Prem Pal Bansal

Effect of Initial Stress Levels on Strength Parameters of Reinforced Concrete Beams Retrofitted Using Ferrocement Jackets

Ferrocement jackets and sheets can be used for local rehabilitation and retrofitting of structures due to their high tensile strength, light weight, overall economy, water tightness, and ease of application. In the present paper the effects of number of layers of wire mesh in the ferrocement jackets, type of section (balanced or under reinforced) and initial stress level on the strength of retrofitted stressed reinforced cement concrete beams have been studied. The results show that there is higher increase in the maximum load, safe load carrying capacity, ductility and toughness for beams with three layers woven wire mesh ferrocement jackets as compared to beams reinforced with two layers of woven wire mesh. It is further seen that the percentage improvement in above properties decreases with increase in initial stress level and change in type of section from under reinforced to balanced. Subsequently an analytical model, based on principles of compatibility of strain and equilibrium of forces, has been presented to predict the safe and maximum load carrying capacity. It is found that predicted safe and maximum load carrying capacities are within 5 % of the experimental one.

Experimental Study on Retrofitting of Stressed RC Beams using GFRP Jackets

In the present study, the effect of fiber orientation and stress level on the strength of stressed beams retrofitted with GFRP jackets is studied. The beams were initially stressed up to 60, 75, and 90% of their safe load and then retrofitted with GFRP jackets with fibers in different orientations. The results show that the beams retrofitted using GFRP jackets with fibers at 45° to the longitudinal axis yield a higher increase in the maximum load carrying capacity, i.e., approximately 30—35% in case of under-reinforced sections and 13—17% in case of balanced sections as compared to beams retrofitted using fibers at 0° to the longitudinal axis. A considerable increase in the ductility ratio is also observed for both the fiber orientations.

Strengthening of RCC Beams in Shear by Using SBR Polymer-Modified Ferrocement Jacketing Technique

There is a common phenomenon of shear failure in RCC beams, especially in old buildings and bridges. Any possible strengthening of such beams is needed to be explored that could strengthen and make them fit for serviceable conditions. The present research has been made to determine the performance of predamaged beams strengthened with three-layered wire mesh polymer-modified ferrocement (PMF) with 15% styrene-butadiene-rubber latex (SBR) polymer. Forty-eight shear-designed and shear-deficient real-size beams were used in this experimental work. Ultimate shear load-carrying capacity of control beams was found at two different shear-span (a/d) ratios 1 and 3. The sets of remaining beams were loaded with different predetermined damage levels of 45%, 75%, and 95% of the ultimate load values and then strengthened with 20 mm thick PMF. The strengthened beams were then again tested for ultimate load-carrying capacity by conducting the shear load test at a/d = 1 and 3. As a result, the PMF-strengthened beams showed restoration and enhancement of ultimate shear load-carrying capacity by 5.90% to 12.03%. The ductility of strengthened beams was improved, and hence, the corresponding deflections were prolonged. On the other hand, the cracking pattern of PMF-strengthened beams was also improved remarkably.