Applying moment redistribution and externally bonded FRP in beams for seismic strengthening of RC frames

Abstract

The approach for seismic strengthening of RC frames using moment redistribution and externally bonded FRP is especially applicable for enhancing the performance of a building that is designed prior to the introduction of the new seismic codes. The design and detailing requirements for these building categories were conducted following the capacity design principle. Based on the more recent codes, these buildings are under-designed, and seismic strengthening has become mandatory. Additionally, the buildings might need to be strengthened to fulfill the stringency design requirements of modern seismic building codes. The moment redistribution theory is based on the principles of transferring a moment to sections with lower stresses when the peak moment reaches the ultimate capacity of the section. The redistribution of moments has to be established before all the critical sections can attain their ultimate flexural strength. FRP materials are characterized by their high strength and lightweight. Externally bonded FRP is relatively cost-effective, less invasive, and easily implementable because of the minimal surface preparation. Apart from the moment capacity increase, externally bonded FRP could also improve the shear capacity at critical sections through confinement to an area within the boundaries of the FRP.