Advanced Concrete Lecture

1
CE 72.52 Advanced Concrete
Lecture 1:
Introduction
Naveed Anwar
Executive Director, AIT Consulting
Director, ACECOMS
Affiliate Faculty, Structural Engineering, AIT
August - 2015

The Role of Structural Engineers
• To help in the creation of the safe built
environment
• Nothing can function, if structural
engineers do not do their job well
• Every other professional “Depends” on the
role of structural engineers
2

All systems absolutely need Structures
• Transportation systems
• Telecommunication systems
• Electricity and power systems
• Water supply, waste water systems
• Irrigation and agricultural systems
• Mining, oil, gas, offshore platforms
• Industrial plants, piping and process
• Housing, commercial Businesses
• Public Buildings
3

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A MUST read for structural
Engineers

Structural Engineering Spectrum
18
Activity Conception – Analysis – Design – Detailing ...
Structure Buildings – Bridges – Trusses – Shells – Towers ...
Code American – British – European – Japanese ...
Material Concrete – PSC – Steel – Timber ...
Model 2D Frame/Truss – 3D Frame/Truss – Full 3D FEM ....
Analysis Linear Static – NL Static – Linear Dynamic – Large Disp. ....
Solution Equation Solution – Finite Elements – Programming ...
Advanced Concrete l Dr. Naveed Anwar

Structural Design Office: Activities
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Design
Management
Structural
Designer
Office
Management
Coordination
Client Dealing
Principle
Conception
Detailing
Design
Analysis
Costing

CAD in Structural Engineering
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Conception Analysis Design Detailing Integrated Expert Systems Others

Reinforced Concrete Building Elements
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Reinforced Concrete Building Elements
22
Reference: James G. Macgregor
Reinforced Concrete: Mechanics and Design, 3rd Edition.

Advanced Concepts and Topics
• Go before and beyond the “Code”
• Integrated, Unified and Generalized approaches
• Main Topics
1. Material Behavior (Stress-strain, creep, shrinkage etc.)
2. Section Behavior and Design (flexure, shear, torsion)
3. Member Behavior and Design (Slabs, Beams, Columns)
4. Deep and Special Members (Strut and Tie, Deep beams, shear
walls)
5. Joints and Connections
6. Material, Section and Member Ductility
7. Seismic Detailing
8. Pre-stressed Concrete
23Advanced Concrete l Dr. Naveed Anwar

Assignment – 1 (Previous year)
• Create a map between structural
engineers role and as many other
disciplines and humanity needs as possible
• (Hint : Use Mind Maps)
24

Assignment – 1 (This year)
• List Top Ten Structural Engineers of All times
• Picture, name, year, country
• Main projects, achievements
33

The Hierarchy of Structures and its Components
• Physical Structures
• When applied to the physical and the built
environment, the term Structure means an
assemblage of physical components and
elements, each of which could further be a
structure itself, signifying the complexity of the
system
34

Basic Member Types and Forms
35

Characterization of Structures
• Based on the member types, the structures
can be broadly categorized as
• Cable structures
• Skeletal structural
• Spatial structures
• Solid structures and
• A combination of these
36

The Structural System
37
pv
EXCITATION
Loads
Vibrations
Settlements
Thermal
Changes
RESPONSES
Displacements
Strains
Stress
Stress Resultants
STRUCTURE

The Structural Elements

Member Cross-sections
Advanced Concrete l Dr. Naveed Anwar 39
• Cross-sections are generally
associated with line type or beam
type members, where the length
is much longer than the other
dimensions
• The design of a line type member
often means the design of its
cross-section, which means the
selection of appropriate
dimensions, proportions and
materials used at the cross-
section level.

The Structural Materials
• Concrete
• Reinforcing Steel
• Pre-stressing Steel
• Hot Rolled Structural Steel
• Cold Formed Structural Steel
• Aluminum other metals
• Structural Timber

The Need for Analysis
• We need to determine the Response of the
Structure to Excitations
so that:
• We can ensure that the structure can
sustain the excitation with an acceptable
level of response
41
Analysis
Design

Analysis of Structure
42
0 vx
zzyyxx
p
zyx 





pv
Real Structure is governed by “Partial
Differential Equations” of various order
Direct Solution is only Possible for:
• Simple Geometry
• Simple Boundary
• Simple Loading

Need for Structural Model
43
pv
EXCITATION
Loads
Vibrations
Settlements
Thermal
Changes
RESPONSES
Displacements
Strains
Stress
Stress Resultants
STRUCTURE
STRUCTURAL
MODEL

Proportioning for Safety
• Prime Concern: “Balance External Actions with
Internal Stress Resultants with adequate
margin for safety”
Sd > = FOS * Fa
• And Check for
• Deflections, Deformations, Vibrations, Crack Width
• Fire Protections, Permeability, Chemical Attacks
• Ductility and Other special considerations

Proportioning for Safety
45
S > A
S
FOS
A
Working Strength Design
S
FOS
A FOS
s
L 
•Ultimate Strength Design
•Limit State Design
•Partial FOS Design
S A FOS 
Load Factor Design
• A = Actions due to loads
• S = Strength of member
• FOS = Factor of safety

46
Various Types of
Structures:
Special Design
Procedures and
Concepts for each
type and material

Structural Design
Process and Concept
47

Design Philosophy and Process
“Structural Design is the process of
proportioning the structure to safely resist the
applied forces in the most cost effective
and friendly manner”

Overall Design Process
• Conception
• Modeling
• Analysis
• Design
• Detailing
• Drafting
• Costing
49
“Integrated Design
Process”

Structural Design Process

The Response and Design

From “Loads” to “Design Actions”

Structural Analysis vs Design
Structural Analysis
• Fairly General, Unified (FEM,
BEM ...)
• Output: Element/ Member
Actions, Displacements ...
Structural Design
• Structural Material (RC, PSC, HRS,
CFS, timber ... )
• Design Code (ACI, BS Codes,
EuroCode, JIS ... )
• Design Approach (working stress,
ultimate strength, limit state ... )
• Structural Members (beams,
columns, slabs, footings ... )
• Local Construction Techniques
and Practices
• Output: Element/ Member Cross-
section, Reinforcement ...

Structural Analysis vs Design

Loads and Stress Resultants

Various Methods of
Structural Designs

Various Methods of Structural Design
• Working Stress Design
• Allowable Stress Design (ASD)
• Working Stress Design (WSD)
• Load Factor Design
• Ultimate Strength Design
• Ultimate Strength Design (USD)
• Strength Design (SD)
• Load and Resistance Factor Design (LRFD)
• Performance Based Design
• Pushover Analysis
• Capacity Based Design

From Serviceability to Performance
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 Allowable
material
 Control on
deformation
limits for design
loads
 Material failure
criteria
 Section capacity
for factored
loads
 Ductility
considerations
 Deformation
capacity
 Load Capacity at
large
deformations
 Extraordinary
load
considerations
Serviceability
Ability
Strength
Design
Performance
Design

From Serviceability to Performance
• Satisfying one design level does not ensure that
other design levels will be satisfied
• Serviceability design only ensures that deflections and
vibrations etc. for service loads are within limits but says
nothing about strength
• Strength design ensures that a certain factor of safety
against overload is available within a member or a cross-
section but says nothing about what happens if load
exceeds design level
• Performance design ensures that structure as a whole
reaches a specified demand level. Performance design
can include, both service and strength design levels

Design Philosophies
and Methods

Limit State Design Concept
61
Types of Limit State Description
Ultimate Limit states • Loss of equilibrium
• Rupture
• Progressive Collapse
• Formation of plastic mechanism
• Instability
• Fatigue
Serviceability limit states • Excessive deflections
• Excessive crack width
• Undesirable Vibration
Special limit states Due to abnormal conditions and abnormal loading such as
• Damage or collapse in extreme earthquakes
• Structural effects of fire, explosion
• Corrosion or deterioration

• Limit state design involves
• Identification of all potential modes of failure
(i.e. identify significant limit states
• Determination of acceptable levels of safety
against occurrence of each limit state
• Consideration by the designer of significant
limit states
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Safety Factors
• Material safety Factor γm
• Member Factor γb
• Load Factor γf
• Structural Analysis Factor γa
• Structure Factor γi
63

Section Design Process
64
Characteristic value of
material basic strength
Design Strength
Design member
capacity
Characteristic value of
Load
Design load
Design member
capacity
Ym Yb
Yf Ya
Verification
Yi

65
Material/Stress Type γm
Reinforcement 1.15
Concrete in flexure or axial load 1.50
Concrete shear strength without shear reinforcement 1.25
Concrete bond strength 1.40
Concrete other >1.50
Values of γm (BS 8110)

66
Load Combination
Load Type
Dead Load Imposed Load Wind
Adverse Beneficial Adverse Beneficial
Dead and Imposed 1.4 1 1.6 0 -
Dead and wind 1.4 1 - - 1.4
Dead , wind and imposed 1.2 1.2 1.2 1.2 1.2
Design Load = γf x Characteristic Load
Values of γm (BS 8110)

What is Advanced
in this course?

Advanced Concrete Lecture

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