Research On Dynamic Damage Constitutive Model Of Steel Fiber Reinforced Concrete

Nowadays,terrorist attacks on important buildings by terrorist organizations are increasingly frequent in the world,the terrorist bombing atteacks are one after another in the world,the protection problems of important buildings are becoming more and more prominent.Steel fiber reinforced concrete(SFRC)is widely used in all kind of protective structures due to its excellent ductility,toughness and energy absorption capacity.In order to realize the rational design of SFRC structure,the dynamic response of SFRC structure under impact or blast load should be further studied.Constitutive model is a comprehensive macroscopic reaction of the basic mechanical properties of concrete,and it is also an important basis for studying the dynamic response of concrete structures,especially when analyzing the failure mechanism and essence of the component,it is the essential foundation.At present,the research on the constitutive model of SFRC is weak,and there are few mature and recognized results,it is necessany to further study and establish the dynamic damage constitutive model of SFRC.This paper mainly carries out the following research:(1)The background and research significance of dynamic damage constitutive model of SFRC are expounded.The research progress of constitutive model of concrete at home and abroad is introduced.(2)The commonly used dynamic damage constitutive models(HJC,RHT,K&C)of LS-DYNA are introduced,through the numerical simulation test of uniaxial tension,uniaxial compression and triaxial tension of a single element model,the ability of each model to predit SFRC dynamic response is evaluated.(3)K&C model is improved: based on 96 groups data of triaxial compression experimental,the influence of steel fiber volume fraction on triaxial strength was considered,and the failure strength surface parameter model of SFRC was established;a new damage evolution model was established by trial-and-error method,and the damage parameters of tensile and compressive were calibrated;based on 122 groups data of uniaxial compression experimental of SFRC under high strain rate,the influence of steel fiber content on the cmopression dynamic increase factor value and transition strain rate was considered,and the dynamic increase factor model of SFRC under pressure was established.(4)The dynamic response of SFRC plate is simulated by LS-DYNA explicit dynamic analysis software.The simulation results demonstrated the effectiveness and reliability of the modified K&C model.