Papers by Author: Fa Xing Ding

Abstract: Based on appropriate numerical constitutive model of lightweight aggregate concrete filled steel tubes (LCFST), layered method was adopted to predict the complete moment-curvature curves of LCFST composite section subjected to pure bending. A FORTRAN program for the moment-curvature curves was developed. Applying the layered method, the influences of the significant parameters, such as steel ratio, yield strength of steel and strength of lightweight aggregate concrete on the moment-curvature curves of the composite section subjected to pure bending were discussed. The practical composite flexural stiffness, ultimate moment and practical moment- curvature relationship of LCFST composite section were presented. The predicted results of both layered method and practical moment-curvature relationships of LCFST composite section are in good agreement with the test results from reference. Compared with the layered method, practical calculate method could remove the step of composite section layered and improve the calculation speed while achieving similar results.

Abstract: Based on the research achievements of the mechanical properties of concrete at uniaxial compression and steel at uniaxial tension after exposed to high temperatures, the axisymmetric- triaxial-compressive stress-strain relationships of concrete and multiaxial stress-strain relationships of steel after exposed to high temperatures was suggested. Based on continuum mechanics, the mechanical model of concentric cylinders of circular steel tube with concrete core of entire section loaded after exposed to high temperature was determined. By applying Elasto-Plastic Analysis Method, theoretical calculation formulas for composite elastic modulus and composite stress-strain relationships of concrete-filled circular steel tubular (CFST) stub columns were proposed and a FORTRAN program was developed and the load-axial strain relationships of CFST stub columns after exposed to high temperatures were analyzed. The analysis results were in reasonable agreement with the experiment ones from references.