Research On Two-dimensional Stochastic Modeling Methods Of Hybrid Fiber Reinforced Concrete

Fiber reinforced concrete(FRC) is increasingly used in thepractical engineering.Hybrid fiber reinforced concrete (HFRC)with certain fiber dosage proportioncangive full play to the synergistic effect of each phase, and can improvethe strengthand toughness of FRC more effectively. At present,researches about the strength andtoughness enhancement mechanism and failure mechanism of HFRC are mostlybased on the macroscopic experimental tests which could not really reflect themulti-phases and heterogeneity in this material.Meso-mechanicalnumericalsimulation of HFRC, which is an efficient method to study this composite,can capture the heterogeneity and randomness in material and facilitate to evade theinfluences resulted from human or environment in macroscopic experimental tests.Hence, one of the most important subjectsin HFRC’s meso-mechanical numericalsimulation is to build a numerical calculationmodel which could really reflect themesoscopic structure of HFRC to the utmost extent and consider the capacity ofexisting computer and general finite element software simultaneously.In view of the mesoscale, on the one hand,this paper obtainedconcretegeometric models and HFRC geometric modelswhich wererandomly generated bycomputer.On the other hand, it gainedgeometric models of actual concrete and actualsteel fiber reinforced concrete (SFRC)based on digital image processing technique(DIP). Finally, two-dimensional finite element models of FRC were built base ongeometric modelsabove-mentioned.This articlemain accomplished five aspects:1) By means of summarizing andimproving the traditional algorithm of two-dimensional concreteaggregates,two-dimensional full-graded aggregate random generation anddistributionwere proposed with three different shapes of circle, ellipse and convexpolygon.2) Algorithm of intersection judgment between steel fibers and3kinds ofaggregates, and algorithm of intersection judgment between polypropylene fiber and3kinds of aggregates were presented, which realized two-dimensional randomgeneration and distribution of SFRC, polypropylene fiber reinforced concrete (PFRC)and steel-polypropylene hybrid fiber reinforced concrete (SPHFRC).3) According to the former algorithms, a user-friendly interactive CONCRETE/FRC programwasachieved.4) DIP was utilized to acquire the geometric information about aggregates,fibers and voids in the cross-section diagrams of concrete and SFRC.5) Based onthe two geometric models (one was randomly generated by computer, the other wasobtained by DIP), finite mesh generations were presentedtentatively.The two-dimensional numerical modelingapproach of HFRC which is presentedin this study, lays a foundation of carrying out the meso-mechanical numericalsimulation of HFRC and exploring the relationship between mesostructureandphysical and mechanical performances of HFRC in macro scale.