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RISS 인기검색어
- 검색키워드
- 저자 : Mohamed Lachemi (검색결과 3 건)
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Khandaker M. A. Hossain,Mohamed Lachemi,Said M. Easa 한국계산역학회 2006 Computers and Concrete, An International Journal Vol.3 No.6
This paper develops an artificial neural network (ANN) model for uniformly loaded restrained reinforced concrete (RC) slabs incorporating membrane action. The development of membrane action in RC slabs restrained against lateral displacements at the edges in buildings and bridge structures significantly increases their load carrying capacity. The benefits of compressive membrane action are usually not taken into account in currently available design methods based on yield-line theory. By extending the existing knowledge of compressive membrane action, it is possible to design slabs in building and bridge decks economically with less than normal reinforcement. The processes involved in the development of ANN model such as the creation of a database of test results from previous research studies, the selection of architecture of the network from extensive trial and error procedure, and the training and performance validation of the model are presented. The ANN model was found to predict accurately the ultimate strength of fully restrained RC slabs. The model also was able to incorporate strength enhancement of RC slabs due to membrane action as confirmed from a comparative study of experimental and yield line-based predictions. Practical applications of the developed ANN model in the design process of RC slabs are also highlighted.
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Lightweight Self-consolidating Concrete with Expanded Shale Aggregates
Abdurrahmaan Lotfy,Khandaker M. A. Hossain,Mohamed Lachemi 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.2
This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30?0.40 water-to-binder ratio, high range water reducing admixture of 0.3?1.2 % (by total content of binder) and total binder content of 410?550 kg/㎥. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH?LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH?LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.
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Effects of Milled Cut Steel Fibers on the Properties of Concrete
Okan Karahan,Erdogan Ozbay,Cengiz D. Atis,Mohamed Lachemi,Khandaker M. A. Hossain 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7
This study presents the mechanical and transport properties of milled cut steel fiber reinforced concretes (MCSFRC). Properties studied include unit weight, workability, compressive strength, flexural strength, splitting tensile strength, bond strength, water absorption, water porosity, water sorptivity, rapid chloride ion permeability and drying shrinkage of concrete. Mixtures with a waterbinder ratio of 0.40, total binder content of 500 kg/m3 and milled cut steel fiber content of 0, 0.25, 0.50 and 1.00% by concrete volume were produced and tested. The laboratory results showed a slight reduction in compressive strength with the use of milled cut steel fiber. On the other hand milled cut steel fibers significantly improved the tensile strength and decreased the drying shrinkage. Although no significant increase was observed in the absorption, porosity and sorptivity, chloride ion permeability increased drastically with the increase of milled cut steel fiber content.
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