Elastic-Plastic Analysis Of A Beam With One Degree Of Indeterminacy Under High Temperature

The steel structure has been widely used in civil engineering because of its advantages,such as high strength, light wight, good plasticity and toughness, high earthquake resistance and high reliability. However its poor performance of fire resistance which can not be ignored.As the temperature of the steel rising, the property index of material and mechanical will have significant change, especially its mechanical property index. The occurrence of the fire will significantly decrease the bearing capacity of the structure, which make the whole building collapse and lead to a great number of economic loss and casualties. So the research on the fire resistance of the steel structure and how to improve the fire resistance of the steel structure are important contents in steel structures application. Based on the research results at home and aboard,this paper analyses the stress and deformation of a steel beam with one degree of indeterminacy under high temperature. The main works are summarized as follows:(1) This paper mainly introduces International Standardization Organization(ISO)time-temperature curve, and on this basis a brief description and summary of the practical calculation method on the steel members under high temperature and the changing rules of material property and mechanical property of steel structure under high temperature at home and aboard are given; By comparison and analysis of the calculation formula to select which one is much more suitable for this paper.(2) This paper introduces the calculating method of internal force and deformation of steel structure under high temperature by considering the property index of material and mechanical. The elastic-plastic process of the beam with one degree of indeterminacy under high temperature is deduced in this paper.(3) Combining with the examples to discuss the change process of ultimate uniform load ,mid-span ultimate deflection and end reaction under different temperature on the steel beams with different cross section forms.(4) Through ANSYS finite element software to analyze the temperature field and static of the steel beams under high temperatures. The steel beams have different cross section forms and the same connecting format which is one end hinged and the other end fixed,and compared the results of simulation with theoretical calculation.