Experimental validation of different approaches in modelling tensionstiffening of bending members reinforced with steel and GFRP bars

Abstract

In the present study, deformation behaviour of bending members reinforced with steel and glass fibre reinforced polymer (GFRP) bars have been investigated using four tension-stiffening approaches: 1) Stress transfer; 2) Fracture mechanics; 3) Concrete related average stress-average strain; 4) Reinforcement related average stress-average strain. The analysis was based on the experimental results obtained by the authors. The stress transfer approach was implemented in a numerical algorithm, taking into account bond stress-slip behaviour of the tensile reinforcement. The fracture mechanics approach was represented by finite element software ATENA. Using the third and the fourth approaches, average stress-average strain tensionstiffening relationships were derived by the inverse analysis technique proposed by the authors. It was also shown that shrinkage occurring prior to loading might have quite significant influence on the results of derivation of constitutive relationships. The comparative study gave new insights into constitutive modelling of tension-stiffening.