Kang-Seok Lee

This study proposes a novel seismic retrofitting method involving a reinforced concrete (R/C) frame infilled with precast modular reinforced blocks (PMRBs) to address the limitations of conventional infilling techniques. The retrofitting system for the R/C frame infilled with PMRB maximizes the advantages of factory‐produced modular reinforcement blocks, considerably improving the constructability and joint integrity between the existing frame and the reinforcement, without substantially increasing the structural weight. Moreover, this approach uses a typical frame‐infilling method to enhance lateral load capacity, simplifying the calculation of the required amount of seismic reinforcement; thus, it is ideal for R/C buildings with non‐seismic detailing dominated by shear failure because it helps secure the necessary strength. A pseudo‐dynamic test was conducted using a full‐scale two‐story frame test specimen, based on an existing R/C building with non‐seismic detailing, to verify the restoring force characteristics, strength‐increasing effects, reinforcement strain and seismic response control capabilities of the PMRB frame‐infilling system. Nonlinear dynamic finite element analysis (FEA) was performed to compare and estimate the results of the pseudo‐dynamic test. The study results showed that the average deviation ratio for the seismic response load and displacement between the nonlinear dynamic FEA and the pseudo‐dynamic test was approximately 10%, indicating similar outcomes. Under a design basis earthquake of 200 cm/s² in seismic intensity, the unreinforced R/C frame experienced shear failure, whereas the PMRB‐reinforced frame sustained only minor earthquake damage, even under seismic accelerations of a maximum considered earthquake of 300 cm/s² and a large‐scale earthquake of 400 cm/s². Thus, the newly developed PMRB frame‐infilling system shows great promise for seismic reinforcement.