Fatigue resistance of partially prestressed concrete beams

Experimental Investigations on the behaviour of partially prestressed concrete (PPC) beams under pulsating loads have been conducted and the results reported. The object is to study the influence of partial prestressing ratio on deflections, crack widths, stresses and strains in concrete and steel and on the fatigue life of the beams. The main input variable is the Partial Prestressing Ratio (PPR). Four different levels of PPR's have been taken in the experimental study. These beams are tested in cyclic fatigue at a constant load range varying between 40% and 60% of the ultimate load capacity of the beam. A computer program has been developed for the ultimate load analysis of partially prestressed concrete sections by strain compatibility method. The fatigue resistance of the beams is found to be more and loss of static strength is less with small PPR's. The increase in deflections and increase in crack widths of the beams have been stabilised when PPR is less. The residual deflections are found to be more in the case of high PPR.