Stress-strain models and numerical simulations of high-strength steel Q690E and Q960E at low temperatures

To promote the analysis/design of high-strength steel (HSS) Q690E/Q960E structures, this paper firstly devel-oped stress-strain (cr-e) constitutive models of HSS Q690E/Q960E at different low temperatures (T) of-80,-60,-30, and 20 degrees C. The prediction equations on key parameters in the cr-e constitutive models (e.g., yield/ultimate/ fracture strength and their corresponding strains, and elastic modulus) of HSS Q690E/Q960E at varying low temperatures were developed. Validations against 39 test results confirmed that proposed constitutive models offered reasonable estimations on the low-temperature cr-e constitutive models of HSS Q690E/Q960E. Finite element models (FEMs) with the continuum damage plasticity model (CDPM) and proposed cr-e models were developed for HSS Q690E/Q960E materials at ambient/low temperatures. Validations of FEM simulations against 39 tensile tests on HSS coupons proved that the FEMs with CDPM predict well cr-e behaviours of HSS Q690E/Q960E at -80-20 degrees C. This paper also developed FEMs with CDPM to simulate the low-temperature compression behaviour of HSS Q690E/Q960E tubular columns. Validations against six compression tests confirmed that the FEMs with the CDPM and proposed cr-e constitutive models were capable of simulating the HSS Q690E/Q960E structural members.