Multiaxial constitutive model of hybrid fiberrecycled aggregate concrete before and after high temperature
Fires caused by earthquakes may lead to the cracking of recycled concrete,and adding fibers is an effective measure to improve the anticracking performance of recycled concrete.This article investigates the mechanical properties and multiaxial constitutive model of hybrid fiber recycled aggregate concrete(HFRAC)under confining pressure before and after high temperature.The results show that confining pressure has significant influence on the failure mode of HFRAC test block.HFRAC blocks subjected to different temperatures will produce penetrating cracks after uniaxial compression,and the cracks are larger in width.With the increase of confining pressure,the penetrating oblique fractures are gradually replaced by local oblique fractures.Under the action of multi-axial stress,the volume of HFRAC test block decreased significantly after high temperature exposure.An improved failure criterion considering the effect of temperature is established in the octahedral stress space.Considering the effects of steel fiber content,length-diameter ratio and temperature on the stress-strain relationship of HFRAC,an improved triaxial constitutive model is proposed.The experimental results show that the improved constitutive model can more accurately reflect the stress-strain relationship and damage evolution of HFRAC under uniaxial and low confining pressure conditions.
hybrid fibersrecycled concretehigh temperaturedestruction criteriaconstitutive model
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