Efficiency Assessment of RC Jacket Applied on a Distressed RC Column Using Different Codal Provisions

Abstract

Reinforced structural elements undergo damage when they are subjected to external agencies such as earthquakes, exposure to fire and ageing due to environmental factors. When important reinforced concrete (RC) structures undergo damage that is within a repairable limit, repair or retrofit strategies are adopted to restore the strength, stiffness and stability of such damaged buildings. In this work, an RC column is considered having the dimensions 250 mm × 500 mm × 3200 mm. The RC column in this study is cast with concrete having a compressive strength of 18 N/mm2. The distress in this case is in the form of low compressive strength of concrete leading to low load-carrying capacity. Due to this reason, a strength modification of the concrete compressive strength in the RC column is required to enhance the load-carrying capacity. In this case, the RC column is retrofitted with the external application of reinforced concrete (RC) jacket around it. The RC jacket retrofitting method is applied when the increase in the load-carrying capacity to be enhanced is more than 25%. The reinforced concrete jacketing which is to be provided around the distressed RC column is designed by Indian codal provisions (IS 15988: 2013) and ACI codal provisions (ACI 318: 2008) separately. The design parameters provided and obtained using these codes are compared. From this study, the optimum thickness of the RC jacket applied is also evaluated. The Indian codal provision takes into account an upper bound while considering the factor of safety for design and leading to the overestimation of design parameters and quantities. The effectiveness of design with respect to the strength can be achieved by considering the optimum requirement of the quantities as per ACI codal provisions such that the cost of the overall retrofit can be minimized.