Faculty Publications
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Item Strength deformation behaviour of circular concrete filled steel tubes subjected to pure bending(2009) Chitawadagi, M.V.; Narasimhan, M.C.The strength deformation behaviour of circular steel tubes filled with different grades of concrete under flexure is presented. The effects of steel tube thickness, the cross sectional area of concrete, strength of in-filled concrete and the confinement of concrete on moment capacity and curvature of Concrete Filled steel Tubes (CFTs) are examined. Measured flexural strengths are compared with the values predicted by EC4-1994 and LRFD-AISC-1999 code provisions. A total of ninety nine specimens, all one metre long, were tested with concrete fills of 20, 30 and 40 N/mm2 characteristic strength and with D / t ratio 22.3 to 50.8. Based on the experimental results, an interaction model to predict moment and curvature of the CFT sample is developed. © 2009 Elsevier Ltd. All rights reserved.Item Axial strength of circular concrete-filled steel tube columns - DOE approach(Elsevier Ltd, 2010) Chitawadagi, M.V.; Narasimhan, M.C.; Kulkarni, S.M.This paper presents the effect of changes in diameter of the steel tube (D), wall thickness of the steel tube (t ), strength of in-fill concrete (f cu), and length of the tube (L) on ultimate axial load (P ue) and axial shortening at the ultimate point (?ue ) of circular Concrete Filled steel Tubes (CFT). Taguchi's approach with an L9 orthogonal array is used to reduce the number of experiments. With the help of initial experiments, linear regression models are developed to predict the axial load and the axial shortening at the ultimate point. A total of 243 circular CFT samples are tested to verify the accuracy of these models at three factors with three levels. The experimental results are analyzed using Analysis Of Variance to investigate the most influencing factor on strength and axial shortening of CFT samples. Comparisons are made with predicted column strengths using the existing design codes, AISC-LRFD-2005 and EC4-1994. © 2010 Elsevier Ltd. All rights reserved.Item Axial capacity of rectangular concrete-filled steel tube columns - DOE approach(2010) Chitawadagi, M.V.; Narasimhan, M.C.; Kulkarni, S.M.This paper presents the effect of change in wall thickness of the steel tube (t), strength of in-filled concrete (fcu), cross-sectional area of the steel tube (A) and length of the tube (L) on ultimate axial load and axial shortening at ultimate point of rectangular concrete-filled steel tubes (CFT). Taguchi's approach with an L9 orthogonal array is used to reduce the number of experiments. With the help of initial experiments, linear regression models are developed to predict the ultimate axial load and the axial shortening at ultimate point. A total of 243 rectangular CFT samples are tested to verify the accuracy of these models at three factors with three levels. The experimental results are analyzed using Analysis Of Variance to investigate the most influencing factor on strength and axial shortening of CFT samples. Comparisons are made with predicted column strengths using the existing design codes, AISC-LRFD-1994 and EC4-1994. © 2009 Elsevier Ltd. All rights reserved.