ACI member Manfred Curbach has been Professor at the Institute of Concrete ..... Stahlbetonbau 99 (2004) 6, S. 437â443 « only available in German ». 13 ...
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STRENGTHENING OF RC-STRUCTURES WITH TEXTILE
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REINFORCED CONCRETE (TRC)
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Silvio Weiland, Regine Ortlepp, Anett Brückner and Manfred Curbach
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Biography: Silvio Weiland, Regine Ortlepp and Anett Brückner are research associates at
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the Institute of Concrete Structures, Dresden University of Technology, Germany. They
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received their civil engineering degree from the University of Dresden.
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ACI member Manfred Curbach has been Professor at the Institute of Concrete Structures,
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Dresden University of Technology, Germany since 1994. Born in 1956 he received his civil
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engineering degree from the University of Dortmund, Germany. His research interests
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include strengthening of reinforced concrete structures with TRC as well as concrete under
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multiaxial states of stress.
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ABSTRACT
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Strengthening by textile reinforced concrete noticeably increases both the ultimate load
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bearing capacity as well as the serviceability – especially deflections, crack widths and crack
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spacing are reduced. Beside that there are still some practical applications. This paper will
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give an overview of the ongoing research work with this new composite material Textile
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Reinforced Concrete (TRC).
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Keywords: textile reinforced concrete (TRC); reinforced concrete; strengthening;
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retrofitting; TRC application, fiber
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INTRODUCTION
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Fibers are used more and more as reinforcement in concrete. Especially short fibers have
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been used for many decades. Textile fabrics used as reinforcing material is a relatively new
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application for concrete construction. These textiles consist of continuous high performance
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fiber bundles, which are processed to create flat structures. Glass fibers, aramid fibers and
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carbon fibers are examples of feasible fiber materials. If these flat structures are used as
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reinforcement in concrete, the material is called “Textile Reinforced Concrete” (TRC).
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Plane textile structures for TRC are made out of yarns or rovings using a textile technique.
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This enables an optimal alignment and arrangement of fibers in structural members (Fig. 1).
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It results in a higher load bearing capacity compared to (Short) Fiber Reinforced Concrete
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(FRC) at equal fiber content or a smaller amount of still expensive high performance fibers
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for equal load capacity respectively. With Textile Reinforced Concrete not only new
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extremely thin concrete parts with a high load capacity can be produced but also existing
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structures can be strengthened.
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More information about used materials, sample applications and possible production methods
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can be found elsewhere [1], [4]-[9]. The load bearing behavior of this composite is very
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similar to Reinforced Concrete (RC) but it is formed clearly through the bond properties
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between textile reinforcement and the cement matrix. Cracking behavior, load capacity,
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deformation behavior and durability are investigated systematically along with the material
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behavior. Dimensioning concepts and models have to be developed on this basis. This paper
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will give an overview of the ongoing research work with this new composite material.
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TEXTILE REINFORCED CONCRETE
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Textile reinforced concrete is a relatively new and sophisticated composite material. It
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generally comprises a cementitious matrix and alkali-resistant (AR) glass fiber reinforcement,
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although the reinforcement may also consist of any other fiber material, e.g. carbon fibers. In
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contrast to steel bar reinforcement, the single AR glass or carbon fibers in the textile can be
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positioned in almost any direction and subsequently nearly perfectly adopted to the
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orientation of the applied load. An extremely effective reinforcement is therefore possible.
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The textile reinforcement is built in as a multiaxial fabric. Up to four different orientations of
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the fibers are possible in the same multiaxial fabric. High strength fine grained concrete with
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a maximum aggregate size of 4 mm (0.1575 in.) is used as a matrix.
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Due to the very small diameter of the reinforcement, it is possible to get new, very thin
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concrete elements as applications for the new material. The diameter of the rovings in the
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textile reinforcement is usually one or two dimensions lower than the necessary diameter of
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steel bar reinforcement. In addition no minimum thickness of concrete cover is now needed
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to prevent corrosion of the reinforcement, because the fibers do not rust like steel. Both of
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these advantages allow the development of concrete elements with a thickness of only 10 to
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20 mm (0.3937 to 0.7874 in.). Lower thickness may not only be helpful for new concrete
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elements, but also makes the lightweight strengthening of already existing concrete structures
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possible. Strengthening with textile reinforced concrete noticeably increases both the ultimate
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load carrying behavior, as well as the serviceability.
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Characteristic Material Behavior
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The typical load-deformation behavior of textile reinforced concrete under uniaxial tension
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according to figure 2 is primarily equivalent to RC except for state III, because the materials
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used did not have any plastic capacity.
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As long as the strain in the matrix is below its failure strain the composite behaves with
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approximately the stiffness of the matrix (state I). Theoretically the simple law of mixture
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leads to an increase of stiffness because of the higher modulus of elasticity of the build in
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fibers. Practical experience shows that this effect could be neglected. It has been shown that
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the presence of transverse fibers has a higher impact on the material stiffness. This is due to
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the fact that the yarns are not able to carry any load in transversal direction so they behave
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like a pore with infinite length transversal to the applied stress.
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When passing the tension failure strain of the matrix (first cracking takes place) the material
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changes into state II. In the crack all load is transferred through the fabric reinforcement.
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Further cracks are formed (state IIa) with an increased load, if additional stress is transferred
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into the concrete by the bond between fabrics and concrete and if the tension failure strain of
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the matrix is passed again. The stress-strain curve shows a very low incline during the
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multiple cracking process.
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If cracking has finished (state IIb), no further cracks appear and fabrics are stressed at an
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increasing load until their tensile strength is reached. In this section the stress strain curve of
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the composite runs along a parallel line to the stress strain curve of the reinforcement. This is
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due to the tension stiffening effect.
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Any plastic deformation (state III), as known from RC, could not be observed with textile
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reinforced concrete be-cause the materials used for reinforcement (AR-glass, carbon) did not
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have plastic capacity. The quasi-ductile behavior is based on matrix cracking and a sufficient
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high breaking strain of the reinforcement.
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Following some previous publications [1]-[5], unlike steel bar reinforcement the tensile
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strength of fabric reinforcement could not be fully utilized in the composites. Reasons for
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this include: damage of fiber materials caused by fabric fabrication process, bond properties
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of fiber bundles in concrete, alignment of reinforcement and surface condition of fibers. Thus
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– deviating from RC – the bond behavior of the rovings has a significant influence on the
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failure modes of a member. Since rovings did not form a homogenous cross section, a direct
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analogy to bond behavior of steel bar reinforcement is not possible.
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STRENGTHENING OF RC-MEMBERS WITH TRC
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In recent years, the need of strengthening and retrofitting of existing structures has been
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increased significantly. During the day-to-day use of buildings, many issues can arise which
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may lead to the requirement of a strengthening of RC-members. Examples are structural
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damage or an increase of live loads. Enhancement of load carrying capacity can be achieved
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by different methods. Near the classic and established procedures for strengthening (shotcrete,
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FRP etc.) the use of textile-reinforced concrete could be another sophisticated alternative.
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Advantageous properties of the CFRP-plates are among other things high tensile strength,
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low weight, easy handling and high corrosion resistance. Disadvantageous are high costs,
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diffusion-tightness, low ductility, no fire resistance, sensitivity against UV-radiation as well
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as lateral pressure and humidity. A repassivation of the uncovered steel reinforcement caused
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by damages is only possible when additional arrangements were made.
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In order to provide a new corrosion protection for the existing reinforcement a rehabilitation
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method is suitable, which is based on a cementitious matrix. The advantages are the
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repassivation of existing reinforcement influenced by the basic milieu of the new shotcrete
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and the insensitivity towards soaking and UV-radiation. Several disadvantages occur when
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traditional steel reinforcement for shotcrete is used. Those are for instance the costly
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production and installation of the strengthening, significantly enlarged measurements of the
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total cross-section, in consequence of the concrete covering which is needed and because of
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the high dead weight of the additional layer.
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When using a TRC-layer, which is applied by spraying or laminating, we combine the
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advantages of strengthening by CFRP/GFRP-plates and shotcrete-strengthening with steel
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reinforcement to a progressive rehabilitation method. The advantages of TRC result from the
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combination of both materials, a combination of the textile reinforcement and the concrete,
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which then makes a composite material that has as main qualities high tensile strength, low
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layer thickness, low weight, high corrosion resistance and corrosion protection for the layer
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of older concrete reinforcement which lies beneath it.
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This TRC-strengthening is suitable for nearly every acting force. It is possible to strengthen
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for bending, shear, torsion or axial forces. In all cases following criteria must be considered:
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the load carrying capacity,
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the criterion of the minimum reinforcement,
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the necessary anchorage of the textile reinforced concrete layer.
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A very complex composite material (Fig. 3) appears from strengthening of reinforced
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concrete with TRC. Before the strengthening layer can be applied, the old RC-member has to
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be prepared by sandblasting. Any fine grains on the surface have to be removed, so that
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sufficient bond can be formed between the old concrete and the strengthening layer. Then the
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textile reinforced concrete strengthening is applied in layers; alternate layers of fine grained
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concrete and the textile reinforcement are applied to the RC-members.
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BONDING BEHAVIOUR OF STRENGTHENING LAYER
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Load Transfer into the Strengthening Layer
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When an old RC-member is strengthened with TRC, then the additional tension force in the
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strengthening layer has to be transferred back to the old concrete at the end of strengthening.
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This could be problematic, when a subsequently applied flexural strengthening layer of slabs,
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which are installed in the structure, ends in front of the supports (Fig. 4, top). Also in the case
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of a shear strengthening of T-beams, the strengthening layer does not reach the compression
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zone (Fig. 4, right).
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The questions regarding force transfer mechanisms between the textile-reinforced
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strengthening layer and the old concrete are investigated using separate bond test specimens.
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The aim of these bond tests is to describe the relationship between shear loading and
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deformation, as well as the necessary bond length and the transferable bond forces. Bond
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models for adhesive bonded steel plates or CFRP-strips can be found e.g. [11], [12].
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Strengthening layers made from TRC show, as opposed to steel plates and CFRP-strips, a
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pronounced non-linear behavior of the material due to crack formation already in the
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serviceability limit state [11]. Furthermore, there is strong interlocking between the old
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concrete and the strengthening layer as a result of the sandblasted surface of the old concrete
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and the direct laminating. Thus, bond failure can only occur in two different layers: firstly in
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the old concrete and secondly in the textile layer.
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Bond Strength
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In order to transfer the tensile force from the strengthening layer to the old concrete via the
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bond joint, a definite bond length is required, which depends on certain variables, for
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example the properties of the textile reinforcement. If the available bond length is shorter
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than the necessary bond length, only a part of the ultimate strength of the strengthening layer
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can be anchored to the old concrete of an RC-member. In this case, the specimen fails due to
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bond failure in the test.
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Figure 5 shows the ultimate bond forces per slab width and the associated bond length of
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strengthening layers. These are reinforced with the same textile as is used for the
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strengthening of slabs. If the bond stress that has to be transferred becomes higher than the
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load carrying capacity of the old concrete of the RC-member, the bond will fail in the old
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concrete. If the bond stress, reaches the load carrying capacity of the fine grained concrete in
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the textile layer before it reaches the load carrying capacity of the old concrete, a bond failure
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will occur through a delamination of the textile layer. To use the strengthening to full
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capacity, the bond properties should be optimized in such a way, that the weak point of the
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construction is not situated in the newly applied strengthening layer, but in the old
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construction. This can be achieved through the enlargement of the inner width of the textile
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fabric.
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The necessary bond length, which is able to anchor the ultimate tensile force of the
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strengthening layer and corresponds to the maximum bond stress, can be determined for each
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textile in bond tests which are carried out at the University of Dresden [13]-[15]. According
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to the test results, this means, that if the bond length is longer than a definite bond length,
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then the strengthening layer fails because it reaches its ultimate tensile load before bond
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failure can occur. The load carrying capacity of the strengthening layer can therefore be fully
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utilized, with the use of a sufficient bond length, for all textiles which have been tested.
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Comparable research, carried out with adhesive bonded CFRP laminates, gave only a
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utilization rate of approx. 10 to 25 % at the anchoring region and with steel plates max. 50 %
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respectively [16]. This shows the potential of the new material textile reinforced concrete for
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utilization.
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A bond length of approx. 50 to 60 mm (1.9685 to 2.3622 in.) is necessary for anchoring the
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maximum tensile force at a reinforcing ratio of six textile layers in the strengthening layer
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(Fig. 5). If the strengthening contains only four textile layers, a bond length of less than
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40 mm (1.5748 in.) is sufficient, because the ultimate tensile force of the strengthening layer
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is lower. Thus, an exact bond length exists for every number of textile layers at which the
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ultimate uniaxial tensile load of the strengthening layer can be anchored to the old concrete of
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the RC-member. This bond length can be taken from the diagram in figure 5. The small crack
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spacing in the flexural strengthened RC-slabs and shear strengthened RC-beams ensure that
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no bond failure can occur because of the relatively short bond length.
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FLEXURAL STRENGTHENING
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Experimental Investigation
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The properties of textile reinforcement for flexural strengthening were investigated with slabs
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with a thickness of 100 mm (3.937 in.) and an effective span of 1.60 m (1.750 yd). Each slab
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had a percentage of 0.2 %, 0.34 % or 0.5 % steel reinforcement. During the tests different
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parameters – the number of textile layers, the kind of anchoring and the percentage of steel
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reinforcement, AR-glass and carbon textiles – were varied.
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The kind of anchoring can be divided in slabs with a strengthening layer extending beyond
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the support line and slabs with a strengthening layer ending in front of the support. The
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advantage of the former is the sufficient anchoring of the textile layers outside the tensile
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zone of the slabs. In this case the tested load carrying capacity of the strengthened slabs is
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determined by the tensile strength of the TRC strengthening layer.
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In existing buildings the support area of the RC-member cannot be reached. The anchoring
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has to end in front of the support area as in the second variety of test. In this case the load
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carrying capacity will be lower, as the bond length is too short for anchoring.
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The ultimate load carrying capacity of the slabs has been tested in 4 point-bending tests. This
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test set-up was chosen in order to avoid shear forces simultaneously occurring together with
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bending moments in mid-span. The results were compared with non-strengthened reference
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slabs.
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The crack pattern in the tension zone of the slabs was documented after the test. Water with
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ink was distributed on the bottom of the slabs. If the surface was varnished before the test
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was started, only the cracks would be colored.
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Experimental results of flexural strengthening
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The load-displacement-diagram (Fig. 6) shows the typical behavior of reinforced concrete in
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states I (non-cracked), II (multiple cracking) and III (yielding of steel reinforcement) for all
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slabs. But the rises of the curves are diverse. In comparison to the non-strengthened slabs, the
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load-displacement-curve of the strengthened slab rises much more sharply. The reason for
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this is the larger moment of inertia due to the additionally applied strengthening layer in the
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original non-cracked state. After the occurrence of multiple cracking, the steeper rise of the
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curve is caused by the load carrying properties of the TRC-layer.
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The textile reinforcement improves both the load carrying capacity and also the properties of
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serviceability. The displacement of the strengthened slabs, related to the service load, is
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smaller than the displacement shown by the reference slab. This is caused by the fine crack
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pattern.
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Developing a safety concept, the deformability, i.e. the ductility of the textile strengthened
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slabs at the ultimate limit state, is very important. Due to the difference in deformation, it is
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necessary to differentiate between brittle and ductile failure modes when partial safety factors
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have to be defined. The measure of the ductility is the plastic rotation capacity.
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The measured angle of rotation is compared with the recommendations of the CEB [17] and
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the Eurocode 2 in figure 7. The rotation capacity of all slabs is higher than the specified limit
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values, i.e. the slabs with textile strengthening have sufficient ductility.
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SHEAR STRENGTHENING Experimental Investigation
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The shear strengthening with textile reinforced concrete was tested with both rectangular
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beams and T-shaped beams (Fig. 8). Both RC-members have special properties for the
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strengthening. The experimental investigation for the rectangular beams can be found in [5],
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[8] and [18].
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The shear strengthening with textile reinforced concrete was also tested on T-beams with a
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span of 2 m (2.187 yd) in 3-point-bending tests. For the strengthening of the T-beam, the
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textile reinforcement was wrapped around the web down to the bottom line of the connected
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slabs. A direct anchoring of the strengthening layer inside the compression zone of the T-
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beam is impossible. Thus, the tensile forces have to be transferred from the textile
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reinforcement to the web of the T-beam by the adhesive tensile bond (Figure 9 a) or by a
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mechanical anchoring of the strengthening layer (Figure 9 b).
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The second parameter (besides mechanical anchoring) which was varied during the tests was
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the number of textile layers. A multiaxial fabric with an inclination of the AR-glass fibers in
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the main load direction of the fabric of ±45 degrees is used as textile reinforcement.
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Test Results for Shear Strengthening
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The shear loading capacity of the T-beams can be increased with the help of TRC. The
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strengthened specimen fails at a significantly higher ultimate load than the unstrengthened
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specimen. The efficiency of the textile reinforcement depends on the anchoring of the
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strengthening layer, which is located outside of the compression zone, due to the connecting
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slabs. The maximum transferable load within the anchoring length is limited by the adhesive
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tensile bond between the strengthening layer and the web. An additional increase of the
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loading capacity demands a mechanical anchoring of the strengthening layer.
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The difference between the strengthening with and without a mechanical anchoring may be
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seen in the diagram in figure 10. At the beginning of the loading the displacements of the
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strengthened T-beams with four textile layers are similar for both kinds of anchoring. When
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the strengthening layer starts to peel off the web side of the T-beam, the load-displacement-
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curves do diverge from each other.
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COLUMN STRENGTHENING
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In order to prevent the whole structural member from buckling, the investigation will be done
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by means of short columns. Therefore, the share of the load bearing of the core cross-section
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and the strengthening layer has to be determined.
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The arrangement of the experiment which was done with a cylinder with a diameter of 100
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mm (3.937 in.) and 300 mm (11.811 in.) in height is shown in figure 11. The strengthening
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consisting of 2 or 4 layers of glass or carbon textile is applied additionally by wrapping the
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textile reinforcement – which is embedded in a fine concrete matrix – around specimen body.
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The testing of the cylinders with various reinforcement contents proved that there is an
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increase of the loading up to 32 % compared with unstrengthened reference cylinder.
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Figure 12 shows the force-deformation-diagram of examined samples. For calculating
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determination of the load-bearing capacity, at the moment a model is missing which can be
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easily handled. This will be worked out in ongoing research.
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PRACTICAL APPLICATION OF TRC
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Strengthening of RC shell structures
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A characteristic feature of textile reinforcement is the expansion in two dimensions. Textile
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reinforcements have mostly plane character and posses the necessary deformability to adapt
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themselves also complicated and curved geometry. Beside that it can be fallen back on simple
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and tested procedures for the application of the TRC. Detailed information about the
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Krümmel Tower (Geesthacht) shown in figure 13 can be found in [19].
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Repair Concept of a Column
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With the reconstruction of the old canteen of the Dresden University of Technology the TRC
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is applied to repair detoriated columns. For this purpose carbonated concrete cover is
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removed up to reinforcement, an adjustment layer and a very thin TRC-layer is applied
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(Fig. 14).
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Textile Reinforced Concrete Brigde
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On the occasion of the Landesgartenschau (regional horticultural show) 2006 in Oschatz one
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of three footbridges over the Döllnitz is designed and planned and already built using TRC.
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The footbridge has a sidewalk width of 2.50 m (2.734 yd) and a span of 8.60 m (9.405 yd).
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What makes this bridge fascinating is its construction unit thickness of only 30 mm (1.181
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in.) (Fig. 15). A comparable bridge from reinforced concrete would weigh approximately 25
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metric tons (27.558 tons). On the contrary, the new construction with only 5 metric tons
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(5.512 tons) is extremely light.
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The nine meter (9.843 yd) long footbridge consists of ten 900 mm (35.433 yd) long segments.
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All segments are prefabricated in the Oschatz concrete factory and are prestressed with six
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steel tendons from SUSPA-DSI. Afterwards the compound bridge will be transported to the
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abutments at the horticultural show. Corners of the handrails and the frame are recesses for
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the internal bondless preliminary tension.
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As the complete bridge has now successfully been tested up to its ultimate limit with the most
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modern computer-assisted technology at the Otto-Mohr-Laboratory of Dresden University of
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Technology, a second bridge is now produced for the regional horticultural show in 2006.
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CONCLUSIONS
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The test results indicate that RC-members can be strengthened with textile reinforced
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concrete. Both, the load carrying capacity and the shear loading capacity, can be increased
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with TRC strengthening layer. Furthermore the ultimate load and the serviceability will be
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improved. Beside that it was shown that textile-reinforced concrete represents a sophisticated
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alternative to conventional materials.
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ACKNOWLEDGMENTS
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The authors would like to gratefully acknowledge the financial support from Deutsche
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Forschungsgemeinschaft (DFG) under the framework of the Collaborative Research Centre
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(CRC) 528 “Textile Reinforcements for Structural Strengthening and Repair”. The authors
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would also like to thank their partners within the Collaborative Research Centre 528 for their
17
support.
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REFERENCES [1] [2]
[3]
[4] [5] [6] [7]
Curbach, M. et al.: Sachstandbericht zum Einsatz von Textilien im Massivbau, Deutscher Ausschuss für Stahlbeton (DAfStb), Heft 488, Beuth Verlag, Berlin 1998. Curbach, M. (Hrsg.): Sonderforschungsbereich SFB 528 – Textile Bewehrungen zur bautechnischen Verstärkung und Instandsetzung. Arbeits- u. Ergebnisbericht für die Periode II/1999-I/2002, Institut für Tragwerke und Baustoffe, TU Dresden, 2002. Hegger, J. et al.: Sonderforschungsbereich SFB 532 – Textilbewehrter Beton – Grundlagen für die Entwicklung einer neuartigen Technologie. Arbeits- und Ergebnisbericht für die Periode II/1999-I/2002. Lehrstuhl und Institut für Massivbau, RWTH Aachen, 2002. Hegger, J. (Hrsg.): Textilbeton. Tagungsband zum 1. Fachkolloquium der Sonderforschungsbereiche 528 und 532, Aachen, 15.-16.02.2001. Curbach, M. (Hrsg.): Textile Reinforced Structures. Proceedings of the 2nd Colloquium on Textile Reinforced Structures (CTRS2), Dresden, 29.9-01.10.2003. Jesse, F., „Tragverhalten von textilbewehrtem Beton.“ Dresden : Technische Universität Dresden, Institut für Massivbau, 2005 – Diss. « only available in German ». Offermann, P. et al.: Technische Textilien zur Bewehrung von Betonbauteilen. In: Be-ton- und Stahlbetonbau 99 (2004) 6, S. 437–443 « only available in German »
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
[8] [9] [10] [11]
[12] [13]
[14]
[15]
[16] [17] [18] [19]
Möller, B.; Brückner, A. et al.: Verstärken mit textilbewehrtem Beton – Experimente und numerische Simulation. In: Beton- und Stahlbetonbau 99 (2004) 6, S. 466–471 « only available in German » Friedrich, Th.: Vom Werkstoff zum Produkt dank innovativer Produktionstechnologie. In: Beton- und Stahlbetonbau 99 (2004) 6, S. 476–481 « only available in German » Curbach, M.; Jesse, F.: Verstärken von Stahlbetonbauteilen mit textilbewehrtem Beton. In: Beton- und Stahlbetonbau 100 (2005) S1, S. 78–81 « only available in German » Neubauer, U.: Verbundtragverhalten geklebter Lamellen aus Kohlenstoffaser-Verbundwerkstoff zur Verstärkung von Betonbauteilen. Technische Universität Braunschweig : Eigenverlag, 2000 – Diss. « only available in German ». Ulaga T., “Members with Bar and Lamella reinforcement: Bond and Tension modeling”, Diss., Zurich, 2003 « only available in German ». Ortlepp, R. and Curbach, M., “Bonding Behaviour of Textile Reinforced Concrete Strengthening”, in ‘High Performance Fiber Reinforced Cement Composites – HPFRCC 4’, Proceedings of the 4th International RILEM Workshop, Ann Arbor, June 2003 (Naaman, A. E. and Reinhardt, H.-W., RILEM Proceedings PRO 30, Bagneux, 2003) pp. 517–527. Jesse, F., Ortlepp, R. and Curbach, M., ‘Strength-Reducing Effects in Composites with Continuous AR Glass Fibres’, in Proceedings of the 13th Congress of the International Glassfibre Reinforced Concrete Association – GRC 2003, Barcelona, October 2003 (GRCA, c/o The Concrete Society, Growthorne, 2003) paper 21. Brückner, A., Ortlepp, R. and Curbach, M., “Textile Reinforced Concrete – Applications and Bond Specifics”. In: CEB-FIB (Edt.): Proceedings of the fib-Symposium "Concrete Structures – the Challange of Creativity", Avignon, 26.-28.4.2004. pp. 161-162 – Book of abstracts and CD-Rom Onken P. and Grunewald, G., ‘Strengthening of Bridge Structures Using FRP-Material’, Presented at the ’14. Brückenbausymposium’, Dresden, 2003 « only available in German ». CEB-FIB Model Code 1990, (CEB, Bulletin D’Information No. 213/214, Lausanne, 1993). Brückner, A., Ortlepp, R. and Curbach, M., Textile Reinforced Concrete for Strengthening in Bending and Shear. In: Materials and Structures – paper accepted Zastrau, B.; Lepenies, I.; Matheas, J.; Zarzour, H.: Verstärkung der Stahlbetonkuppel des Krümmeler Wasserturms mit Textilbeton. In: Möller, B. (Hrsg.): Baustatik-Baupraxis 9. Dresden, 2005, S. 117-128 – (ISBN 3-00-015456-6)
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TABLES AND FIGURES List of Figures:
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35 36
Fig. 1 – Reinforcement systems for concrete
37
14
1 2
Fig. 2 –Stress-strain-curve with primary and regular cracking
3 4
5 6
Fig. 3 – Composite material made of steel reinforced concrete and textile reinforced fine
7
grained concrete
8 9
10 11
Fig. 4 – Anchoring Problem.
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15
1 2 3
4 5
Fig. 5 – Ultimate bond force per slab width versus bond length.
6
7 8
Fig. 6 – Load-displacement-diagram.
9
16
1 2
Fig. 7 – Rotation capacity versus x/d.
3
4 5
Fig. 8 – Geometry (units in mm – 1 in. = 25.4 mm) of the a) beams and b) T-shaped
6
beams.
7
17
1 2
Fig. 9 – Anchoring of the strengthening layer.
3
4 5
Fig. 10 – Load-displacement diagram.
6
7 8 9
Fig. 11 – Testing of short columns with TRC confinement
10 18
1 2 3
Fig. 12 – Force-deformation-diagram for short columns with TRC confinement
4
5 6
Fig. 13 – Krümmel Tower (Geesthacht) – strengthening of the shell.
7 8
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1 2
Fig. 14 –Repair of a column of the old canteen at the Dresden University of Technology
3 4 5 6 7 8 9 10 11
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1
Fig. 15 – Textile Reinforced Concrete Bridge – elevation, transport of the prototype and
2
cross section (units in m, cm - 1 ft. = 30.48 cm - 1 yd. = 0,9144 m)
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