The effect of location of post drilled web opening on the strength of reinforced concrete beam

Abstract

The construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as electricity, air conditioning, telephone, and network cables. Web openings in Reinforced Concrete (RC) beams enable the installation of these services under lower floor to floor height without compromising any architectural headroom. However, the requirement of opening often reaches the engineers and contractors after the beam has been constructed. As such, there is a need to reassess the new strength of the beam with the newly added opening without the placement of trimmer reinforcement bar. Methods to assess the reduced strength of the RC beams due to post drilling these opening are often complicated. To overcome this, a research has been carried out with the aim to provide simple guidance to engineers to access the new strength of the RC beams due to small post drilled transverse circular web openings at different location of the beam. RC beams with a series of opening at different location were analysed using LUSAS, by conducting nonlinear analysis to determine the new strength of the RC beam. A graph of relative load bearing capacity of an RC beam with respect to location of post drilled web opening is proposed to aid design engineers to assess the beam capacity without a need for detail calculation.