Simplified Bending Capacity Formulation Based on the Continuous Strength Method

Abstract

ABSTRACTIn the frame of the current revision of the Eurocodes, there is a trend to simplify the existing design formulae while, at the same time, providing higher efficiency and reliability. To consider the effect of strain hardening present in the material behaviour of stainless steel, advanced design formulae are proposed in the 4th edition of the Design Manual for Structural Stainless Steel. The method called the continuous strength method (CSM), is a deformation‐based design approach that uses a bilinear hardening material model, leading to the introduction of several new parameters depending on which stainless steel family is considered and one additional design formula for the cross‐section verification. The CSM was proven to be accurate for austenitic, duplex and ferritic grades.The idea developed in the present paper is that there exists a reasonable and equally accurate approximation of the cross‐section capacity considering hardening through the combination of the elastic and plastic section modulus. The concept uses the current well‐known plastic section modulus and, to deal with the hardening effect, an additional contribution is added for which an equation is proposed. This equation only combines the elastic section modulus, the yield‐to‐ultimate strength ratio as well as their difference. Then, the cross section bending resistance is determined through well‐known cross‐section geometrical parameters.The presented approach is compared to the formulation of the CSM for I‐section and rectangular hollow sections beams, for austenitic, duplex and ferritic grades. It is shown to be only slightly more conservative for hollow sections. The formulation deals with tangible concepts, is easy to apply for daily engineering practice and guarantees a more rational use of the material benefit.