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Journal Cover Challenge Journal of Structural Mechanics
  [5 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2149-8024
   Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.3 No.3

    • Authors: Journal Management CJSMEC
      PubDate: 2017-09-18
      Issue No: Vol. 3, No. 3 (2017)
       
  • Modal identification of a reduced-scale masonry arch bridge with
           experimental measurements and finite element method

    • Authors: Emre Alpaslan, Burcu Dinç, Kemal Hacıefendioğlu, Gökhan Demir, Olgun Köksal
      Pages: 108 - 115
      Abstract: This study aims to investigate modal parameters such as mode shapes, natural frequencies and damping ratios of a reduced scale one-span historical masonry arch bridge constructed in laboratory conditions by performing numerical and experimental analysis. Sarp Dere historical masonry bridge, in Ordu, Ulubey, has 15.5m in length and 4.75m in width was chosen as a prototype model. The reduced-scale bridge model and structural details were carried out in the scale of 1:12.5. Operational Modal Analysis (OMA) technique was used for experimental study. The experimental modal parameters of the bridge model were figured out by using Enhanced Frequency Domain Decomposition (EFDD). ANSYS software was used to create 3D finite element (FE) model and to expose the analytical modal parameters of the reduced-scaled bridge model. Moreover, FE model of the reduced-scale bridge model was calibrated based on the experimental results by using the Response Surface based FE model calibration technique to obtain more accurate results. The analysis results of experimental, initial and calibrated FE model were compared. It is noted that there are significant differences between the modal parameters obtained from experimental and initial FE model. Model calibration techniques are beneficial to get a more reasonable FE model.
      PubDate: 2017-09-18
      DOI: 10.20528/cjsmec.2017.06.012
      Issue No: Vol. 3, No. 3 (2017)
       
  • The influence of elevated temperatures on the mechanical properties of
           polypropylene fiber reinforced concrete

    • Authors: Majid Atashafrazeh, Ahmet Ferhat Bingöl, Murat Caf
      Pages: 116 - 122
      Abstract: This paper describes the strength of Polypropylene Fiber Reinforced Concrete (PFRC) exposed to the elevated temperatures. In the study, control specimens without any fibers and the concrete specimens with the ratios of 0.30, 0.60, 0.90 and 1.20 kg/m³ polypropylene fibers both in woolen and bar shape fiber have been produced. The specimens have been kept in the laboratory conditions for 28 days. Shortly after the curing period was completed, every group was heated at 23, 150, 300, 450, 600 and 750°C for two hours then the compressive strengths of them were determined. The maximum compressive strength was obtained by the specimens including 0.30 kg/m³ woolen polypropylene. For this group, the compressive strength increase was 8% according to the control specimens. The compressive strengths of bar polypropylene fiber concrete were higher than the wool fibers under elevated temperatures. On the other hand, more compressive strength values are obtained from the control specimens than fiber groups at 600°C temperature. Melting the polypropylene fiber at 500°C formed some pore spaces in concrete and caused reduction of the compressive strength.
      PubDate: 2017-09-18
      DOI: 10.20528/cjsmec.2017.08.013
      Issue No: Vol. 3, No. 3 (2017)
       
  • Vertical stiffeners and internal pressure - influencing factors on
           distribution of meridional stresses in steel silos on discrete supports

    • Authors: Lyubomir A. Zdravkov
      Pages: 123 - 128
      Abstract: Steel silos are interesting, complicated facilities. In order to ensure unloading of whole amount of stored product by gravity, they are often placed on supporting structure. Values of stresses in joints between thin sheets and supporting frame elements are very high, which could cause local loss of stability in thin shells. Many researchers have worked on values and distribution of the meridional stresses in that joints. Their traditional approach is to divide in their minds cylindrical shell on two parts - discretely supported ring beam and continuously supported shell above it. As a result of their efforts critical height of shell Hcr and ideal position of intermediate stiffening ring on shell are determined. The scientific results are based on semi-membrane theory of Vlasov, in which influence of vertical stiffeners and internal pressure is not accounted. On other hand all steel silos are loaded with an internal pressure and majority of them have vertical stiffeners above supports. Is it possible the obtained scientific results to be applied to these silos' In a present article the author will show that stiffeners and pressure should not be ignored in an analysis.
      PubDate: 2017-09-18
      DOI: 10.20528/cjsmec.2017.08.014
      Issue No: Vol. 3, No. 3 (2017)
       
  • Total potential energy minimization method in structural analysis
           considering material nonlinearity

    • Authors: Rasim Temür, Gebrail Bekdaş, Yusuf Cengiz Toklu
      Pages: 129 - 133
      Abstract: Minimum potential energy principle is the basis of the most of the well-known traditional techniques used in the structural analysis. This principle determines the equilibrium conditions of systems with reference to minimization of the sum of the total potential energy of the structure. In traditional applications, this methodology is formulized by using matrix operations. A methodology has been proposed in the last decades for structural analyses based on the idea of using metaheuristic algorithms to obtain minimum potential energy of the structural system instead of following this classical approach. This new method, called “Total Potential Optimization using Metaheuristic Algorithms (TPO/MA)”, has been applied in this paper to truss structures considering linear and nonlinear behavior of the structural material. The metaheuristic method used in this process is teaching-learning based optimization (TLBO) algorithm. The proposed technique is applied on numerical examples and results are compared with other techniques in order to test the efficiency of the proposed method. According to results obtained, TPO/MA method with TLBO algorithm is a feasible technique for the investigated problem.
      PubDate: 2017-09-18
      DOI: 10.20528/cjsmec.2017.02.005
      Issue No: Vol. 3, No. 3 (2017)
       
  • The strain sensitivity of brass fiber reinforced concrete

    • Authors: Egemen Teomete, Erman Demircilioğlu, Serap Kahraman
      Pages: 134 - 137
      Abstract: The structures are challenged by earthquakes and other environmental factors. Structural health monitoring is crucial to protect the lives. The strain gages used in structural health monitoring have low durability and can get point wise measurements which limit their use. In this study, five different concrete mixtures with different brass fiber volume fractions were designed. Along with the control mixture which does not have brass fiber, six mixtures were designed and three cube samples from each mixture were cast and cured. Compression test was conducted with simultaneous measurement of electrical resistance. The brass fiber reinforced concrete has strong linear relationship between the electrical resistance change and strain. Important progress was achieved in development of “Smart Concrete” which can sense its strain and damage.
      PubDate: 2017-09-18
      DOI: 10.20528/cjsmec.2017.02.008
      Issue No: Vol. 3, No. 3 (2017)
       
  • Cover & Contents Vol.3 No.2

    • Authors: Journal Management CJSMEC
      PubDate: 2017-06-13
      Issue No: Vol. 3, No. 2 (2017)
       
  • Modal response identification of a highway bridge under traffic loads
           using frequency domain decomposition (FDD)

    • Authors: Mehmet Akköse, Hugo C. Gomez, Maria Q. Feng
      Pages: 63 - 71
      Abstract: In this study, a four-span, 224m long, post-tensioned concrete box girder bridge supported on single column piers was subject to a series of controlled vehicle tests. Bridge acceleration response datasets were used to study the effect of truck speed and a sudden stop, on the modal identification of the bridge structure. Natural frequencies and mode shapes of the bridge were determined using the frequency domain decomposition technique for all datasets. The passing of the truck rendered difficult to identify the first bridge frequency. Conversely, the vehicle tests improved the identification of higher vibration modes. This is because the truck preferentially excites the bridge vertical response, which is associated with higher modes of vibrations, especially when a sudden stop of the vehicle occurs. Thus, carefully conducted vehicle-crossing tests provide detailed information about the bridge structure dynamics in the vertical direction. However, to identify lower modes, no vehicle on the bridge is preferred.
      PubDate: 2017-06-13
      DOI: 10.20528/cjsmec.2017.03.009
      Issue No: Vol. 3, No. 2 (2017)
       
  • Modelling of non-linear seismic ground response using elasto-plastic
           constitutive framework within a finite element soil column model

    • Authors: Azeddine Chehat, Zamila Harichane, Amina Sadouki
      Pages: 72 - 80
      Abstract: The prediction of seismic ground response is conditioned by the knowledge of each material behavior of soil deposits. The recourse to plasticity criterion to simulate cyclic behavior of soils under seismic loading is becoming more realistic. In this study, an elasto-plastic constitutive equation is cast within the framework of one dimensional finite element (FE) soil column model to account for the spatial and material nonlinearity of the secant shear modulus. To account of the spatial non linearity, shear modulus is written in terms of rigid base shear modulus and height of the soil column, while for material nonlinearity, the shear modulus degradation is deducted by the application of the isotropic evolution of the Von Misès criterion. Obtained results proved the efficiency of the proposed methodology and the predictive capability of the elaborated elastoplastic model which captures both small- and large-strain behaviors. They likewise highlight the important roles that play the spatial and material shear modulus variation in the prediction of the seismic soil responses.
      PubDate: 2017-06-13
      DOI: 10.20528/cjsmec.2017.05.011
      Issue No: Vol. 3, No. 2 (2017)
       
  • Flexural behavior of sustainable reactive powder concrete bubbled slab
           flooring elements

    • Authors: Ashraf Abdulhadi Alfeehan, Hassan Issa Abdulkareem, Shahad Hameed Mutashar
      Pages: 81 - 89
      Abstract: Voided slabs are reinforced concrete slabs in which voids allow to reduce the amount of concrete. The bubbled deck slab is a new and sustainable biaxial floor system to be used as a self-supporting concrete floor. The use of voided slabs leads to decrease the consumption of materials and improve the insulation properties for enhancing the objectives of sustainability. This study presents an investigation into the flexural behavior of sustainable Reactive Powder Concrete RPC bubbled slab flooring elements. Six one-way slabs were cast and tested up to the failure. The adopted variables in this study are: the volumetric ratio of steel fibers, type of slab; bubbled or solid, placing of reinforcement and thickness of slab. The effect of each variable on the ultimate load, deflection and strain has been discussed. The results show that increasing the percent of steel fibers from 1% to 2% in solid and bubbled slabs decreases the deflection by (18.75%) and (50%) respectively. As well as, the deflection increases by (41%) for bubbled slab compared to the solid slab. The slabs reinforced with top and bottom steel meshes show less deflection than slabs reinforced by only bottom steel mesh.
      PubDate: 2017-06-13
      DOI: 10.20528/cjsmec.2017.04.010
      Issue No: Vol. 3, No. 2 (2017)
       
  • The strain sensitivity of copper powder reinforced concrete

    • Authors: Egemen Teomete, Özkan Ayberk Kolatar, Erman Demircilioğlu, Serap Kahraman
      Pages: 96 - 101
      Abstract: Earthquakes, material deteriorations and other environmental factors challenge the structural safety. In order to protect the lives, structural health monitoring is crucial. The metal foil strain gages have low durability, low sensitivity and can get point wise measurements which are disadvantages. In this study six different concrete mixtures were designed; one without any copper powder, the rest five having different copper powder volume fractions. Three cube samples from each mixture were cast and cured. Simultaneous measurement of electrical resistance and strain were conducted during the compression tests. A strong linear relationship between strain and electrical resistance change was obtained for copper powder reinforced concrete. The results are contribution to the development of “Smart Concrete” which can sense its strain and damage.
      PubDate: 2017-06-13
      DOI: 10.20528/cjsmec.2017.02.007
      Issue No: Vol. 3, No. 2 (2017)
       
  • Elastic foundation effects on arch dams

    • Authors: Muhammet Karabulut, Murat Emre Kartal, Omer Faruk Capar, Murat Cavusli
      Pages: 102 - 107
      Abstract: Earthquake response of an arch dam should be calculated under ground motion effects. This study presents three-dimensional linear earthquake response of an arch dam. Thereby, we considered different ground motion effects and also foundation conditions in the finite element analyses. For this purpose, the Type 3 double curvature arch dam was selected for application. All numerical analyses are carried out by SAP2000 program for empty reservoir cases. In the scope of this study, linear modal time-history analyses are performed using three dimensional finite element model of the arch dam and arch dam-foundation interaction systems. According to numerical analyses, maximum horizontal displacements and maximum normal stresses are presented by dam height in the largest section. These results are evaluated for rigid and various elastic foundation conditions. Furthermore, near-fault and far-field ground motion effects on the selected arch dam are taken into account by different accelerograms obtained from the Loma Prieta earthquake at various distances.
      PubDate: 2017-06-13
      DOI: 10.20528/cjsmec.2017.02.006
      Issue No: Vol. 3, No. 2 (2017)
       
  • Cover & Contents Vol.3 No.1

    • Authors: Journal Management CJSMEC
      PubDate: 2017-03-10
      Issue No: Vol. 3, No. 1 (2017)
       
  • Analytical solution for bending and buckling response of laminated
           non-homogeneous plates using a simplified-higher order theory

    • Authors: Ferruh Turan, Muhammed Fatih Başoğlu, Zihni Zerin
      Pages: 1 - 16
      Abstract: In this study, analytical solutions for the bending and buckling analysis of simply supported laminated non-homogeneous composite plates based on first and simplified-higher order theory are presented. The simplified-higher order theory assumes that the in-plane rotation tensor is constant through the thickness. The constitutive equations of these theories were obtained by using principle of virtual work. Numerical results for the bending response and critical buckling loads of cross-ply laminates are presented. The effect of non-homogeneity, lamination schemes, aspect ratio, side-to-thickness ratio and in-plane orthotropy ratio on the bending and buckling response were analysed. The obtained results are compared with available elasticity and higher order solutions in the literature. The comparison studies show that simplified-higher order theory can achieve the same accuracy of the existing higher order theory for non-homogeneous thin plate.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2017.02.001
      Issue No: Vol. 3, No. 1 (2017)
       
  • Research on relation between natural frequency and axial stress of round
           bar with intermediate-supported ends

    • Authors: Tsutomu Yoshida, Takeshi Watanabe, Kunihiko Sakurada
      Pages: 17 - 22
      Abstract: In order to make a method be useful to measure an axial stress of a member by a natural frequency, we investigated a relation between a natural frequency and an axial stress of a round bar with intermediate-supported ends, the boundary condition of which was one between a fix-supported end and a simply-supported end. To define an intermediate-supported end condition, we adopted a parameter, a ratio of a moment of a force to a deflection angle at the end. It was shown theoretically that the parameter of an intermediate-supported end could be evaluated by one at a support on a continuous beam consisted of 3 spans. The 3-spanned beam has same vibration characteristics of a beam with intermediate-supported ends. We manufactured a test device of a 3-spanned beam by which we could simulate a vibration under various intermediate-supported end conditions. The theoretical relation and experimental results between a natural frequency and an axial stress agreed for the most part.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2017.02.002
      Issue No: Vol. 3, No. 1 (2017)
       
  • Metaheuristic approaches for optimum design of cantilever reinforced
           concrete retaining walls

    • Authors: Gebrail Bekdaş, Rasim Temür
      Pages: 23 - 30
      Abstract: An approach is presented for optimum design of cantilever reinforced concrete (RC) retaining wall via teaching-learning based optimization (TLBO) algorithm. The objective function of the optimization is to minimize total material cost including concrete and reinforcing steel bars of the cantilever retaining wall by considering overturning, sliding and bearing stabilities, bending moment and shear capacities and requirements for design and construction of reinforced concrete structures (TS 500/2000). TLBO algorithm is a simple algorithm without any special algorithm parameters. This innovative approach is providing an advantage to TLBO in terms of easily applying to the problem. The proposed method has been performed on numerical examples and the results are compared with previous approaches. Results show that, the methodology is feasible for obtaining the optimum design of RC cantilever retaining walls.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2016.11.031
      Issue No: Vol. 3, No. 1 (2017)
       
  • Influence of blast-induced ground motion on dynamic response of masonry
           minaret of Yörgüç Paşa Mosque

    • Authors: Olgun Köksal, Kemal Hacıefendioğlu, Emre Alpaslan, Fahri Birinci
      Pages: 31 - 37
      Abstract: This paper focuses on the dynamic response analysis of masonry minaret of Yörgüç Paşa Mosque subjected to artificially generated surface blast-induced ground motion by using a three-dimensional finite element model. The mosque is located in the town of Kavak of Samsun, in Turkey. This study intended to determine the ground motion acceleration values due to blast-induced ground motions (air-induced and direct-induced) calculated by a random method. In order to model blast-induced ground motion, firstly, peak acceleration and the time envelope curve function of ground motion acceleration were obtained from the distance of the explosion center and the explosion charge weight and then blast-induced acceleration time history were established by using these factors. Non-stationary random process is presented as an appropriate method to be produced by the blast-induced ground motion model. As a representative of blast-induced ground motion, the software named BlastGM (Artificial Generation of Blast-induced Ground Motion) was developed by authors to predict ground motion acceleration values. Artificial acceleration values generated from the software depend on the charge weight and distance from the center of the explosion. According to the examination of synthetically generated acceleration values, it can be concluded that the explosions cause significant effective ground movements. In the paper, three-dimensional finite element model of the minaret was designed by ANSYS. Moreover, the maximum stresses and displacements of the minaret were investigated. The results of this study indicate that the masonry minaret has been affected substantially by effects of blast-induced ground motion.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2016.12.036
      Issue No: Vol. 3, No. 1 (2017)
       
  • HVAC systems: measurements of airflows in small duct length

    • Authors: Clito Félix Alves Afonso
      Pages: 38 - 46
      Abstract: One of the most feasible ways to measure duct airflows is by tracer gas techniques, especially for complex situations when the duct lengths are short as well as their access, which makes extremely difficult or impossible other methods to be implemented. One problem associated with the implementation of tracer gas technique when the ducts lengths are short is due to the impossibility of achieving complete mixing of the tracer with airflow and its sampling. In this work, the development of a new device for the injection of tracer gas in ducts is discussed as well as a new tracer-sampling device. The developed injection device has a compact tubular shape, with magnetic fixation to be easy to apply in duct walls. An array of sonic micro jets in counter current direction, with the possibility of angular movement according to its main axle ensures a complete mixing of the tracer in very short distances. The tracer-sampling device, with a very effective integration function, feeds the sampling system for analysis. Both devices were tested in a wind tunnel of approximately 21m total length. The tests distances between injection and integration device considered were: X/Dh=22; X/Dh=4; X/Dh=2; and X/Dh=1. For very short distances of X/Dh=2 and X/Dh=1, semi empirical expressions were needed. A good reproducibility of airflow rate values was obtained. These preliminary tests showed that the practical implementation of tracer gas techniques in HVAC systems for measuring airflow rates with a very short mixing distance is possible with the devices developed.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2016.11.027
      Issue No: Vol. 3, No. 1 (2017)
       
  • Universal size effect of concrete specimens and effect of notch depth

    • Authors: Sıddık Şener, Kadir Can Şener
      Pages: 47 - 51
      Abstract: The universal size effect law of concrete is a law that describes the dependence of nominal strength of specimens or structure on both its size and the crack (or notch) length, over the entire of interest, and exhibits the correct small and large size asymptotic properties as required. The main difficulty has been the transition of crack length from 0, in which case the size effect mode is Type 1, to deep cracks (or notches), in which case the size effect mode is Type 2 and fundamentally different from Type 1. The current study is based on recently obtained comprehensive fracture test data from three-point bending beams tested under identical conditions. In this test, the experimental program consisted of 80 three-point bend beams with 4 different depths 40, 93, 215 and 500mm, corresponding to a size range of 1:12.5. Five different relative notch lengths, a/D = 0, 0.02, 0.075, 0.15, 0.30 were cut into the beams. A total of 20 different geometries (family of beams) were tested. The present paper will use these data to analyze the effects of size, crack length. This paper presents a studying to improve the existing universal size effect law, named by Bazant, using the experimentally obtained beam strengths for various different specimen sizes and all notch depths. The updated universal size effect law is shown to fit the comprehensive data quite well.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2017.02.003
      Issue No: Vol. 3, No. 1 (2017)
       
  • Non-linear behaviour modelling of the reinforced concrete structures by
           multi-layer beam elements

    • Authors: Mourad Khebizi, Hamza Guenfoud, Mohamed Guenfoud
      Pages: 52 - 57
      Abstract: A two-dimensional multi-layered finite elements modeling of reinforced concrete structures at non-linear behaviour under monotonic and cyclical loading is presented. The non-linearity material is characterized by several phenomena such as: the physical non-linearity of the concrete and steels materials, the behaviour of cracked concrete and the interaction effect between materials represented by the post-cracking field. These parameters are taken into consideration in this paper to examine the response of the reinforced concrete structures at the non-linear behaviour. Two examples of application are presented. The numerical results obtained, are in a very good agreement with available experimental data and other numerical models of the literature.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2016.11.034
      Issue No: Vol. 3, No. 1 (2017)
       
  • Effect of time step size on stress relaxation

    • Authors: Abdullah Fettahoğlu
      Pages: 58 - 62
      Abstract: Many materials used in industry show time and temperature dependant stress strain relationship. While essentially most of the materials exhibit stress relaxation or in general viscoelastic material properties, some of them are assumed as linear elastic to be able to make their stress calculations simpler. On the contrary, there are some materials showing intense viscoelastic stress strain relationship even at lower temperatures and short time periods. Most of these materials are employed in construction industry as pavements on roads or bridges and needed a better understanding of their viscoelastic material properties and calculation methods for their design. For a better understanding and comparison between several material products in industry, their stress strain behavior shall be evaluated. Stress relaxation of materials, which shows time and temperature dependant properties, is investigated in this paper. For that reason first, relaxation test results existed in the literature are used to verify the numerical stress relaxation calculation of commercial FEM program, ANSYS. Second, the determination of Prony series parameters and the commands to be entered in ANSYS to perform stress relaxation are given. Finally, the amount of error in the numerical calculation depending on time step sizes at different temperatures is presented.
      PubDate: 2017-03-10
      DOI: 10.20528/cjsmec.2016.11.029
      Issue No: Vol. 3, No. 1 (2017)
       
  • Teaching-learning based optimization for parameter estimation of double
           tuned mass dampers

    • Authors: Sinan Melih Niğdeli, Gebrail Bekdaş
      First page: 90
      Abstract: The classical methods for parameter estimation of tuned mass dampers are well known simple formulations, but these formulations are only suitable for multiple degree of freedom structures by considering a single mode. If special range limitation of tuned mass dampers and inherent damping of the main structure are considered, the best way to estimate the parameters is to use a numerical method. The numerical method must have a good convergence and computation time. In that case, metaheuristic methods are effective on the problem. Generally, metaheuristic method is inspired from a process of life and it is formulated for several steps in order to reach an optimal goal. Differently from the single tuned mass dampers, double tuned mass dampers can be also used for the reduction of vibrations. In civil structures, earthquake excitation is a major source of vibrations. In this study, optimum double tuned mass dampers are investigated for seismic structures by using a wide range of earthquake records for global optimum. As an optimization algorithm, teaching learning based optimization is employed. In this algorithm, the teaching and learning phases of a class are modified for optimization problems. The optimization of double tuned mass damper is more challenging than the single ones since the number of design variable is doubled and the design constraint about the stroke of the both masses must be considered. The proposed method is compared with the existing approaches and the methodology is feasible for parameter estimation of double tuned mass dampers.
      PubDate: 2016-11-18
      DOI: 10.20528/cjsmec.2016.11.032
      Issue No: Vol. 2, No. 3 (2016)
       
 
 
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