Rice husk ash is a product confirming to engineering requirements in terms of physical and chemical properties. In this study the effect of RHA as a partial cement replacing material with the addition of Human hair fiber were carried out. A total of 20

The most interesting aim of this research is to assess the capability of artificial neural networks (ANN) to predict the post-fire residual stress-strain curve of unconfined plain and fibrous concretes under axial compression. In this study, the experimental variables are volume fractions of flat crimped steel fibers and polypropylene fibers, inclusion of hybrid fibers and temperature of exposure under natural cooling. A total number of 126 cylindrical specimens of different types of concrete were prepared. These specimens were then exposed to the elevated temperatures ranging from room temperature to 800 °C, and the mechanical properties were evaluated. Based on the test results, an ANN model is developed for the prediction of complete residual stress-strain responses of plain and fiber-reinforced concrete at elevated temperatures. The Levenberg-Marquardt (LM) algorithm has been used in the training. The performance parameters MSE and R values were obtained as 2.2944e−03 and 0.9885, respectively. The stress-strain curves of different samples were predicted and compared with the curves which were obtained experimentally. A good match between the predicted and experimentally obtained stress-strain curves can be observed. An equation based on the weights between the artificial neurons and biases of ANN model was also proposed in this study. The proposed ANN model is unified in nature as this single model is capable in predicting the stress-strain curves for all ranges of temperatures and various compositions of added fibers.

Summary In this study, constitutive relationships have been developed for confined concrete subjected to elevated temperature to specify the fire‐performance criteria for concrete structures after exposé to fire. This study extends over a total of 63 circular hoop confined concrete specimens that were casted and tested under concentric compression loading after exposure to high temperature. The test variables studied are the yield strength of transverse reinforcement, spacing of the hoop, and exposure to temperatures from ambient to 800°C. It is shown that all of these variables have significant influence on concrete behavior at different temperatures and further an improvement in the thermal resistance of concrete when confined using transverse steel reinforcement. On the basis of experimental results, a model for confined concrete after exposed to high temperature is proposed to predict the results of residual behavior after thermal cycles. The proposed empirical stress‐strain equations are suitable to predict the postfire behavior of confined normal strength concrete in compression. The predictions were found to be in good agreement and well fit with experimental results.

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