Therefore, we will also make predictions based on a best estimate of KIc, a material state property which governs crack growth under LEFM conditions. We are aware that most field-observed fractures have initiated around the bottom weld, probably because of concrete slab effects and higher weld quality in the top weld. We do not know whether this latter effect will be present in the present test. Therefore, we offer best-estimate fracture predictions based on both criteria. The Finite Element Model Figure 1 shows our 2D geometry and finite element models.
All elements are quadratic-order, isoparametric, with appropriate thickness.
The uncracked model had about 12,000 DOF, and this increased to about 15,000 DOF for the longest crack modeled. Predicted curvilinear crack trajectories were governed by the appropriate fracture theory, and were not constrained by the mesh. All analyses were performed on a DEC 3000 Model 300 engineering workstation, and each solution step typically required about 1 minute of computer time. The hypothesis is that, if fracture occurs, it will initiate in the beam-column flange weld. This value will control fracture initiation if LEFM is valid.