Development Of Steel And Masonry Material User Subroutine Based On ABAQUS/Explicit

Masonry that consists of units and mortar has the advantages that the material is easy to obtain,cheap price,and convenient construction, so the masonry structure has been used widely today. To meet the seismic requirement, the masonry wall has been changed into the reinforced masonry(RM) wall. Large parts of wall structures are masonry walls. Simulation study for nonlinear analysis of URM wall and RM wall under seismic loads becomes the key point for safety assessment during earthquake. Material constitutive plays an important role in the simulation study of masonry structure under earthquake. Due to the good interactive means and powerful nonlinear analysis ability, the general finite element program ABAQUS has been widely used in wall analysis. However, the application of ABAQUS is limited in wall analysis because there is no suitable material constitutive of masonry and constitutive model of steel cannot consider the degradation of stiffness. An effective and practical constitutive model is chosen for masonry material, which takes no account of three stresses in plane stress elements, so only the relationship between normal stress and normal strain and the relationship between shear stress and shear strain relation should be considered. A good steel model is selected which fits the experimental result well. Both masonry material subroutine and steel material subroutine are developed based on the second developed platform provided by ABAQUS. The developed user subroutines are verified by the element level test. Then the user subroutine is used for URM wall and RM wall,which gives satisfactory results compared with the experiment. The research contents as following:(1) The selected steel model can reflect the degradation of stiffness, which takes into account the Bauschinger effect. The stress-strain relation obtained by using steel subroutine model the beam under cyclic uniaxial loads consists with this model.(2) The normal stress and normal strain relation equation fitted from Liu Lipeng with experimental results is selected as the compression envelope, and the hysteretic rule proposed by Crisafulli is selected, which has high precision and practicability. The stress strain relation proposed by Lucia Karapitta is used as the shear stress and shear strain relation,and the hysteretic rule has been modified, which makes it applicable. Verified the correctness of masonry subroutine using the method in(1) described above.(3) The simulation studies about two URM walls and four RM walls are performed with the developed subroutine under reciprocating load, the simulation result is well consistent with the experimental result, which can reveal the characteristics of flexural failure and shear failure of the URM walls and RM walls.