| 1. |
- Shrestha, Kshitij C., et al.
(författare)
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Effect of surface roughening on concrete/trm bond
- 2017
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Ingår i: Proceedings of International Structural Engineering and Construction. - : ISEC Press. - 2644-108X. - 9780996043748 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Textile reinforced mortar (TRM) is applied on the concrete surface with the aim of strengthening reinforced concrete structures. The performance of the strengthened structural system is directly related to the bond between the existing concrete substrate and the freshly applied TRM layer. This paper presents the results of an experimental study carried out to investigate the significance of concrete surface preparation, performed prior to strengthening, on the bonding behavior of the TRM system. For this purpose, concrete slabs of size (500 mm × 500 mm × 100 mm) were prepared and strengthened using a 10-mm thick TRM layer. After that, the bond performance of the strengthening layer with the concrete slab was assessed using the pull-off test. Three different levels of surface roughening were considered before strengthening: (i) no roughening (regarded as the reference), (ii) low roughening level, and (iii) high roughening level. Two types of textile materials are used in strengthening systems: carbon and polyparaphenylene benzobisoxazole (PBO). A total number of 72 pull-off tests were performed, of which the results were analyzed to examine the significance of the test variables. Results revealed that as the concrete surface is more roughened before strengthening, the bond between concrete substrate and TRM layer becomes stronger. Moreover, the PBO-TRM systems exhibit more desirable bonding behavior compared to the carbon-TRM counterpart.
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| 2. |
- Shrestha, K. C., et al.
(författare)
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Effect of Surface Roughening on Concrete/TRM Bond
- 2017
-
Ingår i: Proceedings of International Structural Engineering and Construction.
-
Konferensbidrag (refereegranskat)abstract
- Textile reinforced mortar (TRM) is applied on the concrete surface with the aim of strengthening reinforced concrete structures. The performance of the strengthened structural system is directly related to the bond between the existing concrete substrate and the freshly applied TRM layer. This paper presents the results of an experimental study carried out to investigate the significance of concrete surface preparation, performed prior to strengthening, on the bonding behavior of the TRM system. For this purpose, concrete slabs of size (500 mm × 500 mm × 100 mm) were prepared and strengthened using a 10-mm thick TRM layer. After that, the bond performance of the strengthening layer with the concrete slab was assessed using the pull-off test. Three different levels of surface roughening were considered before strengthening: (i) no roughening (regarded as the reference), (ii) low roughening level, and (iii) high roughening level. Two types of textile materials are used in strengthening systems: carbon and polyparaphenylene benzobisoxazole (PBO). A total number of 72 pull-off tests were performed, of which the results were analyzed to examine the significance of the test variables. Results revealed that as the concrete surface is more roughened before strengthening, the bond between concrete substrate and TRM layer becomes stronger. Moreover, the PBO-TRM systems exhibit more desirable bonding behavior compared to the carbon-TRM counterpart.
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| 3. |
- Younis, Adel, et al.
(författare)
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A perspective on seawater/frp reinforcement in concrete structures
- 2017
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Ingår i: ISEC 2017 - 9th International Structural Engineering and Construction Conference. - : ISEC Press. - 2644-108X. ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Predictions show that more than half of the world population will lack sufficient freshwater by 2025. Yet, the construction industry uses a considerable amount of freshwater to produce concrete. To save resources of fresh water, using seawater seems to be a valid potential alternative that can replace freshwater for mixing concrete. This paper presents a short review performed on existing literature related to the usage of seawater in concrete structures. As a summary of the work presented: (a) It is noticeable that the current literature, generally, reports little or no negative effect of seawater on the characteristics of plain concrete, both in the short and in the long term; (b) steel corrosion caused by the presence of chloride appears to be the sole reason for not accepting the use of seawater in concrete preparation; (c) Fiber reinforced polymer (FRP) is discussed as a promising alternative to steel for seawater-concrete reinforcement, owing to their light weight, high tensile strength, and adequate corrosion resistance; and (d) A future outlook for using seawater accompanied by FRP reinforcement in concrete structures is discussed in terms of achieving sustainability goals.
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| 4. |
- Younis, Adel, 1990-, et al.
(författare)
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A Perspective on Seawater/FRP Reinforcement in Concrete Structures
- 2017
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Ingår i: Resilient Structures and Sustainable Construction. - 9780996043748
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Konferensbidrag (refereegranskat)abstract
- Predictions show that more than half of the world population will lack sufficient freshwater by 2025. Yet, the construction industry uses a considerable amount of freshwater to produce concrete. To save resources of fresh water, using seawater seems to be a valid potential alternative that can replace freshwater for mixing concrete. This paper presents a short review performed on existing literature related to the usage of seawater in concrete structures. As a summary of the work presented: (a) It is noticeable that the current literature, generally, reports little or no negative effect of seawater on the characteristics of plain concrete, both in the short and in the long term; (b) steel corrosion caused by the presence of chloride appears to be the sole reason for not accepting the use of seawater in concrete preparation; (c) Fiber reinforced polymer (FRP) is discussed as a promising alternative to steel for seawater- concrete reinforcement, owing to their light weight, high tensile strength, and adequate corrosion resistance; and (d) A future outlook for using seawater accompanied by FRP reinforcement in concrete structures is discussed in terms of achieving sustainability goals.
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| 5. |
- Younis, Adel, et al.
(författare)
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Different FRCM systems for shear-strengthening of reinforced concrete beams
- 2017
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Ingår i: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 153, s. 514-526
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of an extensive experimental study on the efficacy of different fabric-reinforced cementitous matrix (FRCM) systems for the strengthening of reinforced concrete (RC) beams, which are critical in shear. Three types of FRCM systems were assessed; namely, Carbon–FRCM, polyparaphenylene benzobisoxazole (PBO)-FRCM, and Glass–FRCM. Tensile characterization tests were carried out on fifteen (15) FRCM coupons with the purpose of identifying the tensile properties of the FRCM systems. In the core part of this study, sixteen (16) shear-critical RC beam specimens were tested under three-point loading for assessing the effect of FRCM stiffness/type, FRCM configuration, and FRCM anchorage on the load and deformational capacities of the strengthened beams. As for the study results, the average enhancement of the load carrying capacity achieved by FRCM strengthening with respect to the reference specimen is 51%. Continuous strengthening significantly improved all aspects of structural performance of the strengthened beams compared to those of the intermittent counterpart. The effect of FRCM configuration appeared to be significantly related to the amount and the orientation of the effectual fabric within the FRCM system. Moreover, the effect of the FRCM anchorage used in this study was observed to be insignificant on the load carrying capacity of the strengthened beams. Theoretically-predicted values for load carrying capacity were obtained, and showed a reasonable agreement with the experimental results.
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| 6. |
- Younis, Adel, et al.
(författare)
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Dynamic Forces Induced by a Single Pedestrian : A Literature Review
- 2017
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Ingår i: Applied Mechanics Review. - : ASME Press. - 0003-6900 .- 1088-8535 .- 2379-0407. ; 69:2, s. 1-17
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Forskningsöversikt (refereegranskat)abstract
- With the use of lighter construction materials, more slender architectural designs, and open floor plans resulting in low damping, vibration serviceability has become a dominant design criterion for structural engineers worldwide. In principle, assessment of floor vibration serviceability requires a proper consideration of three key issues: excitation source, system, and receiver. Walking is usually the dominant human excitation for building floors. This paper provides a comprehensive review of a considerable number of references dealing with experimental measurement and mathematical modeling of dynamic forces induced by a single pedestrian. The historical development of walking force modeling - from single harmonic loads to extremely complex stochastic processes - is discussed. As a conclusion to this effort, it is suggested that less reliance should be made by the industry on the deterministic force models, since they have been shown to be overly conservative. Alternatively, due to the random nature of human walking, probabilistic force models seem to be more realistic, while more research is needed to achieve enough confidence to implement in design practice.
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| 7. |
- Younis, Adel, et al.
(författare)
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FRCM shear strengthening for concrete beams
- 2017
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Ingår i: ISEC 2017 - 9th International Structural Engineering and Construction Conference. - : ISEC Press. - 2644-108X. - 9780996043748
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental study carried out to examine the efficacy of Fabric-Reinforced Cementitious Matrix (FRCM) in strengthening RC beams susceptible to shear failure. In this paper, seven shear-critical RC beams, of 2,500 mm in length, 150 mm in width, and 330 mm in depth, were tested under three-point loading until failure. Two main test variables were considered, which are: A) Strengthening material: carbon, polyparaphenylene benzobisoxazole (PBO), or glass FRCM, and b) Strengthening application pattern: A single full-length FRCM plate or a set of intermittent and spaced FRCM strips were applied along the critical shear zone. The test results confirmed the efficacy of FRCM strengthening in improving the load capacity of shear-critical RC beams. The FRCM-strengthening contributed to increases in the load capacity ranged between 31% and 100% compared to the reference specimen. The full-length strengthened specimens generally showed a better strength enhancement compared to the intermittent counterparts when using the same FRCM material. Such intuitive observation assures the importance of the amount of strengthening material applied in the critical shear zone. Besides, specimens utilizing carbon fibers in its FRCM strengthening material showed the highest strength enhancement among the three systems.
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| 8. |
- Younis, Adel, et al.
(författare)
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Tensile characterization of textile reinforced mortar
- 2017
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Ingår i: ISEC 2017 - 9th International Structural Engineering and Construction Conference. - : ISEC Press. - 2644-108X. - 9780996043748 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Textile reinforced mortar (TRM) is a composite material consisting of dry fibers embedded in a cementitious matrix, commonly used for strengthening masonry and concrete structures. In general, tensile characterization is required to identify the TRM mechanical properties, which are considered the key parameters needed for the structural design of strengthening systems. This paper presents the results of an experimental study conducted to investigate the tensile properties of TRM. In this effort, a total of 15 TRM coupons of 410 mm in length, 50 mm in width, and 10 mm in thickness were tested under uniaxial tensile load with clevis-Type anchors. Three different types of textile materials were considered: carbon, glass, and polyparaphenylene benzobisoxazole (PBO). As for the study results, a common shape of the TRM tensile constitutive law was observed. Moreover, the average mechanical properties were listed for each type of TRM. Finally, the results and considerations presented in this work can enrich the literature with background data, which are beneficial for future applications of TRM systems in structural rehabilitation and repair.
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