Tension stiffening model for nonlinear analysis of GFRP-RC members

An analytical approach is presented to capture the tension stiffening effect of reinforced concrete member subjected to tensileforces. In this model, the tensile stiffening is described through an analytical relationship of stress-strain law in the cracking range which differs from the CEB-tension stiffening model that is based on the stress-strain curve of reinforcing bars using a bi-linear relationship. The bi-linear relation does not quite capture the post-cracking behaviour of reinforced concrete structures. In view of this, a parabolic branch is selected in the post-cracking phase possessing as asymptotic line to the stress-strain line of the bare bar that minimises the tension stiffening effect at the ultimate load level. This assumption is taken into account in view of material nonlinearities, the bond character and the tension stiffening effect. Analytical results are obtained and compared with experimental data for direct tensile load. In general, the computed results agree well with experimental results. Moreover, the effects of concrete strength, reinforcement ratio and bar diameter on tension stiffening are studied. © 2013 © 2013 The Institution of Engineers, Singapore.