Journal of Computational Engineering and Physical ModelingJournal of Computational Engineering and Physical Modeling
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Feed provided by Journal of Computational Engineering and Physical Modeling. Click to visit.Determining the Drift in Reinforced Concrete Building using ANFIS Soft Computing Modeling
http://www.jcepm.com/article_53677_6612.html
Earthquakes are considered as one of the most significant natural disasters that can potentially cause significant damages to structures. Displacement of buildings’ floors is one of the serious failures in structures caused by earthquakes. In this paper, the drift of a concrete frame with the shear wall is estimated using ANFIS modeling. A dataset of 300 measured data points was used herein as the inputs for the ANFIS model. The dataset has totally six input parameters including frequency, magnitude, peak ground acceleration (PGA), and shear wave velocity (Vs) of an earthquake and the distance from the earthquake epicenter to use in the ANFIS model, while the model has just one output. Moreover, a sensitivity analysis was performed on the dataset in order to determine the efficiency of the individual input variables on the accuracy of the results. The results demonstrate that the ANFIS model is an effective model for predicting the drift in reinforced concrete structures. Finally, according to sensitivity analysis, the acceleration and shear wave velocity of an earthquake have the highest and lowers impacts on the accuracy of the results, respectively.Sun, 31 Dec 2017 20:30:00 +0100Numerical Simulation of Concrete Mix Structure and Detection of its Elastic Stiffness
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Concrete mix stiffness (CM) primarily relies on its ingredients, which mainly consists of stone aggregate and mortar. To analyse the role of the components of CM on its properties a numerical simulation of CM structure is conducted. Within the scope of this study, the structure and the properties of CM are simulated using ANSYS code to apply the finite element method (FEM). The size of aggregate is modelled using direct random nodes and elements and the problem is approximated as two-dimensional plane one. Different ratios of aggregate and mortar were considered to determine their influence on the stiffness of CM. The CM is treated as bi-composite and subjected to compressive loading. For determining the influence of the proportion of stone aggregate on the stiffness of CM, the used specimens only differ in the amount of stone aggregate and their shapes. Although the stone aggregates are assumed to be of cylindrical shapes (plane conditions), the compressive stiffness of CM works well with the mixture rule.Sun, 31 Dec 2017 20:30:00 +0100Reliability-Based Investigation on Compressive Strength Characteristics of Structural-Sized ...
http://www.jcepm.com/article_54890_6612.html
This research work examined the reliability of the Nigerian grown Iroko and Mahogany timber species as column materials. The strength and physical properties of these timber species were determined to predict the suitability of the species as structural material. Forty lengths of timber species of 50mm x 50mm cross-section were purchased from timber market in Ilorin, Nigeria. The prevailing environmental conditions during the test were 31oC and 64% relative humidity. The properties tested included; air dry density, moisture content and compressive strength parallel to grain of forty test specimens each of lengths, 200, 400, 600 and 800mm done in accordance with the British Standard BS 373(1957). Mean air-dried moisture content for Iroko and Mahogany were 12.09 and 14.81% respectively. Mean density of Iroko and Mahogany were 500.8 and 830.1kg/m3 respectively. The derived continuous equations for design of Iroko column and Mahogany column are σ=ć37.552eć^(-0.005λ) and σ=ć37.125eć^(-0.007λ) respectively. The results of the reliability analysis show that Iroko and Mahogany timber species have reliability index of 0.64 and 0.65 for a service life of 50 years, assuming other serviceability conditions are met. This design procedure is distinct and more effective than the usual procedure of classifying compression members as short, intermediate and long using their slenderness ratios.Sun, 31 Dec 2017 20:30:00 +0100Seismic Fragility Assessment of Local and Global Failures in Low-rise Non-ductile Existing RC ...
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The brittle behavior of older non-ductile reinforced concrete buildings such as shear-axial failure in columns can cause lateral instability or gravity collapse. Hence, the attempt is to assess the collapse potential through fragility curves. Current research focuses on fragility assessment of these buildings emphasizing on shear-axial failure using two well-established methods; empirical limit state material versus ASCE/SEI 41-13 recommendations. To this aim, two 2D reinforced concrete models (3 and 5-story) according to typical detail of existing buildings in Iran were modeled using two aforementioned modeling approaches and analyzed under monotonic analysis and incremental dynamic analysis (IDA). In the following, seismic fragility assessment were carried out by means of obtained results from IDA. The results of fragility curves showed that, collapse capacity of buildings modelled by ASCE/SEI 41-13 are more than empirical method and fewer cases can pass the level of safety probability of failure suggested by ASCE/SEI-41.Sun, 31 Dec 2017 20:30:00 +0100The Effect of Diagonal Stiffeners on the Behaviour of Stiffened Steel Plate Shear Wall
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In the current study, the nonlinear behavior of the stiffened steel plate shear wall with diagonal stiffeners is numerically studied. After nonlinear pushover analysis, the finite element modeling results are compared with un-stiffened and stiffened steel plate shear walls, with the horizontal and vertical stiffeners. First, a finite element model of steel plate shear wall is developed and validated by using Abaqus software. After assuring the behavior of the boundary elements (beams and columns) and the infill steel plate, the finite element models of the steel shear walls are developed and analyzed using nonlinear pushover method. Steel plate shear wall models are designed according to AISC 341-10 Seismic Provisions. Finally, the obtained results and the behavior of finite element models are compared with each other. The important seismic parameters (initial elastic stiffness, ultimate shear strength, and ductility) are calculated and percentage of changes are discussed. Based on the results, the performance of steel plate shear walls with diagonal stiffeners enhances as compared with unstiffened steel plate shear walls.Sun, 31 Dec 2017 20:30:00 +0100Settlement Modelling of Raft Footing Founded on Oferekpe/Abakaliki Shale in South East Region ...
http://www.jcepm.com/article_60119_6612.html
In engineering practice, settlement of foundations are experimentally determined or numerically modelled based on conventional saturated soil mechanics principles. The study area, Oferekpe in Abakaliki LGA of Ebonyi State, South Eastern Region of Nigeria is characterised with sedimentary formations highly susceptible to compression under applied load. The study was aimed at evaluating raft footing settlement by both analytical and numerical modelling methods and determine the effect of raft thickness on settlement. Standard penetration test (SPT) data was used to correlate soil properties that were used together with laboratory results to obtain the input parameters used for the prediction of settlement. Four footing embedment depths of 1.5, 3.0, 4.5 and 6.0 m with applied foundation pressures of 50, 100, 200, 300, 400 and 500kN/m2 were considered using a raft footing dimension of 20 x 20 m2 at varying thickness of 0.5, 0.75 and 1.0 m. The numerical modelling finite element application package used was Plaxis 3D. For applied pressure of 100 kN/m2 and at footing embedment depths of 1.5, 3.0, 4.5 and 6.0 m, settlement values of (21.89, 11.51, 9.04 and 6.52), (19.70, 8.60, 6.41 and 4.39), (25.62, 14.88, 12.05 and 9.27) and (25.20, 11.59, 5.57 and 2.58) were respectively predicted by the elastic, semi-empirical, empirical and finite element methods. The elastic method of predicting foundation settlement proposed by Steinbrenner yielded a very close range results generally to those predicted by finite element method. It was generally observed that thickness of raft footing has no significant effect on the predicted settlement.Sun, 31 Dec 2017 20:30:00 +0100Flow and Pollutant Dispersion Model in a 2D Urban Street Canyons Using Computational Fluid Dynamics
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A two-dimensional model is used to simulate temperature distribution, wind speed and pollutants dispersion within an isolated two-dimensional street canyon using SIMPLE algorithm in ANSYS Fluent version 16.2. The simulation is based on the Reynolds-averaged Navier–Stokes equations coupled with a series of standard, RNG and realizable k-ε turbulence models. Simulation domain consisted of a street canyon with two buildings enclosing a street with the aspect ratio of 1. The wind is assumed to be perpendicular to the direction of the street and the source of the pollution is assumed to be liner. The results showed that the RNG k-ε turbulence model is the most optimum model by comparing with the calculated data under different wind speed patterns and pollutant dispersion model. The improvement of turbulent viscosity term of the RNG k-ε turbulence model provides a more accurate and reliable numerical solution for the present study regarding to the pollution dispersion in a street canyon. The simulation results also showed that the dimensionless pollutant concentrations, P, is larger on the leeward side of the buildings and decrease exponentially from floor to top of the upstream buildings. Furthermore, the results showed that the pollutant concentrations on the leeward side of building are more than that on the windward side due to the pollutant transportation of vortex circulation.Sun, 31 Dec 2017 20:30:00 +0100