Design of stainless steel sections with circular openings in shear

•Tests on stainless steel beams of two thicknesses and two grades identify the various forms of local buckling around and between openings.•A simplified model predicts the local stresses around and between the openings.•An approximate treatment of local buckling is based on a buckling wave of 0.2x opening diameter and uses the buckling curve in EN 1993-1-4 for stainless steel.•The method presented in this paper is compared to the test results and also to the method for web openings in hot rolled steel sections in SCI P355.•Finite element methods are shown to be a good tool for predicting local buckling around the openings.

SummaryThis paper addresses the design of stainless steel sections with large circular openings subject to shear and bending. A total of nine tests on pairs of C sections using 2 and 3 mm thick stainless steel in austenitic 1.4301 and lean duplex 1.4162 grades was performed. The tests showed that the shear resistance at an opening is controlled by local compression at a radial cross-section at approximately 25° to the vertical. For closely spaced openings, the angle of highest stress increases to about 65° to the vertical. The shear resistance of a Class 4 web is also affected by local buckling around the opening, which is a function of its diameter to steel thickness ratio. An equilibrium model is presented which predicts the normal stress on the radial planes around an opening. A simplified formula for the local buckling strength around circular web openings is also presented, which agrees well with the test results.