Fracture Investigation of Welded Cruciform Connections

Abstract

As one of the main failure modes of steel structures, fracture in welded connections has widely been discussed based on experimental investigations and numerical simulations. However, the mechanical properties of the weld and Heat Affected Zone (HAZ), such as stress-strain relationships and fracture strains under various stress states, have rarely been considered in these analyses. Therefore, in this paper, the fracture process of welded connections is discussed to investigate the effects of the inhomogeneity of mechanical properties in the weld zone. Tensile tests are conducted on welded cruciform specimens fabricated using 8 mm or 12 mm fillet welds and finite element models are developed by considering or ignoring the material inhomogeneity in the weld zone. The simulation results are compared with the experimental and it is concluded that the assumption of homogenous properties within the weld zone using the properties of the base metal will underestimate the strength of the welded cruciform specimens and using the mechanical properties of the three material areas in the weld zone will increase the accuracy of the simulation results. Using the free parameters calibrated by the fracture strains of the three material areas, the fracture process of the welded cruciform specimens is simulated using the fracture model LMVGM, and the comparison shows that the mechanical properties of the weld and HAZ should be included in the investigation of fracture in welded connections to obtain reliable simulation results.