Improved MPS model for concrete creep under variable humidity and temperature

Abstract

The creep of concrete is significantly affected by ambient temperature and humidity. In design codes, the influence of ambient temperature and humidity on concrete creep is approximately considered by correction coefficient terms. However, this method is not suitable for creep analysis of specific structure under complex temperature and humidity environments. At present, the Microprestress-Solidification (MPS) theory is widely adopted to analyze the complex influence of temperature and humidity on concrete creep. However, the MPS theory still has some shortcomings (The MPS theory fails to reflect the size effect in drying creep. Besides, the humidity dependence of transient thermal creep cannot be correctly modeled.). On the basis of MPS theory, this paper makes some appropriate corrections and modifications: firstly, the evolution equation of micro-prestress S is reasonably updated by redefining the relationship between the long-term creep viscosity and micro-prestress S. Meanwhile, based on the thermodynamics, the influence of temperature and humidity variation on the evolution of micro-prestress S is reformulated and the transient thermal creep effect is modified to be humidity-dependent. In order to verify the improved MPS model, experiment data in literatures are adopted to make verifications. Results prove the correctness of the modifications and the practicability of the improved model.