Journal of Soft Computing in Civil EngineeringJournal of Soft Computing in Civil Engineering
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Feed provided by Journal of Soft Computing in Civil Engineering. Click to visit.Neural Network based model to Estimate Dynamic Modulus E* for mixtures in Costa Rica
http://www.jsoftcivil.com/article_89875_9647.html
Various dynamic modulus (E*) predictive models have been developed to estimate E* as an alternative to laboratory testing. The most widely used model is the 1999 I-37A Witczak predictive equation based on North American mixtures laboratory results. The differences in material properties, traffic information, and environmental conditions for Latin American countries make it necessary to calibrate these models using local conditions. Consequently, the National Laboratory of Materials and Structural Models at the University of Costa Rica (in Spanish, LanammeUCR) has previously performed a local calibration of this model based on E* values for different types of Costa Rican mixtures. However, further research has shown that there is still room for improvement in the accuracy of the calibrated model (Witczak-Lanamme model) based on advanced regression techniques such as neural networks (NN). The objective of this study was to develop an improved and more effective dynamic modulus E* predictive regression model for mixtures in Costa Rica by means of NN based models. A comparison of the predicted E* values among the Witczak model, Witczak-Lanamme model and the new and improved model based on artificial neural networks (E* NN- model) indicated that the former not only met the model adequacy checking criteria but also exhibited the best goodness of fit parameters and the lowest overall bias. The findings of this study also supported the use of more advanced regression techniques that can become a more attractive alternative to local calibration of the Witczak I-37A equation.Sun, 31 Mar 2019 19:30:00 +0100Evolutionary algorithm performance evaluation in project time-cost optimization
http://www.jsoftcivil.com/article_89544_9647.html
The time-cost trade-off problem pertains to the assessment of the best method of activity construction so that a project is completed within a given deadline and at least cost. Although several evolutionary-type of algorithms have been reported over the last two decades to solve this NP-hard combinatorial problem, there are not many comparative studies independently evaluating several methods. Such studies can provide support to project managers regarding the selection of the appropriate method. The objective of this work is to comparatively evaluate the performance potential of a number of evolutionary algorithms, each one with its own variations, for the time-cost trade-off problem. The evaluation is based on two measures of effectiveness, the solution quality (accuracy) and the processing time to obtain the solution. The solution is sought via a general purpose commercial optimization software without much interference in algorithm parameter setting and fine-tuning in an attempt to follow the anticipated project manager approach. The investigation has been based on case studies from the literature with varying project size and characteristics. Results indicate that certain structures of genetic algorithms, particle swarm optimization, and differential evolution method present the best performance.Sun, 31 Mar 2019 19:30:00 +0100Application of Soft Computing Techniques in Predicting the Ultimate Bearing Capacity of Strip ...
http://www.jsoftcivil.com/article_89749_9647.html
The present study attempts to predict the ultimate bearing capacity (UBC) of the strip footing resting on sand and subjected to inclined load having eccentricity with respect to the vertical using three different soft computing techniques such as support vector mechanism with radial basis function (SVM RBF kernel), M5P model tree (M5P) and random forest regression (RFR). The UBC was computed in the form of reduction factor and this reduction factor was assumed to be dependent on the ultimate bearing capacity (qu) of the strip footing subjected to vertical load, eccentricity ratio (e/B), inclination ratio (α/ϕ) and the embedment ratio (Df/B). The performance of each model was analyzed by comparing the statistical performance measure parameters. The outcome of present study suggests that SVM RBF kernel predicts the reduction factor with least error followed by M5P and RFR. All the model predictions further outperformed those based on semi-empirical approach available in literature. Finally, sensitivity analysis performed for the SVM RBF kernel model which suggests that the inclination ratio (α/ϕ) and eccentricity ratio (e/B) was an important parameter, in comparison to other parameters, considered for predicting the reduction factor.Sun, 31 Mar 2019 19:30:00 +0100MODELLING OF CONCRETE COMPRESSIVE STRENGTH ADMIXED WITH GGBFS USING GENE EXPRESSION PROGRAMMING
http://www.jsoftcivil.com/article_91665_9647.html
Several studies have established that strength development in concrete is not only determined by the water/binder ratio, but it is also affected by the presence of other ingredients. With the increase in the number of concrete ingredients from the conventional four materials by addition of various types of admixtures (agricultural wastes, chemical, mineral and biological) to achieve a desired property, modelling its behavior has become more complex and challenging. Presented in this work is the possibility of adopting the Gene Expression Programming (GEP) algorithm to predict the compressive strength of concrete admixed with Ground Granulated Blast Furnace Slag (GGBFS) as Supplementary Cementitious Materials (SCMs). A set of data with satisfactory experimental results were obtained from literatures for the study. Result from the GEP algorithm was compared with that from stepwise regression analysis in order to appreciate the accuracy of GEP algorithm as compared to other data analysis program. With R-Square value and MSE of -0.94 and 5.15 respectively, The GEP algorithm proves to be more accurate in the modelling of concrete compressive strength.Sun, 31 Mar 2019 19:30:00 +0100Application of random forest regression in the Prediction of ultimate bearing capacity of strip ...
http://www.jsoftcivil.com/article_89975_0.html
The paper presents the prediction of the ultimate bearing capacity of the strip footing resting on dense sand overlying loose sand deposit using random forest regression. In this study, 181 data collected from literature were used. 71 % of the total data was randomly selected for training the model and the rest of the data were utilized for the testing purpose. The various input parameters were friction angle of the dense sand layer (1), friction angle of the loose sand layer (2), unit weight of the dense sand layer (1), unit weight of the loose sand layer (), ratio of the thickness of the dense sand layer below base of the footing to the width of footing (H/B), ratio of the depth of the footing to the width of the footing (D/B) and (H+D)/B. Ultimate bearing capacity was the output in this study. Performance measures were used in order to make the comparison with the artificial neural network and M5P model tree. The result of this study reveals that the performance of the random forest regression was superior to the other soft computing techniques. The results of the sensitivity analysis reveals that the unit weight and the friction angle of the loose sand layer were the most important parameters affecting the output ultimate bearing capacity of the strip footing resting on the layered sand deposit.Thu, 04 Jul 2019 19:30:00 +0100