The Temperature Stress Of Square Concrete-Filled Steel Under The Condition Of Fire Fireld

Fire is the most frequently occurred in various disasters and destructive, one of the disaster caused by the direct economic loss after dry, and its early and flood disaster occurred in the frequency of. Especially in recent years, due to the high buildings and large scale models, and use of the fire, fire scale and the increasing of building fire prevention as building a branch, more and more people pay attention to fire, seek the new building structure strong ability has become increasingly important.Concrete filled steel tubular (CFST)structure is between steel and concrete structure is a new kind of structure. It USES steel and concrete two materials in mechanical process, two inter-constraint for their faults, give full play to the advantages of both. This structure not only has excellent mechanical properties, and has good fireproof performance.Oondition in high temperature (fire) under the action of bearing capacity, with the temperature rise. According to concrete filled steel fire under the action of mechanical properties and temperature stress are analyzed in theory. Specific for the following aspects:(1) Summed up research findings on thermal properties and mechanics of steel and concrete under high temperature inside and outside of country.Based on it, the thermal properties and heat mechanics of steel and core concrete that composed conerete filled circular steel tubular colunuls are given.And stress-strain relation models of stell and core concrete are established.The interaction between steel and core concrete is taken into account sufficiently by these models.(2) This article establish finite element model for solving temperature field of concrete filled steel tubular structure, the model analysis theory is well in line with experimental results. First, using the indirect method of thermal analysis to simulate the temperature field of steel square tubular column with the outside temperature changes and taking temperature field as a body load re-loaded into the structure, then making structural analysis, the author simulates temperature stress, strain and displacement vector diagram and nephogram under different temperature and their variation characteristics in the fire and by fire characteristics.(3) The article identifies the theoretical analysis model of concrete filled steel tubular columns'fire resistance characteristics and analyzes the fire resistance limits of concrete filled square steel tubular column and the parameters affecting the fire resistance limits. In this paper, the author used finite element program ANSYS to simulate the temperature field of three-dimensional steel concrete columns under four uniform fire, and through structural analysis further obtained thermal stress, strain and displacement changes of concrete filled square steel tube, and created certain conditions for the further use of ANSYS in-depth understanding the mechanical properties and fire resistance limits of concrete filled steel tubular columns under high temperature.