EXPLOITING STRAIN HARDENING IN STRUCTURAL STEEL DESIGN

摘要

The present generation of international structural steel design codes treat material nonlinearity through simplified elastic-plastic or rigid-plastic material models. However, the actual stress-strain response of structural steel is more complex than this and features, in particular, strain hardening. Strain hardening refers to the increase in strength beyond yield as a result of plastic deformation. The influence of strain hardening on the behaviour and design of steel structures is examined in this study and a method to exploit the additional capacity that arises is outlined. The proposed design method, referred to as the Continuous Strength Method (CSM), is a deformation based design approach employing a continuous relationship between cross-section slenderness and cross-section deformation capacity, together with a material model that allows for strain hardening. This provides a unified methodology for the calculation of a cross-section's ultimate resistance to combinations of axial force and bending moments. Where possible comparisons are made between test results collected from existing studies, and the capacity predictions from the CSM and Eurocode 3 (EC3). For all cases considered, the Continuous Strength Method, through a rational exploitation of strain hardening, offers a more accurate prediction of observed physical behaviour.