CREEP RATE IN CONCRETE 337 Discussion on the Proposed Creep Law

Despite decades of intensive research, an entirely satisfactory constitutive relation for creep in concrete is still unavailable, even for working stress levels [I]. The rate-type creep laws with internal variables [2], although rather effective for numerical creep analysis of large structural systems, seem to be incapable of describing the aging phenomena without at least partially violating some thermodynamic requirements [2]. This suggests that, for a complete description of creep in concrete, an integral-type law might be inevitable.