Effect of Strengthening Vertical Circular Openings with Various Materials on the Behaviour of Reinforced Concrete Beams.

Abstract

Opening in beam develops cracks around the region where the opening is as a result of stress concentration, this opening causes reduction in the beam strength and load carrying capacity as well. This work presents the effect of strengthening of vertical circular openings with various materials on the behaviour of Reinforced rectangular Concrete beam with dimension of 200mm x230mm x700mm.The effect of strengthening of openings was studied in terms of ultimate failure load, flexural strength and maximum deflection. It was observed that strengthening of vertical circular opening has an increase in load capacity and strength. The solid beam gives an average failure load of 251625N with flexural strength of 16.25N/mm2.The unstrengthen circular opening at L/4 and L/8 distance gives an average decrease in ultimate load of 28% and 32% with strength of 13N/mm2 and 12N/mm2 respectively. With steel plate strengthening of 4mm gauge, the ultimate load carrying capacity of the beam increases by 15% and 17% with flexural strength of 15N/mm2 each at a distance of L/4 and L/8 respectively as compared to beam with un strengthen opening. Using galvanize steel pipe of 2mm thickness increases the ultimate load by 9% and 11% with flexural strength of 14N/mm2 at a distance of L/4 and L/8 respectively. While the use of STM increases ultimate load by 3% and 5% with strength of 13N/mm2 at a distance of L/4 and L/8 respectively.