Damage tracking in laboratory reinforced concrete bridge columns under reverse-cyclic loading using fusion-based imaging

Fusion-based imaging using ground-penetrating radar (GPR) and ultrasonic echo array (UEA) was employed to track damage progression in the columns of two full-scale reinforced concrete (RC) bridge column-footing subassembly laboratory specimens. The specimens had different lap-splice detailing were subjected reverse-cyclic lateral loading simulating a subduction zone earthquake. GPR UEA scans performed on east west faces at select ductility levels. Reconstructed images obtained extended total focusing method (XTFM) fused wavelet-based technique. Composite each column's interior created by merging from both sides. A quantitative analysis based structural similarity (SSIM) index accurately captured progression. backwall amplitude reflector also performed. Changes as early first measurement (μ = 0.5 displacement level) could be detected. Damage variation along column height observed, consistent with greater base. proposed analyses distinguished behavior differences between In summary, SSIM metric provides valuable tool for detecting changes, while offers simple yet informative insights into distribution RC members.