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RISS 인기검색어
- 검색키워드
- 저자 : Morteza Madhkhan (검색결과 5 건)
- 무료
- 기관 내 무료
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Roller compacted concrete pavements reinforced with steel and polypropylene fibers
Madhkhan, Morteza,Azizkhani, Rasool,Torki, Mohammad E. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.2
In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic $150{\times}150{\times}150$ mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using a soil-based compaction method and the optimum moisture content obtained from the pertaining experiments, and by adding different percentages of Iranian pozzolans as well as different amounts of steel fibers, each one accompanied by 0.1% of poly-propylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease, but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers, but neither steel nor PP fibers did contribute to increase in the rupture modulus independently. Also, the toughness indices increased when steel fibers were used.
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Flexural strength of roller compacted concrete pavements reinforced with glass-roved textiles
Morteza Madhkhan,Saeid Nowroozi,Mohammad E. Torki 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.1
The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.
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Roller compacted concrete pavements reinforced with steel and polypropylene fibers
Morteza Madhkhan,Rasool Azizkhani,Mohammad E. Torki 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.2
In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango’s vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic 150 × 150 × 150 mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using a soil-based compaction method and the optimum moisture content obtained from the pertaining experiments, and by adding different percentages of Iranian pozzolans as well as different amounts of steel fibers, each one accompanied by 0.1% of poly-propylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease, but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers, but neither steel nor PP fibers did contribute to increase in the rupture modulus independently. Also, the toughness indices increased when steel fibers were used.
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Morteza Madhkhan,Mohsen Shamsaddini,Amin Tanhadoust 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.90 No.5
The mechanical properties and durability of concrete pavements may be degraded in extreme situations, resulting in the need for partial repair or total replacement. During the past few decades, there has been a growing body of research on substituting a portion of Portland cement with alternative cementitious materials for improving concrete properties. In this study, two different configurations of powdered and granulated blast furnace slag were implemented, replacing fine aggregates (by 12 wt.%) and Portland cement (by 0, 20, 40, and 60 wt.%) in the making of roller-compacted concrete (RCC) mixes. The specimens were fabricated to investigate the mechanical properties and durability specifications, involving freeze-thaw, saltscaling, and water absorption resistance. The experimental results indicated that the optimum mechanical properties of RCC mixes could be achieved when 20-40 wt.% of powdered slag was added to concrete mixes containing slag aggregates. Accordingly, the increases in compressive, tensile, and flexural strengths were 45, 50, and 28%, in comparison to the control specimen at the age of 90 days. Also, incorporating 60 wt.% of powdered slag gave rise to the optimum mix plan in terms of freeze-thaw resistance such that a negligible strength degradation was experienced after 300 cycles. In addition, the optimal moisture content of the proposed RCC mixtures was measured to be in the range of 5 to 6.56%. Furthermore, the partial addition of granulated slag was found to be more advantageous than using entirely natural sand in the improvement of the mechanical and durability characteristics of all mixture plans.
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Mohammadreza Baradaran,Morteza Madhkhan 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8
Mega bracing is one of the recently emphasized methods for lateral bracing of structures. In the present study, various configurations of mega bracing systems in terms of installation angle for lateral bracing of steel structures are evaluated and optimized. The investigated frames are designed and optimized using genetic algorithm (GA) according to LRFD-AISC (load and resistance factor design, american institute of steel construction). Frame analysis is carried out by means of finite element method, while optimization is conducted using GA considering three different types of selection and crossover, simultaneously. The results demonstrate that the optimum angle of mega bracing in steel frames is within the range of 36° to 42° with regard to the frame height and span. Furthermore, with increase in frame height, the employment of optimally distributed mega braces along the height of the frame results in reduction of story drifts and also the frame weight. Additionally, simultaneous utilization of various selection and crossover types in GA optimization leads to an increase in convergence rate of optimum weight of the frame as well as reduction in the required computations.
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