Unified Stochastic Damage Constitutive Relation Of Concrete Under Uniaxial Compression

Concrete is a kind of composite material which has been widely used in architecture. However, the ordinary concrete is not suited any more, for the development of high-level building, super tall large structure and special structure etc. The High Strength High Performance (HSHP) concrete and the Super High Strength High Performance (SHSHP) concrete began to be regarded.The discreteness and randomness, as the inherent characteristics of concrete, bring especially difficulties to the research on the constitutive theory of HSHP concrete, which can not be solved in the existing certainty constitutive models. Stochastic damage constitutive model is a kind of uncertainly constitutive model, which mainly includes two parts: based on the random field theory, introduce the intrinsic property parameters into the stochastic damage model to analyze the evolution law of stochastic damage; the other one is simulating the mortar and coarse aggregate of concrete material with mesoscopic spring model to analyze the stochastic properties to establish the stochastic damage constitutive relationship.The existing researches about constitutive theory of concrete are mainly focused on the ordinary strength concrete, but few researches about HSHP concrete and SHSHP concrete have been reported. The strength grade of concrete is not distinguished in the existing uncertainly stochastic damage constitutive models. Based on the existing stochastic damage constitutive theory, a new stochastic damage constitutive model is introduced to analyze the concrete with different strength grades. The unified stochastic damage constitutive relationship of concrete with different strength grades under the uniaxial compression is established.The uniaxial compression test of HSHP concrete is operated to verify the rationality and accuracy of the constitutive model above. Based on the previous results, the influence of coarse aggregate gradation, sand ratio, efficient water reducing agent, water-binder ratio, curing conditions and the age of concrete on the mechanical property of concrete are analyzed. The uniaxial compression test of concrete samples of different strength grades is operated, comparing the theoretical strain-stress relation curves with the corresponding experimental curves, most of the test datas are fallen between the ranges of one time strain-stress curve. The research results can be applied in the actual engineering, and provide fundamental basis for future development of damage theorem and design.