Analysis Of Mechanical Behavior Of Cross-shape Concrete-filled Steel Columns Under High Temperature

With the continuous progress and development of science and technology,engineering technology in the field of new technologies and new structures have also been more and more attention,concrete-filled steel structure is one of them.The concrete-filled steel structure is composed of both steel and concrete.It not only has the excellent compressive performance of concrete,but also has good plasticity and toughness of steel,especially the combination effect of the combination effect,which makes the related performance of its structure resulting in a plus one greater than two effects All kinds of factors together contributed to the large-scale use of concrete-filled steel columns structure in the actual project,and with the rising house prices and people to improve the living environment requirements,concrete-filled steel columns with special-shaped structure because of high space utilization,saving resources and other advantages widely accepted.At the same time,due to the continuous development of the city,the population density in urban construction increases,people's living environment safety performance requirements are increasingly strong,reduce the fire caused by casualties and property damage,the building structure of the fire resistance research to be more and more urgent.Therefore,the research on the fire resistance of concrete-filled steel columns has become one of the hotspots of scientific and technical personnel.In this paper,the following research is carried out on the fire resistance of special-shaped concrete-filled steel columns under high temperature fire environment:1.The theoretical calculation method and the corresponding steps of the axial bearing ultimate bearing capacity of cross-shaped concrete-filled steel columns under high temperature are summarized.The calculation method of ultimate bearing capacity of axial compression is mainly to calculate the bearing capacity at room temperature,and then calculate the influence coefficient of bearing capacity at high temperature.The product of both is the ultimate bearing capacity at high temperature.The calculation method is mainly section division method,equivalent area method,cross section superposition method and continuous multiplication method.The article compares the different calculation methods by establishing the relevant model.2.The finite element numerical analysis method is used to analyze the stress characteristics of concrete-filled steel tubular cross-shaped columns and the accuracy of the theoretical calculation methods.The results show that the concrete-filled steel tubularcolumns are destroyed at the height of 3/5.And the theoretical calculation method needs to be further improved;3.The reinforcement methods of concrete-filled steel columns and the reinforcement methods of under high-temperature damage are summarized.The two methods of FRP reinforced concrete-filled steel tubular columns are compared.The results show that: Tao Zhong 's calculation method is more accurate;4.The experimental method of mechanical properties of concrete-filled steel columns under high temperature is discussed.The corresponding experimental scheme is put forward under the fire experiment platform of Anhui Jianzhu University,which provides the experimental basis for the follow-up study.