Course detail

Prestressed concrete

FAST-BL11Acad. year: 2019/2020

Principle of prestressing. Basic concept of pretensioning and post-tensioning. Material properties, manufacturing, types.
Pretensioning operations, technology. Post-tensioning operations, technology, prestressing systems.
Losses of prestressing of pretensioned and post-tensioned concrete, tendon profiles.
Equivalent load method, statically determinate and indeterminate structures, examples. Response of structures subjected to prestressing, simplifications, decompression state.
Resistance of prestressed members against cracks. Tensile stresses in the concrete after cracking. Control of crack width and deflection of prestressed members.
Ultimate limit state of prestressed members, full stress-strain response, shear resistance.

Language of instruction

Czech

Number of ECTS credits

5

Guarantor

prof. RNDr. Ing. Petr Štěpánek, CSc., dr. h. c.

Department

Institute of Concrete and Masonry Structures (BZK)

Learning outcomes of the course unit

A student gains these knowledge and skills:
• Understanding of the behaviour of prestressed concrete structures.
• Design of prestressed concrete structural members and structural systems, analysis and detailing.

Prerequisites

structural mechanics, theory of elasticity, plasticity, design concrete members and concrete structures

Co-requisites

Not applicable.

Planned learning activities and teaching methods

Not applicable.

Assesment methods and criteria linked to learning outcomes

Not applicable.

Course curriculum

1. Introduction, basic concept of prestressing. Behaviour of non-prestressed and prestressed concrete beams. Material properties of concrete.
2. Material properties of prestressing tendons and bars, manufacturing, mechanical properties, types. Prestressing technology, basic terminology. Pretensioned concrete.
3. Post-tensioning operations, technology, prestressing systems.
4. Losses of prestressing. Frictional loss, anchorage set loss.
5. Losses of prestressing due to elastic concrete deformation, relaxation of prestressing reinforcement, creep and shrinkage. Construction and serviceability stages.
6. Effects of prestressing. Equivalent load method, statically determinate and indeterminate structures, concordant tendon, linear transformation of tendon.
7. Design of prestressing - load balanced method. Allowable stresses, allowable zone of prestressed tendon, and line of pressure. Crack resistance.
8. Structural analysis of step-by-step built structures, non-homogeneity of structures. Creep analysis – analytic solution.
9. Ultimate limit state (ULS) of prestressed members loaded by axial force and bending moment, decompression state, initial state of stress. Secondary effects of prestressing at ULS of the structures.
10. Prestressed members loaded in shear and torsion, stress analysis, proportioning.
11. Anchorage zone analysis, calculation model, check of resistance, proportioning.
12. Serviceability limit states (SLS). Crack resistance, tensile stresses in the concrete after cracking.
13. Control of crack width of prestressed members. Control of deflection.

Work placements

Not applicable.

Aims

Understanding of the behaviour of prestressed concrete structures.
Design of prestressed concrete structural members and structural systems, analysis and detailing.

Specification of controlled education, way of implementation and compensation for absences

Extent and forms are specified by guarantor’s regulation updated for every academic year.

Recommended optional programme components

Not applicable.

Prerequisites and corequisites

Not applicable.

Basic literature

LIN, T. Y. a BURNS, Ned. H.: Design of Prestressed Concrete Structures. New York: John Wiley & Sons, 1981. ISBN 0471018988. (EN)
COLLINS, Michael P. a MITCHELL, Denis: Prestressed Concrete Structures. New Jersey: Prentice Hall, Englewood Cliffs, 1991. ISBN 0-13-691635-X. (EN)
NAVRÁTIL, Jaroslav: Prestressed Concrete Structures. Brno: CERM, 2006. ISBN 80-7204-462-1. (EN)
ROMBACH, Günter: Spannbetonbau. Berlin: Ernst und Sohn, 2010. ISBN 978-3-433-02911-4. (DE)

Recommended reading

ZŮDA, Karel: Výpočet staticky neurčitých mostních konstrukcí z předpjatého betonu. Praha: SNTL, 1971. (CS)
VOVES, Bohumír: Navrhování konstrukcí z předpjatého betonu v příkladech. Praha: SNTL, 1980. (CS)
VÁCHA, Jaroslav: Předpjatý beton pro mostní stavby. Brno: VUT, 1984. (CS)
KLUSÁČEK, Ladislav, PANÁČEK, Josef a ŠTĚPÁNEK, Petr: Betonové konstrukce. Předpjatý beton podle ČSN 73 1201. Brno: VUT, 1991. ISBN 80-214-0267-9. (CS)
GERWICK, Ben C.: Construction of Prestressed Concrete Structures. USA: John Wiley and Sons, 1997. ISBN 978-0-471-18113-2. (EN)
NAVRÁTIL, Jaroslav a ZICH, Miloš.: Předpjatý beton (průvodce předmětem v elektronické podobě). Brno: VUT, 2006. (CS)
NAVRÁTIL, Jaroslav: Předpjaté betonové konstrukce. Brno: CERM, 2008. ISBN 978-80-7204-561-7. (CS)

Type of course unit

 

Lecture

26 hours, optionally

Teacher / Lecturer

prof. RNDr. Ing. Petr Štěpánek, CSc., dr. h. c.

Syllabus

1. Introduction, basic concept of prestressing. Behaviour of non-prestressed and prestressed concrete beams. Material properties of concrete. 2. Material properties of prestressing tendons and bars, manufacturing, mechanical properties, types. Prestressing technology, basic terminology. Pretensioned concrete. 3. Post-tensioning operations, technology, prestressing systems. 4. Losses of prestressing. Frictional loss, anchorage set loss. 5. Losses of prestressing due to elastic concrete deformation, relaxation of prestressing reinforcement, creep and shrinkage. Construction and serviceability stages. 6. Effects of prestressing. Equivalent load method, statically determinate and indeterminate structures, concordant tendon, linear transformation of tendon. 7. Design of prestressing - load balanced method. Allowable stresses, allowable zone of prestressed tendon, and line of pressure. Crack resistance. 8. Structural analysis of step-by-step built structures, non-homogeneity of structures. Creep analysis – analytic solution. 9. Ultimate limit state (ULS) of prestressed members loaded by axial force and bending moment, decompression state, initial state of stress. Secondary effects of prestressing at ULS of the structures. 10. Prestressed members loaded in shear and torsion, stress analysis, proportioning. 11. Anchorage zone analysis, calculation model, check of resistance, proportioning. 12. Serviceability limit states (SLS). Crack resistance, tensile stresses in the concrete after cracking. 13. Control of crack width of prestressed members. Control of deflection.

Exercise

26 hours, compulsory

Teacher / Lecturer

prof. RNDr. Ing. Petr Štěpánek, CSc., dr. h. c.

Syllabus

1. Post-tensioned bridge beam - design: Load, design of a cross section, material characteristics, types of anchors, structural principles, design of prestressing force and its eccentricity. 2. Verification of prestressing force design via loads effects compensation method, design of cables and their trajectory. 3. Effects of prestressing on the structures - examples.¨ 4. Post-tensioned bridge beam - design (continuation): Effects of load, initial (anchoring) stress, immediate changes of prestressing. 5. Simplified calculation of time-dependent changes of prestressing. Time behaviour of prestressing force magnitude. 6. Correction. 7. Serviceability limit states – limit state of stress and cracks limitation (decompression). 8. Ultimate limit state – bending moment. 9. Ultimate limit state - shear, design of shearing reinforcement. 10. Verification of anchors, design of reinforcement in the anchoring area, drawing of active and passive reinforcement. 11. Serviceability limit states – deflection of a beam. Correction. 12. Effects of prestressing on the structures (continution): Effect of prestressing on the structures progressively erected - examples. 13. Design submission. Credit.