Torque and Twist Response of Under-Reinforced and Completely Over Reinforced Concrete Beams with ‘U’ Ferro Cement Wrap

Structures designed are meant for resisting a certain amount of load for an indented period. Prediction of strength of the structures at cracking and ultimate stage is the prime objective of the structural engineers. Existing structures need to be retrofitted due to increased service loading, diminished capacity through aging and degradation and more stringent updates in code regulations. FRP is now considered as best wrapping material and ferrocement may be considered as a substitute for FRP in developing countries. A full wrap on periphery is required for torsional strength upgradation of structures which may not feasible for all cases. Prediction of torque and twist of torsionally under reinforced and completely over-reinforced beams with ferrocement ‘U’ wrap beams has been presented here as design of a torsionally balanced section may not be feasible always as it depends on many parameters. The above-mentioned parameters can be evaluated from the traditional method by conducting experiments or developing analytical method. The above two methods are not providing quick solutions, rather than the first one is based on destruction of prototype structure for the evaluation of strength. To overcome this, soft computing methods have been employed. Methods like MARS, WASPAS and regression analysis are employed here to compute the torsional parameters of ‘U’ wrapped beams. These methods provide quick solutions to estimate the torque and twist at various stages. Predicted values by these methods are within acceptable limits. The cracking torque of completely over reinforced beam with four layers of mesh was found to be increased by 3.67% over the under reinforced section for normal concrete of grade M35 beam while the same was found to be 4.54% for core concrete of M60. The ultimate torque for completely reinforced beam was found be increased by 56.84% and 68.10% over the under reinforced section for M35 and M60 grade concrete respectively. The ultimate twist of under reinforced beams is enhanced by 73.08% and 27.27% over its completely reinforced sections for concrete grade of M60 and M35 grade concrete respectively.