –
popular
• Ideal balance between vertical and lateral load resisting
systems: sufficient shear walls to limit the resultant
tension under gravity plus wind
• Lateral load resistance varies significantly
Typical Characteristics of Office and Commercial Bldg
• Unknown location of partitions and their load
• Need for flexible M/E layouts
• Post-tension or ribbed and flat slab with drop panel –
popular
• Ideal balance between vertical and lateral load resisting
systems: sufficient shear walls to limit the resultant
tension under gravity plus wind
• Lateral load resistance varies significantly

Lecture - 1
Gravity Load Resisting Systems Purpose
“ To Transfer Gravity Loads Applied at the Floor Levels down to the
Foundation Level”
• Direct Path Systems
• Slab Supported on Load Bearing Walls
• Slab Supported on Columns
• Indirect Multi Path Systems
• Slab Supported on Beams
• Beams Supported on Other Beams
• Beams Supported on Walls or Columns
Gravity Load Resisting Systems Purpose
“ To Transfer Gravity Loads Applied at the Floor Levels down to the
Foundation Level”
• Direct Path Systems
• Slab Supported on Load Bearing Walls
• Slab Supported on Columns
• Indirect Multi Path Systems
• Slab Supported on Beams
• Beams Supported on Other Beams
• Beams Supported on Walls or Columns

Lecture - 1
Vertical Load Resisting Systems
1. Slabs supported on Long Rigid Supports
– Supported on stiff Beams or Walls
– One-way and Two-way Slabs
– Main consideration is flexural reinforcement
2. Slab-System supported on Small Rigid Supports
– Supported on Columns directly
– Flat Slab Floor systems
– Main consideration is shear transfer, moment distribution in various
parts, lateral load resistance
3. Slabs supported on soil
– Slabs on Grade: Light, uniformly distributed loads
– Footings, Mat etc. Heavy concentrated loads
Vertical Load Resisting Systems
1. Slabs supported on Long Rigid Supports
– Supported on stiff Beams or Walls
– One-way and Two-way Slabs
– Main consideration is flexural reinforcement
2. Slab-System supported on Small Rigid Supports
– Supported on Columns directly
– Flat Slab Floor systems
– Main consideration is shear transfer, moment distribution in various
parts, lateral load resistance
3. Slabs supported on soil
– Slabs on Grade: Light, uniformly distributed loads
– Footings, Mat etc. Heavy concentrated loads

Lecture - 1
Popular Gravity Load Resting Systems
• Direct Load Transfer Systems (Single load transfer path)
– Flat Slab and Flat Plate
– Beam-Slab
– Waffle Slab
– Wall Joist
• Indirect Load Transfer System (Multi step load transfer path)
– Beam, Slab
– Girder, Beam, Slab
– Girder, Joist
Popular Gravity Load Resting Systems
• Direct Load Transfer Systems (Single load transfer path)
– Flat Slab and Flat Plate
– Beam-Slab
– Waffle Slab
– Wall Joist
• Indirect Load Transfer System (Multi step load transfer path)
– Beam, Slab
– Girder, Beam, Slab
– Girder, Joist

Lecture - 1
– Some Sample Floor Slab Types
– Slab Only
– Hollow Core Slab
– Pre-Cast Slab Panels
– Beam and Slab
– Beam-Slab
– Girder-Beam Slab
– Joist Slab
– Girder-Joist Slab
– Pre-Cast Slab-Beam System
– Some Sample Floor Slab Types
– Slab Only
– Hollow Core Slab
– Pre-Cast Slab Panels
– Beam and Slab
– Beam-Slab
– Girder-Beam Slab
– Joist Slab
– Girder-Joist Slab
– Pre-Cast Slab-Beam System

Lecture - 1
• Some Sample Floor Slab Systems• Some Sample Floor Slab Systems
Flat Slab
Flat Slab + Capital
Flat Slab + Drop Panel
Flat Slab + Drop Panel +
Capital
Waffle Slab
Band Slab
Inverted Band Slab
Metal Deck/ Wood Deck
Composite Metal Deck
Hollow Block Slab
Composite Girder-Slab
Composite Truss Slab
Alpha Truss System
Wooden Beam, Rafter
Plank System
Sandwich Panels
Flat Plate
Flat Plate

Lecture - 1
Selection of Layout and Type of Slab
• Basic Consideration
• Span Length: Small, Medium, Long
• Panel aspect ratio: Square, rectangular, oblong
• Loads: Light, Medium, Heavy
• Ducts and Piping: Electrical, Mechanical, Water supply
• Openings: Size and Location
• Architectural consideration: Aesthetics, clearance, etc
• Special elements: Drop Panel, Column Capital, Beams
• Construction Considerations: Form work, time, case of
considerations
Selection of Layout and Type of Slab
• Basic Consideration
• Span Length: Small, Medium, Long
• Panel aspect ratio: Square, rectangular, oblong
• Loads: Light, Medium, Heavy
• Ducts and Piping: Electrical, Mechanical, Water supply
• Openings: Size and Location
• Architectural consideration: Aesthetics, clearance, etc
• Special elements: Drop Panel, Column Capital, Beams
• Construction Considerations: Form work, time, case of
considerations

Lecture - 1
• Flat plates
Small Spans ( 4.5 to 6 m)
Relatively light load < 500 Kg/m2 ( 5 kPa )
Common for residential buildings
Used where Drop panel or Column capital undesirable
Easy construction. Low overall height of building
• Flat Slabs
Medium Spans ( 6.0 to 9.0 m)
Relatively heavy load > 500 Kg/m2 ( 5 kPa )
Common in industrial floors, parking areas etc.
• Waffle Slab
Large spans ( 7.5 – 12 m )
Relatively heavy loads
Common for public buildings. More aesthetic appearance
Difficult to construct. Requires special form work
• Flat plates
Small Spans ( 4.5 to 6 m)
Relatively light load < 500 Kg/m2 ( 5 kPa )
Common for residential buildings
Used where Drop panel or Column capital undesirable
Easy construction. Low overall height of building
• Flat Slabs
Medium Spans ( 6.0 to 9.0 m)
Relatively heavy load > 500 Kg/m2 ( 5 kPa )
• Waffle Slab
Relatively heavy loads
Common for public buildings. More aesthetic appearance
Difficult to construct. Requires special form work

Lecture - 1
Selection of Slab System
• Beam-Slabs / Beam and Slabs
Medium to large spans ( 5 to 10 m)
Relatively economical in concrete and steel cost
Greater depth: Increase in building height
• Band Slab
Medium spans ( 5 to 9 m)
More economical than Flat Slab
• One-way Joist and Beams
Easier to construct than Waffle slabs
Suitable for high-rise office building
Beams on shorter side, Joist on longer side
Selection of Slab System
• Beam-Slabs / Beam and Slabs
Medium to large spans ( 5 to 10 m)
Relatively economical in concrete and steel cost
Greater depth: Increase in building height
• Band Slab
Medium spans ( 5 to 9 m)
More economical than Flat Slab
• One-way Joist and Beams
Easier to construct than Waffle slabs
Suitable for high-rise office building
Beams on shorter side, Joist on longer side

Lecture - 1
Purpose
“ To Transfer Lateral Loads Applied at any location in the
structure down to the Foundation Level”
• Single System
• Moment Resisting Frames
• Braced Frames
• Shear Walls
• Tubular Systems
• Dual System
• Shear Wall - Frames
• Tube + Frame + Shear Wall
Purpose
“ To Transfer Lateral Loads Applied at any location in the
structure down to the Foundation Level”
• Single System
• Moment Resisting Frames
• Braced Frames
• Shear Walls
• Tubular Systems
• Dual System
• Shear Wall - Frames
• Tube + Frame + Shear Wall

Lecture - 1
Lateral Loads
• Primary Lateral Loads
– Load generated by Wind Pressure
– Load generated due to Seismic Excitation
• Other Lateral Loads
– Load generated due to horizontal component of Gravity
Loads in Inclined Systems and in Un-symmetrical
structures
– Load due to lateral soil pressure, liquid and material
retention
Lateral Loads
• Primary Lateral Loads
– Load generated by Wind Pressure
– Load generated due to Seismic Excitation
• Other Lateral Loads
– Load generated due to horizontal component of Gravity
Loads in Inclined Systems and in Un-symmetrical
structures
– Load due to lateral soil pressure, liquid and material
retention

Lecture - 1
Sample Lateral Load Resistance Systems
• Bearing wall system
– Light frames with shear panels
– Load bearing shear walls
• Fully Braced System (FBS)
– Shear Walls (SW)
– Diagonal Bracing (DB)
• Moment Resisting Frames (MRF)
– Special Moment-Resisting Frames (SMRF)
– Concrete Intermediate Moment-Resisting Frame (IMRF)
– Ordinary Moment-Resisting Frame (OMRF)
• Dual Systems (DS)
– Shear Walls + Frames (SWF)
– Ordinary Braced Frame (OBF)
– Special Braced Frame (SBF)
• Bearing wall system
– Light frames with shear panels
– Load bearing shear walls
• Fully Braced System (FBS)
– Shear Walls (SW)
– Diagonal Bracing (DB)
• Moment Resisting Frames (MRF)
– Special Moment-Resisting Frames (SMRF)
– Concrete Intermediate Moment-Resisting Frame (IMRF)
– Ordinary Moment-Resisting Frame (OMRF)
• Dual Systems (DS)
– Shear Walls + Frames (SWF)
– Ordinary Braced Frame (OBF)
– Special Braced Frame (SBF)

Lecture - 1
Moment Resisting Frame
• The Load is transferred by shear in columns, that produces moment in
columns and in beams
• The Beam-Column connection is crucial for the system to work
• The moments and shear from later loads must be added to those from gravity
loads
Shear Wall and Frame
• The lateral loads is primarily resisted by the shear in the walls, in turn
producing bending moment
• The openings in wall become areas of high stress concentration and need to
be handled carefully
• Partial loads is resisted by the frames • Traditionally 75/25 distribution haws been
used
Moment Resisting Frame
• The Load is transferred by shear in columns, that produces moment in
columns and in beams
• The Beam-Column connection is crucial for the system to work
• The moments and shear from later loads must be added to those from gravity
loads
Shear Wall and Frame
producing bending moment
• The openings in wall become areas of high stress concentration and need to
be handled carefully
• Partial loads is resisted by the frames • Traditionally 75/25 distribution haws been
used

Lecture - 1
• Shear Wall - Frame
• The Walls are part of the frame and act together with the frame members
producing bending moment.
• Partial loads is resisted by the frame members in moment and shear
Braced Frame
• The lateral loads is primarily resisted by the Axial Force in the braces, columns
and beams in the braced zone.
• The frame away from the braced zone does not have significant moments
• Bracing does not have to be provided in every bay, but should be provided in
every story
• Shear Wall - Frame
• The Walls are part of the frame and act together with the frame members
producing bending moment.
• Partial loads is resisted by the frame members in moment and shear
Braced Frame
• The lateral loads is primarily resisted by the Axial Force in the braces, columns
and beams in the braced zone.
• The frame away from the braced zone does not have significant moments
• Bracing does not have to be provided in every bay, but should be provided in
every story

Lecture - 1
• Tubular Structure
• The system is formed by using closely spaced columns and deep spandrel beams
• The lateral loads is primarily resisted by the entire building acting as a big cantilever with
a
tubular/ box cross-section
• There is a “shear lag” problem between opposite faces of the tube due to in-efficiency of
column beam connection
• The height to width ratio should be more than 5
Braced Tube Systems
• Diagonal Braces are added to the basic tubular structure
• This modification of the Tubular System reduces shear lag between opposite faces
• Tubular Structure
• The system is formed by using closely spaced columns and deep spandrel beams
• The lateral loads is primarily resisted by the entire building acting as a big cantilever with
a
tubular/ box cross-section
• There is a “shear lag” problem between opposite faces of the tube due to in-efficiency of
column beam connection
• The height to width ratio should be more than 5
Braced Tube Systems
• Diagonal Braces are added to the basic tubular structure
• This modification of the Tubular System reduces shear lag between opposite faces

Lecture - 1
Transfer of Lateral Loads
• The lateral loads are mostly applied or generated away from
the lateral load resisting systems
• They must be transferred to the LLRS through the “in-plane”
stiffness of the floor diaphragm
• The in-plane stiffness may be prided by:
– Concrete Floor Slab
– In-plane trusses
Transfer of Lateral Loads
• The lateral loads are mostly applied or generated away from
the lateral load resisting systems
• They must be transferred to the LLRS through the “in-plane”
stiffness of the floor diaphragm
• The in-plane stiffness may be prided by:
– Concrete Floor Slab
– In-plane trusses

Lecture - 1
Building Response
• Objective: To determine the load path gravity and lateral loads
• For Gravity Loads - How Gravity Loads are Distributed
– Analysis of Gravity Load Resisting System for:
• Dead Load, Live Live Load, Pattern Loads, temperature, shrinkage
– Important Elements: Floor slabs, beams, openings, Joists, etc.
• For Lateral Loads – How Lateral Loads are Distributed
– Analysis of Lateral Load Resisting System for:
• Wind Loads, Seismic Loads, Structural Un-symmetry
– Important elements: Columns, shear walls, bracing , beams
Building Response
• Objective: To determine the load path gravity and lateral loads
• For Gravity Loads - How Gravity Loads are Distributed
– Analysis of Gravity Load Resisting System for:
• Dead Load, Live Live Load, Pattern Loads, temperature, shrinkage
– Important Elements: Floor slabs, beams, openings, Joists, etc.
• For Lateral Loads – How Lateral Loads are Distributed
– Analysis of Lateral Load Resisting System for:
• Wind Loads, Seismic Loads, Structural Un-symmetry
– Important elements: Columns, shear walls, bracing , beams

Lecture - 1
Excitation Structure Response Basic Analysis Type
Static Elastic Linear Linear-Elastic-Static Analysis
Static Elastic Nonlinear Nonlinear-Elastic-Static Analysis
Static Inelastic Linear Linear-Inelastic-Static Analysis
Static Inelastic Nonlinear Nonlinear-Inelastic-Static Analysis
Dynamic Elastic Linear Linear-Elastic-Dynamic Analysis
Dynamic Elastic Nonlinear Nonlinear-Elastic-Dynamic Analysis
Dynamic Inelastic Linear Linear-Inelastic-Dynamic Analysis
Dynamic Inelastic Nonlinear Nonlinear-Inelastic-Dynamic Analysis

Lecture - 1
Some More Solution Types
• Non-linear Analysis
– P-Delta Analysis
– Buckling Analysis
– Static Pushover Analysis
– Fast Non-Linear Analysis (FNA)
– Large Displacement Analysis
• Dynamic Analysis
– Free Vibration and Modal Analysis
– Response Spectrum Analysis
– Steady State Dynamic Analysis
Some More Solution Types
• Non-linear Analysis
– P-Delta Analysis
– Buckling Analysis
– Static Pushover Analysis
– Fast Non-Linear Analysis (FNA)
– Large Displacement Analysis
• Dynamic Analysis
– Free Vibration and Modal Analysis
– Response Spectrum Analysis
– Steady State Dynamic Analysis

Lecture - 1
Static Vs Dynamic
• Static Excitation
– When the Excitation (Load) does not vary rapidly with Time
– When the Load can be assumed to be applied “Slowly”
• Dynamic Excitation
– When the Excitation varies rapidly with Time
– When the “Inertial Force” becomes significant
• Most Real Excitation are Dynamic but are considered
“Quasi Static”
• Most Dynamic Excitation can be converted to
“Equivalent Static Loads”
Static Vs Dynamic
• Static Excitation
– When the Excitation (Load) does not vary rapidly with Time
– When the Load can be assumed to be applied “Slowly”
• Dynamic Excitation
– When the Excitation varies rapidly with Time
– When the “Inertial Force” becomes significant
• Most Real Excitation are Dynamic but are considered
“Quasi Static”
• Most Dynamic Excitation can be converted to
“Equivalent Static Loads”

Lecture - 1
Elastic Vs Inelastic
• Elastic Material
– Follows the same path during loading and unloading and returns to
initial
state of deformation, stress, strain etc. after removal of load/ excitation
• Inelastic Material
– Does not follow the same path during loading and unloading and may
not
returns to initial state of deformation, stress, strain etc. after removal of
load/ excitation
• Most materials exhibit both, elastic and inelastic behavior
depending upon level of loading.
Elastic Vs Inelastic
• Elastic Material
– Follows the same path during loading and unloading and returns to
initial
state of deformation, stress, strain etc. after removal of load/ excitation
• Inelastic Material
– Does not follow the same path during loading and unloading and may
not
returns to initial state of deformation, stress, strain etc. after removal of
load/ excitation
• Most materials exhibit both, elastic and inelastic behavior
depending upon level of loading.

Lecture - 1
Linear Vs Nonlinear
• Linearity
– The response is directly proportional to excitation
– (Deflection doubles if load is doubled)
• Non-Linearity
– The response is not directly proportional to excitation
– (deflection may become 4 times if load is doubled)
• Non-linear response may be produced by:
– Geometric Effects (Geometric non-linearity)
– Material Effects (Material non-linearity)
– Both
Linear Vs Nonlinear
• Linearity
– The response is directly proportional to excitation
– (Deflection doubles if load is doubled)
• Non-Linearity
– The response is not directly proportional to excitation
– (deflection may become 4 times if load is doubled)
• Non-linear response may be produced by:
– Geometric Effects (Geometric non-linearity)
– Material Effects (Material non-linearity)
– Both

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