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Weight minimum design of concrete beam strengthened with glass fiber reinforced polymer bar using genetic algorithm

  • Rahman, Md. Moshiur;Jumaat, Mohd Zamin;Islam, A.B.M. Saiful
    • Computers and Concrete
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    • v.19 no.2
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    • pp.127-131
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    • 2017
  • This paper presents a generalized formulation for optimizing the design of concrete beam reinforced with glass fiber reinforced polymer bar. The optimization method is formulated to find the design variables leading to the minimum weight of concrete beam with constraints imposed based on ACI code provisions. A simple genetic algorithm is utilized to solve the optimization task. The weights of concrete and glass fiber reinforced polymer bar are included in the formulation of the objective function. The ultimate limit states and the serviceability limit states are included in formulation of constraints. The results of illustrated example demonstrate the efficiency of the proposed method to reduce the weight of beam as well as to satisfy the above requirement. The application of the optimization based on the most economical design concept have led to significant savings in the amount of the component materials to be used in comparison to classical design solutions.

Corrosion behavior of concrete produced with diatomite and zeolite exposed to chlorides

  • Gerengi, Husnu;Kocak, Yilmaz;Jazdzewska, Agata;Kurtay, Mine
    • Computers and Concrete
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    • v.19 no.2
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    • pp.161-169
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    • 2017
  • Chloride induced reinforcement corrosion is widely accepted to be the most frequent mechanism causing premature degradation of reinforced concrete structures. The electrochemical impedance of reinforcing steel in diatomite- and zeolite-containing concrete exposed to sodium chloride was assessed. Chemical, physical and mineralogical properties of three concrete samples (20% diatomite, 20% zeolite, and a reference containing neither) were correlated with corrosion investigations. The steel-reinforced samples were exposed to 3.5% NaCl solution for 500 days, and measured every 15 days via EIS method. Results indicated that porosity and capillary spaces increase the diffusion rate of water and electrolytes throughout the concrete, making it more susceptible to cracking. Reinforcement in the reference concrete was the most corroded compare to the zeolite and the diatomite samples.

A numerical study on behavior of CFRP strengthened shear wall with opening

  • Behfarnia, Kiachehr;Shirneshan, Ahmadreza
    • Computers and Concrete
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    • v.19 no.2
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    • pp.179-189
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    • 2017
  • Concrete shear walls are one of the major structural lateral resisting systems in buildings. In some cases, due to the change in the occupancy of the structure or functional requirements like architectural and even mechanical ones, openings need to be provided and installed in structural walls after their construction. Providing these openings may significantly influence the structural behavior of the constructed wall. This paper considers the results of a nonlinear finite element analysis of shear walls with opening strengthened by carbon fiber reinforced polymer (CFRP) strips with different configurations. Details of bond-slip constitutive model of link elements to simulate the connections of FRP strips to concrete surface is presented. The proposed model in this research has been validated using experimental results available in the literature. The results indicated that the proposed configuration of CFRP strips significantly improved the lateral resistance and deformation capacity of the shear walls with opening.

Influence of TBM operational parameters on optimized penetration rate in schistose rocks, a case study: Golab tunnel Lot-1, Iran

  • Eftekhari, A.;Aalianvari, A.;Rostami, J.
    • Computers and Concrete
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    • v.22 no.2
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    • pp.239-248
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    • 2018
  • TBM penetration rate is a function of intact rock properties, rock mass conditions and TBM operational parameters. Machine rate of penetrationcan be predicted by knowledge of the ground conditions and its effects on machine performance. The variation of TBM operational parameters such as penetration rate and thrust plays an important role in its performance. This study presents the results of the analysis on the TBM penetration rates in schistose rock types present along the alignment of Golab tunnel based on the analysis of a TBM performance database established for every stroke through different schistose rock types. The results of the analysis are compared to the results of some empirical and theoretical predictive models such as NTH and QTBM. Additional analysis was performed to find the optimum thrust and revolution per minute values for different schistose rock types.

Soil foundation effect on the vibration response of concrete foundations using mathematical model

  • Dezhkam, Behzad;Yaghfoori, Ali
    • Computers and Concrete
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    • v.22 no.2
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    • pp.221-225
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    • 2018
  • In this paper, vibration analysis of concrete foundations resting on soil medium is studied. The soil medium is simulated by Winkler model considering spring element. The concrete foundation is modeled by thick plate elements based on classical plate theory (CPT). Utilizing energy method consists of potential energy, kinetic energy and external works in conjunction with Hamilton's principle, the motion equations are derived. Assuming the simply supported boundary condition for the concrete foundation, the Navier method is used for calculating the frequency of the structure. The effect of different parameters such as soil medium, mode numbers, length to width ratio and length to thickness ratio of the concrete foundation are shown on the frequency of the structure. At the first, the results are validated with other published works in order to show the accuracy of the obtained results. The results show that considering the soil medium, the frequency of the structure increases significantly.

Using generalized regression neural network (GRNN) for mechanical strength prediction of lightweight mortar

  • Razavi, S.V.;Jumaat, M.Z.;Ahmed H., E.S.;Mohammadi, P.
    • Computers and Concrete
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    • v.10 no.4
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    • pp.379-390
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    • 2012
  • In this paper, the mechanical strength of different lightweight mortars made with 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 percentage of scoria instead of sand and 0.55 water-cement ratio and 350 $kg/m^3$ cement content is investigated. The experimental result showed 7.9%, 16.7% and 49% decrease in compressive strength, tensile strength and mortar density, respectively, by using 100% scoria instead of sand in the mortar. The normalized compressive and tensile strength data are applied for artificial neural network (ANN) generation using generalized regression neural network (GRNN). Totally, 90 experimental data were selected randomly and applied to find the best network with minimum mean square error (MSE) and maximum correlation of determination. The created GRNN with 2 input layers, 2 output layers and a network spread of 0.1 had minimum MSE close to 0 and maximum correlation of determination close to 1.

The effect of architectural form on the earthquake behavior of symmetric RC frame systems

  • Inan, Tugba;Korkmaz, Koray;Cagatay, Ismail H.
    • Computers and Concrete
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    • v.13 no.2
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    • pp.271-290
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    • 2014
  • In this study, structural irregularities in plan, which has a considerable effect on earthquake behavior of buildings, have been investigated in detail based on Turkish Earthquake Code 2007. The study consists of six main parametric models and a total of 144 sub-models that are grouped based on RC structural systems such as frame, frame + rigid core, frame with shear wall, and frame with shear wall + rigid core. All models are designed to have both symmetrical plan geometry and regular rigidity distribution. Changes in the earthquake behavior of buildings were evaluated according to the number of storeys, number of axes and the configuration of structural elements. Many findings are obtained and assessed as a result of the analysis for each structural irregularity. The study shows that structural irregularities can be observed in completely symmetric buildings in terms of plan geometry and rigidity distribution.

Experimental and numerical studies on seismic behaviour of exterior beam-column joints

  • Asha, P.;Sundararajan, R.
    • Computers and Concrete
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    • v.13 no.2
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    • pp.221-234
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    • 2014
  • A nonlinear finite element analysis using ANSYS is used to evaluate the seismic behavior of reinforced concrete exterior beam-column joints. The behavior of the finite element models under cyclic loading is compared with the experimental results. Two beam-column joint specimens (SH and SHD) with square hoop confinement in joint and throughout the column with detailing as per IS 13920 are studied. The specimen SHD was provided with additional diagonal bars from column to beam to relocate the plastic hinge formation from beam-column interface. The load-displacement relationship, joint shear stress and strain in beam obtained from numerical study showed good agreement with the experimental results. This investigation proves that seismic behaviour of reinforced concrete beam-column joints under reversed cyclic loading can be evaluated successfully using finite element modeling and analysis.

Design procedure for prestressed concrete beams

  • Colajanni, Piero;Recupero, Antonino;Spinella, Nino
    • Computers and Concrete
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    • v.13 no.2
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    • pp.235-253
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    • 2014
  • The theoretical basis and the main results of a design procedure, which attempts to provide the optimal layout of ordinary reinforcement in prestressed concrete beams, subjected to bending moment and shear force are presented. The difficulties encountered in simulating the actual behaviour of prestressed concrete beam in presence of coupled forces bending moment - shear force are discussed; particular emphasis is put on plastic models and stress fields approaches. A unified model for reinforced and prestressed concrete beams under axial force - bending moment - shear force interaction is provided. This analytical model is validated against both experimental results collected in literature and nonlinear numerical analyses. Finally, for illustrating the applicability of the proposed procedure, an example of design for a full-scale prestressed concrete beam is shown.

Temperature effect on multi-ionic species diffusion in saturated concrete

  • Damrongwiriyanupap, Nattapong;Li, Linyuan;Limkatanyu, Suchart;Xi, Yunping
    • Computers and Concrete
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    • v.13 no.2
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    • pp.149-171
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    • 2014
  • This study presents the mathematical model for predicting chloride penetration into saturated concrete under non-isothermal condition. The model considers not only diffusion mechanism but also migration process of chloride ions and other chemical species in concrete pore solution such as sodium, potassium, and hydroxyl ions. The coupled multi-ionic transport in concrete is described by the Nernst-Planck equation associated with electro-neutrality condition. The coupling parameter taken into account the effect of temperature on ion diffusion obtained from available test data is proposed and explicitly incorporated in the governing equations. The coupled transport equations are solved using the finite element method. The numerical results are validated with available experimental data and the comparison shows a good agreement.