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Publisher: TULPAR Academic Publishing   (Total: 2 journals)   [Sort by number of followers]

Showing 1 - 2 of 2 Journals sorted alphabetically
Challenge J. of Concrete Research Letters     Open Access   (Followers: 4)
Challenge J. of Structural Mechanics     Open Access   (Followers: 5)
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Challenge Journal of Structural Mechanics
Number of Followers: 5  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2149-8024
Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.5 No.2

    • Authors: Journal Management CJSMEC
      PubDate: 2019-06-11
      Issue No: Vol. 5, No. 2 (2019)
       
  • Effect of basalt, polypropylene and macro-synthetic fibres on workability
           and mechanical properties of self-compacting concrete

    • Authors: Zinnur Çelik, Ahmet Ferhat Bingöl
      Pages: 35 - 41
      Abstract: In this study, the effects of different fibre types on the workability and mechanical properties of self-compacting concrete were investigated. Fresh and hardened properties of self-compacting concrete, different fibre content 0.90, 1.35 and 1.80 kg/m3 were evaluated using basalt, polypropylene and macro synthetic fibres with different fibre lengths of 24, 19 and 40 mm, respectively. The properties of fresh concrete were evaluated in terms of slump flowing, viscosity and flowability. In addition, compressive, flexural and splitting tensile strength were obtained from hardened concrete properties. To characterize mechanical properties 90 specimens were experimentally tested. The results show that the use of fibre reduces the workability of self-compacting concrete. On the other hand, tensile and flexural strength of the self-compacting fibre reinforced concrete increased with increasing fibre content, but it was determined that the fibre addition had no significant effect on the compressive strength.
      PubDate: 2019-06-11
      DOI: 10.20528/cjsmec.2019.02.001
      Issue No: Vol. 5, No. 2 (2019)
       
  • A comparative study of concrete strength prediction using artificial
           neural network, multigene programming and model tree

    • Authors: Preeti Kulkarni, Shreenivas N. Londhe, Pradnya R. Dixit
      Pages: 42 - 61
      Abstract: In the current study 28 day strength of Recycled Aggregate Concrete (RAC) and Fly ash (class F) based concrete is predicted using Artificial Neural Network (ANN), Multigene Genetic Programming (MGGP) and Model Tree (MT). Four sets of models were designed for per cubic proportions of materials, Properties of materials and non-dimensional parameters as input parameters. The study shows that the predicted 28 day strength is in good agreement with the observed data and also generalize well to untrained data. ANN outperforms MGGP and MT in terms of model performance. Output of the developed models can be presented in terms of trained weights and biases in ANN, equations in MGGP and in the form of series of equations in MT. ANN, MGGP and MT can grasp the influence of input parameters which can be seen through Hinton diagrams in ANN, input frequency distribution in MGGP and coefficients of input parameters in MT. The study shows that these data driven techniques can be used for developing model/s to predict strength of concrete with an acceptable performance.
      PubDate: 2019-06-11
      DOI: 10.20528/cjsmec.2019.02.002
      Issue No: Vol. 5, No. 2 (2019)
       
  • Structural analysis of reinforced concrete mansard roof structures
           according to different structural plans

    • Authors: Hasan Selim Şengel, İsmail Kanber, Serdar Çarbaş
      Pages: 62 - 71
      Abstract: In this study, analysis and evaluations were carried in order to determine the optimum conditions of reinforced concrete mansard roof applications. In total 96 mansard and 24 non mansard structure analysis were performed. The constructed models are symmetrical from all directions and it is modeled under the minimum conditions allowed by the regulation. As the column span, the distance between the columns was determined as 4 meters. The span conditions were determined as 3 spans, 4 spans, 5 spans and 6 spans by evaluating the parcel sizes and zoning conditions. Thus, a total of 120 calculation models were created. The base shear force, column moments and the maximum top displacement values were discussed in concordance with these calculations. As a result of the analysis, the graphical values of the mansard buildings were examined along with the non mansard buildings from the 3rd floor to the 8th floor, according to the zoning plan. In this study, graphs of parcels, span values and the number of storeys were drawn by keeping the values constant, and evaluations were made on the same graphs with and non mansard. In addition, by looking at the movements of the graphs obtained from this study on the same series, equations were adapted to the graphs and the series created with these equations were expanded and stochastic parabolic cones were formed at the shear force for 10 storeys, in the column moments. The mean values for the top displacement chart were taken and when the 20-storey displacement value was placed on this curve, it was determined that it appeared at a point very close to the estimating equation curve. Based on the analysis results, it is understood that it is possible to create a set of estimations for different number of storeys and plans.
      PubDate: 2019-06-11
      DOI: 10.20528/cjsmec.2019.02.003
      Issue No: Vol. 5, No. 2 (2019)
       
  • Arch effect in silos on discrete supports - Is it a myth or reality'

    • Authors: Lyubomir A. Zdravkov
      Pages: 72 - 79
      Abstract: Steel silos are interesting, complicated facilities. In order to assure its complete emptying by gravity they are often placed on supporting frame structure above the ground. Values of stresses in joints between thin walled shell and supporting frame elements are very high. It can cause the local buckling in the shell. The simplest way to design steel silos is to divide hypothetically the cylindrical shell into two parts - ring beam, supported in some points and shell above, uniformly supported. This conception is accepted by European Standard EN 1993-4-1. The particular moment is that the ring beam and cylindrical body above it are separated. Actually the two elements are jointed and work together in the same time. Considering the last results of Zeybek, Topkaya and Rotter from 2019, and as well as his own research, the author asks the question if it is true that the transferring of discrete base reactions to the cylindrical body is done by bending work of the ring beam, which is the conception in EN 1993-4-1' Or the vertical reaction forces are actually redistributed on the height based on the work of the cylindrical shell under compression as an arch. Using the contemporary capabilities of the programs for spatial analysis of building structures the author will try to find the answer of this question.
      PubDate: 2019-06-11
      DOI: 10.20528/cjsmec.2019.02.004
      Issue No: Vol. 5, No. 2 (2019)
       
  • Cover & Contents Vol.5 No.1

    • Authors: Journal Management CJSMEC
      PubDate: 2019-03-12
      Issue No: Vol. 5, No. 1 (2019)
       
  • Estimation of capacity of eccentrically loaded single angle struts with
           decision trees

    • Authors: Saha Dauji
      First page: 1
      Abstract: Single angle struts are used as compression members for many structures including roof trusses and transmission towers. The exact analysis and design of such members is challenging due to various uncertainties such as the end fixity or eccentricity of the applied loads. The design standards provide guidelines that have been found inaccurate towards the conservative side. Artificial Neural Networks (ANN) have been observed to perform better than the design standards, when trained with experimental data and this has been reported literature. However, practical implementation of ANN poses problem as the trained network as well as the knowhow regarding the application should be accessible to practitioners. In another data-driven tool, the Decision Trees (DT), the practical application is easier as decision based rules are generated, which are readily comprehended and implemented by designers. Hence, in this paper, DT was explored for the evaluation of capacity of eccentrically loaded single angle struts and was found to be robust and yielded comparable accuracy as ANN, and better than design code (AISC). This has enormous potential for easy and straightforward implementation by practicing engineers through the logic based decision rules, which would be easily programmable on computer. For this application, use of dimensionless ratios as inputs for the development of DT was found to yield better results when compared to the approach of using the original variables as inputs.
      PubDate: 2019-02-09
      DOI: 10.20528/cjsmec.2019.01.001
      Issue No: Vol. 4, No. 4 (2019)
       
  • Dynamic instability of castellated beams subjected to transverse periodic
           loading

    • Authors: Sahar Sahib Elaiwi, Boksun Kim, Long-yuan Li
      First page: 9
      Abstract: In this study, an analytical solution is developed for the investigation of free vibration, static buckling and dynamic instability of castellated beams subjected to transverse periodic loading. Bolotin’s method is used to perform the dynamic instability analysis. By assuming the instability modes, the mass, stiffness, and geometric stiffness matrices are derived using the kinetic energy, strain energy and potential of applied loads. Analytical equations for determining the free vibration frequency, critical buckling moment, and excitation frequency of castellated beams are derived. In addition, the influences of the flange width of the castellated beam and the static part of the applied load on the variation of dynamic instability zones are discussed.
      PubDate: 2019-02-11
      DOI: 10.20528/cjsmec.2019.01.002
      Issue No: Vol. 4, No. 4 (2019)
       
  • Improving the impact resistance of recycled aggregate concretes with
           different types of fibers

    • Authors: Muhammet Gökhan Altun, Meral Oltulu
      First page: 19
      Abstract: In this study, the aim was to use different types of fibers to improve the impact resistance of recycled aggregate concrete (RAC) that normally shows poor performance against mechanical impacts compared to normal concrete (NC). For this purpose, 18 groups of concrete were cast using different parameters. The study examined different types of concrete mixtures where the proportion of RCA (recycled coarse aggregate) used was 30% and 50% respectively, and where steel fiber-reinforcement was used in proportions of 1% and 2%, and polypropylene fiber-reinforcement was used in proportions of 0.1%. While the material performance of RAC compared to NC is analyzed in existing published literature, there is no evidence on whether the use of RCA and hybrid fibers affect the impact properties of concrete. Drop weight impact testing was conducted on test specimens and the impact resistance of these specimens was studied at 28 days. It was observed that the increasing use of RCA reduced the impact resistance. The use of 30% RCA does not significantly influence the strength of concrete. According to the results, the performance of both the NC and RAC was increased with an increase in the volume fractions of steel fiber used. In addition, hybrid fiber-reinforced concretes showed the best results of all the concrete groups.
      PubDate: 2019-03-05
      DOI: 10.20528/cjcrl.2019.01.003
      Issue No: Vol. 4, No. 4 (2019)
       
  • Research on effect of the quantity and aspect ratio of steel fibers on
           compressive and flexural strength of SIFCON

    • Authors: Nurullah Soylu, Ahmet Ferhat Bingöl
      First page: 29
      Abstract: SIFCON (Slurry Infiltrated Fiber Reinforced Concrete) is a composite which occur hardening of the matrix phase, consists of cement, water, mineral additives, fine sand, water reducing plasticizer, and reinforced with high volume fiber (5–20%). The main difference from the high strength concrete (HSC) is the ductile behaviour at failure. However, the brittleness increases with the strength increase in HSC, SIFCON has a ductile behaviour because of the high volume fiber content, low permeability, high durability. Despite fiber content is 2-3% in fiber reinforced concrete, fiber content may be ten times more in SIFCON and ductility is gained. This concrete is suggested to be used in military buildings against explosion, industrial grounds, airports, and bridge feet. In this study, in order to investigate the compressive and flexural strengths of SIFCON, the aspect ratio and fiber volume of steel fibers were chosen as variable and the effects of these parameters on compressive and flexural strengths were investigated. In the study, steel fibers with aspect ratio of 40, 55, 65, and 80 were used in 0, 4, 8 and 12% ratios. The water/binder ratio was kept constant at 0.35. Silica fume is used 10% and water-reducing plasticizer is used 1.5% of cement by weight. 7 and 28 days cured samples were subjected to compressive and flexural tests and the results were compared. As a result of the tests carried out, increases in both the compressive and flexural strengths of SIFCON specimens were determined with increasing fiber volume up to 8%. Strength reductions were observed at higher ratios. In cases where the fiber volume is too high, it has been seen that the strengths were decreased. The reason of strength reduction can be explained by the difficulty of passing ability of mortar between the fibers. The highest strengths were obtained from fibers with the aspect ratio of 80. Increase in the aspect ratio as well as increases in compressive and flexural strengths have been found.
      PubDate: 2019-02-12
      DOI: 10.20528/cjsmec.2019.01.004
      Issue No: Vol. 4, No. 4 (2019)
       
 
 
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