STRUCTURAL RETROFITTING OF CONCRETE BEAMS USING FRP - Debonding Issues
Författare
Summary, in Swedish
Popular Abstract in English
Concrete is one of our most common building materials and is used both for buildings,
bridges and other heavy structures. Typically, concrete structures are very durable, but
sometimes they need to be strengthened. The reason may be cracking due to environmental
effects, that a bridge is to be used for heavier traffic, new building codes, or damage resulting
from earthquakes.
Concrete is a material that can withstand compressive loads very well but is sensitive to
tensile forces. Therefore, concrete structures are typically reinforced by casting in steel bars in
areas where tension can arise. This cannot be done afterwards, and one strengthening method,
is therefore to glue reinforcement on the exterior of the structure in the areas exposed to
tension.
Fibre composite can be used in reinforcing concrete structures externally. Fibre composite
materials have low density, can be easily installed and are easy to cut to length on site.
Therefore, fibre composite as external reinforcement for concrete structures has become very
attractive and popular around the world.
It is important to understand the behaviour of a strengthened structure well and realize
what parameters affect the failure mode and load-bearing capacity. The aim of this thesis is
therefore to investigate and improve the understanding of the behaviour of reinforced concrete
beams strengthened with fibre composite.
These structures have a critical problem implying that they may fail in a sudden manner.
This failure involves separation between composite and concrete. Special attention is paid to
this phenomenon, which is called debonding.
One scope of this study was to develop computer modelling framework. Therefore, three
dimensional computations were conducted considering the nonlinear behaviour of the
materials. A new model for the concrete-fibre composite interface was included.
The computations were verified against experiments. The results confirmed the ability of
the computations to recreate the load-deflection behaviour, the crack distribution, and the
failure modes. Simulations and experiments showed that application of fibre composite can
increase the load capacity and the stiffness of the beams.
The influence of several parameters such as length and width of fibre composite and
properties of adhesive were investigated. Large width and length of fibre composite and soft
adhesive would yield to reduce tendency of debonding and increase thus of the utilization of
fibre composite and increase load capacity.
The findings from this study yield a proposal for a modification of design code rules.
Concrete is one of our most common building materials and is used both for buildings,
bridges and other heavy structures. Typically, concrete structures are very durable, but
sometimes they need to be strengthened. The reason may be cracking due to environmental
effects, that a bridge is to be used for heavier traffic, new building codes, or damage resulting
from earthquakes.
Concrete is a material that can withstand compressive loads very well but is sensitive to
tensile forces. Therefore, concrete structures are typically reinforced by casting in steel bars in
areas where tension can arise. This cannot be done afterwards, and one strengthening method,
is therefore to glue reinforcement on the exterior of the structure in the areas exposed to
tension.
Fibre composite can be used in reinforcing concrete structures externally. Fibre composite
materials have low density, can be easily installed and are easy to cut to length on site.
Therefore, fibre composite as external reinforcement for concrete structures has become very
attractive and popular around the world.
It is important to understand the behaviour of a strengthened structure well and realize
what parameters affect the failure mode and load-bearing capacity. The aim of this thesis is
therefore to investigate and improve the understanding of the behaviour of reinforced concrete
beams strengthened with fibre composite.
These structures have a critical problem implying that they may fail in a sudden manner.
This failure involves separation between composite and concrete. Special attention is paid to
this phenomenon, which is called debonding.
One scope of this study was to develop computer modelling framework. Therefore, three
dimensional computations were conducted considering the nonlinear behaviour of the
materials. A new model for the concrete-fibre composite interface was included.
The computations were verified against experiments. The results confirmed the ability of
the computations to recreate the load-deflection behaviour, the crack distribution, and the
failure modes. Simulations and experiments showed that application of fibre composite can
increase the load capacity and the stiffness of the beams.
The influence of several parameters such as length and width of fibre composite and
properties of adhesive were investigated. Large width and length of fibre composite and soft
adhesive would yield to reduce tendency of debonding and increase thus of the utilization of
fibre composite and increase load capacity.
The findings from this study yield a proposal for a modification of design code rules.
Avdelning/ar
Publiceringsår
2011-11
Språk
Engelska
Publikation/Tidskrift/Serie
TVSM-1000
Issue
TVSM-1023
Fulltext
Dokumenttyp
Doktorsavhandling
Förlag
Department of Construction Sciences, Lund University
Ämne
- Mechanical Engineering
Status
Published
Handledare
ISBN/ISSN/Övrigt
- ISSN: 0281-6679
- ISBN: 978-91-7473-194-1
Försvarsdatum
6 december 2011
Försvarstid
10:15
Försvarsplats
Lecture hall V:C, V-building, John Ericssons väg 1, Lund University Faculty of Engineering
Opponent
- Björn Täljsten (Prof.)