Experimental Study On Strain Localization Of Concrete Structures And Software Development Of Finite Element Post-processing

Plasticity and damage problems need to be settled urgently for large concrete projects such as high dams, nuclear power station, highway and military works. Four aspects were done about the problem of plasticity and damage analysis for concrete materials and structures.(1) The digital speckle correlation method (DSCM) was used to study on the destruct phenomena of concrete beams with single-edge notched and double-edge notched under which are in the different boundary conditions, loaded with four-point-shear force. The deformation localizability phenomena are observed, the results shows that the influence of boundary conditions to the test is important. So the contact between specimen and supports should be treated well.(2) Numerical simulations were done on evolution of damage process zone of concrete structures, and the size and evolution of damage process zone were studied. The geometrical model adopted is four-point-shearing beam, and Abaqus/Explicit software was taken as the numerical tool.(3) With FORTRAN language, the software was developed on the basis of AutoCAD plat form. With this software, mesh and numerical results obtained from a Finite Element Analysis can be converted into DXF file at AutoCAD environment. Consequently visualization of results of Finite Element Analysis can be realized. Numerical results of 2-dimensional elastoplastic finite element analysis of an oil well were taken as examples for validation purpose of the software developed here. Mesh and deformed mesh along with stress distribution were visualized. (4) New damage model coupled with plasticity for concrete has been implemented into Abaqus via UMAT subroutine for concrete. The new damage model has property of triaxiality dependent hardening. Numerical results of damage fields obtained with the new implemented model have been exported to the ODB file which is the storage file of numerical results prepared for postprocess via UVARM subroutine. FORTRAN language was used. Validation of the UMAT subroutine developed here was carried out with an example of one-element cubic block under uniaxial compression and an example of a simple-supported beam under concentrated force in the middle of the beam. Numerical results indicate that the UMAT subroutine developed here has improved the ability of Abaqus software in simulating the plastic damage behavior of concrete.