Long-Term Tension-Stiffening Effects in Concrete

The authors have reported some very interesting data on the behavior of axially loaded reinforced concrete prisms in tension. An analysis of one of the authors' specimens was performed using the approach proposed by Choi et al. Tension stiffening is modeled using a simple bilinear stresss-train relationship. The same relationship was used for time-dependent response employing the age-adjusted effective modulus approach to account for creep. Better correlation could be obtained by replacing the post-peak response with a nonlinear function that initially decreases more rapidly, but at higher strains, increases at a slower rate. For flexural members, the decay in tension stiffening may be fairly rapid; however, the time-dependent response will still be largely determined by creep of concrete in the compressive zone so that the incremental deflection may still be the desired criterion to satisfy.