Circular Steel High Temperature Self-compacting Concrete Column Fire Resistance

Due to the reciprocities between steel tube and core concrete, the concrete-filled steel tubes are applied widely. Presently the reseach on the concrete-filled steel tubes under high temperature mostly concentrates on the ordinary concrete-filled steel tubes. However, the research on the self-compacting concrete-filled steel tubes has seldom been investigated. This paper carried out a set of academic analysis and research aimed at the fire resistance of self-compacting concrete-filled circular steel tubular columns under fire. The main content as follows:(1) On the basisi of the thermal properties of steel and concrete under high temperature, the calculation methods of temperature are discussed. ANSYS is applied to calculate the temperature field on the steel surface of concrete-filled steel tubes with safeguard, and the theoretical results fit with those of tests satisfactorily.(2) Eleven large-scale Self-compacting concrete-filled circular steel tubular columns were tested for the fire resisitance, the measure content including: the temperature on surface of steel, the relations of axial deformation and time, and the relations of deflection and time. And the influence of many factors on the ultimate strength, axial deformation and deflection of self-compacting concrete-filled steel tubular columns is analyzed. It includesthe steel ratio, the load eccentricity ratio, ratio of axial compressive force and the fire protection thickness.(3) Bassis on the heat mechanics and the heat-force constitutive relations of steel and ordinary concrete, ANSYS is applied to calculate the relations of axial deformation and time, and the relations of deflection and time. And the theoretical results are compared wiht the test results of self-compacting concrete-filled circular steel tubular columns.(4) Based on the ANSYS model, the influence of many factors on the ultimate strength is analyzed. It includesthe steel ratio, the load eccentricity ratio, ratio of axial compressive force and the fire protection thickness.