COST COMPARISON OF CFRP AND STEEL PLATE RETROFITTING OF RC COLUMNS UNDER CONTROLLED DRIFT

Abstract

Retrofitting of existing reinforced concrete (RC) buildings has been a major solution to raise structural capacity, deal with deformation, and prolong service life, especially in cases where the original structures lacked enough stiffness or ductility. As two of the most popular methods for strengthening, retrofitting with steel plates and carbon fiber reinforced polymer (CFRP) have different merits in terms of stiffness improvement, load-carrying capacity, installation needs, and total cost efficiency. For example, while steel plates can significantly increase the strength of a structure, they also increase the dead load considerably as well as require the welding to be done, which is labor-intensive and needs surface preparation. On the other hand, CFRP is a lightweight, high-strength composite material which can be very quickly applied with almost no architectural disruption. This research solely compares these two retrofitting systems by analytical modeling through ETABS and the comparison is based on their impact on stiffness, drift reduction, and structural elements' response, especially beams and columns. Since Bangladesh is located in a seismically active area that is affected by the Himalayan arc, Dauki fault, and Indo-Burman ranges, the retrofitted building model is also checked under BNBC 2020 earthquake loads to see if each method can effectively bring old BNBC 1993/2006-designed structures up to the current drift and lateral load requirements. The findings display that there are clear performance and cost trade-offs: steel plates can give high gains of stiffness but increase the weight of the structure and the complexity of installation, whereas CFRP can achieve very high strength-to-weight ratio and the application is quicker even though the material cost is higher. Thus, the research acts as a comparative performance-cost study that is of assistance to engineers in making the right choice of the most feasible and efficient method for retrofitting to enhance both the seismic resistance and the structural reliability of the existing reinforced concrete buildings in Bangladesh