Course detail

Prestressed concrete

FAST-CL01Acad. year: 2012/2013

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

Mode of study

Not applicable.

Department

Institute of Concrete and Masonry Structures (BZK)

Learning outcomes of the course unit

Understanding of the behavior of prestressed concrete structures.
Knowledge of calculation of effect of prestressing on statically determinate structures and statically indeterminate structures.
Knowledge of pre-tensioning technology and post-tensioning technology.
Design and construction of prestressed concrete structural members and structural systems, analysis and detailing:
- design of tendon trajectory and magnitude of prestressing force (methods of design)
- calculation of losses
- assessment by ultimate limit state and serviceability limit state.

Prerequisites

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

Co-requisites

do not required

Planned learning activities and teaching methods

Teaching methods depend on the type of course unit as specified in the article 7 of BUT Rules for Studies and Examinations. Education runs in the forms of lectures and trainings. Character of the lectures is based on definition of basic principles, problems and methodology. In the trainings the main subject matters are trained on individually defined projects (examples).

Assesment methods and criteria linked to learning outcomes

To gain the credit, the students should elaborate individually defined design and calculate specified task. The students are obliged to consult the design continuously in the given terms and submit it to the fixed date. The presences in training lessons are checked. An exam consists both of the written part, in which the task is elaborated, and the theoretical part. To pass the exam successfully, both parts should be accomplished.

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

COLLINS, Michael P. a MITCHELL, Denis: Prestressed Concrete Structures. New Jersey: Prentice Hall, 1991. ISBN 0-13-691635-X. (EN)
LIN, T. Y. a BURNS, Ned H.: Design of Prestressed Concrete Structures. New York: John Wiley & Sons, 1981. ISBN 0471018988. (EN)
ROMBACH, Günter: Spannbetonbau. Berlin: Ernst und Sohn, 2010. ISBN 978-3-433-02911-4. (DE)
VOVES, Bohumír: Navrhování konstrukcí z předpjatého betonu v příkladech. Praha: SNTL, 1980. (CS)

Recommended reading

GERWICK, Ben C.: Construction of Prestressed Concrete Structures. USA: John Wiley and Sons, 1997. ISBN 978-0-471-18113-2. (EN)
KLUSÁČEK, Ladislav, PANÁČEK, Josef a ŠTĚPÁNEK, Petr: Betonové konstrukce. Předpjatý beton podle ČSN 73 1201. Brno: VUT, 1991. ISBN 80-214-0267-9. (CS)
NAVRÁTIL, Jaroslav a ŠTĚPÁNEK, Petr: Předpjaté stavební konstrukce. Modul M01 (část studijní opory v elektronické podobě). Brno: VUT, 2009. (CS)
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)
PROCHÁZKA, Jaroslav a kol.: Navrhování betonových konstrukcí podle norem ČSN EN 1992 (EUROKÓDU 2). Část 2: Předpjatý beton. Praha: ČBS Servis, 2010. ISBN 978-80-87158-21-0. (CS)

Classification of course in study plans

  • Programme N-K-C-SI Master's

    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory

  • Programme N-P-C-SI Master's

    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory

  • Programme N-P-E-SI Master's

    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory
    branch S , 1 year of study, winter semester, compulsory

Type of course unit

 

Lecture

26 hod., optionally

Teacher / Lecturer

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

13 hod., compulsory

Teacher / Lecturer

Syllabus

1. Effect of prestressing on statically determinate structures. Students are to solved tasks individually.
2. Effect of prestressing on statically indeterminate structures. Students are to solved tasks individually.
3.- 4. Project: Design and assessment of prestressed roof girder. Action and combination of loads, design of cross-section, characteristics of materials, types of prestressing steels, structural requirements.
5.– 6. Continuation of project. Design of eccentricity and magnitude of prestressing force, design of amount of prestressed strands.
7. Continuation of project. Immediate (short-term) losses of prestress.
8. Continuation of project. Long-term (time dependent) losses of prestress.
9.– 10. Continuation of project. Verification of design by serviceability limit state – stress limitation, crack control.
11. Continuation of project. Verification of design by ultimate limit state – bending moment.
12. Continuation of project. Scheme of girder reinforcement by prestressing strands.
13. Project and tasks submission. Credit.