Seismic retrofitting for factories or warehouses with inadequate seismic performance can be hindered by operational disruptions and fire risks. This study introduces a novel method that involves attaching strengthening members to existing structures using high-strength bolts. Cyclic loading tests were conducted on braced frames with varying eccentricities to investigate the influence of the eccentricity and bolted connections. The test results indicate that an increase in brace eccentricity leads to a reduction in stiffness and strength of braced frame. Furthermore, the proposed structural model accurately evaluates the stiffness and strength of braced frames with eccentric braces.