فهرست مطالب

Civil Engineerng Infrastructures Journal - Volume:52 Issue: 2, 2019
  • Volume:52 Issue: 2, 2019
  • تاریخ انتشار: 1398/09/10
  • تعداد عناوین: 12
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  • Saman Rashidyan *, Arup Maji, Tang Tat Ng Pages 205-224

    Sonic Echo (SE) testing method is a well-known, versatile method to gather information pertaining to unknown bridge foundations. Many studies on the applicability and methodology improvement of SE tests to evaluate individual piles and foundations supporting the superstructure have been reported previously. However, there is a rare opportunity for obtaining the performance of SE tests without the bridge deck. In the current study, three piles of a dismantled unknown bridge foundation were tested.  Unusual vibrations on velocity signals were found which are independent of the location of the sensors. Such signals do not contain identifiable echoes from the pile toe. Therefore, they cannot be used to determine the depth of the piles. The results and observations of this study show that there is little future application for conducting SE tests on bridges that are out of service.

    Keywords: foundation, Nondestructive, Pile, Sonic Echo, wood
  • Seyyed Ahmadreza Shahangian, Massoud Tabesh *, Mohammad Hossein Mirabi Pages 225-243
    The aim of this paper is numerical and experimental study of the effects of flow hydraulics, pipe structure (particularly elastic behaviour) and submerged jet on leak behaviour. In this regard, experimental tests were performed on a high-pressure circulation set up. Experiments were performed on an old steel pipe and a High Density Polyethylene (HDPE) pipe discharged to the atmosphere in a wide range of pressures up to 50 m. To analyze the leak behaviour, the effect of the surrounding environment and the pressure on leak area, the experimental setup was modeled by ANSYS software. Then, the numerical model was validated using experimental results and used to analyze and generalize leakage results in other situations. The results indicated that: 1) Standard k-ε turbulence model showed a better performance and relatively better results in modelling leakage in comparison with the other turbulence models, 2) Combining the Finite Volume and Finite Element methods for taking into account the impact of pressure allowed simultaneous examination of the pipe hydraulics and the structure of the leak area to obtain more reasonable results from hydraulic analysis of the flow and pipe structure, 3) Pressure fluctuations in the submerged jet affect the leakage discharge so that it is reduced compared to discharging to the atmosphere, 4) it was observed that the leakage exponent is close to the theoretical value of 0.5, considering the effect of pressure head on leak area behaviour. Furthermore, there is a linear relationship between pressure head and leak area for elastic pipes.
    Keywords: Leak Area, Leak Behaviour, Leakage Exponent, Pipe Structure, Submerged Jet
  • Ahmad Mechaymech, Joseph Assaad * Pages 245-263
    The main objective of this paper is to assess the effect of different viscosity-enhancing admixture (VEA) types and concentrations on deformability and stability of self-consolidating concrete (SCC). Two polysaccharide-based VEAs, one cellulose-based VEA, and a modified-startch VEA are used in this investigation. Regardless of polymer type, results showed that the incorporation of VEA leads to reduced passing ability represented by higher difference between the slump flow and J-Ring tests. The rheological properties followed an enhancing trend with VEA additions, given the higher degree of association and entanglement of polymer chains that increase resistance to flow. For given VEA dosage of 0.035%, mixtures made with cellulose VEA showed the highest stability levels including deformability and resistance to bleeding and surface settlement. Series of predictive charts are established to predict the changes in SCC stability as a function of rheological properties.
    Keywords: Admixture Compatibility, Rheology, Self-Consolidating Concrete, Stability, Viscosity-Enhancing Admixture
  • Milad Mohammadi *, Amir Tarighat Pages 265-275
    The production of ordinary Portland cement (OPC) as the most expensive constituent of concrete is associated with destructive environmental effects and significant energy consumption. Thus, the use of supplementary cementitious materials such as Natural or synthetic pozzolans is a fundamental solution that affects the kinetics of hydration of cementitious materials. In this article, to evaluate the effect of ball clay in the presence or absence of silica fume on the performance of cementitious materials, compressive strength and ultrasonic tests were performed at replacement weight percentages of 0, 10 and 20% for ball clay and 0 and 7% for silica fume. Also, thermodynamic modeling during hydration was carried out based on the Gibbs free energy minimization. The results showed that mere presence of ball clay does not have a positive effect, but it can improve the structure and strength of cement in the presence of silica fume, since it resulted in complete consumption of portlandite and consequently increasing C-S-H gel. In addition to examine the type and volume of phases formed during hydration, the optimum substitution of ball clay and silica fume was studied. Accordingly, the best overall performance of ball clay was observed in the 10% substitution in the presence of 7% silica fume.
    Keywords: Ball Clay, compressive strength, Hydration, Thermodynamic Modeling, Ultrasonic Pulse Velocity
  • Hossein Karimi, Iradj Mahmoudzadeh Kani * Pages 277-293
    Like other structures, shallow domes have imperfections from the prescribed values obtained by specifications during the construction process. Specifications define some tolerance values for imperfections. Despite consideration of these values, the critical load of a dome varies for each imperfection pattern. So the reliability plays an important role in domes safety. Theoretical evaluation procedure is the most accurate one to obtain reliability function, but it is only applicable to small structures. Semi-empirical evaluation procedure, on the other hand, is more implemented. In the present research reliability of real domes with stochastic initial imperfections has been investigated by comparing finite elements method, theoretical and semi-empirical results. Also, it has been shown that the automatic perturbed analysis is not sufficiently reliable for domes. So it is recommend that a suitable safety factor be applied on the automatic perturbed load or the method utilized in this paper be used to obtain the critical load – reliability diagram.
    Keywords: Bifurcation, Finite Elements Method, Monte Carlo method, reliability, Shallow Domes
  • Mohammad Hossain Jalal Kamali, Abolfazl Hasani *, Javad Sodagari Pages 295-308

    Abrasion susceptibility of highway pavements has a great impact on the skid resistance, and consequently accident rate. A rotational abrasion device is introduced, providing the advantage of field simulation of wheel passage, in comparison with existing standard methods. The device was used to measure abrasion susceptibility of concrete pavements with different textures. The obtained results were evaluated using the standard Wide Wheel Abrasion Test. It is shown that there is a good conformity between abrasion rates acquired from the two tests. The results also show that negative textures, such as grooving, lead to a highly variant unreliable outcome in Wide Wheel Abrasion Test. The brushed samples (perpendicularly or parallelly brushed) underwent the highest abrasion level due to high interaction between texture and wheel (the average final measured abrasion amount is 90% more in brushed samples compared to non-textured samples). Since Rotational Abrasion Test is able to apply extensive loading, its results, as compared to the other test, is not susceptible to random surface protuberances or cavities (burlap dragged and grooved samples).

    Keywords: Abrasion Resistance, Concrete Abrasion, Concrete Macrotexture, Rotational Abrasion Test, Wide Wheel Abrasion Test
  • Hadi Sabermahany *, Morteza Bastami Pages 309-322
    Analytical methods presented to analyze the buried steel pipelines at strike-slip fault crossing use the Euler-Bernoulli beam theory. The cross-section of a buried pipe that is completely surrounded by soil cannot rotate freely and would not be remained perpendicular to the bending line after deformation. So it would be better to take into consideration a rotation between the cross-section and the bending line. The developed model improves the existing methodologies by using the Timoshenko beam theory and considering the shear deformations as a refinement to the existing methodologies. The proposed model results are compared with the results of an existing analytical model and it is found that the maximum bending and axial strains decrease with taking into consideration the shear deformations. Furthermore, it is shown that the difference between the results of models increases with an increase in the burial depth.
    Keywords: Buried Steel Pipelines, Stress-Strain Analysis, Strike-Slip Fault Crossing, Structural Design Of Pipelines, Timoshenko Beam Theory
  • Aref Alipour *, Sharareh Alipour Pages 323-334
    Benford’s law predicts the frequency of the first digit of numbers met in a wide range of naturally occurring phenomena. In data sets, following Benford’s law, numbers are started with a small leading digit more often than those with a large leading digit. This law can be used as a tool for detecting fraud and abnormally in the number sets and any fabricated number sets. This can be used as an effective tool for processing data sets from laboratory tests, site investigation tests data, geotechnical design (both financial and technical) in engineering and specially included in geotechnical engineering and, etc. In this paper, data sets from geotechnical data are gathered and analyzed. It is shown that most of them follow Benford’s law. Therefore, we can use this observation for similar applications to detect the validity of data. Also, this can be assumed as an evidence for natural numbers that follow Benford’s law.
    Keywords: Benford’s law, Data processing, Geotechnical Data
  • Mohammad Mahdi Dibaee, Amir Kavussi * Pages 335-348
    Fatigue characteristics of asphalt binder have an important role in asphalt mix resistance against cracking. Viscoelastic Continuum Damage (VECD) analysis of asphalt binders has been successfully used in highway research works in order to predict fatigue behavior of hot mix asphalt (HMA). In this method an intrinsic property of the material, called damage function is obtained which is independent of damage path. However, achieving damage function needs application of various loading paths and a trial and error procedure. In this study, a quick characterization procedure has been proposed to implement VECD analysis that results in fatigue prediction of HMA. The procedure is comprised of a testing setup, along with the analysis required to derive VECD parameters from experimental data. The test consists of a stepwise loading scheme including a few strain levels with relatively large increments in between. Subsequently, an optimization method has been introduced to be performed on the test results, to yield damage function, i.e. modulus as a state function of Internal State Variable (ISV). The analytical framework leading to the optimization problem, along with its solution methods are presented. Consequently, the fatigue life prediction model has been obtained, relating the change in shear modulus to loading conditions such as strain level and frequency. Eventually, the introduced characterization method was validated, comparing the results with those achieved in conventional procedure. The validation showed that the results of optimization and conventional methods agree, with an acceptable precision.
    Keywords: Asphalt Binder, fatigue, Fatigue Accelerated Test, Viscoelastic Continuum Damage
  • Seyed Ehsan Vakili *, Peyman Homami, M. R. Esfahani Pages 349-363
    This study evaluated the effect of macro steel fiber (SF), micro glass fiber (GF) and micro polypropylene fiber (PF) in lightweight aggregate concrete, (LWAC) beams reinforced with glass fiber reinforced polymer (GFRP) bars. Firstly, concrete mixtures with different volume fractions of GF, PF and SF were tested up to compressive strength, then determine the optimum fiber content GF, PF and SF added into LWAC mix by 0.3%, 0.8% and 0.25% by the volume of concrete, respectively. Meanwhile, eight rectangular cross-section beams with 100 mm (width) × 200 mm (depth) × 1500 mm (length) were tested by four-point bending beam test up to the ultimate load. The GFRP bars were used to reinforce all beams. The failure modes, load-deflection behavior, ductility, flexural capacity and energy absorption were compared in the test results. The experimental results shown added fibers into LWAC improved the flexural capacity, ductility and energy absorption also enhanced moment capacity by 10.07% to 110%. The results indicated that failure modes of GF and PF specimens were in good consistency with the ACI 440.1R-06 predicted failure modes, but for SF specimens, only concrete crushing failure modes accrued. At the end step, the correction factor ( ) obtained from calculated of the experimental results with the flexural capacity according to the ACI 440.1R-06 and ISIS design manual No. 3.
    Keywords: GFRP Bar, Lightweight Aggregate Concrete, Macro Steel Fiber, Micro Glass Fiber, Micro Polypropylene Fiber
  • Morteza Madhkhan *, Saeed Bahrami Pages 365-377
    Precast concrete structures in Iran are generally designed as continuous columns with hinged beams, thereby making them simple frames. In this system in site show walls in two directions of buildings guaranteed lateral resisting system. However, in order to obtain a seismic resisting frame, the connection between beam and column should be moment resisting and ductile, allowing the formation of plastic hinges at these connections as well as at the column base. In this paper, experimental tests were conducted for precast concrete elements with modified beam-column connection under cyclic load. The precast connection considered for this study was a semi precast beam with welded longitudinal bars to embedded plate into beam where the beam is connected to corbel with welding embedded plated to plate on the corbel. According to the results, the connection shows suitable performance until drift of 2.75% in terms of stiffness, damping and moment resistance.
    Keywords: Concrete Corbel, energy dissipation, Precast Beam-Column Connection
  • Elahe Ebrahimi, Gholamreza Abdollahzadeh *, Ehsan Jahani Pages 379-395
    In order to increase the accuracy of evaluating seismic response of structures, it is critical to conduct dynamic analyses based upon precise nonlinear models being as consistent as possible with the real conditions of corresponding structures. The concentrated plasticity model including one elastic element and two nonlinear spring elements at both ends has been considered within the research community for simulating beams and columns, counting the effect of strength and stiffness degradation. In this type of simulation, the axial force ratio generated in each structural component, which is a major factor in introducing nonlinear springs, has always been considered constant in the literature. The main objective of the present research is, therefore, to modify the fundamental weakness in this type of modeling approach; indeed, any variation of element’s axial effort, owing to redistribution of axial forces during an earthquake, is applied in the calculation of parameters of the concentrated plasticity model as a decisive step toward the development of nonlinear dynamic analysis. Moreover, an algorithm is presented for implementing this approach in the OpenSees software. Verification is established and the efficiency of the proposed method is illustrated through a reinforced concrete moment frame subjected to a specific record, as a case study building. Regarding the results, it is confirmed that the proposed algorithm is an appropriate tool for achieving quite a realistic nonlinear model and estimating reasonably accurate responses of structural systems with cyclic degrading behavior under earthquake loading.
    Keywords: Axial Load Variation, Lumped Plasticity Model, Nonlinear Dynamic Analysis, RC-Structures, Seismic Response