Basic creep formula for aging concrete. Sinh-Double power law

An alternative simple formula for the compliance function for basic creep of concrete is proposed and evaluated. It consists of a hyperbolic sine combined with the double power law. For short creep durations it asymptotically approaches the double power law, and for very long durations it asymptotically approaches the logarithmic law, which is the same behavior as for the previously formulated log-double power law. The formula allows a good fit of basic creep data from the literature. It presents them as well as the log-double power law and better than the double power law, although the difference is not large. Compared to the double power law, a significant improvement is obtained in the final slope of the creep curves. Compared to the log-double power law, the proposed formula is somewhat better for extension into the short-time dynamic range.