Civil Engineering  Pre-stressed Concrete Structures
   
 
Title: Pre-stressed Concrete Structures
Department: Civil Engineering
Author: Prof. Devdas Menon , Prof. Amlan Kumar Sengupta
University: IIT Madras
Type: WebLink
Abstract: Module 1: Introduction, Prestressing Systems and Material Properties (7 Hours)
Topic

Hours
Basic Concept
Early Attempts of Prestressing
Brief History
Development of Building Materials

1
Definitions
Advantages of Prestressing
Limitations of Prestressing
Types of Prestressing
• Source of prestressing force
• External or internal prestressing
• Pre-tensioning or post-tensioning
• Linear or circular prestressing
• Full, limited or partial prestressing
• Uniaxial, biaxial or multiaxial prestressing

1
Prestressing Systems and Devices
Pre-tensioning
• Introduction
• Stages
Advantages
Disadvantages
Devices
• Jacks
• Anchoring devices
• Harping devices

1
Post-tensioning
• Introduction
• Stages
Advantages
Disadvantages
Devices
• Anchoring devices
• Sequence of anchoring
• Jacks
• Couplers
• Grouting

1
Constituents of Concrete
• Introduction
• Aggregate
• Cement
• Water
• Admixtures
Hardened Concrete
• Strength of concrete
• Stiffness of concrete
• Durability of concrete
• High performance concrete
• Allowable stresses in concrete

1
Hardened Concrete
• Stress-strain curves for concrete
• Creep of concrete
• Shrinkage of concrete
Properties of Grout
Codal Provisions

1
Prestressing Steel
• Introduction
• Forms of prestressing steel
• Types of prestressing steel
• Properties of prestressing steel
• Stress-strain curves for prestressing steel
• Relaxation of steel
• Durability
• Fatigue
Codal Provisions

1

Module 2: Losses in Prestress (3 Hours)
Topic

Hours
Notations
• Geometric properties
• Load variables
Losses in Prestress
• Elastic shortening
• Pre-tensioned axial members
• Pre-tensioned bending members
• Post-tensioned axial members
• Post-tensioned bending members

1
Losses in Prestress (Part I)
• Friction
• Anchorage slip
Force Variation Diagram

1
Losses in Prestress (Part II)
• Creep of concrete
• Shrinkage of concrete
• Relaxation of steel
Total Time-dependent Loss

1

Module 3: Analysis of Members (6 Hours)
Topic

Hours
Analysis of Members Under Axial Load
• Introduction
• Analysis at transfer
• Analysis at services loads
• Analysis of ultimate strength
• Analysis of behavior

1
Analysis of Member Under Flexure (Part I)
• Introduction
Analysis at Service Loads
• Based on stress concept
• Based on force concept
• Based on load balancing concept

1
Analysis of Member Under Flexure (Part II)
• Cracking moment
• Kern point
• Pressure line

1
Analysis of Member Under Flexure (Part III)
Analysis for Ultimate Strength
• Variation of stress in steel
• Condition at ultimate limit state
Analysis of Rectangular Sections

1
Analysis of Flanged Sections
1
Analysis of Partially Prestressed Sections
Analysis of Un-bonded Post-tensioned Beams
Analysis of Behaviour

1

Module 4: Design of Members (6 Hours)
Topic

Hours
Design of Members
• Calculation of demand
Design of members for Axial Tension
• Design of prestressing force
• Analysis of ultimate strength
Design of Member for Flexure
• Calculation of moment demand.
• Preliminary design

1
Design of Sections for Flexure (Part I)
• Final design
• Final design for type 1 members
• Special case

1
Design of Sections for Flexure (Part II)
• Final design of type 2 members

1
Design of Sections for Flexure (Part III)
• Choice of sections
• Determination of limiting zone
• Post-tensioning in stages

1
Design of sections for Flexure (Part IV)
• Magnel’s graphical method

1
Detailing Requirements for Flexure
Detailing Requirements for Shear
Detailing Requirements for Torsion

1

Module 5: Analysis and Design for Shear and Torsion (6 Hours)
Topic

Hours
Analysis for Shear
• Introduction
• Stress in an uncracked beam
• Types of cracks
• Components of shear resistance
• Modes of failure
• Effect of prestressing force

1
Design for Shear (Part I)
• Limit state of collapse for shear
• Maximum permissible shear stress
• Design of transverse reinforcement
• Detailing requirement for shear

1
Design for Shear (Part II)
• General comments
• Design steps
• Design of stirrups for flange

1
Analysis for Torsion
• Introduction
• Stresses in an uncracked beam
• Crack pattern under pure torsion
• Components of resistance for pure torsion
• Modes of failure
• Effect of prestressing force

1
Design for Torsion (Part I)
• Limit state of collapse for torsion
• Design of longitudinal reinforcement
• Design of transverse reinforcement

1
Design for Torsion (Part II)
• Detailing requirements
• General comments
• Design steps

1

Module 6: Calculations of Deflection and Crack Width (1 Hour)
Topic

Hours
Calculation of Deflection
• Deflection due to gravity loads
• Deflection due to prestressing force
• Total deflection
• Limits of deflection
• Determination moment of inertia
• Limits of span-to-effective depth ratio
Calculation of Crack Width
• Method of calculation
• Limits of crack width

1

Module 7: Transmission of Prestress (2 Hours)
Topic

Hours
Transmission of Prestress (Part I)
• Introduction
• Pre-tensioned members
Transmission length
Development length
End zone reinforcement

1
Transmission of Prestress (Part II)
• Post-tensioned members
End zone reinforcement
Bearing plate

1

Module 8: Cantilever and Continuous Beams (3 Hours)
Topic

Hours
Cantilever Beams
• Introduction
• Analysis
• Determination of limiting zone
• Cable profile

1
Continuous Beams (Part I)
• Introduction
• Analysis
• Incorporation of moment due to reactions
• Pressure line due to prestressing force

1
Continuous Beams (Part II)
• Concordant cable profile
• Cable profiles
• Partially continuous beams
• Analysis at ultimate limit state
• Moment redistribution

1

Module 9: Special Topics (6 Hours)
Topic

Hours
Composite Sections
• Introduction
• Analysis of composite sections
• Design of composite sections
• Analysis for horizontal shear transfer

1
One-way Slabs
• Introduction
• Analysis and design

1
Two-way Slabs (Part I)
• Introduction
• Analysis
• Features in modeling and analysis
• Distribution of moments to strips

1
Two-way Slabs (Part II)
• Checking for shear capacity
• Spandrel beams
• Anchorage devices
• Additional aspects

1
Compression Members
• Introduction
• Analysis
• Development of interaction diagram
• Effect of prestressing force

1
Circular Prestressing
• Introduction
• General analysis and design
• Prestressed concrete pipes
• Liquid storage tanks
• Ring beams
Conclusion
 
   
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