Comprehensive exploration of technological tensioning effects in welded thin plate girders: an in-depth investigation

Thin-walled plate girders are widely used in structures and construction due to their effectiveness in transferring loads. The permanent deformations of the girder lead to a lack of stability, which necessarily leads to its replacement. Replacing permanently deformed thin-walled load-bearing structures requires large financial outlays. Technological prestressing is one of the most effective methods for studying and treating permanent deflections in girder elements. This study looks at the defection of welded thin-plate S235JR steel girders, examining how technological tensioning effects interact with different loading conditions. Four girders, A2 (welded in bottom caps), A3 (welded in two side caps), and A4 (welded in two side caps and bottom caps), as well as the prestressed B2 girder, which has two welded side caps, were subjected to a bend test. The girders were subjected to a load P (20, 40, 60, 80 and 95) kN. All points were examined during the 95 min of cooling time. For technological compression, the results showed that there is a convergence between the analytical solution and the experimental results, as the most significant deviation achieved in the analysis was 5.21 mm compared to 6 mm experimentally. When the girder is loaded with the force P = 50 N, the maximum deflection achieved at girder A4 is 4 mm, compared with 1mm at girder A2. In prestressed girder B, the deflections that were reached were 2.50 mm, 3.50 mm, and 3.52 mm in the analytical, experimental, and FE numerical models, respectively. The tensions that were reached were 36.96 MPa, 44.28 MPa, and 27.93 MPa.