Post-Tensioning in Building Construction

Cover
Half Title
Title Page
Copyright Page
Table of Contents
About this book
About the author
Chapter 1 Post-tensioning in buildings
1.1 Prestressing
1.1.1 Prestressing: concept and development
1.1.2 Pre-tensioning and post-tensioning
1.1.2.1 Pre-tensioning
1.1.2.2 Post-tensioning
1.2 Growth of post-tensioning in building construction
1.2.1 Early developments
1.2.2 Extended development
1.2.2.1 Hardware
1.3 Bonded post-tensioning system
1.4 Structural performance of bonded and unbonded post-tensioning systems
1.4.1 Response to member deformation
1.4.2 Distribution of precompression
1.4.3 Response to support restraint
1.5 Building code requirements
1.6 Design concepts
1.6.1 Load balancing
1.6.2 Adoption of strip method to post-tensioning
1.6.3 Adoption of single ‘representative’ stress for design
1.7 Software application
1.7.1 Strip method
1.7.2 Single level finite element technology
1.7.3 Multi-level and building information modeling (BIM)-based modeling and design
Notes
References
Chapter 2 Application of post-tensioning in building construction
2.1 Introduction of post-tensioning in building construction
2.2 Column-supported floors
2.2.1 Flat slab construction
2.2.2 Podium slabs
2.3 Beam and slab construction
2.4 Ground-supported construction
2.4.1 Mat foundation
2.4.2 Slabs on expansive soil
2.4.3 Industrial floors
2.5 Transfer floors
2.6 Repair and retrofit
2.7 Application in high-risk seismic zones
2.7.1 Flat slab construction
2.7.2 Correction of seismic deformation
2.8 Redistribution of reactions
2.9 Special application of post-tensioning
2.10 Walls and frames
References
Chapter 3 Basics of post-tensioning design
3.1 Prestressing steel
3.2 Post-tensioning design requirements
3.3 Post-tensioning design method options
3.4 Straight method
3.5 Load balancing method
3.5.1 Simple load balancing
3.5.2 Extended load balancing
3.5.3 Load balancing summary
3.6 Comprehensive method
3.7 Application of the methods
Notes
References
Chapter 4 Building codes for post-tensioning design
4.1 Major building codes
4.2 Basic code considerations
4.2.1 Design steps
4.2.2 Load path
4.2.3 Analysis schemes
4.3 Additional design requirements
4.3.1 Deflection control
4.3.2 Crack control
4.3.3 Member ductility
4.4 EC2 specific code provisions
4.4.1 Minimum reinforcement
4.4.2 Maximum reinforcement
4.5 ACI 318 specific code provisions
4.5.1 Minimum precompression
4.5.2 Arrangement of prestressing tendons
4.5.3 Transfer of column moment to slab
4.5.4 Minimum bar length
4.6 Notable differences between EC2 and ACI 318
4.6.1 Strength and material factors
4.6.2 Contribution of prestressing to member strength
4.6.3 Punching shear
4.6.4 Application of cracking moment
4.7 European code for design of post-tensioned members
4.7.1 EC2 code compliance basics
4.7.2 Stress threshold
4.7.2.1 Hypothetical extreme fiber stress
4.7.2.2 Design crack width
4.7.3 Load combinations
4.7.4 Serviceability design thresholds; design limits
4.7.5 Serviceability design flow charts
4.7.6 Strength design
4.7.6.1 Load combination
4.7.6.2 Cracking moment and flexural strength
4.7.6.3 Punching hear
4.7.6.4 Detailing
4.8 ACI 318 provisions for post-tensioned floors
4.8.1 Floor slab categorization and geometry
4.8.2 Define loads
4.8.3 Validate sizing and material properties
4.8.3.1 Punching shear check
4.8.4 Check for live load deflection
4.8.5 Subdivide the slab into design strips
4.8.6 Select post-tensioning and arrange tendons
4.8.7 Check for average precompression
4.8.8 Analyze structure; obtain design values
4.8.8.1 Analysis of structure
4.8.8.2 Extraction of design values
4.8.9 Serviceability check (serviceability limit state – SLS)
4.8.9.1 Deflection control
4.8.9.2 Load combinations
4.8.9.3 Stress checks
4.8.9.4 Minimum non-prestressed reinforcement
4.8.10 Safety check (ultimate limit state – ULS)
4.8.10.1 Load combinations for strength
4.8.10.2 Strength calculation
4.8.11 Punching shear
4.8.12 Initial condition; transfer of prestressing
4.8.12.1 Load combination
4.8.12.2 Allowable stresses51
4.8.13 Detailing
4.8.13.1 Tendon arrangement
4.8.13.2 Rebar arrangement
Notes
References
Chapter 5 Column-supported floor example
5.1 Column-supported floor
5.2 Geometry; load path; design strip
5.2.1 Structure
5.2.2 Design strip
5.2.3 Design strip section properties
5.3 Material properties
5.3.1 Concrete
5.3.2 Prestressing
5.3.3 Non-prestressed reinforcement
5.4 Loads
5.4.1 Self-weight
5.4.2 Superimposed dead load
5.4.3 Dead load
5.4.4 Live load
5.5 Design parameters
5.5.1 Applicable codes
5.5.2 Cover to reinforcement
5.5.3 Post-tensioning system; effective stress
5.5.4 Allowable design stress; crack control
5.5.4.1 EC2 crack control
5.5.4.2 ACI 318 crack control
5.5.5 Fraction of dead load to balance; minimum precompression
5.5.6 Tendon selection and layout
5.6 Summary of service loads
5.7 Analysis
5.8 Actions from dead loads
5.9 Actions from live loads
5.10 Actions from prestressing forces
5.11 Serviceability check; serviceability limit state (SLS)
5.11.1 EC2 serviceability check
5.11.1.1 Stress thresholds
5.11.1.2 Minimum and maximum reinforcement
5.11.1.3 Check hypothetical extreme fiber stresses for frequent load combination
5.11.1.4 Check hypothetical extreme fiber compression stresses for quasi-permanent load combination
5.11.1.5 Deflection check
5.11.1.6 Crack control
5.11.2 ACI serviceability check
5.11.2.1 Deflection check
5.11.2.2 ACI stress check
5.11.2.3 ACI minimum rebar
5.12 Safety check; ultimate limit state (ULS)
5.12.1 Strength design versus capacity check
5.12.2 Calculate hyperstatic moments
5.12.3 Strength check (ULS)
5.12.3.1 EC2 strength check
5.12.3.2 ACI strength check
5.12.4 Cracking moment safety check
5.12.4.1 EC2 cracking moment check
5.12.4.2 ACI cracking moment check
5.13 Punching shear check
5.13.1 Based on EC
5.13.2 Based on ACI51
5.14 Initial condition; transfer of prestressing
5.14.1 Load combination
5.14.2 EC2 stress check
5.14.3 ACI stress check
5.15 Detailing
5.15.1 EC2 detailing
5.15.2 ACI detailing
5.16 Trim bars
Notes
References
Chapter 6 Design of a post-tensioned beam frame
6.1 Geometry and structural system
6.1.1 Effective flange width
6.1.2 Section properties
6.2 Material properties
6.2.1 Concrete
6.2.2 Non-prestressed reinforcement
6.2.3 Prestressing
6.2.4 Cover to reinforcement
6.3 Loads
6.3.1 Dead load
6.3.2 Live load
6.4 Design parameters
6.4.1 Applicable code
6.4.2 Allowable stresses
6.4.3 Cracking limitation
6.4.4 Allowable deflection
6.5 Actions from dead and live loads
6.6 Post-tensioning
6.6.1 Selection of post-tensioning tendon force and profile
6.6.2 Post-tensioning actions
6.7 Code check for serviceability limit state (SLS)
6.7.1 Deflection check
6.7.2 Stress check/crack control
6.8 Code check for strength (ULS)
6.8.1 EC2 load combination
6.8.2 Calculation of hyperstatic actions
6.8.3 Calculation of design moments
6.8.4 Strength design for bending and ductility
6.8.5 One-way shear design
Notes
References
Chapter 7 Member shortening; precompression: member strength
7.1 Post-tensioning; shortening; precompression
7.2 Relationship between shortening and precompression
7.3 Precompression and member strength
7.3.1 No support restraint
7.3.2 Finite support restraint
7.3.3 Full support restraint
7.4 Example
7.5 Precompression in multi-story buildings
7.5.1 Inter-story redistribution of precompression
7.5.2 Impact of stiff walls at interior of floor slab
7.6 Long-term shortening
Notes
References
Chapter 8 Stress losses in post-tensioning
8.1 Stress losses
8.2 Immediate losses
8.2.1 Friction
8.2.2 Elongation
8.2.3 Seating (draw-in) losses
8.3 Long-term stress losses
8.3.1 Elastic shortening of concrete (ES)
8.3.2 Creep of concrete (CR)
8.3.3 Shrinkage of concrete (SH)
8.3.4 Relaxation of prestressing steel (RE)
8.4 Examples
8.4.1 Friction loss calculation
GIVEN
REQUIRED
8.4.2 Long-term loss calculation of member with unbonded tendons
GIVEN
REQUIRED
8.4.3 Long-term loss calculation of member reinforced with bonded tendons
GIVEN
REQUIRED
Note
References
Chapter 9 Tendon layout and detailing
9.1 Distinguishing features in detailing PT and RC slabs
9.1.1 Crack control and disposition of tendons
9.1.2 Development of floor strength
9.2 Tendon arrangement
9.2.1 Tests on tendon arrangements
9.2.2 Tendon arrangements in practice
9.2.2.1 Banded-distributed layout
9.2.2.2 Distributed-distributed layout
9.2.2.3 Banded-banded layout
9.2.2.4 Irregular tendon layout
9.3 Tendon profile
9.3.1 Common conditions
9.3.2 Tendon at discontinuities
9.4 Non-prestressed reinforcement
9.4.1 Trim bars
9.4.2 Trim bar details
Other conditions
References
Chapter 10 Post-tensioning construction in buildings
10.1 Post-tensioning in building construction
10.2 System components
10.3 Prestressing steel and strand
10.4 Prestressing systems
10.4.1 Bonded system
10.4.2 Unbonded system
10.5 Construction
10.5.1 Quantities
10.5.2 Construction cost
10.5.3 Local practice
10.5.4 Construction sequence and cycle
10.6 Stressing operation
10.6.1 Time of stressing
10.6.2 Stressing equipment
10.6.3 Elongation measurement
10.6.4 Evaluation of elongation
10.6.5 Removal of shoring; propping
10.7 Grouting
10.8 Finishing the stressing recess
10.9 Maintenance
References and Acknowledgment
Note
Index