The Material Constitutive Subroutine Development Of ECC Based On Fiber Beam Element And Nonlinear Analysis Of R/ECC Structure

Engineered Cementitious Composites(ECC)is a kind of high ductility,high toughness and fine crack characteristics of fiber reinforced cement matrix composites.For the new material ECC,its tensile/compression/bending properties have been studied at home and abroad,and most of them are studied in the form of members.The means of scientific research are not only limited to experimental research,numerical analysis is important also.According to the characteristics of fiber beam element,it can be seen that the main factor affecting the calculation accuracy is the accuracy of the material constitutive relation model used in the numerical model.Therefore,this paper takes ABAQUS,a large universal finite element software,as the platform to develop ECC,concrete and steel constitutive user material subroutine(UMAT)based on fiber beam element.First,the user material subroutine is tested to determine the constitutive model within the subroutine as the target constitutive.The developed ECC material constitutive subroutine is verified at the material level based on the existing material compression and tensile hysteretic tests,and the numerical simulation results are in good agreement with the test results.The R/ECC composite beam bearing capacity test,the ECC beam hysteretic test,the ECC column hysteretic test and the R/ECC composite edge joint seismic performance test were selected for component level verification,whose results show that the developed subroutine can well simulate the mechanical properties of R/ECC composite components.The shaking table test of R/ECC composite frame is selected to verify the structure hierarchy.The verification shows that the user material subroutine developed in this paper can reflect the dynamic characteristics of R/ECC composite frame structure.In order to study the seismic performance of R/ECC composite frame further,a 3D 6-storey concrete frame is designed,and the R/ECC composite frame is formed by replacing the bottom beam-column joints of the designed concrete frame with ECC material.The FEM software ABAQUS and the user material subroutine developed were used to build the 6-storey concrete frame and R/ECC composite frame.Appropriate seismic waves are selected according to the basic design information,and the incremental dynamic analysis method widely used in structural nonlinear analysis is adopted.The seismic performance of concrete frame and R/ECC composite frame is compared and analyzed by using the incremental dynamic analysis method.The analysis results show that R/ECC composite frame has better seismic performance than ordinary concrete frame.