Numerical Study of Panel Zone in a Moment Connection without Continuity Plates

ABSTRACT

Built-up box columns are more frequently used in earthquake-prone regions such as Japan and Iran. As the installation process of continuity plates and welding inspection are difficult, expensive, and time-consuming, this study was aimed at experimentally and numerically investigating continuity plate elimination from built-up box columns with regard to the seismic design specifications of special and intermediate moment resisting frames. Results of an experimental study of three full-scale rigid connections between I-beam and box-column subjected to cyclic loading were used for comparison and verification of numerical results. Experimental study showed that samples reached story drift angle of 0.06 radians before experiencing the permissible strength degradation. Therefore, the tested connections satisfied the criterion for special moment resisting frame (SMRF) in AISC. Based on observations of crack initiation and propagation in the experimental study, a rupture index (RI) was employed to investigate the effects of different complete joint penetration (CJP) groove welding methods used in the experimental study on connection ductility as well as to identify the regions prone to crack initiation and propagation. Both the numerical and experimental results showed the superiority of using back plate in CJP welding.

KEYWORDS:

• Numerical study
• moment connection
• continuity plate
• built-up box column
• seismic design

Notes

¹ For building-up a box column reinforced with continuity plates, a U-shaped section is built first. Then, a continuity plate is welded to three plates using full penetration groove weld. The prepared U-shaped section is covered and welded by a plate with limit length as the fourth side of the box column. The continuity plate is welded to the fourth side of box column by welder, manually. These fourth sides of box column are welded to the U-shaped section at the level of each story, and finally, the parts not covered are completed and welded. Another approach to welding continuity plates inside a tubular column is electro-slag welding, which welds the continuity plates to the fourth side automatically. A laser technology for innovative connections in steel constructions is RFCS LASTEICON, which is a new method. Due to sanctions, this technology is not available in Iran.