Finite element analysis and design of retrofitted beam-to-column joints with welded haunches

Abstract This paper presents numerical investigations on the design of beam-to-column joints retrofitted by welded haunches. Finite element models (FEMs) were developed and validated against experimental results. A FE parametric study was then conducted concerning some critical characteristics, including the axial column load, haunch height, and haunch dip angle. The numerical results generated herein were utilised to evaluate the moment resistance given by the European, American, Japanese, and Chinese standards and the elastic rotational stiffness provided by the European and Japanese standards. Results showed that the improved moment resistance of enlarged panel zones depended mainly on the haunch height and axial column compression. The reversal of the shear force in shear plates would be more significant following the increase of haunch dip angles and the decrease of haunch heights. Although welded haunches reinforced both the panel zone and the beam, the yielding of joint assemblies was still dominated by the yielding of panel zones. Moreover, the Eurocode overestimated the elastic rotational stiffness by 16.1%–25.1%, and the Chinese standard overestimated the resistance by 12.6%–33.1%. In contrast, predictions by the Japanese code agreed well with FE results. The design methods were proposed based on the parametric analyses and comparisons, including the recommended configurations, mechanical behaviour calculations, moment-rotation behavioural model, and checking procedures.