Numerical Simulation On Dynamic Behavior Of Ultra High Toughness Cementitious Composites

With the increasing requirements for structural reliability,recent years have seen more attention paid to the influence of impact loads on building structures.Therefore,it is significantly important to study the dynamic mechanical properties of building materials.At the meantime,with the development of computer technology,finite element software has been popularly applied to simulate the dynamic mechanical properties of concrete materials.Numerical simulation can not only better understand the dynamic behaviors of materials but also effectively reduce the cost of scientific research and improve its efficiency.This paper investigates the dynamic behavior of PVA fiber reinforced ultra high toughness cementitious composites(PVA-UHTCC)using Split Hopkinson Pressure Bar(SHPB)test simulation based on HJC constitutive model at LS-DYNA software.The main contents and conclusion of this paper are as follows:(1)Parameters of HJC constitutive model are innovatively classified into three categories and determined separately through systematical analysis.(2)Numerical simulation of PVA-UHTCC on its dynamic compressive behavior is conducted under 5 different applied velocities(2.0m/s,4.5m/s,6.3m/s,7.6m/s and 9.4m/s respectively).The results show that compressive stress-strain curves,peak stress,peak strain and ultimate strain are all influenced by strain rates.Among them,Dynamic Increase Factor(DIF)of peak stress shows different strain-rate sensitivity in different strain rates.Furthermore,compressive failure patterns of specimen are proved to be related to strain rates,which shows high coincidence with experiments.(3)Besides,numerical simulation of SHPB spalling test for PVA-UHTCC is also performed.The research indicates that spalling strength is associated with strain rates,compressive damage as well as fiber characteristics.In addition,the propagation laws of peak values of stress waves are related to impact velocities.By analyzing facture signals of velocity waveforms at the free end of the specimen,its damage evolution is studied.Finally,the spalling failure processes and patterns of the PVA-UHTCC specimen at different impact velocities are analyzed to better understand the spalling behavior of PVA-UHTCC.