<p>Complete Joint Penetration (CJP) welds are commonly used in many industries such as structural steel-fabrication, pressure vessels, pipelines, nuclear industries, etc. However, CJP weld could be susceptible to defects such as lack of fusion, slag, porosity, etc. The 1994 Northridge earthquake and the 1995 Kobe earthquake revealed that there was a significant loss in the ductility of CJP welded connections due to the presence of defects. There are very limited experimental and numerical studies available to understand the overall behavior and strength of CJP welded connection in the presence of defect. This study aims to bridge this gap. The objective of this study is to understand the influence of defects on ultimate strength and ductility of the CJP welded connection. To achieve this objective, a total of twelve specimens were tested, out of which four specimens were without any defect, while eight specimens had defects in the weld. A process was developed to introduce defects in the CJP weld specimens. A simplified lower bound approach using ductile damage criteria was proposed based on benchmarked finite element models to simulate the weld fracture. Moreover, a parametric study was performed to understand the effects of various parameters such as length and depth of defect, failure criteria, etc. on behavior and ductility of the welded connections. It was found that the welded specimens having no defect were able to reach the ultimate strength and ductility of the base metal. Whereas loss in ductility and strength was observed in the specimens with defects. The loss in ductility as compared to base metal ranges from 30% to 88% for different specimens. The maximum loss in strength was observed to be 12% only for specimens with the worst defect. The study concluded that the depth of defect had significant influence over ductility as compared to length of defect. If the depth of defect (d) is greater than half of plate thickness (d > t/2), it exhibits similar behavior regardless of actual depth. However, no significant influence of defect was observed if the depth of defect was less than t/8.</p>

<p dir="ltr">Steel-plate composite (SC) structures offer superior structural performance and accelerated construction schedules. However, potential construction flaws can compromise their integrity, which are not directly addressed by the existing codes and standards. These potential construction flaws such as voids in concrete, delamination or separation between steel faceplate and concrete infill, defective stud welding, CJP weld defects and plate-plate (module) weld misalignments can compromise their performance.</p><p dir="ltr">This study investigates the impact of potential flaws on SC structures under axial compression, pushout, and axial tension loading. The study also includes a literature review of potential non-destructive evaluation (NDE) methods used for detecting flaws in SC structures. Experimental and numerical analyses were conducted on scaled SC specimens with intentionally introduced flaws. Results indicate that within defined limits, most flaws do not significantly influence the load-bearing capacity of SC specimens, however, can influence the failure modes. Delamination (equal to plate thickness) can significantly affect the interfacial shear behavior and strength of the SC specimens. Steel plate-plate weld misalignment coupled with CJP weld defects can adversely affect both load-bearing capacity and ductility. This study provides guidance and outlines the reduction in strength and changes in behavior (such as failure mode and ductility) caused by flaws mentioned above.</p>