Study on Torsional Behaviour of Retrofitted Rectangular RC Beams with Web Openings

Abstract

In modern building construction web openings become necessary to provide utility ducts like water supply lines, air conditioning ducts etc. These ducts cause potential weakness in any construction hence affecting strength, serviceability and stability of the structure. There will be more adverse impact on structures if web opening has to pass through the beams or columns. Sometime in unavoidable situations openings are essential to pass through existing load bearing elements of structure hence required to strengthen externally to restore the strength. External jacketing by glass, carbon, basalt fibre fabrics provides a popular, simple and effective method for restoring the strength capacity of such elements. Many research works have been published on behaviour of retrofitted RCC beams with opening of different size and shapes especially under shear and flexure. Very few works are published to study the effect of beams with opening in torsion. The aim of the present work is to experimentally investigate the behaviour of rectangular RCC beams with rectangular small and large openings. The beams are retrofitted with GFRP fabrics of different orientations and width. GFRP strips of widths 10cm and 20cm fiber orientations (90/90/90/90/90) and (45/90/45/90/45) are used for retrofitting. The behaviour of beams were studied in terms of collapse load, torsional moment vs angle of twist, failure patterns.