| 1. |
- Abdeljaber, Osama, et al.
(författare)
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Analysis of the Trajectories of Left-turning Vehicles at Signalized Intersections
- 2020
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Ingår i: Transportation Research Procedia. - : Elsevier BV. ; , s. 1288-1295, s. 1288-1295
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Konferensbidrag (refereegranskat)abstract
- Internationally, an annual number of more than a million fatalities are caused by road traffic crashes, with particularly signalized intersections being crash prone locations within the highway system. An accumulation of conflicts between drivers is caused by the different movements (through and turning) from different directions at the intersection; hence, studying the trajectories of turning vehicles is an important step towards improving traffic safety performance of these facilities. In view of that, the current paper aims at providing further insight into the behaviour of left-turning vehicles (right-hand traffic rule) at signalized intersections in the State of Qatar. At first, a total of 44 trajectories of free-flowing vehicles were manually extracted from a recorded video for a single approach of Lekhwair signalized intersection in Doha City, State of Qatar. After that, the extracted trajectories were statistically analysed in an attempt to explore the factors affecting the path of left-turning vehicles at signalized intersections. The results suggest that the characteristics of the extracted paths are significantly related to the vehicle’s entry speed, minimum speed throughout its turning manoeuvre, and the lateral distance between the exit point and the curb (i.e., targeted exit lane). Provided that the speed parameters can be fairly an indication to the driving behaviour, it can be concluded that the driver’s attitude plays an important role in drawing the manoeuvre of a turning vehicle as does the pre-selection of the exit lane. Finally, the effort presented in this paper can be regarded as a way forward towards understanding the behaviour of turning vehicles at signalised intersection in the State of Qatar.
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| 2. |
- Abdeljaber, Osama, et al.
(författare)
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Extraction of Vehicle Turning Trajectories at Signalized Intersections Using Convolutional Neural Networks
- 2020
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Ingår i: Arabian Journal for Science and Engineering. - Heidelberg : Springer. - 2193-567X .- 2191-4281 .- 1319-8025. ; 45, s. 8011-8025
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims at developing a convolutional neural network (CNN)-based tool that can automatically detect the left-turning vehicles (right-hand traffic rule) at signalized intersections and extract their trajectories from a recorded video. The proposed tool uses a region-based CNN trained over a limited number of video frames to detect moving vehicles. Kalman filters are then used to track the detected vehicles and extract their trajectories. The proposed tool achieved an acceptable accuracy level when verified against the manually extracted trajectories, with an average error of 16.5 cm. Furthermore, the trajectories extracted using the proposed vehicle tracking method were used to demonstrate the applicability of the minimum-jerk principle to reproduce variations in the vehicles’ paths. The effort presented in this paper can be regarded as a way forward toward maximizing the potential use of deep learning in traffic safety applications.
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| 3. |
- Younis, Adel, et al.
(författare)
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Cost effectiveness of reinforcement alternatives for a concrete water chlorination tank
- 2020
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 27, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Reinforced concrete tanks in water/wastewater treatment plants are susceptible to severe corrosion due to aggressive exposure conditions resulting from the application of certain treatment chemicals and methods. Non-corrosive materials, such as stainless steel or fiber reinforced polymer (FRP), may be attractive alternative reinforcement options for such concrete structures. However, the high initial cost of such materials imposes constraints on their use, although such thinking ignores improvements in long-term concrete durability. The current paper addresses the use of non-corrosive reinforcement in a concrete water chlorination tank using life-cycle cost analysis (LCCA) that aims to evaluate the cost effectiveness of different reinforcement alternatives. A comparison was established between four concrete reinforcing materials, namely, black steel, epoxy coated steel, stainless steel, and glass-FRP (GFRP) through a 100-year analysis period. The results of this study suggest that the use of non-corrosive reinforcement helps achieve a considerable long-term cost saving. LCCA showed that GFRP becomes more economical than black steel in 35 years following construction. The net present cost (NPC) obtained for the GFRP-reinforced concrete was approximately 43% lower than that of the black steel reinforced concrete. The use of stainless steel also had a potential advantage but was less cost-effective than GFRP, with a 50-year payback period and an NPC 25% lower than that of the conventional design. Epoxy coated steel also showed a long-term cost benefit when compared to black steel, with approximately 11% reduction in NPC and 15-year extension in the service life. Sensitivity analyses were performed to assess the effects of the analysis period, discount rate, construction costs, concrete strength, and the use of supplementary cementitious materials on the LCCA outcomes.
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| 4. |
- Younis, Adel, 1990-, et al.
(författare)
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Effect of using multiple fabric plies on the tensile behaviour of carbon textile reinforced mortar
- 2020
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Ingår i: Proceedings of the 8th Euro-American Congress (REHABEND 2020). ; , s. 2255-2261
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Konferensbidrag (refereegranskat)abstract
- Recently, textile reinforced mortar (TRM) has emerged as a viable strengthening material for reinforced concrete (RC) and masonry structures. Understanding the TRM tensile behaviour is important to achieve an accurate design for TRM strengthening systems. This paper investigates the tensile properties of carbon-TRM composite with multiple fabric plies. Twenty TRM specimens (410 × 50 mm), which varied in the number of fabric plies (one/two/three/four), were prepared and tested in accordance with AC 434 provisions (clevis-grip mechanism). The results revealed a significance of the number of fabric plies on the tensile capacity as well as the failure behaviour of the TRM composite. The failure mode had changed from ductile fabric slippage (associated with up to 3 fabric plies) to brittle fabric delamination in carbon-TRM specimens when using 4 layers of fabric. As expected, the TRM tensile capacity had proportionally increased with the number of fabric plies. The effect of the number of fabric plies was less significant (within 20%), though, on the ultimate tensile stresses of the impregnated fabric. The results verified the established bilinear trend for TRM tensile stress-strain relationship that indicates two sequential phases, namely, noncracked/stiff and cracked-section phases. However, the TRM cracked tensile modulus had somewhat increased with an increase in the number of fabric plies. © 2020, University of Cantabria - Building Technology R&D Group. All rights reserved.
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| 5. |
- Younis, Adel, 1990-, et al.
(författare)
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Effects of Using Seawater and Recycled Coarse Aggregates on Plain Concrete Characteristics
- 2020
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Ingår i: International Conference on Civil Infrastructure and Construction (CIC 2020). - : Qatar University Press. ; , s. 794-800, s. 794-800
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Konferensbidrag (refereegranskat)abstract
- Using seawater and/or recycled coarse aggregates (RCA) for concrete mixing is deemed advantageous from a sustainability perspective. This paper reports on the results of an experimental study on fresh and hardened properties of concrete mixed with seawater and RCA. Three concrete mixtures were investigated, namely, Mix A (traditional concrete), Mix B (concrete made with seawater), and Mix C (concrete made with seawater and RCA). It was concluded that the use of seawater and/or RCA had a notable effect on fresh concrete properties. Mix B concrete showed a slightly lower strength performance than that of Mix A (<15%), whereas the strength of Mix C concrete had a significant drop (~30%) compared to the reference (Mix A). The permeability performance of hardened concrete for Mixes A and B was similar, whereas Mix C concrete showed 60% increase in water absorption and 100% increase in chloride permeability as compared to Mix A.
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| 6. |
- Younis, Adel, 1990-, et al.
(författare)
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Long-Term Cost Performance of Corrosion-Resistant Reinforcements in Structural Concrete
- 2020
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Ingår i: International Conference on Civil Infrastructure and Construction (CIC 2020). - : Qatar University Press. ; , s. 801-805, s. 801-805
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Konferensbidrag (refereegranskat)abstract
- Corrosion, which leads to the premature deterioration of reinforced concrete (RC) structures, is increasingly an issue of global concern. Accordingly, corrosion-resistant materials have emerged as alternative reinforcement solutions in concrete structures. Yet, the high initial cost of such materials may mitigate their potential use. This paper reports on the results of two life-cycle-cost-analysis (LCCA) studies that aim at verifying the long-term cost performance of corrosion-resistant reinforcements in structural concrete. The first study conducted a 100-year-based LCCA study to evaluate the relative cost savings of structural concrete that combines seawater, recycled coarse aggregates, and glass fiber-reinforced polymer (GFRP) reinforcement in high-rise buildings as compared to a traditional reinforced concrete (i.e., freshwater-mixed, natural-aggregate, black-steel- reinforced). In the second study, a life-cycle-cost comparison was established among four reinforcement alternatives, viz., conventional steel, epoxy-coated steel, stainless steel, and GFRP for a RC water chlorination tank considering a 100-year study period. The results of these two studies suggest that the use of corrosion-resistant reinforcement (especially GFRP) in structural concrete may potentially lead to significant cost savings in the long term: the net present cost of GFRP-RC structures was generally 40–50% lower than that reinforced with black steel.
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| 7. |
- Younis, Adel, et al.
(författare)
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Performance of Sewater-Mixed Recycled-Aggregate Concrete
- 2020
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Ingår i: Journal of Materials in Civil Engineering. - : American Society of Civil Engineers (ASCE). - 0899-1561 .- 1943-5533. ; 32:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The use of seawater and recycled coarse aggregate (RCA) in concrete mixtures leads to the production of a very sustainable concrete. The potential risk of steel reinforcement corrosion (due to chloride in the seawater) in such mixtures may be eliminated when considering plain concrete or noncorrosive reinforcement (e.g., fiber-reinforced polymer). This study investigated the fresh and hardened properties of a proposed green concrete mixed using seawater and recycled coarse aggregates. Two different concrete mixtures were studied, namely conventional concrete (Mix 1) and seawater-mixed concrete with RCA (Mix 2). Blast furnace slag was used as supplementary cementitious material at a 65% replacement level in both concrete mixtures. Fresh and hardened properties of the two concretes, including workability, strength gain, drying shrinkage, permeability, and microstructure, were characterized and compared. The results suggest that the use of seawater and RCA together has negative effects on concrete performance. Compared with the reference (Mix 1), Mix 2 concrete had approximately 5% lower density, 25% lower slump flow, 50% lower setting time, 33% lower strength gain, 10% higher drying shrinkage, 60% higher water absorption, and 100% higher charge passed (in rapid chloride permeability tests). Consequently, strategies to improve the performance of such concretes, such as a reduction in the water:cementitious materials ratio and the use of chemical admixtures, are suggested. These strategies, however, may somewhat reduce the green aspect of the proposed seawater-mixed concrete with RCA.
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| 8. |
- Younis, Adel, et al.
(författare)
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Short-term flexural performance of seawater-mixed recycled-aggregate GFRP-reinforced concrete beams
- 2020
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Ingår i: Composite structures. - : Elsevier. - 0263-8223 .- 1879-1085. ; 236, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Combining seawater, recycled coarse aggregate (RCA), and glass fiber reinforced polymer (GFRP) reinforcement in concrete is potentially advantageous from a sustainability perspective. This paper reports on the results of an experimental study on the short-term flexural performance of seawater-mixed recycled-aggregate concrete beams with GFRP bars. Twelve medium-scale reinforced concrete (RC) beams (150×260×2200 mm) were tested under four-point loading. The test variables included the mixing water (seawater/freshwater), aggregate type (conventional/recycled), and reinforcement material (black steel/GFRP). A wide range of flexural properties, including failure mode, cracking behavior, load-carrying capacity, deformation, energy absorption, and ductility were characterized and compared among the beam specimens. The results suggest that the use of seawater and RCA in concrete has insignificant effects on the flexural capacity of RC beams, especially if concrete strength is preserved by adjusting the mixture design. Altering reinforcement material had a strong influence on the flexural capacity and performance of the tested specimens: the GFRP-RC beams exhibited higher load-carrying capacities (on average 25%) but inferior deformational characteristics as compared to their steel-reinforced counterparts. Theoretical predictions were obtained for the flexural capacity, crack width, and deflection of steel- and GFRP-RC beams based on their corresponding design guides, and compared with the experimental results.
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| 9. |
- Younis, Adel, et al.
(författare)
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Tensile characterization of multi-ply fabric-reinforced cementitious matrix strengthening systems
- 2020
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Ingår i: Structural Concrete. - : John Wiley & Sons. - 1464-4177 .- 1751-7648. ; 21:2, s. 713-723
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Tidskriftsartikel (refereegranskat)abstract
- Fabric reinforced cementitious matrix (FRCM) is a composite consisted of high-strength fibers impregnated in a cement-based mortar, and is commonly used for strengthening reinforced concrete and masonry structures. Comprehending the tensile behavior of FRCM is important to achieve a reliable and accurate design of FRCM strengthening systems. The current paper reports on the results of an experimental study on the tensile characterization of FRCM. A total of 40 FRCM specimens (410 × 50 mm, varied in thickness) were prepared and tested. The tensile characterization tests were conducted according to AC 434 guidelines using clevis-grip mechanism. The tests were used to assess the effect of two parameters: (a) fabric type (carbon/glass) and (b) number of fabric plies (one/two/three/four). The results showed that the tensile strength of carbon-FRCM specimens was approx-imately 1.33 times that of the glass-FRCM counterparts. Three distinct failure modes were observed, namely, (a) ductile fabric slippage in carbon-FRCM (up to three plies of fabric); (b) brittle fabric delamination in carbon-FRCM with four plies of fabric; and (c) brittle fabric rupture in glass-FRCM systems. The FRCM tensile load-carrying capacity had proportionally increased with the number of fabric plies; less significant effect (within 20%) was observed on the corresponding ultimate tensile stresses (considering the net fabric area as the effective area).
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