Strengthening under Load: Experimental and Numerical Research

The paper presents experimental and numerical research of strengthening of columns under load using welded plates. Three sets of three columns each were tested. All columns were 3 m long. The load from loading cylinders was transmitted through knife-edge bearings, which ensured pinned boundary condition perpendicular to the weaker axis. Set (A) comprised columns with welded T shaped cross-section. Set (B) comprised columns with welded monosymmetric I shaped cross-section. Both sets (A) and (B) had been loaded monotonically until collapse occurred. Set (C) contained columns with T shaped cross-section with the same dimensions as the columns in set (A). The columns from set (C) were first loaded to 70 kN. The force was being held constant and the second flange was being welded to the web under load. After the welding process was finished and the specimen cooled, the column was loaded to failure. The average forces at collapse of column sets (A), (B) and (C) were 143kN, 308 kN and 323 kN, respectively. It was unexpected that the columns strengthened under load (C) had higher average resistance than the columns welded without preload (B). It could be caused by the residual stress and distortion caused by welding. The study includes the results of finite element models of the problem created in ANSYS software. The results from the experiments and numerical simulations were compared.