| 1. |
- Gonzalez-Libreros, Jaime H., et al.
(författare)
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Experimental investigation on RC beams strenghened in shear with externally bonded composites
- 2016
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Ingår i: Eighth International Conference onFibre-Reinforced Polymer (FRP) Composites in Civil Engineering. - Hong Kong, China : The Hong Kong Polytechnic University. ; , s. 384-389
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental campaign carried out to investigate the behavior of reinforcedconcrete (RC) beams strengthened in shear using externally bonded advanced composite materials. In order tocompare their performance, two different types of composite materials were used to strengthen the beams: fiberreinforced polymer (FRP) and fiber reinforced cementitious matrix (FRCM) composites. The beams were thentested in four-point bending scheme, and measurements regarding applied load and mid-span displacements wereacquired. Observations regarding the gain in shear strength, influence on mid-span deflection and ductility, andcomparison of the performance of the two strengthening systems are provided. For specimens strengthened withFRCM composite, the contribution to the shear strength provided by the FRCM strengthening system is comparedwith the value predicted by an analytical model found in the available literature.
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| 2. |
- Gonzalez-Libreros, Jaime H., et al.
(författare)
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Shear strengthening of RC beams with FRCM: What do we know so far?
- 2016
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Ingår i: Eighth International Conference onFibre-Reinforced Polymer (FRP) Compositesin Civil Engineering. - Hong Kong, China : The Hong Kong Polytechnic University. ; , s. 462-467
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Konferensbidrag (refereegranskat)abstract
- Shear failure of reinforced concrete (RC) beams is an undesirable mode of failure due to its sudden and brittlenature and thus needs to be carefully evaluated when planning a strengthening intervention. The use of fiberreinforced polymer (FRP) composites has shown to be capable of providing an adequate increase in shear strength.However, in recent years, there is interest in developing new techniques in which the positive attributes of FRPare utilized but some of its drawbacks are overcome. Among these techniques, fiber reinforced cementitious matrix(FRCM) composites, in which the organic resins are replaced by inorganic mortars, have shown promising results.In this paper, a bibliographical review of the available literature on FRCM shear strengthening of RC beams iscarried out. Two available design models are evaluated using a database compiled by the authors. The reviewshows that FRCM is able to provide an increase in strength and performance comparable to RC beams strengthenedwith FRP. However, the models are not able to accurately predict the behavior of FRCM strengthened beams.
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| 3. |
- Sabau, Cristian, 1989-, et al.
(författare)
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Influence of the fiber type and matrix age on the bonding of FRCM composite strips applied to concrete substrates
- 2016
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Ingår i: Eighth International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering. ; , s. 456-461
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Konferensbidrag (refereegranskat)abstract
- Fiber reinforced cementitious matrix (FRCM) composites represent an alternative to fiber reinforced polymer(FRP) composites for strengthening existing civil structures. FRCM is comprised of fibers, usually in the form ofa textile with an open-mesh configuration, embedded in an inorganic mortar matrix. It shares the advantages ofFRP systems and overcomes some of its drawbacks, which makes it suitable for a wide range of applications.Although research on this topic is still scarce, it has been shown that debonding represents a key factor in itsperformance. In order to gain more insight in this issue, a series of classical push-pull single-lap direct shear testswere carried out on basalt, carbon, and glass FRCM-concrete joints. The results allow for comparing theperformance of the joints with carbon, basalt, and glass fibers in terms of applied load – global slip response andfailure mode. The influence of matrix age was also investigated. The curing time of the mortar matrix was foundto influence the load carrying capacity of carbon FRCM – concrete joints.
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| 4. |
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| 5. |
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| 6. |
- Gonzalez-Libreros, Jaime, et al.
(författare)
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Effect of Confinement with FRCM Composites on Damaged Concrete Cylinders
- 2017
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Ingår i: Strain-Hardening Cement-Based Composites. - Dordrecht : Springer. - 9789402411935 - 9789402411942 ; , s. 770-777
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Konferensbidrag (refereegranskat)abstract
- Confinement of axially loaded concrete members in existing structures is required when a change in use is expected or when there is a need to upgrade the structure to meet current design standards. In addition, after unusual overloading events (e.g., earthquakes), axially loaded members can suffer damage that increases the need of their retrofitting by means of confinement. The study of fiber reinforced cementitious matrix (FRCM) composites for confinement of compression members has gained attention in recent years due to the capability to overcome some of the disadvantages associated with more traditional strengthening techniques. However, the available experimental evidence is still scarce, and research on the topic is necessary. In this paper, the results of an experimental campaign performed on concrete cylinders confined with FRCM jackets are presented. Before strengthening, some specimens were preloaded in order to achieve specified damage levels. The specimens were then subjected to uniaxial concentric compressive loading. The axial load and axial strain response was recorded for each specimen. In addition, the elastic modulus of confined and unconfined specimens was determined. Results show that confinement with FRCM composites is able to provide an increase in the axial capacity of undamaged and damaged concrete cylinders.
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| 7. |
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| 8. |
- Sarmiento Nova, Silvia Juliana, et al.
(författare)
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A risk-based robustness evaluation of a prestressed concrete bridge
- 2023
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Ingår i: Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability - Proceedings of the 11th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2022. - London : CRC Press. - 9781032345314 ; , s. 2045-2052, s. 2045-2052
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Konferensbidrag (refereegranskat)abstract
- Existing bridges were designed to satisfy old specifications, and most of them were based on a member-oriented approach. A bridge superstructure is constituted by a group of elements that together form a system, and depending on how robust the system is, a member-oriented approach losses accuracy. Therefore, in this study a preliminary framework of how to assess concrete bridges' robustness is presented. The framework integrates a metamodel-based reliability analysis, and the risk concepts to evaluate the robustness level for concrete bridges considering failure probabilities and consequences. A case study of a prestressed multi-beam concrete bridge is used to validate and illustrate the methodology. The capacity of the individual elements, as well as of the intact and damaged structural system are calculated using finite element modeling (FEM). It was concluded that the framework proposed can be used to assess structural robustness with low computational cost, for the cases in which FEM is implemented.
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| 9. |
- Sarmiento Nova, Silvia J., et al.
(författare)
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Pressure Distribution Patterns Between the Ballast and the Concrete Slab in Railway Trough Bridges
- 2021
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Ingår i: Proceedings of the 31st European Safety and Reliability Conference and (ESREL 2021). - Singapore : Research Publishing (S) Pte Ltd.. ; , s. 1093-1100
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Konferensbidrag (refereegranskat)abstract
- In Sweden, a substantial amount of railway bridges is approaching their intended lifespans and are planned to be replaced. However, it is not sustainable neither from a financial nor an environmental perspective to replace these bridges if they are still sound and safe. Thus, an evaluation of their actual capacity is required with the aim of extending their lifespans. A way to obtain a more accurate capacity is to determine the loads that are acting on them. Available literature points out the lack of experimental investigations on sleeper-ballast contact pressure, as well as on the stress distribution along and across the ballast. Consequently, railway bridge design has been based on traditional rather than rational assumptions, which can be quite conservative. In this paper, a review of models is carried out for evaluating stress patterns on the surface of the slab on ballasted concrete bridges. Then, a simplified finite element model of a concrete trough bridge, a common type of structure in Sweden, is used in a parametric analysis aimed to understand how the identified pressure distribution patterns affect the performance of this type of structure. Finally, with the purpose of studying how some parameters influence the bridge safety, a probabilistic reliability analysis is used. The reliability index beta (b) is obtained using the polynomial response surface method and its value is compared for different boundary condition scenarios. Also, the sensitivity factors for the considered random variables are compared and analyzed. Results show that the assumption of support condition and pressure pattern has a significant impact on the capacity, failure mode and probability of failure of this type of structure.
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