AD 431: Column web panel strengthening

Figure 1: Vierendeel bending around column web panel

The purpose of this Advisory Desk note is to draw attention to the contribution that full-depth stiffeners make to the shear resistance of column web panels.

SCI publication P398 covers the design of moment–resisting connections to Eurocode 3 and provides information on types of column strengthening in Table 2.1. Within this table, horizontal stiffeners are not credited with increasing the shear resistance of the web panel.

The special case of full depth stiffeners in both the tension zone and the compression zone is covered by clause 6.2.6.1(4) of BS EN 1993-1-8. This clause allows an additional contribution to the web panel shear resistance, based on the bending resistance of the flanges and the stiffeners which bound the web panel. The stiffeners and flanges can be envisaged as part of a Vierendeel truss, as shown in Figure 1.

If this additional contribution is to be utilised, the transverse stiffeners should be full depth and approximately the same width and thickness as the column flanges. The welds between the stiffeners and the flanges should be full strength, because the full plastic moment resistance of the stiffeners is assumed in the calculation.

Contact: Richard Henderson
Tel: 01344 636555
Email: advisory@steel-sci.com