A limit states design method for welded tension connections to I-section webs

Abstract

Abstract Tension branch members welded orthogonally to the web of an I-section (wide flange member) often have a width which approaches that of the clear distance between the I-section's root fillets, especially if fillet welding of the branch member is involved. The strength of such connections has typically been determined by simple yield line analyses, with sometimes a uniform punching shear check also being incorporated. However, when the ratio, β′, of the branch member width (including welds) to the clear distance between the I-section root fillets approaches unity, connection strength estimates by both the classical yield line method and the punching shear model become extremely unsafe. This is demonstrated by 11 tension tests on such connections which are described in the paper. The actual failure mode for these connections having a high β′ value involves simultaneous flexure of the I-section web and shearing of the web material at the toes of the fillet welds adjacent to the I-section flunges. This action can be best represented by a combined flexural and punching shear yield line model which is proposed by the authors. By comparison with the test results this model is shown to provide a much better estimate of the connection ultimate strength than do either the simple yield line or the uniform punching shear models. Hence it is used as the basis for a limit states method which is described for these connections.