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.