Journal of Structural Engineering and Geo-TechniquesJournal of Structural Engineering and Geo-Techniques
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Feed provided by Journal of Structural Engineering and Geo-Techniques. Click to visit.An investigation into a Geocell-reinforced Slope in The Unsaturated Numerical Model
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Considering unsaturation conditions of soil significantly helps to produce relatively real results. Numerical methods have been assumed as conventional methods in soil mechanics to examine soil behavior. However, the accuracy of numerical methods dramatically depends on applying the appropriate behavioral model to solve problems. One of the known elastoplastic models for unsaturated soils is the Barcelona Basic Model which is added to FLAC2D software through codification. Geocell-reinforced slope functions as a beam in the soil due to the three dimensional nature of the reinforcement, i.e. height is included. Furthermore, the reinforcement causes a reduction in slope displacement and an increase in the factor of safety of slope due to its bending characteristics including moment of inertia and consequently bending strength. Moreover, soil unsaturated conditions are applied to the modelling and suction variations in soil are incorporated. This makes the maximum horizontal displacement of slope occur in the upper part of the Geocell layer while the horizontal displacement values for the slope height are substantially reduced below the Geocell layer. Increasing suction, geocell axial force declines by at most 18.5%. As overhead pressure increases, there is an increase in the force concentrated at the soil-geocell interface and the tensile force is consequently enlarged in reinforcements. Sat, 30 Mar 2019 19:30:00 +0100Deep Excavation Hazard Assessment Zoning in District 1 in Shiraz Municipality Using Geographic ...
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This research presents the geotechnical zoning map of district 1 in Shiraz municipality with focus on municipal deep excavation hazard assessment on data from 160 boreholes. For this purpose, the mechanical properties are determined according to the results of direct shear, uniaxial, and SPT tests and then excavation hazard assessment with depths of 3, 6 and 9 m, in situations where the excavation depth of the neighbor foundation is below 0 and 0 to 20 meters have been calculated. Finally, using ArcGIS software, the assessment hazard excavation for 6 different modes was zoned and the zoning map of the assessment hazard excavation with the normal, high and very high hazard index is provided. The zoning maps shows that with increasing depth of excavation, the danger is increased, so that in maps whit depth of excavation of 9 meters, more than 90 percent of points have high hazard index.Sat, 30 Mar 2019 19:30:00 +0100Mix Design Selection For Old and New Generation of SuprePlasticizers
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Determination the optimal mix design plays an important role in order to gain the maximum characteristic strength. This research was conducted as a case study for Manjil tunnel project located in Qazvin-Rasht highway. For this purpose, 18 concrete mix designs were prepared at the study phase of the project with specifications such as conventional water-to-cement ratios of 0.4, 0.5 and 0.6, the use of two generations of new and old conventional superplasticizer in Iran (naphthalene sulphonate and polycarboxylate ether types, respectively) with cement weight percentages of 0.2, 0.4 and 0.6. Superplasticizers are used to increase the fluidity of concrete without adding excess water. The naphthalene sulphonate is a polymeric molecule formed by condensation of naphthalene sulfonic acid and formaldehyde, in which the hydrophilic groups are mainly sulfonic groups. It has been demonstrated that polycarboxylate ether can mitigate plastic shrinkage of matrix because of the reduction of the build-up rate of capillary pressure by polycarboxylate ether. Finally, the optimal water-to-cement ratio and superplasticizer weight percentage were determined. Concrete mix designs with different ages of curing were made (0, 3, 7, 14 and 28 days).Sat, 30 Mar 2019 19:30:00 +0100Behavior Study of Cemented Specimen by Biological Technique after Disturbance
http://www.qjseg.ir/article_665797_1133025.html
With the population growth and consequently the requirement for development of civil constructions, it is necessary to design appropriate foundations for resisting structural loads. Soil weakness in bearing capacity of geotechnical elements has forced the researchers to continuously follow a solution to compensate for this deficiency. Within the past two decades, many studies have been carried out regarding the performance of this technique in optimization of the soil. One technique which is nowadays highly considered due to compatibility with the environment, high efficiency and low cost, is Biological Optimization Technique. One of the characteristics of this type of optimization is its ability for recovering after disturbance. In this research it has been tried to analyze the behavior of cemented specimens after disturbance and reconstruction. For this purpose, after construction of cubic specimens with dimensions of 2*6*6 cm and applying the disturbance and reconstruction, their shear strength under different vertical stresses has been evaluated by direct shear test.Thu, 30 May 2019 19:30:00 +0100Determination of Lateral load Capacity of Steel Shear Walls Based on Artificial Neural Network ...
http://www.qjseg.ir/article_665835_1133025.html
In this paper, load-carrying capacity in steel shear wall (SSW) was estimated using artificial neural networks (ANNs). The SSW parameters including load-carrying capacity (as ANN’s target), plate thickness, thickness of stiffener, diagonal stiffener distance, horizontal stiffener distance and gravity load (as ANN’s inputs) are used in this paper to train the ANNs. 144 samples data of each of this parameters was calculated using SSW simulation in abaqus. Load-carrying capacity of SSW was estimated using radial basic function (RBF) and multi-layer perceptron (MLP) neural networks. Spread parameter in RBF and number of hidden layer, number of neurons in this layers and activation function in MLP optimized using a trial and error method. The results showed that the load-carrying capacity of SSW could estimate using RBF and ANN by 84 and 96 percent of precision respectively.Sat, 30 Mar 2019 19:30:00 +0100Investigating the Effect of natural Pozzolans on Mechanical Properties of Roller Compacted Concrete
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Roller Compacted Concrete (RCC), is a concrete with zero slump, which is used in damming and road pavement. Roller Compacted Concrete Pavement (RCCP) bear heavy traffic loads and severe weather conditions. This type of concrete is due to its economic and environmental capabilities, including reduced construction and maintenance costs, longer durability and longer lifetime, as well as environmental compatibility. This paper presents the results of laboratory studies on the effect of natural pozzolan (zeolite) on the mechanical properties of RCC specimens. In this study, cement materials of were used The rheological performance test (VeBe) and compressive and tensile strengths at the age of 7, 14 and 28 days and the flexural strength tests at 14 and 28 days were performed on the specimens. The results show that the higher amount of pozzolan reduced concrete efficiency (the time of VeBe increased). In addition, the compressive, tensile and flexural strength of the samples are decreased, significantly. However, reducing resistance does not mean compliance with the requirements of the Code.Thu, 28 Feb 2019 20:30:00 +0100