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Title: Effect of Initial Stress Levels on Strength of Beams Retrofitted Using Pre-Stressed Fibre Composites
Authors: Mehta, Ankur
Supervisor: Bansal, Prem Pal
Keywords: Beams;Pre-Stressed Fibre Composites
Issue Date: 25-Nov-2011
Abstract: Many existing structures now-a-days are unable to give their service effectively. Due to various reasons, they get deteriorated or get damaged much before the time for which they are designed for. The evaluation of the damage can be measured by various non-destructive tests, pulse velocity tests etc. In view of this, the word comes “Retrofitting” which simply means to repair the structures or to increase the strength of the structures to increase their service life. Various structures like bridges, dams, for which rehabilitation is very difficult, in such cases retrofitting can be used as an effective measure. There are various methods for this like jacketing, shear wall, infill wall etc., apart from these conventional methods Fibre composites can be used very effectively. A lot of research is being carried on all across the globe for the use of Fibre composites for retrofitting. On the lights of the above discussion, a research is carried on to study the effect of initial stress levels on retrofitting of beams. In other words the effect of the extent of damage in the beams is studied on the retrofitting using pre-stressed carbon fibre sheets. For this the beams of size 600mm×300mm are used which are stressed to three different initial stress levels taken respectively from elastic zone, elasto-plastic zone and plastic zone from the load-deflection plot of the beam taken as control specimen. These initially stressed beams are then retrofitted using pre-stressed fibre composite mechanism. The effect of these initial stress levels on retrofitting are then studied. Through this study it is observed that load carrying capacity of the retrofitted beams is remarkably improved compared to that of fresh control beam. The control specimen is failed at 94.35kN and the retrofitted beams are seen to be failed in the range of 125kN to 136kN. Subsequent decrease in the deflection is also seen as compared to that of the fresh control beam at all the stress levels. The 53% stressed beam showed the maximum deflection whereas the 100% stressed beam showed the minimum deflection with overall decrease of around 65% of that of control beam. Stiffness has also increased after retrofitting at all stressed levels as compared to the control beam. The 53% and 89% stressed beams showed almost same stiffness but the 98% stressed beam showed the maximum stiffness with increase of around 25% of that of control specimen.
Description: M.E. (Structures)
Appears in Collections:Masters Theses@CED

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